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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: nscaleworld on July 03, 2012, 04:48:42 AM
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I have an Amiga 3000T that has a couple of problems. First, I can not boot from any disk unless I first hold down both mouse buttons and then turn cpu cach off. Only after turning off the cpu cach will the Amiga 3000T boot from a disk. Second, I can not get the computer to recognize any SCSI hard drive. I can load up HDTools and low level format, partition, and verify a hard drive, but after I reboot, the hard drive does not show up in Workbench 3.1. The harddrive does not even show up in the list on the WB 3.1 Install disk.
Here are the specs of my Amiga 3000T:
030 processor on motherboard
2 megs chip memory
16 megs fast memory
Rev 08 WD SCSI chip
Kickstart 3.1 roms
880K Amiga 3000 disk drive (DF0)
1.76 MB Amiga 3000 disk drive (DF1)
Newer Ramsey and Demac chips
I am really scratching my head on this problem.
PS: Battery was removed and the motherboard is clean, almost new.
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Hey buddy are you going to ridicule people trying to help you here like @ eab? Are you going to put the batt in to make scsi work? :)
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I think its beyond hope - you should send it to me for a reasonable price.
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Have you changed the caps on the motherboard? I remember I had a similar issue with a 4000D and some caps needed to be replaced along with an IC.
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Well he doesnt believe me that the A3000T SCSI NVRam settings are stored on the batt. He doesnt have one installed. This could be a solution.
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Well he doesnt believe me that the A3000T SCSI NVRam settings are stored on the batt. He doesnt have one installed. This could be a solution.
No it isn't. NVRAM setting are only needed if you use a slow spin up SCSI drive on COLD boot (a reset will help), a CD changer that uses LUN ID's or if you ignorantly use a SCSI ID 7 for a device and need to set a different ID for your controller.
Any 3000(T) will work perfectly fine with default settings in 99.997% of the cases.
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Have you changed the caps on the motherboard? I remember I had a similar issue with a 4000D and some caps needed to be replaced along with an IC.
The caps on the Amiga 4000 are smt, the caps on the Amiga 3000T are higher quality thru-hole. I will be replacing all of the caps with new Nichicon caps from Japan.
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So, again, here are the problems:
Amiga 3000T will not boot an 880k disk unless I first disable cpu cach.
Amiga 3000T will not recognize a hard drive after reboot.
Do any of you know what the default jumper settings are for an Amiga 3000T with onboard 68030, I need the default for all of the jumpers on the motherboard.
Thank you.
Oh, and as far as the battery is concerned, I know that Amiga computers work just fine without a battery, but, I do plan on installing a CR2032 battery holder and diode, because I plan to install Workbench 3.9 and I want the correct date and time displayed. Do any of you know what diode I should use? Will a 1N4001 diode work?
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So, again, here are the problems:
Amiga 3000T will not boot an 880k disk unless I first disable cpu cach.
Amiga 3000T will not recognize a hard drive after reboot.
Do any of you know what the default jumper settings are for an Amiga 3000T with onboard 68030, I need the default for all of the jumpers on the motherboard.
Thank you.
Oh, and as far as the battery is concerned, I know that Amiga computers work just fine without a battery, but, I do plan on installing a CR2032 battery holder and diode, because I plan to install Workbench 3.9 and I want the correct date and time displayed. Do any of you know what diode I should use? Will a 1N4001 diode work?
http://www.l8r.net/technical/t-3000-jumpers.shtml
Spend some time on Google, there's a lot out there...
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...another thought, check your SCSI termination. I believe there are, or should term resistors on the motherboard (but I haven't seen a A3000 in years).
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http://www.l8r.net/technical/t-3000-jumpers.shtml
Spend some time on Google, there's a lot out there...
This information, as far as the jumpers, is basicly useless, because it does not tell you what the working default set by Commodore is. What I really need is for someone that has an Amiga 3000T, that they have never messed with the jumpers, to pull the cover off and write down what the jumper settings are for all of the jumpers. Or take a few pictures of the jumpers, showing how they were setup by Commodore. This would help a lot.
Also, why would 880k disks refuse to boot unless you first hold down both mouse buttons and turn off cpu cashe? I have never seen this problem on any Amiga computer. It's got me scratching my head trying to figure it out.
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...another thought, check your SCSI termination. I believe there are, or should term resistors on the motherboard (but I haven't seen a A3000 in years).
I only have the one 249 mb Seagate hard drive installed. It is terminated and is set for SCSI ID 0. The terminator resistor packs on the motherboard were removed and a Commodore terminator is plugged into the 25-pin SCSI port. I tried 3 different SCSI ribbon cables, does not fix problem with hard drive not showing up in Workbench 3.1. The ribbon cables are about 6 FEET long. I wonder if they are too long.
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The CPU Cache thing makes you wonder if the CPU itself is 100%. Do you have a 3640 to test with?
Also, what Kick 3.1 are you using? Original or burned? Do you have a set of 2.04 ROM's to use?
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The CPU Cache thing makes you wonder if the CPU itself is 100%. Do you have a 3640 to test with?
Also, what Kick 3.1 are you using? Original or burned? Do you have a set of 2.04 ROM's to use?
Yes, I do have an A3640 board, but, it is a revision 3.0.
The Kiskstart 3.1 roms appear to be original, but, I am not sure. How can you tell if they are burned (copies)?
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Well he doesnt believe me that the A3000T SCSI NVRam settings are stored on the batt. He doesnt have one installed. This could be a solution.
Well, I don't believe you either. C'mon, stored on the batt? That Amiga 3000T used a standard -for the time- rechargeable "barrel" battery. It has no circuitry for anything like NVRam.
Now, if you mean powers the NVRam, sure, but that is entirely different.
-P
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Ok, I poached this from another A3000T thread going on at Amibay, this looks like the default jumpers but I can't guarantee the source -:
The jumpers back to factory for the CPU, for the onboard 030:
J100 1-2
J102 2-3
J103 3-4
J104 1-2
J105 ALL OPEN
J106 ALL OPEN
J107 ALL OPEN
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Ok, I poached this from another A3000T thread going on at Amibay, this looks like the default jumpers but I can't guarantee the source -:
The jumpers back to factory for the CPU, for the onboard 030:
J100 1-2
J102 2-3
J103 3-4
J104 1-2
J105 ALL OPEN
J106 ALL OPEN
J107 ALL OPEN
Thank you so much, I will try these.
I am wondering if it would be wise to install a PPC board in my Amiga 3000T? I have a GVP video card.
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I tried 3 different SCSI ribbon cables, does not fix problem with hard drive not showing up in Workbench 3.1. The ribbon cables are about 6 FEET long. I wonder if they are too long.
6 feet long?! That's way too long. That causes errors, and data loss may occur.
Try shorter cables of 10" - 15" inch max.
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So, again, here are the problems:
Amiga 3000T will not boot an 880k disk unless I first disable cpu cach.
Amiga 3000T will not recognize a hard drive after reboot.
Do any of you know what the default jumper settings are for an Amiga 3000T with onboard 68030, I need the default for all of the jumpers on the motherboard.
Thank you.
Oh, and as far as the battery is concerned, I know that Amiga computers work just fine without a battery, but, I do plan on installing a CR2032 battery holder and diode, because I plan to install Workbench 3.9 and I want the correct date and time displayed. Do any of you know what diode I should use? Will a 1N4001 diode work?
Here are the 3000T jumper settings
060
100 3-4
102 1-2
104 1-2
103 2-3
040
100 3-4
102 2-3
104 2-3
103 1-2
030
100 1-2
102 2-3
104 1-2
103 2-3
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The Diode for the CR2032 Battery is preferred as a 1N914 although the 1N4001 should work the both have the same VF Characteristics, although the IN914 is the recommended item according to some of the Amiga battery hack files.
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Check the chips inside your Amiga 3000 computer. Most of them did NOT have the military-rated versions as supplied by Commodore only to the government. If this is the case, you are wasting your time. Throw that POS in the dumpster where it belongs, and get yourself an Amiga 2000 computer. Connect it to your stereo, load up a sh!tty Amiga game of your choice, and enjoy. Just don't forget to TURN UP THE VOLUME!
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To get something a little more constructive in this thread:
The 'does not boot unless cache turned off' problem may be due to mismatched ZIP RAMs. When the first bank consists entirely of static column (SC) chips Ramsey's burst mode is turned on - but it will only be used for filling the cache.
A problem arises when the rest of the RAMs are not 100% SC (xx4402) but fast page (FP xx4400) - the burst will not work and the machine will crash.
Check if ALL chips are SC and if they're mixed move one of the FP chips to the left frontmost socket.
As to SCSI cable length (http://en.wikipedia.org/wiki/SCSI#Parallel_SCSI): we're talking SCSI-1 here, so the cable may be up to 6m (nearly 20'). I'd stay below 3m (for Fast SCSI) to make sure.
Double and triple check termination, some A3ks have misprinted socket labels, so terminator (resistor) packs installed 'correctly' may not work. The 220 Ohm side must go to termpower (5V), the 330 Ohm side to GND. Check whether termpower reads 5V (or close to), the fuse may be blown. If you have the chance try cable terminators, preferably active ones. Most have a LED to show whether termpower is on.
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Check the chips inside your Amiga 3000 computer. Most of them did NOT have the military-rated versions as supplied by Commodore only to the government. If this is the case, you are wasting your time. Throw that POS in the dumpster where it belongs, and get yourself an Amiga 2000 computer. Connect it to your stereo, load up a sh!tty Amiga game of your choice, and enjoy. Just don't forget to TURN UP THE VOLUME!
What the heck are you talking about dude? :confused:
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To get something a little more constructive in this thread:
The 'does not boot unless cache turned off' problem may be due to mismatched ZIP RAMs. When the first bank consists entirely of static column (SC) chips Ramsey's burst mode is turned on - but it will only be used for filling the cache.
A problem arises when the rest of the RAMs are not 100% SC (xx4402) but fast page (FP xx4400) - the burst will not work and the machine will crash.
Check if ALL chips are SC and if they're mixed move one of the FP chips to the left frontmost socket.
As to SCSI cable length (http://en.wikipedia.org/wiki/SCSI#Parallel_SCSI): we're talking SCSI-1 here, so the cable may be up to 6m (nearly 20'). I'd stay below 3m (for Fast SCSI) to make sure.
Double and triple check termination, some A3ks have misprinted socket labels, so terminator (resistor) packs installed 'correctly' may not work. The 220 Ohm side must go to termpower (5V), the 330 Ohm side to GND. Check whether termpower reads 5V (or close to), the fuse may be blown. If you have the chance try cable terminators, preferably active ones. Most have a LED to show whether termpower is on.
Will the zips actually have SC or FP printed on the chips? What kind of zip memory should I have installed, SC or FP? Where do I check for the 5v termpower? The termination resistor packs on the motherboard were removed so that I have the option of using the 25-pin SCSI port. Right now there is a Commodore terminator plugged in.
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Some good suggestions from Zac67 regarding the memory, certainly worth checking all of the ZIPs are the same. More information here (http://amiga.serveftp.net/A3000_HardwareGuide/memory.html).
The Diode for the CR2032 Battery is preferred as a 1N914 although the 1N4001 should work the both have the same VF Characteristics, although the IN914 is the recommended item according to some of the Amiga battery hack files.
As for the RTC backup power supply; you're far better off using a small signal Schottky diode as opposed to a standard silicon diode (e.g. 1N914, 1N4148, 1N400x, etc).
To look at the maths behind it...
From the RP5C01 datasheet (http://amiga.serveftp.net/Datasheets/RP5C01A-RealTimeClock.pdf) we can see the minimum input voltage is 2.2V at a current of 15µA. The RTC has a 1.2k Ohm resistor in series with the battery (see schematic (http://amiga.serveftp.net/images/RTC_circuit-big.jpg)). So it'll develop (1.2k x 15µA) = 18mV, or round to 20mV across it. So the actual minimum voltage at the RTC becomes (2.2V + 20mV) = 2.22V
If a 1N914 (http://www.vishay.com/docs/85622/1n914.pdf) diode was used, we can see it has a forward voltage drop of around 0.55V at 15µA. So it'll only provide a clock backup until the cell reaches a voltage of (2.22V + 0.55) = 2.77V. The CR2032 cell is 3V nominal, meaning it only has to discharge by 0.23V to a terminal voltage of 2.77V before it'll need to be replaced, so that's using well under half of the cell's capacity.
If a Schottky diode was used instead, say a common BAT85 (http://www.nxp.com/documents/data_sheet/BAT85.pdf) for example, we can see the forward voltage drop will be less than 0.24V at 15µA. So the cell can discharge further to (2.22V + 0.24) = 2.46V before it needs to be replaced. You still won't get to use the full rated capacity of the cell (230mAHr), but at a guess you'd still get about 60% of that (140mAHr). At a current draw of 15µA, I'd expect a clock backup time of 389 days or 13 months. Of course that depends on the exact cell being used, age/condition of the cell, exact current draw of the RTC on standby and the temperature.
So in summary, while the silicon diode will work, you'll get far longer out of the coin cell if you use a small signal Schottky diode.
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What the heck are you talking about dude? :confused:
It's a joke/reference to a rather insane person we had here (under numerous user IDs) several years back. He had an irrational obsession with A2000s, ceramic-housed ("mil-spec") chips, and throwing away perfectly good hardware that was suffering from minor configuration problems. Core lesson: never, ever, ever enter into any sales or repair agreements with anyone from Beaverton, Oregon.
Back on subject, I think Zac67 and Castellen are putting you on the right track, but I thought of one more thing you might try. Even though the battery has been removed, the SCSI settings can sometimes get garbled - I had a desktop 3000 suffering from this some time ago. If you can get the machine booted, get SetBatt (http://aminet.net/package/util/wb/SetBatt-1.2) on there and run it with the amnesia flag (SetBatt -a, if I recall) which should clear things up.
I think you should hold off on the PPC until you can get the stock configuration working :)
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This information, as far as the jumpers, is basicly useless, because it does not tell you what the working default set by Commodore is. What I really need is for someone that has an Amiga 3000T, that they have never messed with the jumpers, to pull the cover off and write down what the jumper settings are for all of the jumpers. Or take a few pictures of the jumpers, showing how they were setup by Commodore. This would help a lot.
Also, why would 880k disks refuse to boot unless you first hold down both mouse buttons and turn off cpu cashe? I have never seen this problem on any Amiga computer. It's got me scratching my head trying to figure it out.
I'm fairly sure the chart tells you, by revision what the jumper settings should be, but hey why bother helping?
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I'm fairly sure the chart tells you, by revision what the jumper settings should be, but hey why bother helping?
So, which set of jumpers do I use, the ones under 313181 -01,-03,-05 or the ones under 313181 -02,-04,-06 ? What the heck does that even mean?
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Will the zips actually have SC or FP printed on the chips?
No, the SCs end in 4402, the FPs in 4400.
What kind of zip memory should I have installed, SC or FP?
SC is slightly faster with an '030 but is harder to get.
Where do I check for the 5v termpower?
One of of end pins of the resistor pack sockets carries termpower (the other's GND). Also in the internal SCSI pin 26 or external pin 25.
The termination resistor packs on the motherboard were removed so that I have the option of using the 25-pin SCSI port. Right now there is a Commodore terminator plugged in.
That's a good config if termpower's working.
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Hi Anthony,
To look at the maths behind it...
From the RP5C01 datasheet (http://amiga.serveftp.net/Datasheets/RP5C01A-RealTimeClock.pdf) we can see the minimum input voltage is 2.2V at a current of 15µA. The RTC has a 1.2k Ohm resistor in series with the battery (see schematic (http://amiga.serveftp.net/images/RTC_circuit-big.jpg)). So it'll develop (1.2k x 15µA) = 18mV, or round to 20mV across it. So the actual minimum voltage at the RTC becomes (2.2V + 20mV) = 2.22V
Question - is there any harm in removing and bridging that resistor (R179), when replacing the original battery with a diode and 2032 coin? I've done this on my 2000's, by simply installing the diode (1N60 in my case) in place of the resistor (R803). Based on what you've written, it would seem the RTC battery should last quite a bit longer. Any potential issues with this?
Edit: Just pulled my 2000 from the closet, it's been sitting off for well over a year, and the battery is nearing 3 years old. I was surprised to find that it had only lost 20 minutes. Looks like the RTC on the A2000 is good all the way down to 2.0V, which helps.
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Well, I checked my stash of zip memory chips and they are indeed mixed. So, they are most likely mixed in my Amiga 3000T too. I did not know that there are 2 different types of zip memory and that you are not suppose to mix them. So, I just spent the last hour sorting thru my pile of zips. I put all of the SC in one anti-static bag, and all of the FP zips in another. So, this mixup will never happen again. Tomorrow, I will remove the Amiga 3000T motherboard from the case. Then I will remove all of the zip memory and start over. So, SC zips are best for the 030 processor?
I want to thank all of you guys for helping me. But, I will continue to need your help until I get the old girl back up and running perfectly. I think correcting the zip memory will fix the disk drive and cpu cashe problem. I am also going to install the coin battery and hopefully that will fix the problem of Workbench 3.1 not "seeing" the hard drive.
Thanks a lot, guys, you are a big help. :razz:
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Question - is there any harm in removing and bridging that resistor (R179), when replacing the original battery with a diode and 2032 coin? I've done this on my 2000's, by simply installing the diode (1N60 in my case) in place of the resistor (R803). Based on what you've written, it would seem the RTC battery should last quite a bit longer. Any potential issues with this?
The purpose of the resistor in series with the battery is to limit charging current to a safe value when a rechargeable nickel based battery is fitted. With the lithium cell + diode, the resistor serves no purpose so can be bypassed (short circuit) if you want to, although the gain in battery life in doing so will be miniscule; hardly worth the effort.
As I recall, the 1N60 is a germanium diode so should have forward voltage characteristics comparable to a Schottky diode. Can't remember the exact specs of them, but put your voltmeter across the diode. If you see any more than about 0.3V with the computer off, then you can make a worthwhile gain by replacing the 1N60 with a BAT85 or whatever.
Edit: Just pulled my 2000 from the closet, it's been sitting off for well over a year, and the battery is nearing 3 years old. I was surprised to find that it had only lost 20 minutes. Looks like the RTC on the A2000 is good all the way down to 2.0V, which helps.
The A2000, A500+, A501, etc, use a different RTC device, a Seiko/Epson MSM6242 (http://amiga.serveftp.net/Datasheets/MSM6242-RealTimeClock.pdf) which does have a lower data retention voltage of 2V as opposed to 2.2V on the Ricoh RP5C01.
Of course it depends on the device and temperature. While the minimum data retention voltage of 2.0V is the specification, in practice some devices may operate below that.
A little off topic but perhaps worth adding is the fact that the crystal oscillator on the RP5C01 and probably the MSM6242 varies in frequency slightly according to the applied voltage. I generally calibrate them for f0=32.768kHz at 3.6V (for nickel batteries). If the voltage drops much below that, the oscillator runs slightly slow. When the computer is running and the supply voltage is 5V, it runs slightly fast.
And of course as quartz crystals age, they usually drift low in frequency, so that and the lower operating voltage explains your time drift. Not to mention that those crystals aren't brilliantly accurate over wide temperature ranges.
While you can trim the crystal frequency using the trimming capacitor, you'll need a high impedance input (10M Ohm or better) scope or frequency counter to do it correctly. Any load on the oscillator circuit from the measuring equipment will change the frequency.
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Question - is there any harm in removing and bridging that resistor (R179), when replacing the original battery with a diode and 2032 coin? I've done this on my 2000's, by simply installing the diode (1N60 in my case) in place of the resistor (R803). Based on what you've written, it would seem the RTC battery should last quite a bit longer. Any potential issues with this?
Edit: Just pulled my 2000 from the closet, it's been sitting off for well over a year, and the battery is nearing 3 years old. I was surprised to find that it had only lost 20 minutes. Looks like the RTC on the A2000 is good all the way down to 2.0V, which helps.
I think it depends on the battery. The NiMH batteries that I've used seem to lose their charge after a few weeks - much quicker than the NiCd originals.
Well, I checked my stash of zip memory chips and they are indeed mixed. So, they are most likely mixed in my Amiga 3000T too. I did not know that there are 2 different types of zip memory and that you are not suppose to mix them. So, I just spent the last hour sorting thru my pile of zips. I put all of the SC in one anti-static bag, and all of the FP zips in another. So, this mixup will never happen again. Tomorrow, I will remove the Amiga 3000T motherboard from the case. Then I will remove all of the zip memory and start over. So, SC zips are best for the 030 processor?
It might be easier to pull the chips with the motherboard in the case, thus providing a strong anchor. You'll definitely want to remove the drive bridge, though, if you haven't already. Well, use your best judgement. And caution.
Also, make sure your ZIPs are all the same size. I'd guess that they are, since Workbench probably reported 16 megs, but since you had some SC/FP mixups, it doesn't hurt to check for a capacity mixup as well :)
Good luck!
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Well he doesnt believe me that the A3000T SCSI NVRam settings are stored on the batt. He doesnt have one installed. This could be a solution.
When the 3000(t) does not have a battery,it falls back to the default scsi settings, worst case it is just not set to synchronous usually. It should still work fine.
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6 feet long?! That's way too long. That causes errors, and data loss may occur.
Try shorter cables of 10" - 15" inch max.
That is absolutely wrong, where do you get this stuff. a 6ft cable is fine.
SCSI I standard specifies up to 6 METERS(over 18ft~) for cable length.
SCSI II standard specifies 3 meters which is over 9ft.
I run long cables in my 3000t's with no issues whatsoever for many years.
Besides,you would be lucky to reach anything in a 3000t with 15" cable.
If anything the revision 4 WD scsi chip is a problem child. Many times you cannot use multiple devices on this and i believe its known to have a broken scsi II command set, it can also be a source of scsi going haywire and giving errors when a A3640 is added into the mix.
Updating to the western digital rev 8 or the Amd chip solves most scsi woes on the 3000.
It might be wise to learn a bit more about scsi instead of putting out bad information on the forums that gets repeated year after year.
Mech
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Some good suggestions from Zac67 regarding the memory, certainly worth checking all of the ZIPs are the same. More information here (http://amiga.serveftp.net/A3000_HardwareGuide/memory.html).
As for the RTC backup power supply; you're far better off using a small signal Schottky diode as opposed to a standard silicon diode (e.g. 1N914, 1N4148, 1N400x, etc).
To look at the maths behind it...
From the RP5C01 datasheet (http://amiga.serveftp.net/Datasheets/RP5C01A-RealTimeClock.pdf) we can see the minimum input voltage is 2.2V at a current of 15µA. The RTC has a 1.2k Ohm resistor in series with the battery (see schematic (http://amiga.serveftp.net/images/RTC_circuit-big.jpg)). So it'll develop (1.2k x 15µA) = 18mV, or round to 20mV across it. So the actual minimum voltage at the RTC becomes (2.2V + 20mV) = 2.22V
If a 1N914 (http://www.vishay.com/docs/85622/1n914.pdf) diode was used, we can see it has a forward voltage drop of around 0.55V at 15µA. So it'll only provide a clock backup until the cell reaches a voltage of (2.22V + 0.55) = 2.77V. The CR2032 cell is 3V nominal, meaning it only has to discharge by 0.23V to a terminal voltage of 2.77V before it'll need to be replaced, so that's using well under half of the cell's capacity.
If a Schottky diode was used instead, say a common BAT85 (http://www.nxp.com/documents/data_sheet/BAT85.pdf) for example, we can see the forward voltage drop will be less than 0.24V at 15µA. So the cell can discharge further to (2.22V + 0.24) = 2.46V before it needs to be replaced. You still won't get to use the full rated capacity of the cell (230mAHr), but at a guess you'd still get about 60% of that (140mAHr). At a current draw of 15µA, I'd expect a clock backup time of 389 days or 13 months. Of course that depends on the exact cell being used, age/condition of the cell, exact current draw of the RTC on standby and the temperature.
So in summary, while the silicon diode will work, you'll get far longer out of the coin cell if you use a small signal Schottky diode.
May i also add the LIR2032 3.6v lithium is a direct replacement for the cr2032 coin cell and is rechargeable,but should NOT be recharged by the amiga,Use the diode as you normally would.Because it starts at 3.6v you will also buy some time before its dead. They make external wall chargers to recharge these coin cells.
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I think it depends on the battery. The NiMH batteries that I've used seem to lose their charge after a few weeks - much quicker than the NiCd originals.
That may be the case with cells optimized for high capacity - self-discharge is ridiculously high. Use long retention cells instead and you're set.
I've got a barrel type NiMH (cheap GP 80 mAh) in my 3k and it lasts ~6 months.
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The purpose of the resistor in series with the battery is to limit charging current to a safe value when a rechargeable nickel based battery is fitted. With the lithium cell + diode, the resistor serves no purpose so can be bypassed (short circuit) if you want to, although the gain in battery life in doing so will be miniscule; hardly worth the effort.
As I recall, the 1N60 is a germanium diode so should have forward voltage characteristics comparable to a Schottky diode. Can't remember the exact specs of them, but put your voltmeter across the diode. If you see any more than about 0.3V with the computer off, then you can make a worthwhile gain by replacing the 1N60 with a BAT85 or whatever.
The A2000, A500+, A501, etc, use a different RTC device, a Seiko/Epson MSM6242 (http://amiga.serveftp.net/Datasheets/MSM6242-RealTimeClock.pdf) which does have a lower data retention voltage of 2V as opposed to 2.2V on the Ricoh RP5C01.
Of course it depends on the device and temperature. While the minimum data retention voltage of 2.0V is the specification, in practice some devices may operate below that.
A little off topic but perhaps worth adding is the fact that the crystal oscillator on the RP5C01 and probably the MSM6242 varies in frequency slightly according to the applied voltage. I generally calibrate them for f0=32.768kHz at 3.6V (for nickel batteries). If the voltage drops much below that, the oscillator runs slightly slow. When the computer is running and the supply voltage is 5V, it runs slightly fast.
And of course as quartz crystals age, they usually drift low in frequency, so that and the lower operating voltage explains your time drift. Not to mention that those crystals aren't brilliantly accurate over wide temperature ranges.
While you can trim the crystal frequency using the trimming capacitor, you'll need a high impedance input (10M Ohm or better) scope or frequency counter to do it correctly. Any load on the oscillator circuit from the measuring equipment will change the frequency.
Many thanks for the thoughtful reply. Measuring a 0.3V drop here, and 3.05V total on the anode side - looks like it'll go a few more years yet, with the potential to do a bit better with a Schottky.
This is probably obvious, but it's worth mentioning I've had great luck with the Renata (or anything made in Japan) 2032's. The Chinese ones die quickly.
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I'm confused, is this an A3640 problem (i.e., data cache) or a SCSI controller issue? I think the battery is well covered. I'm guessing that trying another SCSI controller would help sort out the boot problem
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That is absolutely wrong, where do you get this stuff. a 6ft cable is fine.
He he... I was mistaken with IDE. Guess I had drunk too much that night. LOL! :razz: :pint: :crazy:
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Mechy you are right about the rev 4 scsi chip and multiple devices but in this case, I doubt this is the cause of the problems.
And yes 6ft cables are fine for scsi usages as you said :)
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Oh and mechy, your post counter is the number of the beast 666. Post a reply or something quickly, before bad things might happen with you... :nervous:
:razz:
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Oh and mechy, your post counter is the number of the beast 666. Post a reply or something quickly, before bad things might happen with you... :nervous:
:razz:
Something bad happened, he's still at that number as we speak!
I found the A3000T to be really nit-picky on jumpers, memory and hard drives. Other than that, when you have it up and running it is the most awesome of all ;-)
It took me some time to get the jumpers right, and not all given settings on the net are right. Also, check if your ZIPs are seated correctly, I've seen them wriggling out over the years. Could also be some ZIP chips are dying, maybe you can take them out easily and run with memory on a different card?
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Oh and mechy, your post counter is the number of the beast 666. Post a reply or something quickly, before bad things might happen with you... :nervous:
:razz:
BOO! hehehe :angryfire:
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Many thanks for the thoughtful reply. Measuring a 0.3V drop here, and 3.05V total on the anode side - looks like it'll go a few more years yet, with the potential to do a bit better with a Schottky.
This is probably obvious, but it's worth mentioning I've had great luck with the Renata (or anything made in Japan) 2032's. The Chinese ones die quickly.
No problem with original sony coin cells here, i guess the people having capacity problems are buying those cheap china cells.
Also if there is a bad diode in the circuit or left over leakage from a bad battery that was not cleaned well and can be conductive in some cases.
it can drain the batteries prematurely.
Mech
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Dude, why waste your time trying to fix that POS computer? Everyone knows that the best computer is the Amiga 2000. (The great Doom Master even thinks so!) It's a work horse and never has issues like this! :)
My A3000T is also not working. I think it has a flakey CPU slot on it. It's just a big hunk of metal right now. Dead as a doornail. I have to open it up every so often and reset the CPU card on it to get it to work. Never have this problem with my Amiga 2000's...
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Dude, why waste your time trying to fix that POS computer? Everyone knows that the best computer is the Amiga 2000. (The great Doom Master even thinks so!) It's a work horse and never has issues like this! :)
My A3000T is also not working. I think it has a flakey CPU slot on it. It's just a big hunk of metal right now. Dead as a doornail. I have to open it up every so often and reset the CPU card on it to get it to work. Never have this problem with my Amiga 2000's...
This is the reason why I am using the onboard 68030 chip. I will be sorting out the zip memory problem and I will install a CR2032 coin battery. I will let you guys know how this turns out. Even though the Amiga 2000 is more stable, I think that the Amiga 3000T is an absolutly beautiful computer, and I always wanted one. I plan to install a PPC board and Amiga OS 4.0 I already have a GVP graphics board and a network board.
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Make sure that the threaded standoffs that are used to secure the processor board in the Amiga 3000T computers cpu slot are the correct size. If the standoffs are the wrong size you will have problems with the cpu slot. You can not just plug in the processor board. It must also be screwed to the aluminum standoffs, and the standoffs are screwed to the motherboard.
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Dude, why waste your time trying to fix that POS computer? Everyone knows that the best computer is the Amiga 2000. (The great Doom Master even thinks so!) It's a work horse and never has issues like this! :)
My A3000T is also not working. I think it has a flakey CPU slot on it. It's just a big hunk of metal right now. Dead as a doornail. I have to open it up every so often and reset the CPU card on it to get it to work. Never have this problem with my Amiga 2000's...
I cant tell if you are joking or what,but siding with doomy has already blown it for you.. :biglaugh:
The 3000(t) can be as reliable as anything if its in good condition, 90% of these i have fixed have been problems with bad connections somewhere, the rest were power supplies,bad factory chip socket here and there,etc.
Its a known problem the accelerators can work their way out with heating/cooling cycles on big box machines. That is why there are metal standoffs to secure it to. Use them,they stop many problems of bad connections to the accelerator boards.Socketed machines will eventually all suffer more connection problems than surface mount machines down the road..Commodore did not exactly use the best sockets.
While i did start on a A2000 in 87' and loved the old girl,nothing beats a proper 32bit amiga :knuddel:
Let me know if you get tired of the 3000T and want to sell it.
Mech
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While i did start on a A2000 in 87' and loved the old girl,nothing beats a proper 32bit amiga :knuddel:
Truly spoken, m8!
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I agree, the A2000 was like a battle tank! She took a hell of a pounding and kept coming back. For me the next in line is the A4000T: thin, flimsy metal case by Enlight, but with a standard AT power supply (still available new today), a large roomy interior ( just waiting to get filled with a spigetti bowl of wires, 2 video slots, and room for 5 external access drive bays and one internal drive "area" that only the brave would use (since it sits directly over the CPU card preventing cooling). Her motherboard is simple in design with no daughter cards, easy to access -- once you get the drive cage out -- and durable; I
Don't know how many times I thought I killed her over the past 18 years.
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Make sure that the threaded standoffs that are used to secure the processor board in the Amiga 3000T computers cpu slot are the correct size. If the standoffs are the wrong size you will have problems with the cpu slot. You can not just plug in the processor board. It must also be screwed to the aluminum standoffs, and the standoffs are screwed to the motherboard.
Thanks, I think I need to find some better ones, and maybe some that will screw the cpu card down. I have a Cyberstorm MKII 060 in there now.
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Thanks, I think I need to find some better ones, and maybe some that will screw the cpu card down. I have a Cyberstorm MKII 060 in there now.
some 3000/3000t's came with the wrong length standoffs so beware of this. If you need i can take some measurements of the proper length ones.
mech
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Dude, why waste your time trying to fix that POS computer? Everyone knows that the best computer is the Amiga 2000. (The great Doom Master even thinks so!) It's a work horse and never has issues like this! :)
My A3000T is also not working. I think it has a flakey CPU slot on it. It's just a big hunk of metal right now. Dead as a doornail. I have to open it up every so often and reset the CPU card on it to get it to work. Never have this problem with my Amiga 2000's...
Yes, that CPU slot is a pig. To seat my 060 I had to push so hard I was worried about the motherboard breaking and wow, all those little solder joints are really small deadly pins with that much force
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IT'S ALIVE, IT'S ALIVE! I finally repaired my Amiga 3000T. There were 3 FP ZIP memory mixed in with the SC ZIP memory. I also installed a CR2032 battery holder, diode, and a new CR2032 coin battery. I posted a picture of my work in the Amiga 3000T section of the Gallery. The computer works perfectly, and keeps the correct time and date. My Amiga 3000T is in like brand new condition, and I am so happy that she is working again. :pint:
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:banana:
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IT'S ALIVE, IT'S ALIVE! I finally repaired my Amiga 3000T. There were 3 FP ZIP memory mixed in with the SC ZIP memory. I also installed a CR2032 battery holder, diode, and a new CR2032 coin battery. I posted a picture of my work in the Amiga 3000T section of the Gallery. The computer works perfectly, and keeps the correct time and date. My Amiga 3000T is in like brand new condition, and I am so happy that she is working again. :pint:
I, hereby declare you knight of the Amigan Order. Such persistence and bravery, valliantly saving such a precious piece of technology for the generations to come, can only be met with the utmost respect.
All bow! (http://www.bsabantamclub.com/wp-content/sp-resources/forum-smileys/bow.gif)
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WOOT! Nice job!
:pint:
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IT'S ALIVE, IT'S ALIVE! I finally repaired my Amiga 3000T. There were 3 FP ZIP memory mixed in with the SC ZIP memory. I also installed a CR2032 battery holder, diode, and a new CR2032 coin battery. I posted a picture of my work in the Amiga 3000T section of the Gallery. The computer works perfectly, and keeps the correct time and date. My Amiga 3000T is in like brand new condition, and I am so happy that she is working again. :pint:
Perfect! Congratz!
There is no need to change the caps on A3000(T), unlike A600/A1200/A4000.