Amiga 3000 repair Faqs

[Prime]

I am trying to gather all the FAQs for troubleshooting the Amiga 3000. Please answer them if you are sure of the answer to help others out as well.
Here are some basic questions:
When I say "run" I mean see a kickstart screen of some kind.

#1 Can the Amiga 3000 run without the daughter board?
No - already established

#2 without a floppy drive?

#3 without a hard-drive?

#4 without a mouse?

#5 without a keyboard?

#6 without the battery?

#7 Can you buy the weird 15 pin molex type power connector anywhere to make a longer power supply cable?
Knowing Amiga & Commodore this is probably proprietary.

#8 Is there a way to test for bad roms?

#9 Can you use other Amiga Model parts to use in the 3000, CIA's, Denise, Paula, etc....

#10 Can you use other Amiga Hardware, say an A500 internal floppy on a A3000?  (I don't care if it mounts or fits (we know it wont) I just care if it would actually boot a floppy)

Almost everything I have read states that Amiga 3000's are bulletproof. I am going CRAZY :crazy: trying to fix one that worked great, till I opened it up, now I get no video, and no boot.
Also, the cap lock light works for about 12 times then dies, so the CPU is not receiving data from the CIA.

AHHHHHHHHH HELP.





  :crazy:  :crazy:  :crazy:  :crazy:  :crazy:

[tonyyeb]

#2 - Yes

#3 - Yes

#4 - Yes

#5 - Yes

#6 - Fairly certain yes

#7 - Not sure about one end of the cable but as Nathan on here makes ATX to A3000 cables then they *may* exist.

[redrumloa]

#6 - Fairly certain yes

Yes.

[Castellen]

To answer your questions....

#1 Can the Amiga 3000 run without the daughter board?
For OS2.x and OS3.x the Zorro riser board must be fitted.

#2 without a floppy drive?
Yes, though I think you end up with a DF0: icon on WB.

#3 without a hard-drive?
Yes, you'll eventually end up with select kickstart screen (V1.4 ROMs) or the insert disk screen (OS2.x or 3.x).

#4 without a mouse?
Yes.

#5 without a keyboard?
Yes.

#6 without the battery?
Yes, the RTC doen't need to be fitted either.

#7 Can you buy the weird 15 pin molex type power connector anywhere to make a longer power supply cable?
Haven't seen them for sale, but your best bet would be Digi-Key for small volumes.

#8 Is there a way to test for bad roms?
Put them in a known working computer.  It's incredibly rare to have bad ROMs, unless someone has dome something stupid with them (bent pins, wrong polarity).  Swapping positions of the two ROMs won't damage anything, but the computer won't boot as every 32-bit word read from the ROM pair will be swapped.

#9 Can you use other Amiga Model parts to use in the 3000, CIA's, Denise, Paula, etc....
Yes, a majority of the parts are swappable with the A500 and A2000.

#10 Can you use other Amiga Hardware, say an A500 internal floppy on a A3000? (I don't care if it mounts or fits (we know it wont) I just care if it would actually boot a floppy)
Yes, the floppy interface on all models is the same.

Also...
The computer doesn't require any fast RAM to boot.

Reseat all the socketed ICs, socket connection problems can cause non-booting and unstable operation.

Check you have correct clock distribution throughout the computer, this mainly comes from U103.

Check the various reset lines are high (5V).

Check FAIL_ is high (5V).

Try disabling the FPU using the.

Check the ROMs are being read by using an oscilloscope, measure on the ROM output enable pin, 20, going low during most of the CPU read cycles.

Check you have a valid TICK signal at J350.


There's various other things you can check too, but I'm running late for work.  Look on my webserver for more documentation and schematics.
http://amiga.serveftp.net

[rkauer]

 Just remember the A3000 will wait forever to boot if a terminator device (or device terminated) is not in the SCSI socket/cable.

[Prime]

Also...
The computer doesn't require any fast RAM to boot.

- The Zip sockets are filled to the brim, it is a LOT of work to remove them all, maybe I will try that last.

Reseat all the socketed ICs, socket connection problems can cause non-booting and unstable operation.

- I re-set all the major proms

Check you have correct clock distribution throughout the computer, this mainly comes from U103.

- clock signal present on all the chips I tested (I am not sure where the 68030 clk is and I dont want to short it out by guessing)

Check the various reset lines are high (5V).
- Yes

Check FAIL_ is high (5V).
- Dont know where FAIL_ is


Try disabling the FPU using the.
- Did not work

Check the ROMs are being read by using an oscilloscope, measure on the ROM output enable pin, 20, going low during most of the CPU read cycles.
- Pin 20 goes high the entire time


Check you have a valid TICK signal at J350.
-TICK signal present @ J350.

I am about ready to throw it in the trash :pissed:.

Thanks

[Castellen]

You can measure the FAIL_ signal on pin 2 of the real time clock and on one of the pins of Gary.  I'm too lazy to get out the schematic... Should be 5V on this line for the system to operate.

If the ROM pin 20 is staying high all the time, it indicates a more low-level problem.  As the timing of this signal is fairly quick (a few µSecs) then you'll ideally need a digital scope to look at it properly, you can use 'single sweep' or 'wait for trigger modes'.

The active low ROM OE signal is generated by the gate array, Gary, when it decodes a specific address range on the address bus.

So check that there is activity on both the address and data bus.  If not, either the CPU is not running for some reason (in reset state, no clock, faulty CPU).  The CPU is easy enough to replace if you can borrow one from a known good A3630 card or whatever.  Assuming you can SMD solder.

If the CPU generates a few address cycles then freezes and no ROM OE signals are generated, then there's possibly a problem with the address decoder in Gary.  Perhaps a bad contact with the IC socket or Gary is faulty?

Failing that, there's not too much more you can easily look at aside from checking other CPU control lines, though I don't think there's much that should prevent it from putting address words on the bus in order to look at the boot vector in ROM.

Non-booting problems can often be rather tricky as I'm sure you now understand :-P

[Prime]

Thanks Castellen,

I will check the Rom pin 20 for going low with my works nice digital Oscilloscope, I didn't realize the signal was going to be that fast. So I will set it to trigger on low.

I will likewise check the FAIL_ on the RTC and Gary.

How hearty are the A3000 motherboards? When I un-soldered the battery maybe I damaged one of the planes? Or maybe I destroyed a trace? The top and bottom plane of the motherboard look great.


I will let you know,
Thanks

[vk3heg]

Castellen wrote:
To answer your questions....

#2 without a floppy drive?
Yes, though I think you end up with a DF0: icon on WB.

#6 without the battery?
Yes, the RTC doen't need to be fitted either.

#7 Can you buy the weird 15 pin molex type power connector anywhere to make a longer power supply cable?
Haven't seen them for sale, but your best bet would be Digi-Key for small volumes.

#2: correct, DF0: with no floppy connected! (mine is like that atm)

#6: I don't have the battery on my a3000. (I use a ntp time synch program, and make sure that I save the time settings in prefs every now and again)

#7: Yes you can still get these, plus the pins that go into it. (My a3000 is powered via a 200w at psu)

[Castellen]

You'll ideally need a 60MHz or faster digital scope to have a look at what's going on.  Of course the signal is going to be fast, electronics has evolved slightly since the days of the Colossus :-P
I forget the exact cycle timings in the 68030, but a ROM read cycle is going to be much less than 1µSec, probably more around the 100nSec mark??

The PCB is fairly resilient.  Top and bottom copper is mostly used for signal layers, with the internal two layers mainly carrying 5V and ground, plus a few signal tracks which couldn't quite fit on the top or bottom.  Besides, I don't think there are any signal tracks running under the RTC area.  In denser parts of the board, like under the CPU, there are a lot of internal signal tracks however.  Unlikely you've damaged anything when the battery was removed.

If the battery has leaked, it's possible it's damaged the sockets of the neighbouring Denise or Paula.  The system won't boot unless they are working correctly.  Fit new sockets if the contacts are green, or better yet, solder the ICs directly into the board.  Check vias around the battery area as well, they can get corroded open circuit.  Here's a drawing I did showing it in more detail.

[Prime]

Castellen,

You are a treasure trove of information!

The battery leakage was actually very minimal, there are a couple of green leads which I will look at closer.

The ROM0 U180 never goes low, I used a 300Mhz digital scope.
It stays high and that's it.

I will check for green corrosion around neighboring chips. Paula and Denise are pristine and the sockets they reside on are as well.

Do you have a pinout for the Fat Gary? I am not sure where pin 1 is on that plcc.

[Zac67]

#9 Can you use other Amiga Model parts to use in the 3000, CIA's, Denise, Paula, etc....

A bit more precisely:
- Agnus is a special A3k type
- Denise can be any OCS or ECS Denise from A1000/500/2000
- Paula has never been changed, not even for AGA - any DIP type fits (A1000/500/2000)
- CIAs haven't been changed either, any DIP type fits
- Fat Gary might be interchangeable with the A4k type
- Super Buster is the same as A4k
- Ramsey is the same as A4k but its rev must correspond to the right SDMAC rev
- any 32 bit ROM set works but fast RAM/SCSI require an A3k ROM

[Plaz]

#7 - Yes. I bought the parts and built on for my 3000.

I can try to find the supplier and part numbers if you like.

It is not an easy task to make one of these though.


Plaz

[kolla]

Huh - Amiga 3000 repair Fags? :lol:

[Prime]

Castellen,

In your A3000 booting problems you reference:

BLACK (No video) = R406 or R215 open R406=1 ohm R215=4.7 ohm Agnus or Denise defective

I cannot find either of these resistors on the motherboard, can you tell me what they are close to, or the general vicinity?

Thanks,