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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: brownb2 on November 19, 2015, 04:49:26 PM
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Reading around this is just a job of soldering a wire somewhere to change the clock divider from 3 to 2 and ensuring the CPU cooling is adequate.
Does anyone have a guide on how best to do this (I can't believe nobody has done this yet...)?
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Found the answer http://www.a1k.org/forum/showthread.php?t=43453
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Found the answer http://www.a1k.org/forum/showthread.php?t=43453
Thanks! If I get the urge one day I might give this a go myself. :hammer:
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Tried it today - took a switch from an old Amiga external floppy* (why would you want the floppy off?) and repurposed it so it slightly protrudes out of one of the front underside keyboard vents nearest the left foot, hot glued it in place inside, looks like its meant to be there :)
Soldered up the wires from the switch to the relevant accelerator points, closed the two points to be "left open" (Jen's PCB/overclock warning) et voilà!
Now I can switch it on the fly when I need more grunt, I get exactly one Amiga more power in over clock mode (0.8 mips) and I have a heatsink on order just in case.
Jen's "economy accelerator" is looking like a sheep in wolf's clothing, I wonder how long the CPU will last lol.
*No external floppies were harmed in the making, I resoldered the drive permanently on.
On a related note anybody recommend some good 020/030 ecs demos to stress test?
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0.8 mips more? I'd of thought it should be higher than that?
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An overclock from 16.67MHz to 25MHz, .8 sounds about right. Great job and write-up, bonus points for saving the floppy drive! :)
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My poor maths... 0.98, not much different.
0.8 mips more? I'd of thought it should be higher than that?
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I'd probably be running it at stock speed till you have a heatsink fitted ;)
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How did you know? ;) adoom without heatsink will kill it - I let it cool for a couple of mins and reached safe temp and its back to life again. I don't think I'll push it again!
I'd probably be running it at stock speed till you have a heatsink fitted ;)
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My poor maths... 0.98, not much different.
Almost x2 standard Amiga's faster. :)
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I installed the heatsink onto the ACA620 (in the small space top side) and ADOOM demo mode with DOOM 2 wad lasts about 5 minutes longer before the A600 freezes.
Unlike previously, an immediate reboot works (without heatsink the A600 needed a minute to cool).
Needless to say, 25mhz for Workbench tasks it's fine just to use a heatsink, but for pushing the limits (i.e. ADOOM), a fan is a definite must.
Not knowing enough about circuit design, if I put a small fan in and attach it to +12V FDD connector and the "ground" on the switch (which is attached via cable to the ACA ground/negative), would this cause any damage?
I'll admit I've already briefly tested it (little knowledge, dangerous thing, also fan was connected to +5V rail) and it seems that the fan (and ACA) works and comes on when I flip the ACA switch and put it into 25mhz mode, but I don't know if this setup is electrically safe as the +12V is going to the ACA negative/ground - can anyone comment?
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Not knowing enough about circuit design, if I put a small fan in and attach it to +12V FDD connector and the "ground" on the switch (which is attached via cable to the ACA ground/negative), would this cause any damage?
Just stick to floppy connector. All connections needed are there, +12v and Ground. So when machine is turned on, fan comes on.
Also might be worth noting, if you do not have good grounding (via the ground cable that comes with ACA) to the ACA620, then it will cause freezing / crashing issues.
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The ACA620 appears to have been designed with the idea that you can't overclock it unless there's a heatsink fitted over the cpu, which connects the two heatsink mounting holes together, allowing the overclocking to be enabled.
One mounting hole is simply connected to ground, so you can use any ground point for this, meaning, if you want to use the same switch to overclock the cpu, and enable the fan, make sure the ground "input" to the switch is solid, and use the output from the switch to go to the fan as you suggested, shouldn't be an issue.
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I never received the extra grounding cable that Jen's mentioned in A1K post, I've not needed it as afaik it was only required for some mainboard revisions. Is this cable required for all mainboards?
Just stick to floppy connector. All connections needed are there,
+12v and Ground. So when machine is turned on, fan comes on.
Also might be worth noting, if you do not have good grounding (via the ground cable that comes with ACA) to the ACA620, then it will cause freezing / crashing issues.
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I bought my ACA620 when they first came out and nor did I receive a grounding cable. Am I supposed to be using one? I had to send mine back for a firmware update to v2, but I wasn't aware of a grounding issue.
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Same here - installation pics and sheet don't show it.
I bought my ACA620 when they first came out and nor did I receive a grounding cable. Am I supposed to be using one? I had to send mine back for a firmware update to v2, but I wasn't aware of a grounding issue.
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Sorry, Ground lead, bad choice of words.
The two screws go into the ground plain. However I found in some cases an extra earth was required. I was thinking of Indivision, ACA doesn't come with ground lead.
I remember having a discussion with IC about including one.
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Sorry, Ground lead, bad choice of words.
The two screws go into the ground plain. However I found in some cases an extra earth was required. I was thinking of Indivision, ACA doesn't come with ground lead.
I remember having a discussion with IC about including one.
I didn't get any screws with my card. All i got was the card. Was I supposed to be provided with screws like the ACA630? The instructions didn't mention screws either iirc.
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I didn't get any screws with my card. All i got was the card. Was I supposed to be provided with screws like the ACA630? The instructions didn't mention screws either iirc.
You must have an early version of board. As new ones have screws.
This must have been the discussion, to include something like that to screw into ground.
Giving you the extra grounding point.
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I had ann unstable V1, sent it back to Amigakit and received a V2 back (both without any screws).
How essential are the screws to the correct operation (i.e. with it overclocked is it likely to be more stable)? I've not seen any problems with it running stock speed.
Do you have a picture of the of the ACA with installed screws (to see if I have anything similar lying about)?
You must have an early version of board. As new ones have screws.
This must have been the discussion, to include something like that to screw into ground.
Giving you the extra grounding point.
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I helped a friend with cooling of his ACA620, although not to overclock but get stable operation in the environment which it was in. Anyway here's what was done:
First we went though a bunch of chipset coolers we had at hand and finaly went with a nice Revoltec Chipset Cooler (http://prices.kitguru.net/productinfo/20868/revoltec-chipset-cooler-bundle) because of the integrated fan with still a low profile aswell as it's almost matching color to the ACA card... almost any chipset cooler will have same hole spacing so don't sweat it if you can't find this exact one.
Next was to cut a piece of aluminum to size to use as a shim (http://safir.amigaos.se/bildgalleri/users2/15955_IMG_0112.JPG). The heatsink was a bit wobbly so, although probably overkill, we added some foam pads (http://safir.amigaos.se/bildgalleri/users2/15958_IMG_0116.JPG) around the hole for good measure.
Now come the modding of the ACA board itself slight. The holes the heatsink utilize had to be widened from 3.0mm to 3.5mm using first a 3.2mm and then a 3.5mm drillbit (gently hand force only (http://safir.amigaos.se/bildgalleri/users2/15959_IMG_0117.JPG)). The "upper right" corner of the CPU sockets leg protruded a bit too much though the PCB and came in contact with the heatsink, with a slightly thicker shim this problem would not exist but it was solved by shortening the legs (http://safir.amigaos.se/bildgalleri/users2/15961_IMG_0119.JPG).
Final result (http://safir.amigaos.se/bildgalleri/users2/15960_IMG_0118.JPG).
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I'm not happy with the +12v going through the ACA's negative that's currently only taking the +5v from the ACA, it still seems a bit dodgy (for me, not having the electronics experience).
I've had a quick Google for step downing +12v to +5v and a car charger for a mobile phone and use the MC34063 mentioned in this thread http://www.instructables.com/answers/How-can-I-convert-12v-down-to-5v/ can probably do the job.
Having said that it may just be too much work and so I'll leave it with an always on fan pressed up against the chip heat sinks I fitted instead (as opposed to the cool shim job mentioned on the last post).
... if you want to use the same switch to overclock the cpu, and enable the fan, make sure the ground "input" to the switch is solid, and use the output from the switch to go to the fan as you suggested, shouldn't be an issue.
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Why convert 12V to 5V inside Amiga when there is already 5V somewhere
in there ? It would be easier to just use wire and take 5V directly from PSU?
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I'm not happy with the +12v going through the ACA's negative that's currently only taking the +5v from the ACA, it still seems a bit dodgy (for me, not having the electronics experience).
I've had a quick Google for step downing +12v to +5v and a car charger for a mobile phone and use the MC34063 mentioned in this thread http://www.instructables.com/answers/How-can-I-convert-12v-down-to-5v/ can probably do the job.
Having said that it may just be too much work and so I'll leave it with an always on fan pressed up against the chip heat sinks I fitted instead (as opposed to the cool shim job mentioned on the last post).
There's 12v and 5v on the floppy connector - 12 is yellow, 5 is red.
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I'm not happy with the +12v going through the ACA's negative that's currently only taking the +5v from the ACA, it still seems a bit dodgy (for me, not having the electronics experience).
I've had a quick Google for step downing +12v to +5v and a car charger for a mobile phone and use the MC34063 mentioned in this thread http://www.instructables.com/answers/How-can-I-convert-12v-down-to-5v/ can probably do the job.
Having said that it may just be too much work and so I'll leave it with an always on fan pressed up against the chip heat sinks I fitted instead (as opposed to the cool shim job mentioned on the last post).
Get one these power splitter cables and a fan with a molex connector to make things easy.
http://m.ebay.co.uk/itm/5-25-4-Pin-Molex-To-3-5-Floppy-Drive-Molex-Power-Splitter-Adaptor-Cable-/371454649551?nav=SEARCH (http://m.ebay.co.uk/itm/5-25-4-Pin-Molex-To-3-5-Floppy-Drive-Molex-Power-Splitter-Adaptor-Cable-/371454649551?nav=SEARCH)
Actually you'd need one that would enable your floppy to be plugged back in...there's a multitude of these configurations of cables...just have a search on ebay.
There's 12v and 5v on the floppy connector - 12 is yellow, 5 is red.
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There's 12v and 5v on the floppy connector - 12 is yellow, 5 is red.
Not in the Amigas it isn't.
If you're worried about grounding the fan through the accelerator, (which probably isn't a good idea) then just get your ground point to the switch from the floppy connector, and have the output from the switch still going to the accelerator (to the screws ground pad, just above connector "CN1")
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Not in the Amigas it isn't.
If you're worried about grounding the fan through the accelerator, (which probably isn't a good idea) then just get your ground point to the switch from the floppy connector, and have the output from the switch still going to the accelerator (to the screws ground pad, just above connector "CN1")
Haha! I'm loosing it lol. It's 12 and -12 isn't it? I run a 12v fan with a similar cable.
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Haha! I'm loosing it lol. It's 12 and -12 isn't it? I run a 12v fan with a similar cable.
I haven't measured in a while but pretty sure floppy connector is +12V-ground-ground-+5V. I run the fan in my A500 off that at 5V so it'll be quieter. I don't need it to move a whole cyclone worth of air, lol. ;)
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The floppy and hdd in the amigas are 5 and 12volt, but those aren't the colours.
Amiga decided to be different (it was probably before the standard was in place) so if you're wiring things up make sure the voltages are correct.
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The floppy and hdd in the amigas are 5 and 12volt, but those aren't the colours.
Amiga decided to be different (it was probably before the standard was in place) so if you're wiring things up make sure the voltages are correct.
Brown is 12v and red is 5v I dare say... :angry:
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Brown is 12v and red is 5v I dare say... :angry:
That would be incorrect, In the Amigas, its normally that Brown is 5volt, Red is 12volt.
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Do this:
-Ground to the floppy ground wiring, to the centre contact of your switch.
-Power from the floppy power, to the fan power (either 5volt or 12volt depending what fan you choose)
-"output" from the switch to the fan ground, as well as the ground contact on the ACA620
(http://imageshack.com/a/img633/6416/Nhvb6P.jpg)