Amiga 1200 unstable with memory and accelerator boards

[spawnerbr]

I have an Amiga 1200 from a long time and I got a long time ago a DKB 1202 RAM board. This board was always unstable and sometimes it resets the 1200, so I tried to use only with one RAM module of 4MB and it worked for some years.
These days, I got my first accelerator board, and E-Matrix 1230-50 (Viper 1230 Mk-V) with 16MB. This boards freezes everytime my Amiga and sometimes resets the machine. The A1200 now don't boot with the DKB and the E-Matrix. Sometimes it boots, but then, when freezes or resets, is impossible to make the Amiga boot. Sometimes with the E-Matrix a red screen appears (it occurs more with a SD>HDD connected) and no way to make these two boards works. The A1200 only works with the board disabled on jumpers or when the boards are disconnected from the 1200. The motherboard revision from the A1200 is 1D3.
Any idea about this behavior?? Thanks.

[khph_re]

do you have an A500 power supply handy? it could be to much draw for the A1200's weedy power brick.

[spawnerbr]

Yes, my power supply is from an A500 and I tested with one A1200 power supply and 2 power supplies from A500. Same behavior.

[Pat the Cat]

Could be anything from a whole list of issues.

But, as it is behaviour across a range of cards, and not the PSU, most likely it is a bad / intermittent connection on the A1200 itself.

One thing to watch out for is the trapdoor slot - sometimes the header for the pins gets loose, moves forward, so cards don't quite connect properly. You can use the tips of tweezers to try gently pushing it back a little, exposing more of the pins.

Or, the pins themselves might have some crud crusted on them. Give them a wipe with isopropyl alcohol or similar cleaner.

A vacuum cleaner might be an idea too - suck the dust out of the machine, and also off the accelerator.

Bad RAM SIMM? That could be another possible cause. Try removing to see if it affects behaviour. They are kind of "clipped" into place and spring loaded, and if not seated properly, could also cause this sort of fault.

Is the machine unstable WITHOUT an accelerator fitted? Does not sound like it.

[spawnerbr]

I opened the A1200 and remove everything (metal plates, keyboard...) just to use and connect the boards and see if it is connected. No pins loose. I cleaned the expansion slot too with isopropyl alcohol.
The boards don't works with or without memory. They are working only when connect and set as disable, which cannot help. The machine is stable without board. I have this DKB for more than 10 years and it was always unstable, but with 4MB (Not 8MB) it worked, but now, nothing is working. There is a Diagnostic board for 1200 or a way to find the problem to fix? Thanks.

[hese]

Originally Posted by spawnerbr

I cleaned the expansion slot too with isopropyl alcohol.

Did you also clean the pins of the accelerator cards? The pins may be oxidized, dirty or too worn.

Have the capacitors of the motherboard been replaced?

[spawnerbr]

Yes, I used a special spray to clean all pins from the accelerator and memory cards, but to be honest, I don't think that the problem is with the boards. Unfortunately, I don't have another A1200 to test but I need to find on my A1200 hardware the problem. There is a Diagnostic program that can check memory, chips...?

[Pat the Cat]

Well... SYSINFO is more of a benchmark than anything else. If your Amiga starts, then usually the hardware is OK. If not, there could be a hardware or software problem.

The colour codes you get can be significant, but misleading with accelerators, as they can copy ROM to fast memory. That could be were your problems come from.

http://wiki.classicamiga.com/Amiga_b...r_code_colours

Logically, it's most likely a problem with the trapdoor connection, or the way the A1200 talks to it. But it could just be both the accelerators are dysfunctional.

This might be of some use, I guess. Doesn't look helpful to me, doesn't really cover A1200 trapdoor issues.

http://amicue.org/TechStuff/TroubleShootingChart.html

[Pat the Cat]

Oh, just found some useful stuff, by searching on A1200 trapdoor issues;-

Originally Posted by rkauer

Hello Dave and welcome at board!

A simple problem can be occurred: sometimes the lip of the upper shield inside the Amiga touch the accelerator connector causing a short to ground. This will not burn the accelerator, only stop it to work.

Open the trapdoor, sack the accelerator and bend the shield lip in the keyboard direction.

If the issue is not solved then, my counsel is: grab another beefier power brick.

Originally Posted by cosmicfrog

or dirty contacts, had to clean my a1200 contacts before now to get a card work

A hard eraser, for rubbing out ink, does quite a job job with contacts. Bit messy though.

[Kin Hell]

Originally Posted by Pat the Cat

Oh, just found some useful stuff, by searching on A1200 trapdoor issues;-

A hard eraser, for rubbing out ink, does quite a job job with contacts. Bit messy though.

Do it dry & from the card to the edge. Not the Edge of the fingers back to the card. - You could lift those track fingers with too much applied pressure....

Then use a new/clean 1" paint brush or such, to flick off the debris. Then use Isopropyl to clean off both sides of the contacts before fitting.

Might be worthwhile seeing a High Res pic of your card, front & Back. I had issues with a DKB 1240 in my A1200. It was a mix of a dry Joint & Memory issues. - Single Sided Simm's were a No-No on this card with a 1D4 mobo & the X-Tal socket had a dry joint.
It was intermittent for me with no Ram. Might boot, might crash at desktop, might crash half way through boot, very random which led to visual dry joint check (the fitted X-Tal Socket solder looked very "Snotty", er.... like Pigeon Sh!t... Not flowed is better) & for re-flowing with a hot Iron & some Flux Paste, mine booted fine without ram every time. Single sided SIMMS as sent with the 1240 refused to work but a 32Mb Double sided SIMM was fine, Anything singled sided in my DKB refused to work for me.
However, your card can take 2 SIMMS & they would need to be 4Mb Singled Sided to fit I guess.

Could be an idea to try the Accelerator without the Top Mobo RF Sheilding in place & see if you have a different result for that.

[spawnerbr]

DKB 1202 was always unstable here. I tested with 2 memory banks and only with 4MB (one bank) I have used it for years. Then, I got this E-Matrix 1230-50 (Viper 1230 Mk-V) with 16MB but it freezes everytime or resets the Amiga.
After some tests, now both boards don't let my Amiga works or startup. It freezes my machine. Both boards. Now, even without the memory banks the computer is not working, but worked before.
I have used isopropyl alcohol, rubber, but nothing happened. Then I removed the metal shield that protects the motherboard. Same thing, no boot.
Someone told me that the problem can be the caps, so this is a thing that I have to do.

[Pat the Cat]

Does it give just a black screen? No colours displayed?

That means either a dead display or more likely the onboard processor has stopped working for some reason, if it won't even stop on a colour.

[spawnerbr]

Without the boards, the computer works. The HDD works. The floppy works. But if I connected one of these boards, black screen only.

[Mrz]

Originally Posted by spawnerbr

Without the boards, the computer works. The HDD works. The floppy works. But if I connected one of these boards, black screen only.

dismantle totally the A1200 and clean the 150 pins connector from both sides (up and down) with alcohol
this trick will work for sure

[Mrz]

if the trick above not worked > get a fine sand paper and sand the connector from both sides removing the first layer of bronze which surely is rusty over the years

this trick also works for memory modules ie PC ddr 1/ 2 /3 etc
I recovered lot of memory modules using this trick which some people though they were dead

[Daedalus]

Just be careful if you're using abrasives (like an ink eraser, wet/dry paper, sandpaper, emery cloth etc.), as on an A1200 the connector is gold flashed. If it's tarnished, you should be able to remove it without damaging the surface using IPA and a cloth, *pencil* eraser, contact cleaner or similar. If you remove the gold flashing, you expose the raw copper or tinplate underneath, which will tarnish again in a matter of weeks or months, dropping you into a never-ending cycle of removing and cleaning them again and again.

Also, different people have different ideas of what "fine" means when it comes to sandpaper. Using a carpenter's "fine" sandpaper might remove the traces entirely...