Amiga 1200 with Apollo 1260 shaky

[phiwer]

Hi,

I have an amiga 1200 with an Apollo 1260. This card has been somewhat problematic over the years, but now it's really shaky.

If I manage to boot the amiga with memory on the 1260, then it reports 0MB of fastram.

Booting without memory is easier than booting with memory.

The card is reported as "Working" when check the boot menu, but memory is not recognized.

It also seems to be quite sensitive to the positioning of the card itself (pulling it out a bit seems to help to get it to boot).

If I remove the card completely, then the amiga has no problem booting.

Any suggestions or remedies to my problem?

I am considering doing one of the following:

1) Buying some other ram to try it out.
2) Buying a new power supply if this could be the culprit (it's an original one)
3) Buying a TF1230 card with 64MB or 128MB of memory
4) Any other card I should be considering? I mainly like classic amiga stuff: Watching demos, coding utils (and plan on getting into demo coding a bit more).

Thanks for your suggestions.

 

[miggymad]

First thing would be to check if the power supply is up to the job. If it is the lightweight variety then suspect the main root of the problem is there. Check the output voltages with a multi-meter as the Apollo 1260's can be a bit power hungry.

Secondly, has the mainboard been recapped at all? If not then that is something that should be done ASAP. Not just for the sake to stop potential cap leakage but also for overall mainboard stability. Also have the timing fix done at the same time (removal of E123C and E125C) should help with the Apollo issue as well.

 

[screemo]

As @miggymad says it could be a cap or psu issue, so definitely check that first.

The simm module(s) could have given out (don't see that too often), but it's also likely the f257a's could have failed.

Sometimes you can add a smaller ram module to determine if it can see some of the ram on 8-16mb modules.

However, it's just a guess - the card connector could be worn, etc. ..

Maybe post some high-res pics of the card ?

 

[phiwer]

The Amiga has been recapped.

I’ve had issues before with the psu. The first time I boot the amiga it won’t boot, I then need to switch the psu on off to get it to boot. Suspecting here that the psu isn’t in perfect shape.

I will check the timing issue.

Providing pictures.

 

[screemo]

The card looks normal for that age I would say, so it's most likely your PSU that will be the first thing to try

 

[phiwer]

Thanks! I’ll try that first.

 

[miggymad]

The card looks normal for that age I would say, so it's most likely your PSU that will be the first thing to try

I agree, the card itself looks to be in good condition.

Definitely suspect the power supply - time to get probing!

 

[StrongARM]

Power supply +1

 

[sq7bti]

PLCC sockets?

 

[miggymad]

PLCC sockets?

That's a possibility as everything works fine with no 1260 in-situ according to the OP.

Going by the pictures supplied, I can't see any problems with the card. All the chips look to be nicely seated in their sockets.

 

[phiwer]

I’ve measured the power supply now.

5V seems alright, but might be difficult to notice the problem without any load?

 

[phiwer]

I got the machine booting now, but no memory detected. Memory should still be detected even without running setpatch etc right? I can’t boot normally as I don’t have enough fastram.

 

[phiwer]

The computer’s graphics starts messing up after a while and when I reboot it, it goes into a continuous reboot cycle which I cannot recover from.

 

[miggymad]

Disconnect the floppy drive power cable from the main board and use the pins there to attach your probes to.

Once you have the A1200 under load you should see more accurate readings from the multi-meter.

The output from the power supply without any load looks okay but appearances can be deceptive

 

[phiwer]

Which one is +5V and which one is ground?

 

[miggymad]

2 ground pins are in the middle of the bank of 4 (Black wires on cable)

+5v is Red wire (pin on the left in your picture))

+12v is either Grey, Brown or Yellow wire depending on your cable (pin on the right)

 

[phiwer]

With ram

Without ram

 

[phiwer]

Apollo 1260 disconnected.

 

[miggymad]

I think we can safely say the power supply's +5v is not at fault here. Can you also check the +12v under load from the floppy drive connector and post pictures please?

There are other known problem areas.....

Does the A1200's edge connector look dull or tarnished? If so, give it a good rub with a pencil eraser to restore. This is more for peace of mind than anything else.

Make sure the RAM is seated firmly in place before you clip it in. Even the tiniest hint of not being straight can cause problems.

Also you mentioned that the card works if you back it off the connector a little bit. Try doing this again but put the trapdoor cover back in place. The lack of it keeping the board straight might be leading to intermittent contact.

Do any chips on the Apollo get very hot?

Spoiler: Don't try this at home kids!

I remember one time I had to hot glue an Indivision ACA card to the case just so it kept in good contact with the mainboard. Those were the days! lol

 

[phiwer]

First pic is without board. Second is with board, but no ram. Third pic is with ram.

I am also considering looking a c123 and c125 on the back. Could it be a timing issue?