Defective 8MB Ram Expansion on A1200

[rincewinda]

So I had finally managed to source an A1200 that I was happy with.

It arrived today, I unpacked it very carefully and I connected the cables, and then powered it on all looked well as the drive made sounds I remember and then this appeared on the screen.

Apparently the 8MB Ram Expansion is defective, then I remember it didn't have a coin cell battery in it, so I powered it off unplugged all the cables and popped in a CR2032 it was all I had and seemed to fit.

I then powered it back on, but same error as before, I'm unsure what to do from here, is the card really defective?

The pictures are of the card and of the error, hopefully someone can see what the issue is I took a photo of some jumpers on the card maybe I need to do something with those perhaps?

[solidcore]

Check ram has voltage. Normally when there is a defective screen like this the CPLD is working fine clearly because you can see the product ID but there's a problem with the ram itself. Another line of enquiry would be the data/address lines between the cpld and ram.

The CRT is unlikely to be responsible for the red screen issue (although not entirely ruled out). A battery only helps keep it's memory for the date/time.

[rincewinda]

Originally Posted by solidcore

Check ram has voltage

How would I check the ram has voltage?

Originally Posted by solidcore

Normally when there is a defective screen like this the CPLD is working fine clearly because you can see the product ID.

What is a CPLD?

Originally Posted by solidcore

Another line of enquiry would be the data/address lines between the cpld and ram.

Do I check that? if so how?

Originally Posted by solidcore

The CRT is unlikely to be responsible for the red screen issue (although not entirely ruled out). A battery only helps keep it's memory for the date/time.

I'm actually using a Sony Bravia TV via Scart.

[solidcore]

Originally Posted by rincewinda

How would I check the ram has voltage?

What is a CPLD?
Do I check that? if so how?
I'm actually using a Sony Bravia TV via Scart.

VOLTAGE
Find out the markings on the ram, find a datasheet and pin for VCC on the datasheet, make sure you find pin 1 identifier on the chip usually a small circle (but not always) but can be found on datasheets, with a multimeter you can check if theres 5v going to the chip or not during power up state (at the red screen). Be careful not to short, failing a datasheet check if there's any power at all on all the pins bit riskier. A safer bet is caps (cans/small smd components , typically in a brown colour, but not always) nearby are a safer bet.

SHORTS/LEAKS.
Another thing to inspect for is shorts while powered OFF, use the continuity setting on the meter and put the positive and negative on the capacitor , if it beeps / shows continuity you have a bad capacitor (shorted). Otherwise check for Leaky caps usually dull and blue/green textured mess on metal pads/legs , pcb solder mask looking odd.

CPLD
Cpld stands for complex programmable logic device often found in accelerators in one form or another but if not possibly a MCU (microcontroller unit). Think of it as a chip that 'communicates' with your a1200 to announce the board exists and the z2 ram configuration , but not only that it also acts a middle man for the memory itself.
You can look at the markings on the chips to figure out which chip is talking to your amiga to let it know about the product ID etc.

RTC
Sorry i meant to type RTC * tired man tonight. imagine that, haha.


Any other questions feel free to ask me mate, I am curious as to why this card is defective, be interested to hear the reason but i suspect ram/ short caps/leaked caps/bad signals nearby ram.

[Lord Aga]

Do you have a SIMM slot on the other side of the card?

[rincewinda]

Originally Posted by solidcore

VOLTAGE
Find out the markings on the ram, find a datasheet and pin for VCC on the datasheet, make sure you find pin 1 identifier on the chip usually a small circle (but not always) but can be found on datasheets, with a multimeter you can check if theres 5v going to the chip or not during power up state (at the red screen). Be careful not to short, failing a datasheet check if there's any power at all on all the pins bit riskier. A safer bet is caps (cans/small smd components , typically in a brown colour, but not always) nearby are a safer bet.

SHORTS/LEAKS.
Another thing to inspect for is shorts while powered OFF, use the continuity setting on the meter and put the positive and negative on the capacitor , if it beeps / shows continuity you have a bad capacitor (shorted). Otherwise check for Leaky caps usually dull and blue/green textured mess on metal pads/legs , pcb solder mask looking odd.

CPLD
Cpld stands for complex programmable logic device often found in accelerators in one form or another but if not possibly a MCU (microcontroller unit). Think of it as a chip that 'communicates' with your a1200 to announce the board exists and the z2 ram configuration , but not only that it also acts a middle man for the memory itself.
You can look at the markings on the chips to figure out which chip is talking to your amiga to let it know about the product ID etc.

RTC
Sorry i meant to type RTC * tired man tonight. imagine that, haha.


Any other questions feel free to ask me mate, I am curious as to why this card is defective, be interested to hear the reason but i suspect ram/ short caps/leaked caps/bad signals nearby ram.

Thank you very much for informative post, as I was overly keen to use it I googled for some pictures of the card I have.

I noticed that in all of the pictures more jumps were on the card, and also in different positions, so I trawled through my little box of pc bits and found some more jumps and put them in the same places as were in the pictures I found and the card is working great, shows just under 8MB ram, but I suspect this is due to some being used.

[rincewinda]

Originally Posted by Lord Aga

Do you have a SIMM slot on the other side of the card?

Yes I do it has an 8MB SIMM in it.

[Lord Aga]

Can you try a 4MB SIMM?
I have a similar card. 4MB - super duper. 8MB - red screen.