AlfaRAM 1200-1 Repair

Today, an Amiga card AlfaRAM 1200-1, arrived from a friend as <<stop working>>. At a first glance, it appears repaired from previews damage (battery acid).
Seems to have undergone further oxidation by cleaning rather bad in the previews repair. Also dont like the cord that is used for connections of the printed board. I prefer the kynar cable.

To have better access to printed board, I want to desolder the base of coprocessor. I would like to know if is useful to something, so to decide if sold this again. There are several memory cards with coprocessor, or is rare and not very useful?? In each case the base will extract without damaging.

Well... one from the next days I start the repair process.:coffee:


http://amibay.com/picture.php?albumid=12&pictureid=151
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@psodas

Wow, you have some work ahead of you,

but theres some good work done on that card, although theres also some rather (quick) work also lol.

I am really looking forward to the re-work pics =)

good luck :thumbsup:

Hi Zetr0,:)

Ok, Gals removed (static electricity reasons), wires, 2 caps, clock ic with base and the fpu base. I think look better now for pcb inspection. Lets start rewire....:whistle:

http://amibay.com/picture.php?albumid=12&pictureid=152

http://amibay.com/picture.php?albumid=12&pictureid=153



Oh,....another card :shhh:with full 9 mb ram and fpu with external crystal! Just as a reference.

http://amibay.com/picture.php?albumid=12&pictureid=154

Oh interesting...

I have two of those boards and bought some ZIP Ram for them recently. If I put them in my A1200 without any Ram both work without problems. But if I put ZIPs on it and set the jumpers a red screen appears always with a warning "board defect" or something like that. Any advice?

@Zetr0

After rewire, I tried to work the card in Amiga 1200 but without luck.:( The Amiga dont boot at all.
I change all the Gals and RTC ic with others from the working card, but nothing change.
If I set the jumber to 0Mb, Amiga boot normally... but without extra Ram.
Some advice? Bad stock ram ic maybe? There are two chip ram at bottom side of pcb.

Naive possibility: the jumpers are in the correct place?

Vulturing: if the card is dead, are you willing to sell the ZIP chips?

@psoda's

my friend this is quite a quandary, however you have done a fair bit of work.

1. Memory works okay with other unit.
2. CPLD / Programmable logic chips work with other unit.

If we are assured the work you have done is the same as what was then the board has a developed problem.

Although its possible any of the capacitors or discrete components, it could also that be more copper track has been eaten up by the acid, underneath the PCB laqure.

I would continuitiy test all the GAL/PAL sockets and the memory array, its quite likely you will have some more re-routing to do...

best of luck! :thumbsup:

Are we supposed to be seeing some pictures in these posts here? Because i for one can not see a thing, no matter what browser..:)

Quote:

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Originally Posted by rkauer

Vulturing: if the card is dead, are you willing to sell the ZIP chips?

---

Nothing from all that is mine. Also, the cards are two. The second is Ok as I say in previews post.:)

After major inspections again and again, its time to extract some ics.

First I remove the 74F86, and try the card to Amiga. But as a result got a yellow screen!

After I remove the 74F38, and try again the card. Not boot at all, as when they are received.

Then I resold the first ic 74F86, and.... IT WORK!!:) But only with 1 Mb stock Ram.:( When I try the card with known working 4 or 5 MB zipram configuration, I take a red screen with a message of bad card.:unsure:

Maybe a bad 74F38 ic? Or another after this, who give the problem when the first is in his position? Who knows! To morrow I try to search this at the local stores.

http://amibay.com/picture.php?albumid=12&pictureid=158

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http://amibay.com/picture.php?albumid=12&pictureid=156

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