Commodore.ca: The PET, VIC, 128, 64 & More Forum

Does anyone here have any experience in repairing a 8296D ?
I've been trying to get my 8296 working again for a long time now, but still no luck.
The problem is that it does not startup.
The power supply is ok, because the diskdrive does startup.
I Have checked all the ram and rom.
And I have replaced one PLA that I got from Ebay and it still does the same.
I also checked/replaced all multiplexer ic's.
I'm starting to suspect that the PLA that I got from Ebay is defective too.
If someone has some spare PLA lying around, I be happy to take them off you hands
The parts I'm looking for are: 324744-01 and 8700-008
Any tips are welcome.

donni wrote:Does anyone here have any experience in repairing a 8296D ?
I've been trying to get my 8296 working again for a long time now, but still no luck.
The problem is that it does not startup.
The power supply is ok, because the diskdrive does startup.
I Have checked all the ram and rom.
And I have replaced one PLA that I got from Ebay and it still does the same.
I also checked/replaced all multiplexer ic's.
I'm starting to suspect that the PLA that I got from Ebay is defective too.
If someone has some spare PLA lying around, I be happy to take them off you hands
The parts I'm looking for are: 324744-01 and 8700-008
Any tips are welcome.

I have read that the PLA's are usually the most common cause of problems on the 8296 machines. Sorry, I do not have any spare chips. If you can't find a working replacement you can build one using an EPROM on an adapter board. Check here:

http://www.vic20.de/html/eprom_pla_8296_und_c64.html

Steve

I have thought about building an adaptor board with an eprom like that
I have repaired a lot of C64 computers that way.
The problem was that I had no 'known to be good' pla at hand for the 8296 to read the data from.
This is great, thanks for the link Steve.
I'll let you know if I get the 8296 going again.

It works again
After replacing the PLA UE5 with the eprom the computer started again, but had no picture.
It turned out that the crt controler 6545 was defective too!
As a precaution I replaced all the electrolytic condensators in the power supply and on the main board.
I also took the trouble of putting all the IC's on sockets, so that future repairs won't be much of a hassle anymore.






-donni

donni wrote:It works again
After replacing the PLA UE5 with the eprom the computer started again, but had no picture.
It turned out that the crt controler 6545 was defective too!
As a precaution I replaced all the electrolytic condensators in the power supply and on the main board.
I also took the trouble of putting all the IC's on sockets, so that future repairs won't be much of a hassle anymore.

-donni

Wow, that's a lot of work. I guess it's worth it as the 8296D is a really great machine. Glad the EPROM worked for you. Is your machine a 220V model?

Steve

sjgray wrote: Wow, that's a lot of work. I guess it's worth it as the 8296D is a really great machine. Glad the EPROM worked for you. Is your machine a 220V model?

Steve

Yes it was a lot of work, but worth it.
The machine runs on 220 Volts and has a QWERTZ keyboard with keys like ä/ö/ü, so it must be German.
While testing it more thorough, it turned out that the build in diskdrive didn't read/write disk.
I'm not sure what the former owner did with his computers, but this is the third defect I found in this machine.
I have exchanged the disk drives main board with the main board from a 8250lp and that did the trick.

But now I have a defective 8250lp that I like to get going again, but can't find a proper schematic diagram anywhere.
Anyone know where I can find that?

-donni

donni wrote:

sjgray wrote: Wow, that's a lot of work. I guess it's worth it as the 8296D is a really great machine. Glad the EPROM worked for you. Is your machine a 220V model?

Steve

Yes it was a lot of work, but worth it.
The machine runs on 220 Volts and has a QWERTZ keyboard with keys like ä/ö/ü, so it must be German.
While testing it more thorough, it turned out that the build in diskdrive didn't read/write disk.
I'm not sure what the former owner did with his computers, but this is the third defect I found in this machine.
I have exchanged the disk drives main board with the main board from a 8250lp and that did the trick.

But now I have a defective 8250lp that I like to get going again, but can't find a proper schematic diagram anywhere.
Anyone know where I can find that?

-donni

Strange how we're in similar situations. I just bought a non-working 8250LP from ebay I will need to work on once it arrives (coming from Germany). I haven't seen 8250LP schematics. Closest you can get is SFD-1001. But since you have two 8250LP boards you could always test the chips by swapping them one at a time into the working one.

Steve

sjgray wrote:Strange how we're in similar situations. I just bought a non-working 8250LP from ebay I will need to work on once it arrives (coming from Germany). I haven't seen 8250LP schematics. Closest you can get is SFD-1001. But since you have two 8250LP boards you could always test the chips by swapping them one at a time into the working one.

Steve

Wow, shipping it from Germany to Canada will cost you mucho $$

I have looked at the schematics of the SFD-1001, but the position numbers of all the components are different.
Also the pin assignment to most of the logic ic's are different, which makes tracking down the problem difficult.
I already swapped every chip on a socked without success.
I found a German company that still sells service manuals for this machine, i'm thinking of ordering one....

-donni

donni wrote:

sjgray wrote:Strange how we're in similar situations. I just bought a non-working 8250LP from ebay I will need to work on once it arrives (coming from Germany). I haven't seen 8250LP schematics. Closest you can get is SFD-1001. But since you have two 8250LP boards you could always test the chips by swapping them one at a time into the working one.

Steve

Wow, shipping it from Germany to Canada will cost you mucho $$

I have looked at the schematics of the SFD-1001, but the position numbers of all the components are different.
Also the pin assignment to most of the logic ic's are different, which makes tracking down the problem difficult.
I already swapped every chip on a socked without success.
I found a German company that still sells service manuals for this machine, i'm thinking of ordering one....

-donni

Yes, shipping was about 60 eur. The seller only accepted bank wire transfers and it cost me another 30 eur in fees... ouch! I'm not buying anything else on ebay unless it's via paypal.

Can you give me the location of the site selling service manuals? Might come in handy! Or, would you be willing to scan them for me for a small fee?

Steve

sjgray wrote:
Yes, shipping was about 60 eur. The seller only accepted bank wire transfers and it cost me another 30 eur in fees... ouch! I'm not buying anything else on ebay unless it's via paypal.

Can you give me the location of the site selling service manuals? Might come in handy! Or, would you be willing to scan them for me for a small fee?

Steve

The company is called schaltungsdienst lange. http://www.schaltungsdienst.de/anleitungen.html?&L=1
There prices are not cheap but they have A LOT of service manuals.
I ordered the service manual for the 8250lp, when I get it I'll email you a copy.

-Donni

donni wrote:

sjgray wrote:
Yes, shipping was about 60 eur. The seller only accepted bank wire transfers and it cost me another 30 eur in fees... ouch! I'm not buying anything else on ebay unless it's via paypal.

Can you give me the location of the site selling service manuals? Might come in handy! Or, would you be willing to scan them for me for a small fee?

Steve

The company is called schaltungsdienst lange. http://www.schaltungsdienst.de/anleitungen.html?&L=1
There prices are not cheap but they have A LOT of service manuals.
I ordered the service manual for the 8250lp, when I get it I'll email you a copy.

-Donni

Thanks, that would be great! I see there is also an 8296D manual, wouldn't that include the 8250LP as well? Looks like it's only available in German though. I didn't see prices listed.

Steve

sjgray wrote:I see there is also an 8296D manual, wouldn't that include the 8250LP as well?

Heh, good point! Maybe I should have ordered that one - more pages for the same money
The price for the service manual including shipping and tax was 21.35 Euro.

My 8250LP finally arrived from Germany. It's in good shape cosmetically, however when turned on the LED blinks 5 times. I think this means either the 6502 or 6530 is bad. Time to start swapping chips...

Steve

sjgray wrote:My 8250LP finally arrived from Germany. It's in good shape cosmetically, however when turned on the LED blinks 5 times. I think this means either the 6502 or 6530 is bad. Time to start swapping chips...

Steve

It's probably the 6530.
I'm still waiting for the service manual to arrive .......

donni wrote:

sjgray wrote:My 8250LP finally arrived from Germany. It's in good shape cosmetically, however when turned on the LED blinks 5 times. I think this means either the 6502 or 6530 is bad. Time to start swapping chips...

Steve

It's probably the 6530.
I'm still waiting for the service manual to arrive .......

Yup, that was it... I had to sacrifice the 6530 from one of my SFD1001 drives. The 8250LP is working great now!

Steve