Cbm pet 8296-d black screen

[Desperado]

I already know what to replace from the early Christmas tree light display...

Really????
but how do you know everything ???
Could it be that it does this because there is no data cable connected?

 

[daver2]

Nope, that is a guess isn’t it ?!

The clue is back in post #493 where I provided you with a link to the USER and MAINTENANCE manual for you to read...

In particular, the MAINTENANCE manual (on page #5) tells you how to decode the flash sequence from the POST firmware (Power Up Self Test).

Now can you tell me what is wrong and requires replacing?

Dave

 

[Desperado]

Nope, that is a guess isn’t it ?!

The clue is back in post #493 where I provided you with a link to the USER and MAINTENANCE manual for you to read...

In particular, the MAINTENANCE manual (on page #5) tells you how to decode the flash sequence from the POST firmware (Power Up Self Test).

Now can you tell me what is wrong and requires replacing?

Dave

6530 ?????

 

[daver2]

Yep...

Which potential devices?

Dave

 

[Desperado]

Yep...

Which potential devices?

Dave

uk3?

 

[daver2]

Yep, or what other component on the next line?

Dave

 

[Desperado]

and UH3?

 

[daver2]

Yep, which is what component?

Dave

 

[Desperado]

Yep, which is what component?

Dave

mos 6502 !!

 

[daver2]

Correct!

So, if you look at the 8050 digital logic board, you will see that it has two (yes two) 6502 CPUs! It is more powerful than the PET computer itself...

Do you have any spare 6502 CPUs and is UH3 in a socket? If so, you could try one in UH3 first.

What can you tell me about the MOS 6530? See if you can find a data sheet for it - or look it up on the internet. There is something very special about this particular chip that is very important if you are going to look for a replacement... Also, what is the exact part number on UK3? 6530-???.

Dave

 

[Desperado]

Do you have any spare 6502 CPUs and is UH3 in a socket? If so, you could try one in UH3 first.

Yes, i have one 6502 spare part and i tested on UH3 but i have always same problem
For 6530 rriot i know that there aren't spare parts....must need to create a pcb and burn eproms

 

[daver2]

Ok, so we know it is not UH3.

What is the exact part number for UK3 on your board, and have you looked for one?

Dave

 

[Desperado]

This is uk3 on board:

 

[daver2]

Yep, that’s a 6530-038 with DOS 2.5 firmware.

The chances of finding one of these is the same as winning your lottery! Unless you can find a donor disk drive digital logic board...

You can get replacements consisting of a 6532, a 74LS32 and an EPROM.

Dave

 

[Desperado]

is this?

https://www.vintage-radio.net/forum/attachment.php?attachmentid=224204&d=1610205779

 

[daver2]

Yep, that’s one.

You can build your own from here: http://www.baltissen.org/newhtm/6530repl.htm.

Zimmers has the ROM image you require.

There is still no 100% guarantee that these will fix the problem though. Just warning you...

Dave

 

[Desperado]

And this?

MOS 6530-048 / 901869-01 (RRIOT)

RAM/ROM Input-Output Timer (RRIOT) for Commodore floppies 8050 and 8250 MOS 6530-48 Commodore P/N 901869-01 (Illustration similar)

www.polyplay.xyz

 

[daver2]

That looks to be for a later 8050/8250 disk drive with DOS 2.7 - so that could work if you want to take a punt on it not being a fake.

Dave

 

[Desperado]

That looks to be for a later 8050/8250 disk drive with DOS 2.7 - so that could work if you want to take a punt on it not being a fake.

Dave

i suspected that's fake site..... but if i can pay through paypal, can i try.....

 

[daver2]

What disk drives do you have (e.g. Tandon)? Some of the firmware is bespoke to the disk drive that is fitted if I remember correctly.

EDIT: Yes, the -048 is only suitable for MPI 101/102 disk drives. Not Micropolis disk drives (this was the -047).

Lots of things here to trip you up!

Dave