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View Full Version : Commodore 8050 5 Flash Part 2



falter
December 25th, 2013, 04:37 PM
To refresh, I have a Commodore 8050 that was working prior to a cross country move and then wasn't upon arrival. It gives a 5 LED flash code.

According to the manual, that means either the 6502 or the 901483-03 (6530). In the lot of chips I bought, I had three 901483-03s. Also have a 6530-003 which I'm not sure is the same thing?

Anyway, I tried the 901483s. Nothing changed the flashing LED. Then I tried the 6502s (I have tons). No change there either. Are there any simple home tests (lacking an oscilloscope for the moment) that I can do to get any sense of whether the 901483's I have are in fact alive?

I don't see any evidence of damage to the board, but being that it broke after a move, I haven't ruled that out.

jltursan
December 26th, 2013, 12:21 AM
Sounds like a cold solder joint to me, have you reseated all the socketed ICs?, try also to double check the 6502/6530 sockets. I suppose that there're no corrosion signs, isn't it?

Pet Rescue
December 26th, 2013, 02:19 AM
Hi it may be worth checking any capacitors, diodes and resistors. They may have gone short or open circuit and then check
any 74lsxxx type chips.

giobbi
December 26th, 2013, 03:29 AM
I discovered the flash led code isn't 100% reliable. When I was fixing my 8250 I got a flash code telling me one of the two 6502 was bad, while the real problem was a broken ROM.
I think it's better to forget the flash code and check other parts, including the ROM ICs.

falter
December 26th, 2013, 11:25 AM
Sounds like a cold solder joint to me, have you reseated all the socketed ICs?, try also to double check the 6502/6530 sockets. I suppose that there're no corrosion signs, isn't it?

The board is in excellent shape from what I can tell -- I am the second owner and it has always been carefully stored. It belonged to a school before me. I've looked for any signs of physical damage without any luck. There are two ceramic ROMs though I kind of wonder about. I've reseated all of them in the past, but I'm going to hunt through my inventory here and replace every chip I can, just to see if I get a different result. I really doubt all of my 6530s are bad.

falter
December 26th, 2013, 11:26 AM
I checked the 2114s but I'll check the 74lsxxxx ones too. Still have to learn how to properly check things like diodes, etc.

falter
December 26th, 2013, 05:45 PM
I've officially swapped every socketed chip on this thing but no luck.. still 5 flash code.

I was looking at the board and noticed something I hadn't seen before:

1653416535

Wondering if maybe those are my problem. They were pretty hot.

jltursan
January 1st, 2014, 11:40 PM
Whoops, seems that CR5 and maybe CR6 had blown. Based on the service manual, both are diodes:

CR5 1N5235 B 6.8V Zener
CR6-15 1N4005

You'll need to check the schematics to identify them. Also keep in mind that something more can be broken next to them, both phisically (look the burnt zone!) or electronically (check the schematics again).