Commodore 3040 disk drive

[magicappstore]

Hi Everyone,

I'm trying to repair a 3040 dual floppy which simply doesn't seem to work at all when I power it on. Looking at the circuit board I can see a capacitor has blown up and is all black and crumbling. It is in position C31, though all that part of the circuit board is black. Assuming it is the same type of capacitor as C29 & C33, what kind of replacement can I use?

I see they only have +1 & +35V markings on them, can anyone advise where I can get replacements from?

 

[carlsson]

Can you use any information from these schematics, or maybe you already looked at them?
http://www.zimmers.net/anonftp/pub/cbm/schematics/drives/old/4040/index.html

 

[dave_m]

From the data provided by Anders, it looks like C29, C31 and C33 are 1 microfarad capacitors rated at 35V minimum. Any mail order parts place can provide them. You may want to use a non polarized type or if you use a polarized type make sure the "+" side goes to pin 2 of each regulator. After replacement, check connector P3 for the following voltages:
pin 1 for +5V
pin 2 for ground
pin 3 for +12V
pin 4 for ground
pin 5 for +12V

http://www.radioshack.com/product/index.jsp?productId=12401431

 

[magicappstore]

Excellent! Thanks for the information, I shall get some ordered straight away and then test the voltages on the connector.

 

[fachat]

Would you mind checking the ROM chip numbers with what is available on the zimmers archive? I am not sure if all the DOS versions are there already.
http://www.zimmers.net/anonftp/pub/cbm/firmware/drives/old/4040/index.html

Many thanks & good luck in your repair!
André