UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Computers

Notices

Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

Reply
 
Thread Tools
Old 28th Dec 2021, 8:35 pm   #1
ScottishColin
Heptode
 
Join Date: May 2012
Location: Perth, Scotland
Posts: 698
Default Cbm 3040

So.....

If I were to buy a non-working CBM3040, has anyone gone through a refurb before? Schematics seem to exists at zimmers.net.

Colin.
ScottishColin is offline   Reply With Quote
Old 30th Dec 2021, 10:54 am   #2
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 7,684
Default Re: Cbm 3040

It doesn't seem like anyone has, for the moment at least.

The main thing about them, assuming we are referring to the floppy drive unit, is that they are obviously part electronic and part mechanical.

With the test gear you have now you could have a stab at any electronic fault on them but mechanical faults could range from bad belts to head alignment, which requires fairly specialised gear to set up, or a failed motor.

So, there would be an element of risk, you might find you have a fault which is not repairable due to unavailability of replacement hardware. On the plus side it appears to be a twin floppy unit, so you could, at a push, combine parts from one drive with parts from the other to make one good one. Not ideal but better than nothing working at all.

If you just wanted the functionality without the fuss, I suspect that the price of an SD2PET would not be much different to what would be being asked for this drive unit, maybe even cheaper.
SiriusHardware is online now   Reply With Quote
Old 30th Dec 2021, 11:59 am   #3
electronicskip
Octode
 
electronicskip's Avatar
 
Join Date: Oct 2010
Location: Gloucester, Glos. UK.
Posts: 1,774
Default Re: Cbm 3040

No idea about the 3040 which is similar to a 4040 by the looks of it but this youtube repair video may help you decide to buy it or not.

https://www.youtube.com/watch?v=W5BBjIEiitY
__________________
Oh I've had that for years dear!!
electronicskip is offline   Reply With Quote
Old 30th Dec 2021, 4:36 pm   #4
TonyDuell
Dekatron
 
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 4,348
Default Re: Cbm 3040

I've repaired the 8050 and 8250LP if that's any help.
TonyDuell is offline   Reply With Quote
Old 31st Dec 2021, 6:23 pm   #5
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 7,684
Default Re: Cbm 3040

To be more precise the circuit diagram which includes the 3040 can be found here on Zimmers:-

http://www.zimmers.net/anonftp/pub/c...schematics.pdf

The first thing I notice is that, being IEEE-488 devices, they use the same line up of three MC3446 buffers as the PET itself does.

If the unit was failing to communicate with the host but all supplies seemed to check out OK, I think I'd be looking at those fairly early on.
SiriusHardware is online now   Reply With Quote
Old 31st Dec 2021, 6:32 pm   #6
TonyDuell
Dekatron
 
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 4,348
Default Re: Cbm 3040

I don't know if the other CBM disk drives do this, but the 8050 blinks an error code on the LEDs (all 3 LEDs blinking in unison) if it detects an error at power-up. It does a checksum of the interface processor ROMs, a RAM test, checks communication to the controller processor [1], etc. Each error gives a different number of flashes, so you know the first fault to find...

[1] The 8050 has a pair of 6502s in it. They are clocked in antiphase, which means it's easy for them to have a shared area of memory to communicate through.
TonyDuell is offline   Reply With Quote
Old 5th Jan 2022, 8:02 pm   #7
ScottishColin
Heptode
 
Join Date: May 2012
Location: Perth, Scotland
Posts: 698
Default Re: Cbm 3040

Apologies for the delay - illness in the house (not serious).

The seller seems to have gone away, so I'll not be buying this one.

Colin.
ScottishColin is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 8:30 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.