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Commodore 8296 Computer
  by Bill Degnan - 09/23/2006 23:04
OEM Commodore?
"Malvern Particle Sizer"

http://www.vintagecomput...commodore/Malvern_8296/

Initial inspection of unit - does not work.

1. Monitor electronics loose

2. Made in England but US electric compat.

3. Took off monitor, unplugged from base unit.

4. The power was disconnected, board detached from monitor. I re-attached, no screen output.

5. Disk drive gave familiar long blink/2 short blinks of a IEEE drive with a good controller. Internal cable IEEE.

6. The P/N of the drive controller is 251203 REV B 1983. (This is the sfd-1001 I have been told...)

7. Motherboard:
"80/40 column CPU 64/128
Ass number 324645"

8. Add on card above motherboard using two connectors to attach to mother board, with power:
"Malvern Instruments Ltd."
"MSM82C55A-5RS"
"42041"
"2,5 PC"

9. No keyboard response to Shift+RUN/STOP

10. Can hear transformer and fan moves.
no part number

11. For kicks, plugged keyboard into B700 (B-128 high profile B Series) The keyboard for the Malvern CBM 8296 is mapped differently, here is an example:

k=?
j=7
@=9
]=Return cursor to top left (HOME)
shift = w
REPEAT = e
CLR/HOME = TAB
4 on keypad = a
etc.


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Commodore 8296 Computer
  by Bill Degnan - 11/13/2006 21:48
This question was forwarded to me, I am posting it anonymously in the event someone can answer. I can only speculate that the Malvern runs PET 8032 software..

Hello, I just bought a malvern 8296 computer off ebay.
Could you pleas tell me is it possible to run commodore
software on this computer. All I can do is turn it on and
it says commodore basic 4.0.THANKS


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Commodore 8296 Computer
  by Bill Degnan - 11/15/2006 23:07
Overall status - It still does not work, but I am working to resolve.
I have removed the add-on card to get at the motherboard to take some pictures
http://www.vintagecomput...odore/malvern_CBM_8296/
See especially
http://www.vintagecomput...n_CBM_8296/p1010008.jpg
The 6545 chip (Cathode Ray Tube Controller) in this picture is hot to the touch, probably is bad. I am currently searching for a replacement.

Questions:
1) does this chip normally run hot?
2) could the display be causing the problem?
3) Any diagnostic ideas?

The Motherboard part number
http://www.vintagecomput...n_CBM_8296/P1010011.JPG
80/40 Column CPU 64-128K
Assy Number 324645 Rev B
Made in West Germany


I have not spent time with a voltmeter, yet but that's next.

Here is a good link with more info:
http://www.sothius.com/h...al/cbm8296addition.html

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Source of CBM IC's
  by Bill Degnan - 11/16/2006 11:32
I placed an order with http://www.unicornelectronics.com/
The minimum order is $20, so I got one each of all possible match chips.

Most likely the plain 6545 or 6845 will work because they are 1 mhz, but due to the fact that this is a custom/OEM 8296 I thought I would be prudent to order some 2mhz's, given the minimum order is $20 and then I have them for future use.

Quantity Name SKU Each Total
1 6545 6545 $3.99 $3.99
1 6545A 6545A $5.99 $5.99
1 6845 6845 $2.99 $2.99
1 68B45 68B45 $7.99 $7.99


Bill Degnan

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Commodore 8296 Computer
  by Bill Degnan - 11/22/2006 21:49
Attempted a 6545 replacement, same symptoms (chip getting hot) so I powered off.

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Commodore 8296 Computer
  by Andre Fachat - 12/31/2006 06:38
Hi Bill,

did you check the PLA outputs (UE5, UE6)? Most 8296 I had that seemed dead had broken PLAs. when they are broken, the outputs show about 2-3V constant instead of 0 or about 5V changing. An oscilloscope or logic probe would be good to check.

André


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Commodore 8296 Computer
  by Andre Fachat - 12/31/2006 06:39
Sorry, forgot: the CRTC (6545) does get pretty warm in normal operation.

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Commodore 8296 Computer
  by Bill Degnan - 01/02/2007 16:20
I can do that. Thanks for the tip.

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8+V Out from pwr supply bad
  by Bill Degnan - 02/05/2012 21:02
returning to this system after a number of years and a lot more general knowledge to apply to this system...the 8V out is bad from the main power supply.

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