Posted By
crock
on 2011-10-22
09:31:32
 |  Pre production Plus4 board manufacturing fault
When I acquired my C= 232, I also acquired this pre-production plus4, serial number 190, from the same source. While trying to find why my diagnostic harness caused the machine to fail to boot, I realized that this machine has a rather major manufacturing fault. You can see it clearly in the picture when you know what to look for. Bonus point for first to spot....
http://www.inchocks.co.uk/c64/190_PCB.jpg
Rob
btw, how do I have to enclose a link to make it clickable in this forum?
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Posted By
TLC
on 2011-10-22
06:08:23
| Re: Pre production Plus4 board manufacturing fault
They somehow forgot about the ROM jumpers...  Not bad... 
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Posted By
crock
on 2011-10-22
06:37:33
| Re: Pre production Plus4 board manufacturing fault
I hadn't actually noticed that!
The more interesting mistake is that the key-ways on the user port are reversed! They should be between contacts 1 & 2 and between 10 & 11. On this board they are between 2 & 3 and 11 & 12.
This means that you could (as I did with my diagnostic dongle) plug devices in upside down, sending 9v AC into all the wrong places! 
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Posted By
TLC
on 2011-10-22
07:14:59
| Re: Pre production Plus4 board manufacturing fault
Didn't know your diag dongle was to be plugged to the user port, I only remembered the ROM part... Well, that looks terrible indeed. I hope the machine sustained no damage... :o
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Posted By
crock
on 2011-10-22
12:21:50
| Re: Pre production Plus4 board manufacturing fault
Well, it did actually  , although the fault may have been there already. One of the drams had a column stuck high. Fortunately is was easy to trace and replace the culprit. It's 100% again now.
My diagnostic setup has loopback dongles on all the external ports. The user port specifically has checks for the 8 general i/o ports and on the RS232 RTS/CTS Rx/Tx, DCD/DSR.
See the movie here:
http://www.youtube.com/watch?v=BCw3PD5cb88
Rob
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Posted By
SVS
on 2011-10-23
03:54:30
 | Re: Pre production Plus4 board manufacturing fault
@crock:
>>btw, how do I have to enclose a link to make it clickable in this forum?
<*u*r*l>complete_link<*/*u*r*l> (without asterisks)
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