thunter0512
Veteran Member
On the LAB-8/e I have been working on (until now most power supply repair and deep clean) I finally assembled a fairly minimal set of boards.
When I powered up this configuration no smoke came out which was pleasing (especially for the owner of the machine).
About 50% of the front-panel lights were dead as confirmed with a multimeter.
I ordered 50 lamps from Mouser but I am in Australia so I am lucky if I see them by the end of next week.
I re-arranged the remaining working lights so that I have 4 address lights and 9 data lights.
This allowed me to do some basic manual memory testing via the deposit and examine switches.
Unfortunately not all is well - bits 4 and 8 behave strange when I verified previously deposited bit patterns. The other bits appeared fine during the limited testing I did (all zeros, all 1s, alternate 01s, alternate 10s and walking zero and walking 1).
Bit 4 is always zero but sometimes (mostly) when it should be 1 instead bit 8 is 1 - even though it is meant to be zero. The bits 4 and 8 interact in some way meaning possibly there is a common component fault.
I have 8 kWords of core implemented via the following boards:
G111C memory sense inhibit
H212 core
G233E memory X/Y drivers
The G233E has a strange bow in the upper middle section other than that there is no obvious damage to the 3 boards. There is no obvious heat damage on the G223E so I am at a loss explaining that bowing. Has anybody else see this?
Could you please advise on how best to isolate the cause of the memory fault?
As the 3 boards are connected via four H851 top-connectors it is not trivial to probe any signals. So I am struggling to come up with a sensible way of debugging the boards.
Also could you please recommend what documents to read to get a better understanding of the core memory implemented by these 3 boards?
Thanks for any help or suggestion.
Best regards
Tom Hunter
When I powered up this configuration no smoke came out which was pleasing (especially for the owner of the machine).
About 50% of the front-panel lights were dead as confirmed with a multimeter.
I ordered 50 lamps from Mouser but I am in Australia so I am lucky if I see them by the end of next week.
I re-arranged the remaining working lights so that I have 4 address lights and 9 data lights.
This allowed me to do some basic manual memory testing via the deposit and examine switches.
Unfortunately not all is well - bits 4 and 8 behave strange when I verified previously deposited bit patterns. The other bits appeared fine during the limited testing I did (all zeros, all 1s, alternate 01s, alternate 10s and walking zero and walking 1).
Bit 4 is always zero but sometimes (mostly) when it should be 1 instead bit 8 is 1 - even though it is meant to be zero. The bits 4 and 8 interact in some way meaning possibly there is a common component fault.
I have 8 kWords of core implemented via the following boards:
G111C memory sense inhibit
H212 core
G233E memory X/Y drivers
The G233E has a strange bow in the upper middle section other than that there is no obvious damage to the 3 boards. There is no obvious heat damage on the G223E so I am at a loss explaining that bowing. Has anybody else see this?
Could you please advise on how best to isolate the cause of the memory fault?
As the 3 boards are connected via four H851 top-connectors it is not trivial to probe any signals. So I am struggling to come up with a sensible way of debugging the boards.
Also could you please recommend what documents to read to get a better understanding of the core memory implemented by these 3 boards?
Thanks for any help or suggestion.
Best regards
Tom Hunter