Originally, when powered on, my Compaq Portable Plus yielded this error code on the display:
1000 201
According to the Maintenance and Service manual, that indicated an error with U38
1000 201 Bank 1, Parity Bit U38 Replace System Board
So, I replaced U38 (an OKI M3764A-15), repaired a questionable trace and confirmed continuity. On startup, it now proceeds to this error code:
7020 201
Removing the extended memory board (a Persyst Time spectrum 384L) or replacing it with a different (working) memory card allows the system to proceed and reach a fixed disk error 1701 prompt. I would like to replace the faulty memory in the Persyst card, so checking out the extended memory codes from the manual
xx Code Beginning Address
70yy 201 448 Kbytes
yy Code Failed Bit
xx20 Data Bit 5
Which chip is bad? The same card was recently listed on eBay https://www.ebay.com/itm/NOS-Vintage-Persyst-Time-Spectrum-384L-Circuit-Board-Card-/273201341598?
My board is fully populated with (TI TMS4164-20NL), so I think the top chip in bank 3 is faulty, if I'm counting correctly.
1) Can someone confirm this should be the faulty chip and also can I replace it with one of my spare OKI memory chips? They should be equivalent and the OKI is a faster chip, so it should work?
2) Does anyone have documentation for this card? (I know that a manual was included in the eBay auction and if I had seen that while it was up, I would have tried to get it) I found where someone asked about the dip switch settings, but I was hoping for a bit more than that.
3) My computer uses standard drive hex top screws to secure the access panels and the expansion cards, but the pictures that I have seen of other CPP's online use torx screws - have mine been replaced or were both types of screws used by Compaq?
1000 201
According to the Maintenance and Service manual, that indicated an error with U38
1000 201 Bank 1, Parity Bit U38 Replace System Board
So, I replaced U38 (an OKI M3764A-15), repaired a questionable trace and confirmed continuity. On startup, it now proceeds to this error code:
7020 201
Removing the extended memory board (a Persyst Time spectrum 384L) or replacing it with a different (working) memory card allows the system to proceed and reach a fixed disk error 1701 prompt. I would like to replace the faulty memory in the Persyst card, so checking out the extended memory codes from the manual
xx Code Beginning Address
70yy 201 448 Kbytes
yy Code Failed Bit
xx20 Data Bit 5
Which chip is bad? The same card was recently listed on eBay https://www.ebay.com/itm/NOS-Vintage-Persyst-Time-Spectrum-384L-Circuit-Board-Card-/273201341598?
My board is fully populated with (TI TMS4164-20NL), so I think the top chip in bank 3 is faulty, if I'm counting correctly.
1) Can someone confirm this should be the faulty chip and also can I replace it with one of my spare OKI memory chips? They should be equivalent and the OKI is a faster chip, so it should work?
2) Does anyone have documentation for this card? (I know that a manual was included in the eBay auction and if I had seen that while it was up, I would have tried to get it) I found where someone asked about the dip switch settings, but I was hoping for a bit more than that.
3) My computer uses standard drive hex top screws to secure the access panels and the expansion cards, but the pictures that I have seen of other CPP's online use torx screws - have mine been replaced or were both types of screws used by Compaq?