dead TT motherboard repair attempt

[jookie]

That's a nicer solution for the SMT boards. The through hole is a pain to desolder and clean up but Lyxman's ram board add-on works well.

Yes, that's what I've thought, and as I could swap my through hole (THT) RAM with this SMD RAM with a friend (for a price of upgrading one of his 2 MB SMD RAM for him), that's what I did - skipped to try the THT, went straight to SMD. But the real motivator here was that I couldn't find the THT chips to buy, but I could get those SMD ones, so also helped with the decision.

Great work

Thank you both

[Steve]

Hi Jookie,

I am struggling to see where the DCU UA01 is on the TT motherboard, could you help point it out for me? Thanks

[jookie]

I'm not currently sure if it's the left one or right one, but you could measure connections from one and other to some known chips to tell them apart. Both are C300581 chips.

You can measure pins PD0-PD7, if they are connected to UA02 (== 5380 SCSI chip, which is on the right on MB), then that chip having the connection to UA02 is UA01. My first guess is that it would be the right one (as the SCSI chip is on the right).

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[Steve]

Thank you. Yesterday I re-flowed all the solder on each surface mounted PLCC chip due to some very odd infrequent issues. Do you think it is possible that you could sometimes have a dry solder joint on one of these chips legs?

[jookie]

Thank you. Yesterday I re-flowed all the solder on each surface mounted PLCC chip due to some very odd infrequent issues. Do you think it is possible that you could sometimes have a dry solder joint on one of these chips legs?

Well, anything is possible... Although there are so many sources of problems on old machines, that one cannot be completely sure

[32bitminus]

Was it ever fixed?

[jwd]

Was it ever fixed?

Just a bump, would like to know too.

[jookie]

Was it ever fixed?

Just a bump, would like to know too.

Mine was fixed - as I wrote before. Steve's one - I have no idea