Piggyback 4164 to Diagnose Memory Fault

[t0nyt]

Do you have more than standard memory?
Check pcb, I had similar result indicating different ICs from time to time. For me it was logic circuitry.

Yes, standard memory

I've been checking continuity, checking for shorts and any obvious breaks, and can't find anything wrong (piggybacking IC3 didn't help either but thought it was worth a try)

To be honest, given my situation and time constraints (and poor soldering skills), I can't face replacing the logic chips (given its definitely got worse since I changed the memory chip) so am going to give up on this

Many thanks for all your advise and patience, truly appreciated, but this mobo is going to the spare parts bin

Many Thanks

[Chris_68]

Hi

I understand you but when you feel for it and are less frustrated cut the pins near the IC. Then apply solder flux and gently heat the pin and use a pair of pliers/Tweezers to remove pin by pin.

Anyway, well done trying to save the QL.

[Derek_Stewart]

Hi,

If you damage the through plating, this can be repaired easily, I have some experience of this type cicruit board repair.

[t0nyt]

Hi,

If you damage the through plating, this can be repaired easily, I have some experience of this type cicruit board repair.

Thanks Derek, but I’ve no idea if/what I’ve damaged on the board

Will hopefully be able to track down a replacement working mobo at some point

I may try replacing the logic chips, as per Chris, when I can find time, by cutting out the chips and maybe tacking new chips (in sockets I can throw away so I don’t waste the chips) onto the old legs to see what happens

Thanks

[Martin_Head]

Looking at the photo, Is the pin 2nd one down on the left supposed to be connected to that large piece of track.

Also there are a of solder splashes that might be bridging tracks, Give them a scrub with an old tooth brush, and/or scrape them off with a small (watch makers) screwdriver.

[t0nyt]

Looking at the photo, Is the pin 2nd one down on the left supposed to be connected to that large piece of track.

Also there are a of solder splashes that might be bridging tracks, Give them a scrub with an old tooth brush, and/or scrape them off with a small (watch makers) screwdriver.

Hi Martin,

I’ve no idea what is meant to be connected to what, forgot to take a photo before I started. There’s no shorts between pins though.

I have cleaned it up a bit since that photo was taken

Thanks

[t0nyt]

Well I changed the larger logic IC

Minerva won't boot but it keeps (every 15 secs or so) reporting different values that ramfail_bas always says is IC8

So I've replaced IC8 with a socket and tried several RAM in there but Minerva still keeps failing IC8 (and I did a much better job of replacing IC8 than IC11, even took a picture before I began )

I feel sure I've damaged something around IC11

[Martin_Head]

Looking at the photo, Is the pin 2nd one down on the left supposed to be connected to that large piece of track.

Also there are a of solder splashes that might be bridging tracks, Give them a scrub with an old tooth brush, and/or scrape them off with a small (watch makers) screwdriver.

Hi Martin,

I’ve no idea what is meant to be connected to what, forgot to take a photo before I started. There’s no shorts between pins though.

I have cleaned it up a bit since that photo was taken

Thanks

I've just had a look at a PCB, and that 2nd pin down on the left should not be connected to the large track on it's right. From the bottom of the board there are not tracks connected to it.

Also the 6th pin down on the right side has two tracks coming out in a NW and SW directions, The SW one on your photo looks like it might be broken.

Let me know if you would like me to try to take a photo of my board.

[t0nyt]

Looking at the photo, Is the pin 2nd one down on the left supposed to be connected to that large piece of track.

Also there are a of solder splashes that might be bridging tracks, Give them a scrub with an old tooth brush, and/or scrape them off with a small (watch makers) screwdriver.

Hi Martin,

I’ve no idea what is meant to be connected to what, forgot to take a photo before I started. There’s no shorts between pins though.

I have cleaned it up a bit since that photo was taken

Thanks

I've just had a look at a PCB, and that 2nd pin down on the left should not be connected to the large track on it's right. From the bottom of the board there are not tracks connected to it.

Also the 6th pin down on the right side has two tracks coming out in a NW and SW directions, The SW one on your photo looks like it might be broken.

Let me know if you would like me to try to take a photo of my board.

Hi Martin,

Thanks for taking the time to look at it

I’ve just re-checked with a continuity meter and there’s no bridge between the 2nd pin down on left and the large track. Also there’s no break to either track on the other pin

If it’s easy to take a picture that would be great please

Many thanks
Tony

[Chris_68]

I have a bare PCB and can take a photo later.

I still suspect the logic circuitry, since it’s random, which one is it you replaced?