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I’ve 3D-printed replacement bumpers for the hard drives - really just round spacers the arm rests against. I presume you have the Quantum GoDrive. I’ve replaced four of them now, two for my Compaq Contura Aeros as well :) I definitely wouldn’t fit an SD card device, it just wouldn’t have the...

I’ve fixed three PB100s. Two of them had a SMD resistor, 420k I think it was, that had gone open circuit - near the display cable connector on the logic board. This caused a no-backlight scenario. The black-LCD scenario (i.e. all pixels black) is usually caused by the ~30V drive voltage not...

Ahh yes, I have a Powerbook 100 LCD where the brown ribbons (with their driver chips) have disintegrated, mainly as a result of the capacitor juice leaked from the 8x rectangular electrolytics on the back :( I have another LCD where the ribbons are intact but there’s a pink splodge from the...

Nice work maintaining continuity of a discussion, it’s what makes this forum great when searching for similar problems :) I notice that in compact Macs that suffered a battery explosion, the tube-shaped quartz oscillator for the RTC is fragile and affected by corrosion. That thread contains good...

How did you go with this one? I have yet another Mac Classic analog board with problems. Like you, I had no vertical deflection at all, but I actually solved that by changing RL2 - a low-ohms tiny resistor under the flyback transformer - it had gone open-circuit. Now I have the usual...

Thanks. The interesting thing is that I had the codes when there were soldering faults, and once I find and fix all the soldering faults (including the output enable lines, etc.), then I have a checkerboard instead. That’s happened with two different sets of RAM chips now. I don’t know what my...

Thanks for this info :) Two things make this interesting. I have one drive that always works fine with the same Mac Classic logic board that I’ve been testing the faulty drives with, so I seem to have the opposite to you, unless perhaps two drives are affected by the logic board fault and the...

Yes. I have two 1.44MB Sony SuperDrives with this exact problem. It’s driving me mad. I call it the Dugaduga problem, though that’s not helping in Google searches, I have to admit :) The leadscrew stepper motor keeps running until the sensor is un-triggered. Moving the heads by hand (to...

If there are shorts on the address lines, the Sad Mac does not display completely (ie. has glitches). If the data lines are all connected but not the address lines, the checkerboard has glitches. I found that out when I fitted 4MB-worth of RAM instead of 1MB and interestingly had a checkerboard...

I think, possibly, we were wrong. Today I’ve fitted two different sets of RAM chips and figured out that this happens; - When address pins are all correctly connected, a clear Sad Mac icon and codes appear. (If some address lines are not connected, there are vertical lines missing from the...

It does doesn’t it, I misread it actually, thought it had two DQ2s. Having two DQ3s and no DQ2, as it says, seems impossible. I reckon these chips will work and I just damaged them. The 1MB 72-pin SIMMs were taken out of Macs during upgrades, long ago. I have at least half a dozen SIMMs; plenty...

The error code 0000000E 0000F000 seems to be a rare one, I had some trouble trying to find a direct translation. The most plausible explanation to me seems to be that some of the RAM was working and the upper part was not. The original RAM had D0-D3 pins, while the RAM I used had DQ0-DQ1 and...

Thank you Phipli for your carefully-considered reply :) that’s just what I was thinking, the clean display of the Sad Mac albeit with the error code (bus error?) makes me think it must have been working to some extent, where a checkerboard pattern feels like the RAM isn’t working. As you said...

Ok, so obviously the answer is neither, but I’m just about at my wit’s end :) Macintosh Classic. The analog board had the usual leaked caps, leaky diodes, faulty optocoupler, etc. so the wobbling checkerboard was fixed by getting the voltages right - a happy bong, and all good. But that was a...

How did you go with this one in the end? I had identically-low 4.3V from two different analog boards after replacing all the parts that you did. One of the boards is fixed after replacing the two mains filter caps. The other, still no change and I don’t know what’s keeping the voltage low.

DP13 on the boards I have is beside the heatsink for the 12v voltage regulator, seems to be a 1N4001 according to the Bomarc schematic. QP2 is a MOSFET that’s some distance away. I wonder if you meant DP12? - that’s a BYD34J in the schematic. I’m chasing the same problem as everyone else. Have...

Mine won’t start at all (actually I have two with identical wobbling screens) - I have 4.6V on both. I shall recap the logic boards anyway and report back, since I note that the voltage jumps to 5.3V with the logic board disconnected. PP1 measures 200 ohms to 0 or thereabouts.

I have the same problem myself. Low 5V, wobbling screen, have now replaced most analog board caps (a few more than in the guide, I did the brown one up by the flyback transformer, since all the brown caps elsewhere had leaked) and I’ve replaced the optocoupler and the diodes, and the small...

Nice work, I’m similarly confronted with one of these. I wonder how all those parts can be faulty at once… Does the MOSFET fail and take out the TDA4605 with it, or was it just the 1N4148 diodes all along? If they all need replacing then it will take me weeks of separate orders. I laughed when...

It’s quite late to revive this old discussion, but I got some nice results last week with about a 5-10% hydrogen peroxide solution in water, keycaps stuck onto blobs of blutack - sticky tack, don’t know what you call it where you are :) Bubbles (released oxygen as the H2O2 turns into H2O) are a...