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I have been working on two of these supplies lately that would not reliably start from cold. While there is actually a reasonable filter capacitor on M51996P Vcc (C8), I suspect the resistor divider providing the kick start voltage is operating with too little margin. The M51996P startup voltage...

I recently had some time to tinker with this and replaced the dubious capacitor on the DC/DC converter output side with known good and brand new Panasonic FK but also tried FP (lower ESR) as well as values 22uF, 33uF and 47uF. None of these made any apparent change of the behavior. Next up may...

Very interesting thoughts! This all sounds very similar to what you experience with your PB 100. The DC/DC converter appears to provide around 28V here as well but it's difficult to do proper measurements with the screen assembled. I will replace the capacitor on the DC/DC converter output side...

The DC/DC converter appears to be very sensitive to temperature. If I cool it softly with compressed air the screen goes blank and that rolling shimmer comes back. Took it off and put it back on again but it did no real change. Maybe the module is flakey somehow. It also makes me wonder about...

Unfortunately I don't have any other compatible machine to do part swaps. However, as far as I can see the inverter board only contains the contrast pot. All the rest is for the backlight. I have traced the contrast pot on the board all the way to the connector and it seems good. I'm beginning...

I had one with a flaky CPU card connector once. It would only boot if I put sideways pressure on the card.

Yes, hold on to them or pass them on to somebody! As said, they are fairly unique. I recently repaired two 7100 boards with that symptom that turned out to be just bad vias/traces. Not difficult. It just takes some time.

I have this Powerbook 145 I've been working on for some time now. It's in quite nice shape, both the screen hinges and the original Conner CP2025 drive are still alright. The LCD of course needed some work. It had really bad and uneven contrast from the start but after an uneventfull recap using...

Bump! Did you guys manage to get this driver archived? I have one of these cards and would very much like to try it out

It's a fairly big 3D print but definitely doable and will fit on most printer beds I believe. I also thought of creating an intermediate board for moving the CPU socket a bit towards the back of the LB but I'm a little worried about the clearance under the PSU. Here is a thread with a photo of...

I agree with you. I was also very surprised and did not notice the issue until the very very end of assembly. The heatsink is indeed the first object making contact with the cage but even if removed it will hit the PCB. In theory one may get away with cutting material off the cylindrical...

Wow! I just got the Socket Booster 2.0 and for giggles I tried it out in my IIcx. It works great! Before and after comparison using Speedometer 3.23 Unfortunately there is a clearance issue with the drive cage so it won't stay in this machine but it was a fun test, and meditative solder work...

Normally I think there is a star ground point somewhere. At least for the LC475 it appears to be around the video connector. I have an LC board running outside the case right now and with nice audio and continuity between the grounds. Question is where... This is what the LC475 schematic looks...

Perhaps the machine is held in reset state during this time? Check the state of the RESET signal. A good place is pin 15 on EGRET U10 I think. While you are there also maybe check the +5V sense line pin 12.

I’m also interrested! Did this get properly archived somewhere?

You're right! That was the problem. The REQ and RST lines were not connected. Hooking up a SCSI device to the bus got it stuck on a grey screen and booting without any device at all on the bus gave the usual ?-disk icon. With that fixed the machine now boots without issues :) So even though...

I made progress! I think the memory has been falsely accused. I found two broken traces in the IOData bus going from the data path chips to the rest of the system. In my case bit 1 and 3 were floating which matches the distortion in the chime. Now the machine has a clean chime and produces...

I actually recently did. Or rather I was a little reluctant to remove all that DRAM so instead I disconnected the shared RAS line from the bus driver and pulled it high (the SIMMs have their own dedicated RAS lines), and installed 4x8MB known working SIMMs. By doing that my idea was that the...

I have a Power Mac 7100/80 with a distorted chime and no video output. Probing the onboard memory there is reasonable activity up until right after the end of chime when the CPU appears to crash with what looks like just noise on the address and data busses. Machine does not respond to any key...