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Well, this isn't good. It looks like the cap managed to leak all over the ROM. I managed to get it out of the socket while only breaking two pins. I'm hoping it'll work well enough to dump. Fortunately replacements are cheap.

I've had an Apple Thermal Transfer printer on the shelf waiting for repair for a while and decided to dive into it. It powered up but then something started smoking. Uhoh! It looks like at least one electrolytic capacitor (C27) severely leaked and may have damaged a nearby ROM. Before digging...

I also have the Amscope trinocular on the boom stand. I bought it during a Black Friday sale of there's a couple of years ago. You may want to considering waiting a bit to see if they do that again. I have the HC210 camera and really do not like it, but am not sure which options would be much...

Just a little follow up on this. I did end up recapping the AC adapter, but it was still dead and I wasn't sure what was wrong. I ended up getting a generic adapter with the same specs that worked fine. Here's the display running..

Is there a resource for common failure points and adjustment of the tray loader drives? I have one that isn't successfully reading discs. I assume the laser power pot needs adjusting and/or the drive needs a recap. It's pretty fiddly so was hoping to find a teardown and repair guide before...

Yeah it works. I might have hit those pins when removing the sticker on top of the IC.

Neat idea. @eric have you considered that as a feature before?

With asking prices for these adapters being kind of absurd, I figured it might be helpful to consider reverse engineering one. It seems like a couple of special purpose ICs, a ROM and a surprising amount of passives. I don't think I'm up for the challenge of reverse engineering it, but figured...

I had a similar issue post recap. esc, 4, 5, 6 and + would short the reset line when pressed. It turns out I shorted a trace right next to C24+ which was the issue. Maybe you did something similar near C15 or C26? I'd check that area first or by C116/C14 if you have the keyboard on the right...

Chassis, without a resistor. I'm still chasing down the problem. I found one open capacitor so far at C39 but replacing it didn't change the symptom.

I found a pad for C1 had come loose from all of the handling of the board. I reattached it and now get a chime, no video and then lose voltage (flup flup flup noises). The rectifier at CR20 seems okay, so maybe I have a bad cap somewhere else now. It's weird that the symptom keeps changing.

Wouldn’t -12V just be needed for audio and maybe serial? I’d be curious to know if it’s required for basic operation.

Update: Replacing Q7 changed the symptom to a vertical line (collapsed horizontal deflection). Q6 tested okay. Will test Q3 next.

Nearby resistors all tested okay. There is a 2N5485 (Q5) off of U2 pin 3 that shows resistance between source and gate in both directions. I'm not sure if this is because my meter isn't suited for it or if the transistor failed, but I've ordered some replacements to try.

Update: +12V, -12V and +5V are all testing okay at the floppy port. Next I'm going to try to check components downstream rom U2 on the analog board.

I discharged a 128K Mac without a bleeder resistor and manage to damage it. At first I got a chime but no raster at all. Per Macintosh Repair & Upgrade Secrets, I replaced the LAG chip on the logic board and got raster lines but a dark screen. I then replaced U2 on the analog board, but the...

I always wondered why many SCSI terminators are dual sided/gendered. Apparently it’s to help terminate further up the chain as needed but also works perfectly to terminate this drive using a typical 25-to-50 pin cable.

Not the backwards IDC-50?!

There is a pair of pins on the front side of the controller, but it’s 0V all the time. The manual for the Seagate drive itself refers to a diagnostic that uses a LED thats enabled by shorting some of the SCSI pins to ground. There’s nothing in the manual about a general activity LED. And...

The face plate has a LED diffuser but there’s no apparent header for it on the drive mechanism. For now I just connected a small green LED with a 100ohm resistor to +5V so at least it does something. Should it be possible to tap into the SCSI IO to make an activity LED?