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I've changed only a couple of capacitors (the ones after the two diodes), I don't have the rest of them in stock. I'll place an order soon. out of the 5 or 6 ABs I've repaired, none of them had capacitor-related problems. They all had a mix of: broken joints, bad optocoupler , shorted diodes or...

Sure is! checked most of the diodes and transistors, none of them are shorted or very leaky. at this point, I'm quite sure there is an open circuit somewhere

In my case, it is R59, but it does absolutely nothing, no matter if it is all the way to one side or to the other, the voltages still remains the same

The trimmer on the analog board does absolutely nothing. I desoldered it and it checks fine. How do you control the +5V cut out? all of the feedback/control is done on the +12V rail. Soon I'll check some diodes and the SCR, maybe one of them is open/leaky

Well, most of the times I end up keeping the machine rather than selling it. So far I have 173 Apple devices scattered around my house and my grandparents garage. As for repairs, I usually invest the money I earn in more (mostly broken) Apple Computers or Arduino/Raspberry Pi stuff. Is the ED...

Hello! I recently scored three ED Macs, two Macintosh Plus EDs and a Macintosh ED (which is a 512ke). The Mac ED only needed a quick reflow of the J1 connector. The first Plus ED produced a very quick ticking noise no matter if the logic board was connected or not. I quickly noticed that the...

Here is the first prototype I tried it on several powerbooks and it works perfectly! I added a 2A Fuse on the battery output to protect the DC-DC Converter and the PowerBook in case of a problem. I also need to add a battery cell monitor, to make sure that the cell voltages don't go too...

At this point, I think that the problem might be a bad PAL, maybe UE6 or UI6. Unfortunately they are soldered, so they are not so easy to swap with the other board

The screen remains all black, the analog board is good (tested with another SE and the half-video SE/30, the one in the other thread) The "slower" tone only happened once, after rebooting the machine it came back as usual I also replaced one of the Bourns filters, RP2 if I recall correctly...

The sound seems to be ok, both the startup chime and the sad mac tone are loud and clear. Only once, the sad mac tome was "slower" than usual.

I found out that the interrupt key produces a sad mac chime only if you press it after the startup chime, if you wait more that 6-10 seconds it does nothing on the other hand, the reset button always works I tried the same thing with the other board (the one with half video) and no matter when...

The video roms are not the problem, I swapped them and both SE's still show the same problems. Swapping the roms was one of the things I've tried, I found out that sometimes, the roms in a ceramic package loose their content. (I've spent ages troubleshooting an IBM XT Clone only to find this...

Update, I replaced UE8 (and lifted a pad in the process of doing it) but the problem is still there. I repaired the lifted pad and all of the connections seem to mach the ones on the schematic.

took a quick look at the schematics: it looks like it needs at least +12V and +5V, -5V and -12V are used only on a few (serial?) chips and on the expansion slot

perfect!, thanks! does the system start up if I only supply +5V using my bench power supply?

the display remains totally black I can borrow a hot air station from a friend, what is the best way and temperature to remove the chip?

But even if the filters (which I have some of them in stock) and/or the SCSI IC are bad, the system should still show something on the display, right?

I just so happen to have it's original user manual, that also includes pinouts of the various connectors. It seems like the -12V is not present on this model, so all of the voltages are OK. I have no idea why it chimes but doesn't boot

Update! just finished the recap, now the chime is loud and clear. It seems like the machine is not booting from its hard drive looking at the floppy port, +5 is 5.00V, +12 is 12.23V but -12V is 0.03V. EDIT: I hooked up an external SuperDrive with a copy of the NAD in it, apart from the...

Hello The Analog board is OK, I used another SE Board to test it and it works fine, I also installed the board in another SE/30 and it still shows the same issue: faint chime and no video (screen is totally black) This seems to be a very early revision board, with the yellow-band capacitors...