Search results

I have two issues with inserting 5.25" floppies into my external Unidisk floppy drive model A9M0104. First issue is that the disk would get stuck while putting the disk in, as shown in this video. The root cause seems to be not enough clearance for the disk to slide in. A 5.25" floppy disk...

Compare measurements on the two boards. Unplug the analog board, pull it out, and put the two boards side by side. Then using a multimeter compare different points against ground to see if you get the same reading on both boards. You should focus on J1 and J2, and see if any of pins get a...

Do you have a spare board to compare multimeter readings?

If you turn it on, and wait 10 seconds or so, are you able to see the disk image behind the fuzz? Or if you boot to OS, can you make anything out or does it stay exactly like what you have shown in the picture the whole time?

This could be a cold soldier joint. They can be very hard to spot sometimes without checking under a microscope. Quickest way to check it to take a plastic wooden stick and poke at it in various places (especially around J connectors) to see if you get any flicker. Also try pull on the corner...

I think that's a really good clue! This means that the feedback is not working at all, so rdmark may be right on the nose! I've had two Mac Plus's where the optocoupler died, causing the voltage adjustment pot to not do anything and voltages to be off. That looks like a really rare part...

Interesting load tester! Can you please share your design?

On the newer compacts Macs where the analog board is separate from the power supply this may be more feasible, but I don’t see how replacing a CRT with and LCD would be an enhancement that makes it more useful today. This would be the equivalent of taking apart an old working CRT tv, pulling...

Small update. I received a 2nd working IIc. First interesting finding is that when I turn on the working IIc, the CPU and ROM stay cold! The CPU being this cool is expected it seems, as no instructions are being fed. I've also swapped the CPUs and both work fine. When I remove the CPU...

The WIMA MKS-4 is a metallized polyester (PET) capacitor, with an operational lifetime of > 300,000 hours. The RIFA is a metallized paper capacitor. They don't state their lifespan on the spec. As you mentioned, the RIFA caps are well known to degrade and fail over time, so it definitely has a...

I got an Apple II Plus which didn't power up. I started with the power supply. Visual inspection of the Astec AA11040 shows that it's in pretty good condition. However when I turn it on there was nothing on the output. First issue I found was that the fuse was blown. This would indicate...

Have you double checked the UE8 connections? This area just looks really bad. I had an SE/30 that looked similar in this spot and gave me lots of trouble. Reflowing the UE8 was a real pain, I noticed if I ever slightly warped the board video would still disappear even after pulling the chip...

Recently, I noticed that two of my Mac Pluses' speakers sound as if they're blown out during the bong boot sound. You know you have a bad speaker if the sound at boot is annoying rather than pleasant. The speaker is mounted to the Mac Plus analog board via a rivet eyelets. Best way to...

Thank you! I checked the book before but somehow completely missed it! Interestingly enough, it says "or replace the disk drive". It's semi-suggesting that replacing the drive may fix the sound? All my floppies have already been re-capped, so not sure how a new drive may help with the...

Had some extra time to investigate more today. Took a Mac Plus apart and laid it out flat so that it's easier to isolate where the sound is coming from, as shown above. The clicking is coming from the transformer (part # Astec 01820 157-0025-A). However due to the electrical interference...

I'm troubleshooting this Apple IIc which shows horizontal lines on boot with no sound: It got into this state because a capacitor on the floppy drive went bad and shorted the +12v to Ground. By the time I found the culprit, the +12v did some damage on the main board, and need help...

A couple of my Mac Plus's make this very faint click click sound. Has anyone ever had the same and figured out what it could be? -It's coming from the lower center half of the analog board -Sounds like small electric shocks -With lights off, no visible arc or spark is seen -Board has been...

U3 strikes again! I re-capped an international Mac Plus analog board. It booted just fine. The 5v rail was a bit low at 4.78v, but when I went to adjust the pot nothing happened. After cleaning and testing the pot, I was still getting the same results. I then realized it was the U3 probably...

Can’t tell from the video, but can you confirm W12 is in place so that this is configured for 110v?

The Apple IIc external power supply (A2M4017) doesn't have a non-destructive way of being taken apart, so if it dies a replacement is likely needed. Here is a guide on how to make a replacement power supply. The Apple IIc manual states that it operates at 12v~15v. Maximum power consumption is...