Search results

Ok so there is a 74F32 near the quartz that could be involved in the clock multiplier. But I can’t found anything about the sc464ayb. I’ll try to find out the circuit, I fear the 166MHz-P to be really different and not comparable to the 100MHz one

I suppose the bus to be 66MHz with 1.5x multiplier but it also could be 50MHz with 2x multiplier. I can’t check it right now, my 4400 is taking a bath (literally) but I would check on mine asap.

That’s… just brilliant ! For two reasons 1) P54C seems to be quite a beast when doing overclocking, I saw some reports of 100MHz P54C running up to 180MHz, early P5 seems to go up to 100MHz. 2) Even with an other faster CPU I totally forgot we had to deal with the clock multiplier ! Ramping...

I did put mu 12’ 100MHz PC compatibility card out from storage and did some testing with my 4400/200. Despite being « not compatible » with this computer it worked fine. Using a Compactflash as an hard disk thing is quite fast! At least for a 100MHz card. I did order VRAM chips to upgrade the...

I can confirm, I used to have same problems. Also, despite being glued, mine had the green signal damaged between the connector pin and wire. It’s worth checking. For the rest as 8tto said, you need to follow the service manual on the screen calibration, but just remember to only use plastic...

Hello Did you replaced the motherboard and analog board capacitors? Looks like the power supply can’t stabilize, which usually happens when the capacitor on the analog board goes wrong.

That's interesting, I guess you are right it's quite a late motherboard revision as it's copyrighted 1990-1992 and the LC was discontinued in 1992. Since the dual floppy configuration was not very popular, Apple certainly did some cost-saving changes while preparing the LC II.

Little update: did some resoldering, now working fine even when cold. I guess it’s another saved color classic! 😀

Kemet is the new owner of Rifa IIRC. They are definitely damaged. White one usually cracks from top. Yellow ones on the side. I’ll look for the replacement part.

Hello First you might want to avoid using the computer without grounding, something is not working properly at all. You should replace the security capacitors, did you a have a picture of them? If they show some cracks you must replace them without question. I use new Rifa but it seems better...

Thanks for the advice, I totally forgot that point. I thought I did some resoldering but I actually didn’t. So I just did some of them. It’s not noisy anymore! I also found the problem with the green signal, the wire wasn’t properly connected to the corresponding pin. Screen is still deformed...

Could also be some goo on other IC of the RAM bus. You might want to check that too. When you have the sad mac did you have any error code that might help? Also did you have any way to check if your ram sticks are fine on another machine? Looking for a defective stick on the SE/30 is kinda...

Hello there, I'm currently trying to finish the repair of my Color Classic but it kinda went wrong. Quite some time ago I did a full recap of all the logic and analog board, with deep cleaning. After calibrating all the video part it was working well. But all that calibration was done while...

Hi and happy new year /o/ So I had this LC III motherboard sitting alone for a while, death chime, original caps. But beside that seems in great condition. I did a recap and indeed after cleaning, the motherboard looks fine, almost like new. Great! Recapping done nicely, no surprises...

I've got some schematics, unless I'm wrong this is not the case on the IIsi. But I missing a page just near the part with the 2 Sony chips. I'm definitely going to check this first, I repaired a LCII with the same behaviour due to a bad ground connection on a chip managing the reset line. I...

Here is a small update, The leak as done a nasty job, the corrosion is quite heavy. Before doing a first test after recap, I was pretty sure it ain't be successful, alas, this IIsi didn't prove more wrong. Using an ATX PSU and matching the power connector pinout, I was able to start the...

Hello there :) With lockdown I decided it's time to dig into some long post-phoned repairs, start with the mighty and wicked fast the "LC" look-alike Macintosh IIsi! I bought it on ebay for a fair price, it was out of order of course, but it was, electronics aside, in a good condition. This...

Unfortunately it’s not an adapter problem, I used one to force the video mode at boot, and the one I use works fine with others LCs. I can’t get my Apple Display to show you a picture of what is displayed. But you can definitely see the happy mac then the desktop, but the video is totally...

Hello LCs enthusiasts! I recently get one of my LC475 unit out of storage in order to fix it and sell it. (Need to make some space :( ) Unfortunately, despite everything seems fine, the video output is missing HSync. PRAM battery is good I used a VGA adapter with DIP switches to force...

I've planned to take some high-res pictures of my board this week-end. Yes, last paragraph of the "Prodigy RAM modules" section. Note that PALs and gate-array are OTP (one-time programming) so if it's mandatory to upgrade them we'll need new-old stock or replacement, and of course the actual...