Recent content by Mark_W

DL21/22 voltage is ok, but DF2 voltage is much higher than it should be (8.2V). Did you install the correct zener diode? Also double check those power resistors and caps nearby, make sure you didn't install anything wrong.

Does the High-res card actually support 512x384? On this site 512x384 is listed as not supported: https://vintageapple.org/gamba2/vid-mon-matrix.html

If the front bezel says "Macintosh SE" and it's on the lower right corner then it's really an SE. If the "Macintosh SE" text is on the left then it should be an SE30 case, "/30" might be sanded off or faded for some reason, I've seen a few SEs without any text on front bezel before. Also...

The screen geometry and color are both way off which is a good hint that something's wrong with secondary voltage outputs from CRT transformer.Start with checking all voltages on CRT side, make sure 24V, 8.4V from transformer output are normal, as well as regulated 18V, 8.2V from zener diodes...

If you want an all in one boot disk, you can try macpack here under preinstalled macos images: https://mega.nz/folder/8hA3AQCJ#pWUq92L70yDXlogy9lk5Dg It contains system 6.0.8, 7.0.1, 7.1.2 and 7.5.5 iirc, and also thousands of classic software and games. I've used this image in an external...

Ok so I finally have an original LC to play with, friend gave it to me for repair, although it looked fine but leaky caps has done some damage to it. One trace from VRAM socket to cultdac is open causing very minor screen artifacts at 256 color mode, mc34119 amplifier is also dead resulting in...

Bought a whole lot of CC II/LC520 and LC475/575 boards from a forum member and been busy repairing them last weekend. Figured I might make a thread here and log my findings. LC575 - 1: Entire board is covered in electrolyte, especially the section near battery so I guess it's been battery...

Ok another idea, can you test the game on an LC II running system 6.0.8? Just looked up DFAC revisions and it appears the sound chip in LC II and III is 344S1033, while in the original LC it's 343S1033. So in theory LC II and III should have the same sound right?

Ok did a quick testing on system 6.0.8 and the problem appeared, volume is very low even at 7, sounds just like @VeryVon 's on post #8. So is this a hardware issue or software issue? I assume all sound are generated by the dfac chip right? Could it be a bad chip or some damaged traces due to...

Hi all, just finished repairing a LC II last weekend and decide to chime in. The sound chip is soaked in electrolyte when I first got it, had to desolder it to clean electrolyte underneath. Anyway here's my testing result on system 7.0.1. Strangely my LC II sounds different than yours, but at...

There's one for sale on ebay right now: https://www.ebay.com/itm/326859293571 Seems like it's used to combine 4x256kb sticks into a single 1mb stick, before 1mb sticks are widely available. Don't think it's very useful today since you can easily find 1mb sticks to max it out, but still a cool...

Not necessarily since all 3 voltages come from the same transformer and they are tied together. I just measure them to confirm the other 2 voltages aren't too out of spec, otherwise there might be some issue with the transformer. As for damaged trace that's normal, every single CC I've dealt...

Yeah it's kinda tricky to do it with analog board installed, what I did is measure voltage, pull analog board out, make very small adjustment, install analog board, measure voltage again, repeat a few times and you can get the voltage spot on. For glued pp1 i just replace them with precision...

Agree with what @jonschultz said before regarding B2 voltage. Also first thing you need to do before adjusting geometry is to adjust the trimmer PP1 near the crt power supply and make sure you get 8.3V/24V/84V on secondary outputs, you can use test points labeled TP1/TP2/TP3. Usually when you do...

Have you reflowed all solder joints yet? That will rule out connection issues. if so then I guess you have the same bad transformer as I do. From my previous research, the transformer probably has a loose or cracked core which creates harmonics in the audible range, making the sizzling sound...