Recent content by chiptripper

Nice pickup. Loved this game growing up. Always surprised by how much they sell for nowadays, it was pretty niche.

Oh that’s a nice thing. The Bomarc schematic makes me go cross-eyed.

That IOSB chip is a nightmare. I was able to life it on my Q610 LB (with great care and tons of ChipQuik). I ran some bodge wires (I use 32AWG magnet wire) to what remained of the legs. Felt like surgery, ultimately wasn’t successful. Now the board is in my parts bin.

Nice pickup! I ended up with a bunch of Umax clone bits and pieces. C500 and J700 bezels, a CPU, several S900 port doors (the piece that often breaks off and gets lost) and a nearly complete S900 / Pulsar (logic board, PSU, panels, etc. Just missing the chassis, but I believe a Dell Dimension...

Necropost hat tip to BMOW for setting me in the right direction. I have an LC II board with the same pinstripe symptom. There was a broken trace hiding under the RAM sockets near the 47uf capacitors, damage from pooled electrolyte. The trace in question went from the CLUT to the VRAM socket.

Ok, so after poring over data sheets and feeling reasonably confident, I sourced a legit (NOS) 100-pin XC3030A, installed it, and… it works. Well, kinda. It works perfectly on an LC II with the Presto 2.0.1 driver extension and Virtual Enabler in the System folder. It does NOT, however, work...

If AB is functioning fine, then it’s likely a logic board issue resulting in vertical collapse. Could be a failed UF8 (counter). They often get the worst of the cap leakage. Or maybe a failed video PAL, but that’s far less likely IMO.

Check the back of analog board for cracked solder joints, particularly the four-pin connector that runs to the CRT, and reflow anything that looks suspect.

Hi, and welcome. C10 is indeed a tantalum. The positive marker is really faint, you can sometimes shine a light on it and see the shadow of the old marking. If not, I’d replace it with a new cap of the same value… it will pop explosively if installed backwards. Yes, dawn and distilled water...

I like the cutout solution too. Wouldn’t be hard to 3D print, paint, and glue on a port-specific strip later on, if desired. I too have a couple of 840av boards waiting to be restored, plus one very battery bombed board and case. So this is interesting. :)

I had the same issue (no sound on a recapped board) and turned out to be the exact same issue. This trace was broken on the underside, disconnecting the DFAC from C9. Nice, thanks for saving me some time!

Can confirm. One of my desktop cards seems to have been upgraded to a 24-21. There are signs of rework on the ROM.

Very cool, thanks for this!

I prefer using isopropyl alcohol 91-99%, methylated spirits probably work fine but sometimes it contains additive MEK, which can damage some plastics. You can also (carefully) use a pencil eraser, or re-tin with flux and solder, then remove excess with braid. But yeah I agree with zigzagjoe...

Thanks for this info on MLCC derating! I have historically used a sprinkling of MLCCs (10uf 16v and 1uf 50v) because they’re easy to install, non-polar, inexpensive, and haven’t caused problems. But “hasn’t caused me any problems so far” is a trap, IMO, so I think I’ll stop using them.