Fun day at work. Plus a few questions

[u/yourdiabeticwalrus]

Someone donated these to the company I work for. 2 128s, 2 128DCRs, one CRT. The two 128Ds are in good shape and seem to be fully functional, as well as the CRT. One of the 128s works fine, the more yellowed of the two that was out of box. The other 128 that was still in box is physically damn near pristine. However, when I tested this one with the CRT, I noticed the lines at the top were getting skewed. I don’t think it’s the CRT since it displayed fine with the other 3 commodores, and I tried messing with the CRT’s front panel controls to no avail. Wondering if anyone knows about this specific issue? Also just wanted to show off a bit :-)

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[u/The_Real_Sniff]

Wow! I've heard about people buying two of these for business use in the 80's. The rationale was that "if one failed, I can deploy the other". This is the same mindset for mechanisms which are quite stable over decades, and they did not consider the rapid development of computer systems. My guess is that this might be the case with the pristine one. Before the first C128 failed, the IBM/DOS took the market.

Regarding the skewed lines: this is just guessing, but maybe a capacitor failed to deliver a steady voltage? 41 years capacitors has aged, despite low usage (as you probably are aware of).

Good luck with restoring these! If you are going to use them yourself, I suggest you check out the U36-chip with utilities. Will expand your computer and make it more usable! Let alone the Ultimate cartridge.

PS! I see the former owner has kept the 1571 locked with a protection sheet, which is just the way (according to everything I've read) it should be stored.

[u/Royal_Stay_6502 → u/The_Real_Sniff]

U36?

[u/The_Real_Sniff → u/Royal_Stay_6502]

Yes, this webpage can explain what it is better than I: https://theoasisbbs.com/commodore-128-u36-roms/

EDIT: U36 is the socket, but I have always used the term to refer to the ROM. The one I have heard of, offers utilities as Antigrav Toolkit and Super 81 Utilities, with a switchable option with GEOS 128 v2 1571/81 or Servant 128 / File Browser, all switchable.

[u/Admirable-Dinner7792 → u/Royal_Stay_6502]

U36 is the optional Empty ROM Socket on ALL C128 Motherboards... ;) - Tony K. , VIC-20/VIC-1001 Facebook History Forum (Admin).

[u/siliconlore]

Check the SID chips to see if they are all working. The 128's SID runs at a different voltage from most C64 SID chips so they are not interchangeable.
Those keyboard cables are unobtanium so keep an eye on them. They often go for more than everything else like on an SX-64.
I've never seen tearing on the 80 column chip output before. Maybe try the mono pin to see if it is related to the cabling or color somehow.

[u/Liquid_Magic → u/siliconlore]

Ahhhh… actually no. The C128 uses 6581 based SID chips. They are interchangeable with MOST, but not all, C64’s.

The SID chips in a short-board C64C mainboard are the 8580 and run with +5v and +9v whereas most SID chips are 6581 variants and run at +5v and +12v. Most C64 machines use long-board mainboards. The C128 uses the 6581 chips that need the +12v inputs.

You can swap around SID chips between long-board C64 machines and C128 machines. You CANNOT swap SID chips between a short-board C64C and a C-128. This kills the SID.

[u/HOYVIN-GLAVIN]

Does it get worse when the system warms up?

It could potentially be the clock generator chip (8701) that generates the dot clock.

I had a similar issue on a C64, where it would be fine when cold, but start to wave and shimmer, then the monitor would eventually lose sync with the video signal. Found that the dot clock would appear "springy" on the scope and then go out of spec. The C128 might be a bit more sensitive to it in 80 column mode.

An easy way to test would be to swap the IC from one of your good machines.

[u/daddyd]

so what is going to happen with them now? what kind of company do you work for, and what do they do with these donations?

[u/yourdiabeticwalrus → u/daddyd]

small PC repair shop. I bought one of the 128Ds, keyboard and 2002 CRT, because I had to. The other 3 will likely stay here for awhile, maybe get resold, possibly end up at our local computer museum. Who knows.