Rollergames display, 100V, and "flame proof" resistors

[kevin]

The displays on Rollergames just stopped working. I checked the pins for 100V DC on the power supply board and it was reading 0. Clay's site said the most common problems are with two of the resistors, R1 and R4, and two diodes, ZR2 and ZR4. All of these checked out fine with the DMM.

Any other ideas?

Also, Clay said that he often replaces the resistors, even if they test as good, with "flame proof" resistors. What the hell is this? Could this fix the problem? It seems like probably a waste to replace resistors that test fine with the DMM.

[eric]

Did you check the HV fuses? There are 3 fuses in the HV sections of 11C power supplies - one for 100V, one for -100V, and one for the AC input from the transformer. All 3 of these fuses must be good for the displays to work.

Are you missing -100V as well? If so, check to make sure you have 85-90 VAC at the input.

If all fuses are good, and you have -100V but are still missing 100V, I would just rebuild the entire HV section rather than replace the one bad component. Components are cheap - GPE sells rebuild kits for like $5 - and while you're under the hood you can replace the 100V Zerners with 91V Zeners to help prolong the life of your displays.

Flameproof means exactly what it sounds like. They won't catch on fire when they fail.

[kevin]

I was actually testing it wrong....it was at 97V and -97V. I'm assuming this is close enough.

Clay seems to next recommend checking chips on the display board. I don't know where this will get me.

[eric]

Yes, those voltages are fine. Also check for 5V, 100V, and -100V on the display board itself. Since you're not seeing anything on the displays, it's more likely a missing voltage or bad connector. Try reseating the ribbon cable on the display board and MPU too.

[eric]

Kevin and I had a look at this over the weekend. The 39k resistors were out of spec. Replacing them fixed the display.