Tempest Troubleshooting Help

[Tempest Troubleshooting Help]

Found this video and tested the supply. Everything checks out there and is in the higher range of acceptable voltages.

[Tempest Troubleshooting Help]

I've got a Tempest cab and I'm trying to solve a power issue with Ground. I believe this is the cause of the video issue, but I'll get to that later...

The Ground on the game board itself meters to ground on the power supply just fine when the game is off. However when I turn it on, the resistance goes up to around 25 Ohms.

So I unplugged the game harness and metered between ground on the power supply and the ground plane on the AR board and got around 20VAC.

I noticed there is no ground bond between the AR board and the power supply. Would installing one improve things?

The "Big Blue" has been replaced with a Bob Roberts cap and I just put in a new rectifier as well. The fuses are all clean and the connections seem to be happy (0.3 - 0.4 Ohms) from the beginings to the ends of their runs. The AR Board looks like it was recapped in the last two or three years.

Any ideas what is going on?

 

 

[Monitor was repaired after the game died. It had the usual burned out low voltage section on the deflection board which has been replaced by an LV2000. I also brought the deflection board up to the last factory revision, and replaced all the caps and chassis Transistors. So I'm really hoping that's good. There were definitely problems with the game board [X and Y outputs] that were repaired by someone else.]]