[jeyurkon]

Well, it appears that I have a quite healthy 10MP4. I moved the ion-trap to the position that the service manual recommended, even though there was no indication that it had ever been in that position.

That gave me a weak beam spot and with a little adjustment I was able to maximize it.

I was able to measure the G1 cutoff and it came out to be -30V. That's within the good range. The focus was excellent.

I think the CRT was replaced at some time in the life of this set. The Sam's and the factory service manual are a little misleading and it's possible the service tech readjusted the HV to 9.5KV instead of 7.5KV. If you just follow the instructions you'll end up doing this. The only place 7.5KV is noted for the 10MP4 is on the schematic. This would explain why the ion-trap was positioned where it was. The 10MP4 can handle 9.5KV easily, but wasn't intended to in this set.

If anyone decides to try this, make sure you start well above G1 cutoff. You don't want to burn a hole in the phosphor. That's why I practiced with a 5AXP4 first that was already suffering.

It helped a great deal having the ion-trap in the correct position to start with. When I wasn't able to get a beam spot at all, it would have been dangerous to have G1 set low and then move the ion-trap around to find the beam because it would have appeared quite suddenly and be much too bright. That meant move, adjust G1, move, adjust G1...

John