6100 low B+

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So I finally got around to working on the 6100 in my Star Wars again. According to the seller it was a gift to him back in 98 and it had sat non-working since at least then. Surprisingly it did work once I fixed the ARII board and replaced the big blue to get the +5 healthy. It didn't last too long unfortunately before the monitor died, which I guess shouldn't be a surprise. Anyway, I ended up installing an LV2000 lite and a Zanen kit. After finding and replacing another xsistor not included with the kit (Q603) the monitor is back to life. The only issue is I can't get my B+ up to 181 which also means my HV should be low (I don't have a HV probe for my Fluke 12B unfortunately) . It only adjusted up to about 165 max so I backed the pot down to where it was, which is currently giving me about 145. I tried replacing xsistors Q901-Q903 with no change. I do have a replacement pot I can try if anyone thinks that sounds like a worthwile shot. I've been doing these readings with the video signal going to the monitor and I've read you should adjust the B+ without any video input. So would not having video hooked up make that big a difference in setting the B+? If not, should I just shotgun the adjustment pot (being careful with how it's set between 5k and 6k to start)? Thanks all.

Edit: Just for clarification, the picture isn't doing anything really wonky. I just thought I would dial the B+ in when I found it wouldn't. Would there be any harm in running the monitor like this this while trying to figure out the issue (assuming measuring it with the video hooked up isn't the whole issue)?
 
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If you haven't replaced the HV pot yet, do so. There's a reason why they include it in the kits...
 
Thanks for the reply, Mod. Dumb question on the pot....I know it's supposed to be set between 5k to 6k before you power it on. Almost every pot I've dealt with are 3 legged and this one has 4. The 6100 FAQ says to adjust using the 2 upper legs, which should be the wipers, but I thought you had to go between a wiper and one of the "end" legs. Those "end" legs should be the 2 close to each other. This seems like it should be really simple, but having 4 legs is throwing me off. So which legs should I be measuring between to preset the pot? :eek:
 
look at the pot in the HV cage with the two narrow spaced legs at the top. (You will actually have the LH side of the cage as the top for this procedure) the arrow on the pot should point to the 1 o'clock position and basically point at the yellowish valley between the 2 green splotches on the HV circuit board. (This will be almost towards the corner of the cage behind the "flyback") This has been close enough on 95% of the HV cages I rebuild until I can get a HV probe on them. If you don't understand what I am saying, then please don't put the power on until I can get you a photo.
 
Thanks Komodo. I'll take a look at it and if I can't figure it out, I'll definitely ask before I power it up.
 
Ok I found this pic on the forum posted by Militiaman and I drew an arrow on it in the direction I'm almost certain you are talking about.

6100hvcage.jpg
 
I just turn it down all the way, turn the game on, check my B+, then turn it up until my B+ is right at 180vdc...
 
Where is the test point for the B+?
I just test it at the orange wire at the top of the neckboard myself.

Okay I swapped out the pot with no real change. I'm past the halfway point of the adjustment range and I don't think I'll hit 181 even if I cranked it and I know that shouldn't be needed. It's still sitting around the same mark of 145.
 
You mark is perfect and a good start if you don't like sticking your hand in places when electricity is flowing. I am thinking that you have other issues in the HV cage. Have you checked the other resistor values in there? I think almost all of them but two will read the correct value without having to desolder them. The two that read low you can desolder one end and then test. If any resistor reads way off, you might want to desolder one end and retest it. You never know who has done work before you and if they used the correct parts when they worked on it. If I had a beer for every chassis/HV cage that has had the wrong parts installed on it, my fridge would be full.
 
I know this post is a bit old, but I'm rebuilding my Tempest 6100, and I'm not getting a reading at all from the replacement pot.

If put my multimeter on a stand alone resister, I get the correct reading, but on any combination of pins on the pot, I get nothing.

This is the second 6100 I've rebuilt, and I can't for the life of me remember if I tested the pot, or just set it to the "1'0clock" spot on the first one.

Should I be getting a reading?


-John
 
Issue resolved. Just me being dumb and having MM on wrong setting....
 
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