Monitor Gurus: Sanyo 20ez working(almost) slight ripple

Black Matrix

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Monitor Gurus: Sanyo 20ez working(almost) slight ripple

Hey all,
Still repairing this bane of my existence and its almost working with the help of the group. So here's whats been done.
1. Cap Kit
2. large Filter Cap replaced
3. some broken pots replaced
4. flyback replaced
5. IC601 and HOT replaced
6. 2SD1090 Current Limiter replaced

After my previous rounds of repairs, I had the monitor unadjustable in the high 130s so I replaced the the IC601 and HOT.

Hooked it up and powered it up and I was getting a white flashy screen so I tried adjusting the B+ pot. Metal screwdriver slipped and touched something in the near area and sent it into HV overvolt protection. Powered down, and back up again. The monitor was back up so I adjusted the bright and saw that the pic was rolling. Adjusted the H-hold and got it zeroed in. Now I have a pretty good pic. But I do have a mild ripple in picture across the vertical of the monitor (like a little wave that runs across the girders). Also, I can't get the B+ to adjust down to 108. I think its fluctuating around 109 is the best I can do. And on the other monitors, adjusting the B+ would send the voltages above and below the target 108, this one just doesn't go low enough.

So I suspect that my tragic slip of the screw driver may have damaged either the B+ pot, or one of the surrounding resistors. But if it was a resistor, would it even have a picture. And it could be a cap, but I doubt its the filter cap which would be the first suspect following the flow chart. Already replaced it....but maybe my slip damage it? I know I'm going to have to pull the chassis again....for the 5th time to look for things. But I wanted to ask the monitor guru's first to see if they had any ideas first. SO...anyone know what causes a slight voltage ripple and slightly high B+ voltage. Many thanks in advance.

And while its probably normal, I have gotten a couple overvoltage protections shut downs when trying to adjust the B+. It would shut down and the b+ would shoot up to 134.
 
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Update: after a little more testing, it seems the ripple quiets down a bit after it warms up. Also, a quick power down and back up can cause it to go into protection mode. The B+ seems to fluctuate quite a bit. I even had it hovering around 108. Tried to fine tune it and it started easing its way back up to 109. I also noticed I had forgotten to put the black ground wire to the neck board and was hoping that was the problem. Unfortunately, it made no difference.

I also found another post that said seemed to describe this as a "hum bar"? I have tested other monitors in this cab, and they are rock solid, but is it possible this is "hum bar. And if so, what part would cause this in a 20ez?
 
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i hate to say it but your slip up probably blew IC601 again.

if the B+ will not stay at 108 or adjust smoothly above or below 108 then that's probably it.

if you are still using that old POS metal pot replace it wile you have it out.

i have done that a time or two and repaired chassis for others and that was what the problem. it was a blown IC601.

Peace
Buffett
 
Ordered another one tonight. The old IC601 may not have even been bad, but I think I'll just wait for the new one. No need to have to pull the chassis any more than possible. At least I have a picture for the first time now. So, we are making progress and its just about done.....I hope.
 
+1 on this. The reason I had to replace my ic601 the first time. Ordered the plastic set a few times from Bob not sure if he is getting them in again but crossing my fingers. Hopefully clear up your issues.

i hate to say it but your slip up probably blew IC601 again.

if the B+ will not stay at 108 or adjust smoothly above or below 108 then that's probably it.

if you are still using that old POS metal pot replace it wile you have it out.

i have done that a time or two and repaired chassis for others and that was what the problem. it was a blown IC601.

Peace
Buffett
 
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