Sany 20 ez, part 2

elfyhead

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OK, so i bought a chassis from gregr, which he said worked last time it was plugged in (to a Punchout).

i connected it to my tube and plugged it into the transformer (let's not repeat *that* stupid mistake!), and nothing.

sigh.

so, to the troubleshooting guide. voltage at TP91 is 134. voltage at pin 9 of IC401 is 0.9V (which i assume is "approx. 0.6V" as on the diagram). so it says check power reg., hold down, and high voltage circuits next, but can anybody give some guidance on just what to check next, since that is pretty broad?

(BTW, the fuses are both good, so Dokert's guide doesn't help me much, but i did check the HOT with a diode test and it checks out good, and visually the FBT looks OK.)

i'm wondering if i've just got a bad tube? what's the best place to directly check the voltages for that?

thanks in advance :)...
 
You are in HV shutdown. (tp91 134vdc)

Adjust the B+ down to 108vdc tp91 / BJ and test again.

If B+ won't come down to 108, turn the brightness down on the flyback and try to adjust the B+ again.
 
*finally* had a chance to get back to this.

thanks for the help dokert.

adjusting B+ won't get it down from ~140 V (measured at BJ), nor does changing the brightness on the flyback. it just sits there at about 140 V no matter what adjustments i make to either B+ or screen knobs...
 
I am having the same problem on my 2 monitors, They have screen droop, and are measuring at 90V. I cant adjust them with the B+, and actually snapped one off.
 
I am having the same problem on my 2 monitors, They have screen droop, and are measuring at 90V. I cant adjust them with the B+, and actually snapped one off.

i suspect yours is a different root problem, as i get no picture at all.

EDIT: and i just realized i left off the "o" in Sanyo in the thread title. d'oh!
 
I am having the same problem on my 2 monitors, They have screen droop, and are measuring at 90V. I cant adjust them with the B+, and actually snapped one off.

Your problem is not the same.

i suspect yours is a different root problem, as i get no picture at all.

EDIT: and i just realized i left off the "o" in Sanyo in the thread title. d'oh!

Verify that the B+ pot is actually changing value when you turn it. If it is, replace the reg Q902.
 
OK, tested the pot, and it reads 4.4k ohms no matter how i adjust it. weird thing is i thought i was testing it wrong somehow, so tried it on my other chassis, and same thing (but 4.7k). it's that way on both boards whether i read it off the legs on the chip side, or the solder side.

if it's truly bad - is there a source for replacements for those pots?
 
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