HELP! Sanyo 20 constant HV shutdown!!! nothing helps!

Oddoakd32

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HELP! Sanyo 20 constant HV shutdown!!! nothing helps!

Hey guys i really need help i am stumped. When i first got this machine the fuses were blown so i replaced the flyback and it worked. Everything was looking good except the B+ was hard to adjust.

So i replaced the caps. The 2sd1090 voltage regulator. IC601. B+pot and filter cap.

Now whenever i turn it on it makes a low buzzing noise. The voltage at the B+ is 88v. As soon as i adjust it... It goes into HV shutdown. I have 4 other IC601 i have tried them all and they all do the same thing. Fixed broken traces here and there. Resistors .... H.O.T. and same thing. Its so sensitive. I wished i wouldve left it alone after the flyback because it looked amazing. I don't know what else to do or check. I reflowed everything!!! Im not a noob at fixing electronics so this is especially frustrating. I hate asking for help but does anyone have any advice or can point me in the right direction. Or if someone can help me fix it... I would be glad to pay $$$$ thank you everyone!!!! You guys are the best!
 
You can always send it out for repair BUT, dumb question here...have you followed the flowchart?

Hey guys i really need help i am stumped. When i first got this machine the fuses were blown so i replaced the flyback and it worked. Everything was looking good except the B+ was hard to adjust.

So i replaced the caps. The 2sd1090 voltage regulator. IC601. B+pot and filter cap.

Now whenever i turn it on it makes a low buzzing noise. The voltage at the B+ is 88v. As soon as i adjust it... It goes into HV shutdown. I have 4 other IC601 i have tried them all and they all do the same thing. Fixed broken traces here and there. Resistors .... H.O.T. and same thing. Its so sensitive. I wished i wouldve left it alone after the flyback because it looked amazing. I don't know what else to do or check. I reflowed everything!!! Im not a noob at fixing electronics so this is especially frustrating. I hate asking for help but does anyone have any advice or can point me in the right direction. Or if someone can help me fix it... I would be glad to pay $$$$ thank you everyone!!!! You guys are the best!
 
Yeah i followed the flow chart. Thats what lead to me fixig the fly back and b+ pot. I have all charts and schematics i went threw and made sure everything is the rightnvalue. Im stumped!
 
Huh. Yeah that's kinda stumping me then too. I'm sure others will chime in with suggestions anytime now. Good luck in your quest to fix it
 
where'd you get the flyback? Could be a bad one it happens occasionally where they can't produce enough volts right out of the box.
 
Got the flyback from twisted quarter. I should note that the flyback worked great and looked great. It was onlynaftet i replaced the b pot and stuff that this started happening
 
it could be a bad flyback. i seem to recall Buffett on here helped with one just recently with low B+ and i can't remember what that was. i would shoot him a pm and see.
 
it could be a bad flyback. i seem to recall Buffett on here helped with one just recently with low B+ and i can't remember what that was. i would shoot him a pm and see.

You think that would cause it to go into hv shutdown each time? I hope it isnt bad then again they are only like 25 bucks and ill do whatever it takes to fix it.
 
check everything to IC 401. off the top of my head I think pin 9 is for shutdown on that chip. if everything else checks out to that point try desolding that pin and see if it stays on then.
 
mine did the exact same thing be at 80, just touch the B+ pot and the B+ would jump to 127and up and shut everything down. i pulled that chassis apart easily 10 times looking everything over and one day i just cranked the b+ down and the h-hold and as i was turning the h-hold the b+ went into the 90's and i started getting picture, garbage but at least picture. i dont know how the h-hold and the b+ are related but they seem to go hand in hand,please do report back your findings after swapping that h-hold pot out.
 
EXACTLY the same thing mine is doing. This all started happening after i was adjusting the B+ and the crappy metal pot fell apart and boom the tv shut off. Then after putting a new pot in it is so sensitive and stays around 80. It makes me so upset because the tv looked amazingbefore hand. When i got it was dead. Replaced the flyback and brought it back to life. Im so frustrated with it im about to start from scratch and replace everything AGAIN.
 
my thread on it, basically replying to myself but seems like your problem too.

https://forums.arcade-museum.com/showthread.php?t=363952
I just read you thread and our problem is identical.

Last night i REFLOWED everything. As in took my desolder tool and sucked the old solder up. Who ever worked on the board before coated it with some brown clear coat stuff so whenever i solder it gunks up everything. I dont have a replacement pot to try since its 3k ohm so im waiting on one. Im also starting to suspect my new fly back. Ill take some pictures of my board later.
 
I just read you thread and our problem is identical.

Last night i REFLOWED everything. As in took my desolder tool and sucked the old solder up. Who ever worked on the board before coated it with some brown clear coat stuff so whenever i solder it gunks up everything. I dont have a replacement pot to try since its 3k ohm so im waiting on one. Im also starting to suspect my new fly back. Ill take some pictures of my board later.

that is probably the old flux making all that brown crap.
 
that is probably the old flux making all that brown crap.

The brown stuff is hard and when i solder it heats up and comes off and takes the green covering with it. Here is a couple pictures and youll see this board is a mess. Huge solder joints when i got it all the fuses were burnt that massive resistor R609 was cracked in half just bad soldering. Also i uploaded my new flyback as it looks like something is leaking out of it. Thanks guys! Take a look!
 

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The brown stuff is hard and when i solder it heats up and comes off and takes the green covering with it. Here is a couple pictures and youll see this board is a mess. Huge solder joints when i got it all the fuses were burnt that massive resistor R609 was cracked in half just bad soldering. Also i uploaded my new flyback as it looks like something is leaking out of it. Thanks guys! Take a look!

Take a toothbrush and some 91% alchohol and clean that thing up :) there's flux all over the place
 
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