TheYeti
Well-known member
Too long, don't want to read: My recently capped Sanyo 20EZ keeps blowing cap C467. I'm thinking it might be the Flyback causing it. I have since replaced the flyback with a repo and cap C467 still explodes.
Fully story: I recently replaced all the caps in a Sanyo 20EZ. (The monitor already worked but the picture was squished down the middle...basically foldover). This was the 5th monitor I've capped and the 4th Sanyo.
Everything seemed to have gone really well after my cap job. I fired up the monitor inside the machine. At first the image was super bright and whacked out. But after the usual pot adjustments, I got the pictured dialed in perfectly.
I had the monitor on for about 30 minutes just playing the game. During that time, I shut it on and off maybe a couple times. Again, everything seemed fine. I wanted to let the monitor run for a while before I took a reading on the B+. But after about 30 minutes, the picture looked so good, I just shut the game down and left it be.
Then after a couple days passed, I went to turn the game back on and nothing shows on the screen, but after a few seconds pass, I hear a faint popping sound followed by a hissing sound. Then up rises a puff of smoke. Of course, I quickly turned off the game.
I removed the monitor from the game and then removed the chassis to start figuring out where that smoke came from.
I quickly realized that cap C467 had popped. I know this normally happens when a cap is installed backwards but I definitely installed mine with the stripe in the correct direction. So I figured...well I must have just got a bad cap or something so I installed a new cap at C467. I also inspected the board for any cold solder joints and also checked to make sure each cap had the proper value and polarity. I also tried to make sure I didn't bridge any solder pads that shouldn't be bridged. I really tried to look over this board to make sure it was good to go.
So I installed it back into the game and turned it on. Nothing comes up on the screen whatsoever and after a second or two...POP!...yes, the same C467 popped again. So I shut the game down again.
I pull the chassis out again and start really looking closely at everything. As far as I can tell, every resistor and diode near C467 checks out OK with my multi-meter.
The only think I can think it might be at this point is the flyback. The negative side of C467 traces directly back to pin 8 on the flyback. Also the flyback has some of that leakage on top of it. Also, I've seen other Sanyo flybacks with this same hole, but it sure looks like a hole in my flyback. (see red arrow in picture below)

I guess another clue would be that if you recall, the monitor worked fine and looked great for about 30 minutes after I initially capped it. So I must have successfully capped the monitor right? Then something coincidentally failed after I turned the monitor back on a couple days later perhaps. Maybe the new stronger caps stressed out the old flyback?
Something else worth noting is that when I go to discharge the monitor, there is still a loud pop sound under the anode cap. If a flyback goes bad, does it still have a strong discharge? Does this sound like a bad flyback or something else? How would I know if a flyback is bad? Is there a way to know besides holes and cracks?
Fully story: I recently replaced all the caps in a Sanyo 20EZ. (The monitor already worked but the picture was squished down the middle...basically foldover). This was the 5th monitor I've capped and the 4th Sanyo.
Everything seemed to have gone really well after my cap job. I fired up the monitor inside the machine. At first the image was super bright and whacked out. But after the usual pot adjustments, I got the pictured dialed in perfectly.
I had the monitor on for about 30 minutes just playing the game. During that time, I shut it on and off maybe a couple times. Again, everything seemed fine. I wanted to let the monitor run for a while before I took a reading on the B+. But after about 30 minutes, the picture looked so good, I just shut the game down and left it be.
Then after a couple days passed, I went to turn the game back on and nothing shows on the screen, but after a few seconds pass, I hear a faint popping sound followed by a hissing sound. Then up rises a puff of smoke. Of course, I quickly turned off the game.
I removed the monitor from the game and then removed the chassis to start figuring out where that smoke came from.
I quickly realized that cap C467 had popped. I know this normally happens when a cap is installed backwards but I definitely installed mine with the stripe in the correct direction. So I figured...well I must have just got a bad cap or something so I installed a new cap at C467. I also inspected the board for any cold solder joints and also checked to make sure each cap had the proper value and polarity. I also tried to make sure I didn't bridge any solder pads that shouldn't be bridged. I really tried to look over this board to make sure it was good to go.
So I installed it back into the game and turned it on. Nothing comes up on the screen whatsoever and after a second or two...POP!...yes, the same C467 popped again. So I shut the game down again.
I pull the chassis out again and start really looking closely at everything. As far as I can tell, every resistor and diode near C467 checks out OK with my multi-meter.
The only think I can think it might be at this point is the flyback. The negative side of C467 traces directly back to pin 8 on the flyback. Also the flyback has some of that leakage on top of it. Also, I've seen other Sanyo flybacks with this same hole, but it sure looks like a hole in my flyback. (see red arrow in picture below)

I guess another clue would be that if you recall, the monitor worked fine and looked great for about 30 minutes after I initially capped it. So I must have successfully capped the monitor right? Then something coincidentally failed after I turned the monitor back on a couple days later perhaps. Maybe the new stronger caps stressed out the old flyback?
Something else worth noting is that when I go to discharge the monitor, there is still a loud pop sound under the anode cap. If a flyback goes bad, does it still have a strong discharge? Does this sound like a bad flyback or something else? How would I know if a flyback is bad? Is there a way to know besides holes and cracks?
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