DAMN! DK Monitor Going Bad - Sanyo EZ

TCinTEXAS

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Hey guys! I powered up the arcade for a couple of hours last night, and my DK monitor started doing THIS after an hour or so:



Is this a "needs caps" issue, or something more serious. I bought it a year ago, and the seller said it had been capped recently, but that's neither here nor there. Also, notice the loud BUZZ! That's new.

Thoughts?

Thanks!
 
That's the "flag wave". Replace C606, B+ filter cap.

EDIT: Read your post more closely. C606 most of the time is not included in cap kits so a "capped monitor" may or may not have had it replaced. Originals are grey I think. Looking at the schematic I'd say a buzz makes sense in this scenario too but I've not experienced myself so can't say for sure.
 
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That's the "flag wave". Replace C606, B+ filter cap.

I haven't worked on Sanyo yet (and haven't investigated this AT ALL), so please ignore the ignorant question: Is that the large cap which usually isn't included in cap kits? I know on WGs I've done, there's always one big filter cap which isn't included in the kits.
 
I've seen the power regulator casue that issue too.

Send your video to Chad Entringer. His username here is arcadecup. He'll give you some likely avenues to try.
 
Thanks. I think I may have a cap kit for that guy. I'm going to dig it out and try it later this week, and go from there.
 
60Hz ripple?
Bad caps in power supply.
Bad connection.
Bad grounding.
Bad 74LS20 ... oh wait, that was something else ... LOL :)
 
I'm pretty sure that Ian's kit's include this cap. But you might want to email him to be sure:

https://iankellogg.com/parts-by-monitors/sanyo/sanyo-20-ez-v/sanyo-20ez-cap-kit.html

I had the exact same issue and it's easy to fix by replacing the filter cap. You might as well cap the entire chassis while you have it out. They are pretty easy to work on but a bear to get out of the frame. Here were my results:

N6raqgWaqr2Tj1tmIh4KKIb0B0W4pR_ydsMQnGbudjApX92IB
sdVLBNZTU0QCiDr4s4FHIub4CzgThmJNNQ3Nu9J62sopX92IB
 
the most common cause of this is a cap kit and filter cap needed. there can be other things but they are so uncommon i would start with a filter cap and cap kit if you haven't done them yet. maybe a B+ pot replacement while you have it out and make sure to reset your B+ to 108vdc when done before adjusting.

https://www.arcadepartsandrepair.co...sanyo-20ez-audio-board-cap-kit-105c-nichicon/

https://www.arcadepartsandrepair.com/store/monitors/470uf-250v-nichicon-105c-b-filter-capacitor/

https://www.arcadepartsandrepair.co...-models-b-5k-ohm-trimmer-potentiometer-p1000/
 
the most common cause of this is a cap kit and filter cap needed. there can be other things but they are so uncommon i would start with a filter cap and cap kit if you haven't done them yet. maybe a B+ pot replacement while you have it out and make sure to reset your B+ to 108vdc when done before adjusting.

https://www.arcadepartsandrepair.co...sanyo-20ez-audio-board-cap-kit-105c-nichicon/

https://www.arcadepartsandrepair.com/store/monitors/470uf-250v-nichicon-105c-b-filter-capacitor/

https://www.arcadepartsandrepair.co...-models-b-5k-ohm-trimmer-potentiometer-p1000/

I'll have to dig it out to see exactly what I have, but I bought a cap kit from you for the 20EZ-Y a while back. Based on your links, it looks like I may need an additional 470uf cap and a pot (which I may have).
 
Could this problem because by a bad connection on the thermistor at PS601? The solder joints were so bad, it was about to fall off the board.

Still doing a cap kit.
 
Life gets in the way....

The PS601 was falling off the board. C161 was a 16v, supposed to be a 50v. Couldn't find C162, but wife is calling, so I'll revisit tomorrow night.

Found C162 on a photo I took while we were watching the news!
 
UPDATE:

Did a cap kit on the chassis, including amp board and the power supply. Getting solid +5, -5 and +12 to the board. STILL getting the wave and buzz.

I did not change the C606 filter cap. Ordered one, but it hasn't shown up yet; hurricane and all.

If it's not the C606, what's next?

By the way B+ is fluctuating, and can't get it over 103V.

Also, I'm getting 106.8VAC to my monitor.

It's not the PCB and it's not the fluorescent fixture.
 
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I'm seeing suggestions for solutions with problem B+:

R601

IC601

Q901

I'm also seeing lots of problem IC601 replacements out there. Where can I get a quality part?
 
I replaced C606, adjusted the B+ and had a beautiful picture. I played DK for a few minutes with no problems. Left it on for about an hour while I cleaned my office a bit. Went back and it's in HORIZONTAL collapse (single line down the center of the CRT)! Son of a monkey!!!!!

What now? More research...

OK! Worst kind of problem! I reattached the alligator clip to reverify B+, powered it up (B+ was good), and the damn monitor is working again. I apparently wiggled something in the process. I either have a poor connection or bad solder joint.
 
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Did you maybe bump the test switch near the filter cap when you were installing it?

No. That was the first thing I checked. I even toggled it back and forth a few times, thinking it might be dirty. No luck.

It's working again. I definitely bumped something when I attached the clip to test B+ a second time.
 
Did you maybe bump the test switch near the filter cap when you were installing it?

By the way, you were right. It was the filter cap C606. I have 2 voltage regulators I didn't use. I didn't change it, because I'd read so much about bad ones out there. Didn't want to take a chance on making things worse, once it was working.
 
I had a wave similar to that on a double dk board I recently purchased, it was only on the left side of the vertically oriented monitor. I was able to find a "sweet spot" using the v-position pot on the double dk pcb, and eliminate it. Sounds like you found the culprit though.
 

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