Out of ideas: Sanyo 20EZ, B+ stuck at 30V

MackAttack

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I've been working on my spare CRTs and this one is giving me grief. I believe I've exhausted the flowchart. Here's what I've done so far trying to rectify the low and unadjustable B+ voltage.
  • Cap kit completed including new filter cap
  • New flyback
  • New B+ Potentiometer
  • New voltage regulator
  • Swapped in a used HOT for kicks
    • Base to Emitter .5V
    • Base to Collector.5V
  • D601-D604 all read .49V
  • R609 180 Ω
  • R604 1.1K Ω
  • Both fuses have continuity
Weird side note: if I test the B+ on the BJ post behind R609 then I get a little crackle of high voltage into the CRT. Odd?

Could the used HOT be failing under load.
What's next?
 
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Pics for kicks.
 

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Did you get this flyback from security001? Was the b+ correct before you put the flyback in? That doesn't look like security001's cap kit because he uses much high quality capacitors. I'm thinking defective new flyback but not sure. Also was this chassis pcb ever flexed hard? Could have broken traces you can't see
 
Did you get this flyback from security001? Was the b+ correct before you put the flyback in? That doesn't look like security001's cap kit because he uses much high quality capacitors. I'm thinking defective new flyback but not sure. Also was this chassis pcb ever flexed hard? Could have broken traces you can't see
Yeah, the flyback is brand new from Peter, Security001. These days I order 95% of my stuff from him and haven't ever really had issues.
I can't remember when I did the capkit, so those Richey caps could've been back in the Bob Roberts days. This monitor has been sitting on a shelf for years.
Is there a known problem with these new Sanyo flybacks?
I've checked continuity on a few of the traces, I could be more thorough and double check that.
The B+ voltage was unadjustable before all this, so I'm still in the same spot.
 
Yeah, it's brand new from Peter, Security001. These days I order 95% of my stuff from him and haven't ever really had issues.
I can't remember when I did the capkit, so those Richey caps could've been back in the Bob Roberts days. This monitor has been sitting on a shelf for years.
Is there a known problem with these new Sanyo flybacks?
All new flybacks are hit or miss these days. When you put the monitor on the shelf do you remember anything about it's running condition? Like did it need a new flyback? Usually with sanyos the flyback doesn't crack and arc externally but it sometimes arcs internally and causes the image to jump and roll off the screen then snap back then do it again and again. I recognized those richey caps and know they work but there's definitely significantly better stuff out there, wouldn't be good for actual coin op service they'll leak quickly with regular use.
 
Yeah, @Mattspad the old flyback was making an arcing buzzing noise so I replaced it. If I could get this chassis working and needed to replace a screen in one of my games I'd consider a new kit with Nichicon caps.
 
Yeah, @Mattspad the old flyback was making an arcing buzzing noise so I replaced it. If I could get this chassis working and needed to replace a screen in one of my games I'd consider a new kit with Nichicon caps.
If they haven't been run may as well keep them in there and use them. I meant they'd fail if you wanted to actually run the machine on location to earn money. For personal use where the machine gets turned on every once and awhile for an hour or two maybe they'll last you forever. You also really can't operate a machine on location with one of these new fly backs either, don't last like the old ones. Do you know if the b+ before was correct while it was arcing with the old flyback, was it producing any image on screen? Also your new voltage regulator could be bad, was there a reason you changed it? Sometimes throwing the parts cannon at an unknown chassis isn't a good idea, these new parts made in China aren't worth a damn. Like the 2sd870 Toshiba hot, Toshiba doesn't exist anymore they're out of business so only "new" Chinese replacements are available. You can still get nos ones, just realized Peter has thousands in stock and there's a reason he's selling those and not just Chinese clones.

Also just found this:

This guy the English tear looks like he had a low unadjustable b+ doesn't say exactly what the voltage was but seems to have rectified it by changing Ic401. Maybe pm him and ask him if he remembers anything about this. Sounds like a similar issue, you said "The B+ voltage was unadjustable before all this, so I'm still in the same spot." by before all this do you mean when you put it on a shelf years ago before doing any work you tested it and the b+ was stuck at 30v unadjustable?
 
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Do you know if the b+ before was correct while it was arcing with the old flyback, was it producing any image on screen?
This is a combo platter:
I picked up this complete Sanyo chassis in a parts buy.
The CRT was from a friend (the original chassis had an exploded R609 among other damaged parts. This chassis never produced an image and the B+ was never adjustable. Back in the day I replaced the B+ pot and did a cap kit with no change. Like I mentioned before it's a little perplexing because the usual suspects all check out or are brand new; there isn't any obvious cold solder joints or broken traces.
Thanks for the link, I'll check out how TheEnglishTear approached it.
 
This is a combo platter:
I picked up this complete Sanyo chassis in a parts buy.
The CRT was from a friend (the original chassis had an exploded R609 among other damaged parts. This chassis never produced an image and the B+ was never adjustable. Back in the day I replaced the B+ pot and did a cap kit with no change. Like I mentioned before it's a little perplexing because the usual suspects all check out or are brand new; there isn't any obvious cold solder joints or broken traces.
Thanks for the link, I'll check out how TheEnglishTear approached it.
So you don't know if the tube works then either? Wonder if something is shorted in the tube possibly causing the flyback not to want to energize it. I'm still thinking you could have a defective new flyback or voltage regulator, can you pull the flyback off the original chassis that this tube came from?
 
where did you get the LA5112N from as that is the first thing i would suspect even before a flyback on that model as there is a ton of fakes/failed used parts so we actually tested 100% of our stock. i would also check the filter cap too.
 
where did you get the LA5112N from as that is the first thing i would suspect even before a flyback on that model as there is a ton of fakes/failed used parts so we actually tested 100% of our stock. i would also check the filter cap too.
I got the LA5112N and flyback from you, so I figured both were legit and not an issue.
The filter cap is a 470uF 160V, that I believe came with the old cap kit from Bob Roberts.
 
lol dude if you used Bob Roberts caps it should be worth noting they're ancient and way under spec. he was reselling shit from 40 years ago and I find it bizarre that with @security0001 saving the universe there's still a Bob Roberts fandom.
Yeah I installed this cap kit years and years ago, other than a couple kits from Ian Kellogg, everything else has been from @security0001.
I'm going to pull out my Sencore and test the tube like @Mattspad mentioned. If I don't figure it out, I'll just toss it back on the shelf for a bit and move to another project until I actually need this.
 
lol dude if you used Bob Roberts caps it should be worth noting they're ancient and way under spec. he was reselling shit from 40 years ago and I find it bizarre that with @security0001 saving the universe there's still a Bob Roberts fandom.
Not to bust your bubble, but I applied 20-year-old, stored on my shelf, Bob Roberts cap kits on two monitors nine months ago, and they are working fine ;-)
But I have a fancy ESR meter to test them first at least and I do buy high-quality for newer stuff when it doesn't cost a fortune to ship from USA sites in my case.
 
Not to bust your bubble, but I applied 20-year-old, stored on my shelf, Bob Roberts cap kits on two monitors nine months ago, and they are working fine ;-)
But I have a fancy ESR meter to test them first at least and I do buy high-quality for newer stuff when it doesn't cost a fortune to ship from USA sites in my case.
Bob's legacy will live on strong, miss those surprise moon pies! Still love security001's dedication and commitment to his products, only guy I trust now for sensitive components. It's still not impossible you got a dud new part but the problem is you took two unknown monitors together to make one, if someone offloaded this to you for cheap it could've been a lost cause. If you had some kind of knowledge of how those the chassis and tube ran individually before you mated them together it would be really helpful.

edit: Also try wiggling all your capacitors and look at the bottom side to see if you have a lifted trace
 
Be sure to look closely for cold solder and damaged traces. 20EZ chassis PCBs crack easily. I recently had one on my bench where I had to repair two major obvious cracks in the board… and spent days chasing down two more subtle hairline cracks across multiple traces.
 
Clean off all of the flux and look at the traces and pads around the flyback closely. Remove the solder from the pads on the flyback and make sure no pad is lifted.
 
I've been working on my spare CRTs and this one is giving me grief. I believe I've exhausted the flowchart. Here's what I've done so far trying to rectify the low and unadjustable B+ voltage.
  • Cap kit completed including new filter cap
  • New flyback
  • New B+ Potentiometer
  • New voltage regulator
  • Swapped in a used HOT for kicks
    • Base to Emitter .5V
    • Base to Collector.5V
  • D601-D604 all read .49V
  • R609 180 Ω
  • R604 1.1K Ω
  • Both fuses have continuity
Weird side note: if I test the B+ on the BJ post behind R609 then I get a little crackle of high voltage into the CRT. Odd?

Could the used HOT be failing under load.
What's next?

What is the VDC of the B+ as measured at the BJ test point?

Have you tested all of the resistors on the 600 section? Specifically the ones around the B+ pot?
 
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