19K7201 Transformer Squeal

aamauzy

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Pulled a WG 19K7201 that has sat on a shelf for the last year for a tube swap due to a cathode short. This monitor has always had an abnormal squeal, I've always thought that it was coming from T3, per the schematics:

https://usermanual.wiki/Document/WellsGardner19k7201SchemPartEnglish.3477949735/view

It was bearable/extremely muffled by the cabinet that it was in. The green cathode short got to a point where it was unusable, so I swapped it with a different monitor. After sitting on a shelf for a year or so, I found a good donor tube. Swapped the tube in this evening - picture is great, but the T3 squeal has become a scream. No amount of tapping or attempts to wedge a toothpick under it or in any seams lowers the scream. I can put pressure on it while in use, which with slightly re-mediate the sound. The scream is constant with spikes on bright flashing colors and loudest on white screens (think of the Neo Geo white attract screen). I've tooth picked the flyback and and tap all over it all day without causing any change in the sound, just to be sure.

I assume at this point the best route would be to replace T3 - it's an EI-40 transformer, part number 053X0648-001 according to the above schematics. My problem is that that part seems to not exist in any available fashion online. Am I missing something, or am I just going to have to watch for a dead 7201 chassis to come along to steal the part from?


(For those of you that span forums and have been around for a bit, here's the beginning of this saga. Hard to believe it's been over 10 years: http://forum.arcadecontrols.com/index.php/topic,86861.msg912046.html#msg912046 )
 
Need to replace d101 d101a first

C101, c57

And the other caps if never replaced before

It's not T3 from my experience

The sound is coming from the t3

Because of the diodes or on the b+ supply
 
Have the same monitor doing the same thing. Haven't had a chance to dig into it at all yet. Going to follow this thread ;)
 
New to posting - I didn't realize I had replies on this! It's been long enough that I don't recall whether or not I've ever capped this chassis, so I'll go ahead and do that. Very interesting regarding the B+ voltage, I'll check out the other components listed as well.

Thanks!
 
DID you ever figure out the source of this I have one also
New caps and diodes and still the squeal

Ok

Need to eliminate the power supply

And any low ohms on b+ trace.

Remove HOT and power up with

60 watt or better inconsistent bulb

Parallel the dc rail and check for good

Regulation. Did you use original part numbers?

see if still squealing with high voltage circuits

Disabled
 
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