Whoops. Stupidly lowered H.Freq too low and PVM shut off.

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TL:DR

I was adjusting service menu stuff and turned H.FREQ down too far and buzzing sound then poof my pvm shutoff.

Fuse was blown on the PS replaced no luck. CHecked pins no power to any of them.

Anyone have any idea along the path what may have blown? Also is it possible I destroyed something on my main board too?

I really appreciate any help.

[tongshadow]

What were you even trying to accomplish? This adjustment is set perfectly from the factory and doesnt need any changes. According to the service manual, to adjust H.FREQ you need to connect a capacitor into the appropriate connector, perhaps this is done to avoid damaging the circuit.

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What were you even trying to accomplish? This adjustment is set perfectly from the factory and doesnt need any changes. According to the service manual, to adjust H.FREQ you need to connect a capacitor into the appropriate connector, perhaps this is done to avoid damaging the circuit.

I didn’t get it from the factory.
I understand how to adjust it shorting it to ground with a capacitor. I was just adjusting it a bit by bit to compare phase vs h.freq and the effect horizontal linearity.

Now I’m not arguing that was a good idea. But it’s too late now lol

Just trying to see if anyone knows mores than me having to pull a bunch of stuff off to test.

I did search on here tho. Just one thread of the same issue and basically people said adjusting in the service menu can’t hurt anything unless something is about to fail and someone saying it can. Which I solved lol

[tongshadow]

If you're not getting ANY voltages at all, then it's likely more fuses have blown on the PS. Some of them look like resistors, you'll have to check the service manual.
At this point it would be easier to get another PS to test.

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Oh ya forgot about those. I’ll check em.

Maybe last one I saw 200 dollars just for a ps.

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Well I checked the fuse and the 4 fusible resistors. Still 0 power to any pins. They were all still fine. I tested two cables and the outlet just in case and it’s fine.


Seems odd.

Any other input? I'm not asking anyone to do the work for me.

But just a hint of guidance for where to check next?

[SuperSpongo]

What is the exact model? Are there any LED blink codes?
Also, does this setting adjust the horizontal frequency, as in the horizontal output transistor? If so, if you turned it down too low, it might have killed the HOT.

EDIT: Okay, I missed the part where you checked the pins of the power supply and there's no voltage. But the PVM model would be interesting nonetheless.

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Oh I thought I posted it.

20M4U


I adjusted it on a digital menu so I think it was just H.FREQ.

Idk about the hot yet since there is no power. I do have a working spare somewhere.

No led blink codes. It's straight dead. I lowered the H.Freq a bit. Then phase and was checking linearity.

I decided to go down to like 60 on my settings for the H.Freq and as I did it started buzzing and then it shut down in like 2 seconds. Like in the same way you hit the power button.

I checked the power from the plug, its fine. It makes it past the fuse and then goes out to the power switch comes back in then gets converted to DC. It comes out of that just fine.

Then from there I can't figure out what happens. No power reaches the other side of the board.

This is where that left me (I'm a noob to all of this and learning the hard way.)


Basically I got to a dead end at those points. One is a switch and the other is some IC that I didn't quite understand. But both voltages past those points were low/none.

Also the power to the transformer was fine on one side but on the other side there was nothing. But a lot these components I only understand at a surface level so not sure where the fault could be.

I tried replacing the switch/thermistor nothing changed.

Appreciate the help if you have any ideas. (the fusible resistors are all fine too, I pulled them just to double check.)

[DejahThoris]

Also the power to the transformer was fine on one side but on the other side there was nothing.

Well if power goes into the transformer, and then doesn't come out of it, I'd imagine that you've found your answer.

[tongshadow]

Also the power to the transformer was fine on one side but on the other side there was nothing.

Well if power goes into the transformer, and then doesn't come out of it, I'd imagine that you've found your answer.

Doubt it's the transformer, they're virtually indestructible. If there are no voltages on the secondary it could mean the PWM pulses generated by the IC, on the primary side, arent being properly formed.

[DejahThoris]

Also the power to the transformer was fine on one side but on the other side there was nothing.

Well if power goes into the transformer, and then doesn't come out of it, I'd imagine that you've found your answer.

Doubt it's the transformer, they're virtually indestructible. If there are no voltages on the secondary it could mean the PWM pulses generated by the IC, on the primary side, arent being properly formed.

I didn't take the original statement as primary vs secondary, since it said "side" I assumed it meant output vs input.

I guess we'll see when OP comes back. And transformers are hardly indestructible. Hardy, sure, but they absolutely do die in CRT's.

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Also the power to the transformer was fine on one side but on the other side there was nothing.

Well if power goes into the transformer, and then doesn't come out of it, I'd imagine that you've found your answer.

Doubt it's the transformer, they're virtually indestructible. If there are no voltages on the secondary it could mean the PWM pulses generated by the IC, on the primary side, arent being properly formed.

Makes sense to me I’ll inspect it tomorrow. I also have a replacement coming just in case and or to see what else is fked.

Thanks for the tip!

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Well if power goes into the transformer, and then doesn't come out of it, I'd imagine that you've found your answer.

Doubt it's the transformer, they're virtually indestructible. If there are no voltages on the secondary it could mean the PWM pulses generated by the IC, on the primary side, arent being properly formed.

I didn't take the original statement as primary vs secondary, since it said "side" I assumed it meant output vs input.

I guess we'll see when OP comes back. And transformers are hardly indestructible. Hardy, sure, but they absolutely do die in CRT's.

Primary side. I got nothing making it to the secondary side and prior to me being a idiot it had a full recap and replaced the voltage regulators. It was running smooth. Damn thing looks so nice everyone thinks it’s 1000tvl lol.

I wanna get her back going, lesson learned lol

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Also the power to the transformer was fine on one side but on the other side there was nothing.

Well if power goes into the transformer, and then doesn't come out of it, I'd imagine that you've found your answer.

Doubt it's the transformer, they're virtually indestructible. If there are no voltages on the secondary it could mean the PWM pulses generated by the IC, on the primary side, arent being properly formed.

Hey there. My new power supply came in. All voltages out measure fine. However when I plug it in, it makes a really loud buzzing sound in the transformer area when I power it on. It sounds alot like when the h-freq dropped too low and then poof.

Any ideas? Is there a way to reset my OSD settings? If it saved it to the last know Hfreq then idk how I can reset it without being able to get to a menu.

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Fixed it. It blew the hot.


So all in all... IDK what blew in my PS but possibly the transformer it was making alot of noise in that area.

It also took the hot out with it or that went first.

Thanks for the help!

[tongshadow]

Havent had the chance to properly study this power supply, but in some monitors the power supply's feedback system is in sync with the flyback transformer. So if I had to make a guess, the power supply couldnt handle the off-spec H.Freq and blew up along with the HOT.

Btw, did you get the idea of adjusting it from this video?
https://www.youtube.com/watch?v=5VHDRNocmBo

[SuperSpongo]

Hooray, it was the HOT

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Havent had the chance to properly study this power supply, but in some monitors the power supply's feedback system is in sync with the flyback transformer. So if I had to make a guess, the power supply couldnt handle the off-spec H.Freq and blew up along with the HOT.

Btw, did you get the idea of adjusting it from this video?
https://www.youtube.com/watch?v=5VHDRNocmBo

Yeah.
I was more or less just trying to lower it a bit/phase to see if I noticed a difference in the linearity to see if it would have been worth it. Lol was too lazy to open it up and hook a cap up.I did actually google the freq thing but I saw some people say it would be fine.(also people saying it could be bad.) I think it blew around 65-69. I did go back and do it the correct way though. It did solve most my linearity issue on the left but the right still has a small squish. Where as before left and right were both horrible

That said when opened up the ps I did find a cap leg stuck to one of my transistors. Stuck on the output leg and looked like it was touching the ground.

No idea if that was another piece of this puzzle. Either way I'm glad it was just the 10 dollar HOT.

Sadly the power supply cost me 100 but oh well I got the 20M4U for 140 bucks. So I can't complain.

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Hooray, it was the HOT

Haha. I still don't know what died in the PS.