Ollie's PVM Giveaway Repair Thread

Inviere · 28-01-2022 08:55PM #1

Just popping a thread up for these PVM's a few of us got. The two I have here don't appear to power on (visually anyway), just wondering are all the others similar or have others seen various other faults with theirs?

Also, if anyone has any leads on where to begin with fault finding, twould be greatly appreciated. Has anyone ordered parts etc at this stage?

KeRbDoG · 29-01-2022 01:23AM

From Ollie's original post, he mentions that he suspects "its an issue with the voltage regulator circuit (possibly the voltage regulator IC itself : STR S6707"

I've got spares incoming, but if you search for 'monitor issue STR S6707' you will find repair logs focusing more so on Sony displays mentioning potential issues with caps connected near to that regulator.

Those will be my first two steps/checks when parts arrive and i crack a monitor open.

I already have the Arduino Nano in hand and programmed for the jungle IC override so RGB can be plumbed into the set...a little premature considering the power issue might stump me

Inviere · 29-01-2022 07:21AM

Cheers @KeRbDoG, definitely keep us posted here about your progress. I'm trying to keep these monitors here and present as long as I can, because if they go onto "the repair list", and into storage, god knows how long it'll be until I get to them.

eddhorse · 30-01-2022 01:15PM

Checked teh 3 I have here, not a peep out of them, didn't have time for any voltage measuring etc.

Is this the RGB mod https://immerhax.com/?p=558

Inviere · 30-01-2022 02:04PM

https://www.boards.ie/discussion/comment/118554015#Comment_118554015

Aye sounds like my two. Not a sign of any life visually or audibly. @KeRbDoG were yours the same, or have we got different issues?

@eddhorse yep that's the blog/page I found re the rgb mod.

BGOllie · 30-01-2022 02:55PM

yeah out of the lot only one worked ... for a bit then shutdowns after a minute or so. The others either didn't start at all or go into HV shutdown.

It typically means there's an issue with either the Xray protection or more likely the main power supply area . I'd do a recap first and then check the voltage regulator and go from there. All areas are clearly marked and layed out on the PCB so it's handy to identify all the various parts of the circuit.

I did try swapping the H.O.T , flyback and vertical IC from a bad one to the "good one" for peace of mind and it still worked so we can rule out these components but that's all I managed to do . would be interesting to see what the issue is because who ever fixes one will pretty much fix all the other ones in the process :)

BGOllie · 30-01-2022 02:57PM

oh and I checked the electrolytic caps ESR in the power supply area and the seemed fine so it could well be one of those filter caps too

Inviere · 30-01-2022 04:13PM

Cheers @BGOllie, appreciate the helpful info. I hope to get a proper look at the chassis over the next week or two

eddhorse · 30-01-2022 07:40PM

Service manual https://archive.org/details/jvctmh140pnservicemanual/page/n8/mode/1up?view=theater

https://ia803006.us.archive.org/16/items/jvctmh140pnservicemanual/JVC%20TM-H140PN%20Service%20Manual.pdf

The Last Bandit · 03-02-2022 01:53PM

Got mine this morning thanks to Ed, not much to report so far apart from it's blowing the main fuse and releasing a bit of the magic smoke.

eddhorse · 03-02-2022 03:07PM

https://www.boards.ie/discussion/comment/118575377#Comment_118575377

Same with mine :)

Did notice a small bit of screen burn saying "VIDEO COMPILATION"

Nice to meet you @The Last Bandit

Inviere · 03-02-2022 03:38PM

@The Last Bandit maybe that's why ours appear to be completely dead....blown internal fuses. Haven't had a chance to open one, prob won't get to do so for another week or two

KeRbDoG · 03-02-2022 05:23PM

Both monitors I have, one powered on for a second and powered off with no life when switched off/on. The other did nothing when power on.

House breakers all non-popped I'm happy to report :D

I checked the internal fuse on one of the monitors, internal fuse was fine. I will check the other later. Just awaiting on that STRS6707 IC but I just received today a large filter cap which will be swapped at the same time as the IC.

Inviere · 03-02-2022 06:25PM

@KeRbDoG great stuff, keep us posted 👍

CiDeRmAn · 03-02-2022 07:53PM

Counting the moments...

o1s1n · 03-02-2022 09:45PM

https://www.boards.ie/discussion/comment/118577547#Comment_118577547

Till someone zaps themselves?

The Last Bandit · 04-02-2022 02:23PM

Bad degaussing PTC on mine, component TH901 (part number Epocs T709) mounted underneath the very large resistor R901. Using Apple II as video source so ignore the blurriness.

Probably a good place to start if yours in blowing the fuse on power up.

o1s1n · 04-02-2022 02:27PM

Rise from your grave - fair play :)

CiDeRmAn · 04-02-2022 02:35PM

https://www.boards.ie/discussion/comment/118578196#Comment_118578196

Waiting for the lights to flicker and the smell of burning hair...

KeRbDoG · 04-02-2022 03:24PM

https://www.boards.ie/discussion/comment/118581062#Comment_118581062

Sweet, be really interested to see how you narrowed that fault down if you can share?

The Last Bandit · 04-02-2022 04:03PM

Since it was the main input fuse was blowing then the fault had to be something shorting in the primary power side.

I pulled the STRS6707 first as it got a bad reputation but it tested fine out of circuit, so just went thru the schematic testing each component that could short both input AC lines. The PTC is one of the first components but seemed ok in circuit but pulled it anyway as these can fail after a few seconds once they heat up.

Colonel Panic · 04-02-2022 05:10PM

Hopefully the issues are all on the power side!

BGOllie · 05-02-2022 01:30AM

https://www.boards.ie/discussion/comment/118581852#Comment_118581852

nice one. yeah the voltage regulator would've been my first guess for most of them alright. PTC thermistors can be tricky to diagnose as they need to heat up before failure is noticeable. good catch .

The Last Bandit · 05-02-2022 07:08PM

Pulled the PTC from an old 14" portable TV and worked perfectly and can't see the burn-in when power up either so very happy with it :) Can't figure out how to adjust the frame speed on poxy iphone hence the sync bands appearing.

Sound is pretty decent as well considering its a monitor, although I must add a second audio jack and passive mixer to get both channels piped in.

BGOllie · 05-02-2022 09:10PM

ah great they're getting a second life :) imagine, they were going straight into a skip

Inviere · 05-02-2022 09:26PM

Damn, Epcos T709's are NOT easy to find online....

The Last Bandit · 05-02-2022 09:46PM

I couldn’t find any either but I fairly sure any 3 pin one will work, they’re all similar enough specs and same pin outs from the few I looked at. The one I pulled from the tv was a completely different part but works grand.

KeRbDoG · 05-02-2022 09:59PM

Could you just remove it and disconnect the degaussing coil?

The Last Bandit · 05-02-2022 10:10PM

Yep that what I done and had lots of discolouration within a few minutes, the speaker is very close to the tube. This completely cleared up as soon as the degauss cycle started again.

So definitely needs the degauss circuit working, I seen other model PTCs on eBay that’ll probably work. I’ll need to get one anyway to replace the one from the tv.

KeRbDoG · 05-02-2022 10:17PM

That would prob be a way for folks to confirm the PTC is the issue or not I guess.

I can confirm that isn't the issue with one of the screens I have. Also swapped out the STRS6707, but to the same fault. Monitor powers on briefly and shuts down. Hunt continues.

I have 10x 3 pin PTCs on route from our Polish friends.

eddhorse · 09-02-2022 02:20PM

https://www.boards.ie/discussion/comment/118588306#Comment_118588306

Who are the polish friends?

Ollie's PVM Giveaway Repair Thread

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