[Guest]

Without a schematic diagram I can't tell what the fuse values are.
I replaced the f4 fuse with a low value surface mounted fuse that I had kicking around.

[amerillove]

Great post! Well, metered each of the (7) inverter transformers primary & secondary windings; all are the same (on my meter x100 range = ~650 ohms.)

[OldIBMer]

[Guest]

Display flashes black for 1-2 seconds, then returns to black. On inverter board checked fuses marked p 1,2,3 and all where fine, less than 1 ohm. Checked fuse marked n and had high resistance 1.5 MOhm. Replaced and set is serviceable.

[OldIBMer]

[J/TECH]

I would like your old inverter board; have one with bad transformer on; can't find supply of board or transformer. Open to offers?
Installed the board and the TV came back to life. Another electronic casualty plucked from the jaws of the landfill!! (at least for now)

So, now I have a dead inverter on my hands. Wish I was smart enough to fix it. I thought some of comparing some voltage levels between the old and new (only have a VOM; no scope), but thought better of it...might end up with two dead boards!

As I mentioned before, there are four components at sites etched with F1-F4. They each carry a single letter identifier: P, P, P, N. They "appear" to meter with an ohmeter like a diode, but they are still in their circuits.
Is it likely that these are being used as fuses?
Is there a way I can test these with only a VOM?
I know this is a tough question to answer without a schematic, but I don't know where one of those might be found.

[quote="OldIBMer"]... So, here is what I have done so far:
1. Carefully inspected power supply PCB for signs of heat, bulging caps, or anything else out of the ordinary...looks OK.
2. Metered 24V DC on the connector going to the inverter PCB.
3. Inspected inverter PCB...looks OK.
4. Metered each of the (7) inverter transformers primary & secondary windings; all are the same (on my meter x100 range = ~650 ohms.)
5. Looked for a fuse or fuses on the inverter PCB. Only thing there are four components etched as F1-F4, three are marked with a "P" and one with a "N" and none of them meter the same. All act like a diode, and all are different (measured each both ways: inf.-1k, inf.-6k, 5k-inf., and inf.-600k on the one marked "N".) Since I am metering them while still in their circuits, I know results would be unpredictable unless they were normal fuses...

[/quote]

All in all, a happy conclusion and I am thankful for the help that the folks on this forum have provided! [/quote]

[vtech]

Can you post a picture of what you are referring to?
I would guess you'd probably have a cap or transistor & /or driver issue. Problem being that a lot of times even if you find the device(s), it may take longer to find a replacement.

Your idea of comparing voltages was not a bad idea but still inconclusive and as you mentioned, possibility of two bad boards.
Now if you have the time & determined to find the culprit(s), one good approach is to attempt a resistance check/comparison with a known good board.

ie; You'd choose a ground plane as a reference point on both boards and select random identical points(start around major components) and compare resistance readings. Chances are pretty good that you would come across a drastic difference at some point between the two boards. Then it would be a matter of tracing it to the faulty device....used to do this on many instances and always had good luck in finding the elusive culprit.

Of course it can't be too complicated of a circuit to get accurate readings & an inverter is definitely not complex.

[OldIBMer]

Today, I received a replacement inverter PCB that I ordered from ShopJimmy.com. Smooth transaction, reasonable shipping cost, and fast...ordered Sat. night, 8/22, and received (by UPS) on 8/27. Cost $69.99 plus 9.78 shipping.

Installed the board and the TV came back to life. Another electronic casualty plucked from the jaws of the landfill!! (at least for now)

So, now I have a dead inverter on my hands. Wish I was smart enough to fix it. I thought some of comparing some voltage levels between the old and new (only have a VOM; no scope), but thought better of it...might end up with two dead boards!

As I mentioned before, there are four components at sites etched with F1-F4. They each carry a single letter identifier: P, P, P, N. They "appear" to meter with an ohmeter like a diode, but they are still in their circuits.
Is it likely that these are being used as fuses?
Is there a way I can test these with only a VOM?
I know this is a tough question to answer without a schematic, but I don't know where one of those might be found.

[Guest]

[jts1957]

Ordered a power supply from D-M. It failed to even produce stand-by 5 volts. They had it picked up, and sent a second. That one worked!
They "claim" the check all boards ... I don't think so. I think they are just "pulled from non-working sets," cleaned up, sold & hope for the best.