1994 Sanyo TV, turns on, no picture, turns right back off.

[MRX37]

There are three large ceramic resistors near the HOT. None of them have any info on them though.

I'll check all the resistors in the area in a bit...

[MRX37]

Okay, so far I haven't found any "bad" resistors. The two larger 10 watt ceramic resistiors in the regulator circuit have seen some heat... so much that their casing is cracked. The info on them was worn away, but my multimeter identified them as 220 ohm resistors. I'm sure as hell going to replace them, but they tested good, so i assume they aren't why the TV still won't get a picture.

[MRX37]

Okay I took out the third ceramic resistor, and it measures about 10 ohms. I don't know if its good or bad because the information on it is cryptic.

The info is: RY8GJ 6R8K I assume the K stands for kilo ohms, so that would indicate the resistor is bad, but I can't be certain.

[radiotvnut]

I think that may be a 6.8 ohm. All the bad ones that I've seen were open. I've never seen one of those go up or down in value.

[MRX37]

Okay, I'll replace it anyway since it's out of spec.

I also found a 2.5K ohm resistor in the flyback area that reads only ~175 ohms. Pretty sure it's supposed to be a 2.5k ohm resistor. Here's a pic of it.


To me it reads red green red gold, which comes out to 2500 ohms at 5% tolerance.

[radiotvnut]

It's in Sams 3466. I'll see if I have a copy so we can make sure of the resistor values.

[MRX37]

Oh that would be great. I HATE resistor color bands. Can't ever tell with 100% certainty what one of those little 4 band bastards is. So i snap a pic of it and use Photoshop's color sampler to get a best guess.

[radiotvnut]

I found the Sams. What are the board location numbers of those two resistors in question?

As far as the shorted HOT blowing something, I'd suspect R007 (5.6 ohm, 2 watt) and/or R001 (1 ohm, 6 watt). One end of R001 connects to one of the contacts on the power relay and the other end connects to the cathode of D002 and the anode of D004. These are two of the four diodes that make up the bridge rectifier in the power supply and the cathode is the end of the diode with the white or silver band.

R007 connects to pin 3 of the regulator.

If these resistors are good, measure the B+ voltage. Take your voltmeter ans set it to measure at least 200 volts DC. Connect the negative lead to one of the heatsinks and the positive lead to pin 4 of the STR regulator IC or pin 2 of the flyback. Turn the set on and you should measure around 130 volts DC. If the voltage is much higher, like in the 160 volt range, either the regulator circuit is not operating properly or the horizontal circuit is not operating. These types of regulators must have a proper load in order to regulate properly.

If the voltage is lower than 130, unsolder pin 2 of the flyback and check again. If the voltage jumps up, the flyback is most likely bad.

[MRX37]

Okay, the supposedly 6.8 ohm ceramic block resistor is R473

The supposedly bad 2.5k ohm resistor is R459

[radiotvnut]

R473 is a 6.8 ohm and R459 is a 180 ohm, 1 watt.

[MRX37]

Okay, so they're both essentally good... R473 might be a tad high. Thanks a lot! Saved me from spending money on the wrong parts, getting frustrated and junking the chassis.

I'll check R001 and R007 when i can.

[MRX37]

R007 is BAAAAD!! Infinite ohms! Finally found you motherfucker!

And of course it's hidden between the big 220 ohm resistors and the heat sink, so were it not for your help, I may have never ever ever found it.

[radiotvnut]

While you're in there, check C474, a 47uf, 160 V cap.

[MRX37]

All right. I've been shotgunning the jamicons anyway. The rubycons seem to be holding up nicely.

[MRX37]

Oh, C474 was one of the first caps I replaced. So that's already been replaced.

Still waitin on the parts I need.