Sanyo DP42849 - No Power At All

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

The results on the IC602, right?

If you could explain to me in detail how to do the test again, I'll redo it, just in case I did do it incorrectly.

Thanks!

[tom66]

Re: Sanyo DP42849 - No Power At All

You should use diode mode on the secondary/cold side (board unplugged) and see about 1V one way and infinity the other way - though if it is in circuit it might not work.
You can also check the voltage across each side and be sure that the multimeter probes are touching each pin - verify with continuity check.

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

For IC602, the two legs on the secondary side, diode mode:
"1" one way
1253 the other.

IC 902:
"1"
1340

IC 201:
"1"
"1"

IC903:
"1"
1196 (but leads are reversed in comparison to the other ICs)

[tom66]

Re: Sanyo DP42849 - No Power At All

IC201 does not look right to me. What part # is printed on it?

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

I'll get that in a second. I redid the voltage test on all of them as well:

IC902: 0.87 --> 1.93
IC201: 0 --> 0
IC602: 0 --> 0
IC903: 16.57 --> 19.86

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

All 4 ICs have same part number:

[tom66]

Re: Sanyo DP42849 - No Power At All

IC201 should test as around 1200~1400 on your meter. So I think it is bad.
SHARP PC123 optocoupler.

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

Let me test one more time to make sure.

So those are the optocouplers? LOL I thought it was that shiny yellow thing above them.

[tom66]

Re: Sanyo DP42849 - No Power At All

Shiny yellow thing is probably a transformer.

[lookimback]

Re: Sanyo DP42849 - No Power At All

I have the exact TV with that power supply on my work bench right now. I have to replace an AS15 on the Tcon. I could probably help you with some comparison readings. I won't be home from work until about 9:00 p.m. EST though.

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

Sweet, thanks!

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

So IC902 and IC903 are oriented the same way in the board, but I have to reverse the leads when doing diode check on them to get comparable readings. Is that normal?

[lookimback]

Re: Sanyo DP42849 - No Power At All

Just post the pins you need readings from and I'll post what I get from them.

Not sure What you have for a meter but I have a Fluke model 115. There will probably be slight variations between our readings but they will probably be close enough. I'm sure with Tom's help and my readings we can figure this out.

[tom66]

Re: Sanyo DP42849 - No Power At All

Compared to IC602?

[lookimback]

Re: Sanyo DP42849 - No Power At All

You have to remember that electricity follows the path of least resistance. You probably aren't getting a reading through the component but rather, through the rest of the circuit. Sometimes you have to remove the component to test it.

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

I see what the problem was with IC201's reading. It's the only IC whose orientation is reversed. When I test it on the other side - red lead on pin1 - I get 1367.

IC903, 602, and 902 are all situated in the board the same way - here's how I get my diode readings:

IC903: Black on pin 1 - 1196
IC602: Red on pin 1 - 1253
IC201 (reversed in board): Red on pin 1 on PRIMARY side - 1367
IC902: Red on pin 1 - 1340

[tom66]

Re: Sanyo DP42849 - No Power At All

Electric current does not follow the path of least resistance. Current takes each path with a magnitude inversely proportionally to its resistance.
(Electrical arcs are the only type of current which follows this least resistance idea - i.e. lightning - but that's a different phenomenon to pure electric current.)

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

So IC201 is good, right?

Why is IC903 different?

[tom66]

Re: Sanyo DP42849 - No Power At All

I wouldn't know why IC903 is different, that is really odd.

[lookimback]

Re: Sanyo DP42849 - No Power At All

I stand corrected. Thank you for explaining that.