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Old 08-25-2012, 08:33 PM
wd409 wd409 is offline
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Anyone know about these sanyo lcd's? my dp26649 has issues.

Greetings people of video karma, I just found out about you. I've been on audiokarma for a little while now though.

someone there recommended I try this here, so heres the post i made there.


alright, short bio, I do this as a hobby, just to mess around, and try to learn.
but, sometimes that isnt easy. particular for this specific model of tv im about to talk about, to which exhaustive efforts to find a service manual have gone unasnwered. so keep in mind i dont know (exactly) what im doing, but I have a good idea, i think.

alright so heres the thing, I bought this sanyo 26" tv at the goodwill a little while ago, knowing it wouldnt turn on, and praying the screen was ok, cuz the rest is fixable, right..

it had a blown 0.1 ohm fuse-resistor in it, which lead directly to two blown transistors, these transistors read 0000 out of circuit in all directions.

so, I look at their styling code and model, and order new ones, now..
the 16n25c's they sent me are different from the ones I asked for. I asked for FQP, which was a metal back... i get FQPD or something like that, that is not metal, but the rest checks out, so I f igure... why not.

so, the tv powered up, looked good enough, you know, for a sanyo.
everything seemed to be legit about this operation, until a few minutes down the road, when it blew all of those components again.


alright so heres the deal, from those transistors the path leads to the transformer, and from there they go to more transistors, sbt150 or something to that end, I did pull those and test them, they seemed a little low, reading 0.200 in diode test, but all 3 gave that so I didnt think anything of it. other transistors, those new ones for example before I just blew them... would have read 0.600 or so, for comparison.

alright so my question is here where I did go wrong just now. was it the plastic case transistors or did I fail to find something further upstream do you think?

Specific information: tv is model DP26649 chassis -00. above situation refers to the power supply board. the blown transistors are on the reverse side of the heatsink that the bridge rectifier is on. bridge rectifier tested good.
and this tv did work for a few minutes time, with absolutely no indications it was having a problem or about to blow.

Thanks in advance for any suggestions that come my way
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Old 08-25-2012, 10:10 PM
radiotvnut's Avatar
radiotvnut radiotvnut is offline
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It could be possible that you ended up with some cheap knock-off transistors. I found this out the hard way, back during the CRT TV days. Many of the mail order parts places that I ordered from carried parts that were very cheap; so, not knowing any better, I ordered the cheap parts. Once, I ordered a bunch of horizontal output transistors and every one of them blew within seconds of turn-on. Once they were replaced with decent transistors, the TV's worked fine.

I ordered a batch of cheap STR53041 regulator IC's, the ones used in those horrible '90's era Zenith TV's. Every one of those were inoperative. On the first one I used, I pulled my hair out trying to figure out why the TV wouldn't power up. After all, the new part couldn't be bad, right? WRONG! After sticking a known good IC in there, the set powered up.

I've also had other experiences of cheap generic semiconductors and flyback transformers failing after short time periods. Now, I always order name brand parts from reputable suppliers.

Besides that, I'd look at bad capacitors in the power supply. Most of these cheap LCD TV's use cheap capacitors and don't be surprised to find more than a few bad ones.

Otherwise, you may be better off replacing the whole board (if one is available at a reasonable price).
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Old 08-25-2012, 10:40 PM
wd409 wd409 is offline
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I ordered the parts from mouser, which ive had good success with in the past.

Mainly im wondering if the metal back version would have survived in this situation, or is there another problem, keeping in mind, something made the originals blow, too..

does anyone by chance know what a good sbt150 transistor measures on a DMM in diode? is 0.200 normal for that? they read around there one way and OL the other.

oh and i did replace the caps on the power board, too. they have new panasonics and nichicons on there as of last week.
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Old 08-25-2012, 11:25 PM
Geoff Bourquin Geoff Bourquin is offline
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SBT150 is a shottky dual-diode,100V 15A. Around .2V across the junctions is right.
As for the FQD16n25c, the extra digit should work OK. I find it is usually a change in mounting style, as you said. There may be a series resistor/capacitor, or diode across the mosfets that died and is not snubbing a pulse that needs snubbing.
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