Sanyo DP42849 - No Power At All

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

you need to check it twice,once just plugged in with wall switch on and tv off,and once with tv turned right on..

but first on the black connector with the black and white mains in wires are

with all plugged in and wall switch on,but not tv on,what voltage do you read?,set your meter to AC volts this time (highest setting),need to find your voltage to see what should be on that cap when powerd up,

your in the high voltage primary section now,so be carefull!,and watch where your sticking the probes

Sorry, I'm not quite clear where on the AC connector you want me to put my leads. Inside the connector like I did with the PS pins? I've circled what I think you're saying on the attached picture.

Black to black, red to white?

Highest I have on my DMM is 500.

[multimeter]

Re: Sanyo DP42849 - No Power At All

Sorry, I'm not quite clear where on the AC connector you want me to put my leads. Inside the connector like I did with the PS pins? I've circled what I think you're saying on the attached picture.

Black to black, red to white?

Highest I have on my DMM is 500.

yep,thats all correct

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

I got 120.

[multimeter]

Re: Sanyo DP42849 - No Power At All

ok,120v x 1.44 = 172.8v,,

so with power on ,tv on you should see around 172-ish volts on the large cap,black probe to the negative side(stripe) red probe to the other,what is the voltage?and be CAREFULL!

im gonna have to sleep now,be back on tomorrow,hopefully that voltage is there,and can do some more testing,in the mean time post up some pics ,so we can see the markings next to the connectors at the power supply end,and the mainboard end

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

Okay I'll see what I can do. Can I take that safety plate off for easier access?

Thanks for all of your help!

[tom66]

Re: Sanyo DP42849 - No Power At All

It's a heatsink not a safety plate. Yes, but you must install it before using the TV. Also, do NOT touch any exposed heatsink while the TV has AC connected - working or not!
Only take it off if you can unscrew it. If you can't, it's not designed to be removed and an alternative method must be tried.

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

It's a heatsink not a safety plate. Yes, but you must install it before using the TV. Also, do NOT touch any exposed heatsink while the TV has AC connected - working or not!
Only take it off if you can unscrew it. If you can't, it's not designed to be removed and an alternative method must be tried.

Gotcha.

Can I safely practice getting my leads in there with the TV unplugged for a bit?

Also - what should I have my meter set to when testing the cap?

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

Tried to get some better photos.

I don't think my meter tests capacitance.

[multimeter]

Re: Sanyo DP42849 - No Power At All

Gotcha.

Can I safely practice getting my leads in there with the TV unplugged for a bit?

Also - what should I have my meter set to when testing the cap?

practice is good !,just unplug the tv ,and let the capacitors drain,you can play with the probes then.to see how you get on.still be carefull though as they still can rise.

the max on that filter cap should be around 172v when tv is powerd on and less with just plugged in.

you want to set your meter to DCV volts, ,think yours is 500v dc max?set it to that.

measure the large cap,black to stripe,red to the other pin and post back both readings,just watch the heatsinks ,(all the aluminium sheilds)as they will bite you if you touch them.and it does hurt!

that meter wont measure capacitance or esr ,if your doing this stuff a lot then you will need an esr meter,but we can still do a little test just to see if they are at fault in a bit.

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

Well, I'm glad I practiced. I hit the heatshielding with my leads every time. I get no reading, btw. Left TV unplugged all night.

I think the smartest thing for me to do right now is to check everything else that I can, and then check this filter cap only as an absolute last resort, at least until I can improve my steadiness with the leads. Or pick-up some alligator clips which would make me feel loads better.

To that end, I pulled the board out and checked the underside for any damage or the like. I'm not seeing anything. I also checked some diodes, and I think I've found a bad one. When I use the diode check on my DMM, I get 018 both ways on D902 when I check on both sides of the board. That means it's shorted, right?

I also have a question about diodes - do their readings get larger as they get larger? Meaning, will a smaller diode give a higher reading than a larger diode?

I've taken pictures of the diode and the underside of the board if you'd like me to post them.

Thanks.

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

Here's what I've got so far:

D602 - 504
D951 - 207
D601 - 597
D902 - 018 both ways
D901 - 513
D301 - 622
D903 - 618
D201 - 554
D251 - 624
D252 - 621

Inside and on heat-shielding

D804 - 379
D808 - 379
D806 - 679

[vinceroger69]

Re: Sanyo DP42849 - No Power At All

with a diode that reads the same way in circuit i always unsolder one side and lift it up a little so not touching the circuit board then retest the reading.post the picture first though so we can see it on the board and the surronding parts.

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

Here are some photos of the diode, the main cap, and the underside of the board.

[tom66]

Re: Sanyo DP42849 - No Power At All

D902 is suspect - can you get a pic of it?

Also, you could try probing across any lead of R322 to any lead of R604 - this is effectively the same voltage as across the big 450V cap but should be easier to do.

Lower right of this pic
https://www.badcaps.net/forum/attach...8&d=1390336658

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

Tried to get a better picture of D902 and surrounding area. Also got a picture of D951, whose reading seems off compared to the others.

Also - could someone tell me what to put my DMM on to test that green resistor in the last photo? I got 3k Ohms with 5% tolerance, but I don't think that's right and I'm terribly bad at maths. Colors are black orange orange gold white.

[tom66]

Re: Sanyo DP42849 - No Power At All

Remove D902 and check it out of circuit but that could be the fault, it's in a position to cause loss of standby voltage.

[multimeter]

Re: Sanyo DP42849 - No Power At All

d902 is knackerd,explains why you got no standby voltage,that diode is coming off the standby transformer

[NihonNoir]

Re: Sanyo DP42849 - No Power At All

Sure would be nice if that's the only problem, but knowing my luck . . .

I just bought a soldering gun, but no solder or wick yet. I'll pick up some today if I can get to RadioShack before they close. We've got snow coming and I have to wash clothes and go food shopping.

I'll try to get to it tonight. Thanks guys!

[tom66]

Re: Sanyo DP42849 - No Power At All

Usually, it's only one fault which brings a set down.

[multimeter]

Re: Sanyo DP42849 - No Power At All

if its a ultrafast diode,make sure you replace with the same,and not a standard one.