Re: Sceptre 32 inch , PSU problem?
I learned my lesson! Also, the TV is now working, I put in a new PSU and it works great!
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Re: Sceptre 32 inch , PSU problem?
Yes, on the underside of the board, a trace comes from the Gate pin to a diode or transistor of some sort and the 3 resistors, route to the Drive pin of the IC (per the docs for a 1606B), the last resistor (bottom on the image) resistor labeled R13 is blown.
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Re: Sceptre 32 inch , PSU problem?
The IC that goes is on the underside of the board which has a resistor (the one above the one of the SMD's I blew out) is marked 1606B it's a PWM/Power factor controller. I have no way to really tell if it actually works.
In addition to the 0.1ohm surge resistor that blew , one of the tiny 1 ohm SMD's around the leg of the bad MOSFET is also blown. Provided that I replace the IC, the MOSFET, the 2 resistors and the fuse, at that point what else would I have to test?
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Re: Sceptre 32 inch , PSU problem?
I tested the MOSFET, it's a K3568. It's shorted out from drain to source. The diode next to it seems to be working fine, also just checked the 3 FETS you mentioned off the center of the board and they appear to test fine.
I didn't take them off the board but it might be interesting to be replace the boost converter FET and the blown resistors and fuse as they are all low cost parts anyway.
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Re: Sceptre 32 inch , PSU problem?
I'm confident knowing the PS was bad the TV would work, however I like the learning process and it's why I undertook this to begin with. So I would very much enjoy going through it, if you don't mind of course.
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Re: Sceptre 32 inch , PSU problem?
Hehe, well ... that went well. I checked the fuse and it was blown so I did of course what you're not supposed to do and jump it. That blew out the R12, the big resistor and one of the smaller ones. The cap seems fine it even read some residual voltage. Now the problem here is...
There is something right at the input of the board that would cause the fuse to blow? It's right at the terminal so maybe the connector is bad?
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Re: Sceptre 32 inch , PSU problem?
I get a voltage, consistently -10.4~-10.5 mV at the legs of the main filter cap. 0v at the other caps. When it's warmed up a bit I get -15mV at the main filter cap and still 0v at the others.
The main filter cap gives it's readings regardless of if there is power applied, so I'm going to assume this is the resting potential of the cap?
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Re: Sceptre 32 inch , PSU problem?
I tried heating up the 2 caps, nothing past 100F and still getting 0v out of the 5VSB.
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Re: Sceptre 32 inch , PSU problem?
I'm sorry, I tested the +5 standby and got nothing. I'm going to try heating up the caps you mentioned and report back.
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Re: Sceptre 32 inch , PSU problem?
Here are some pictures, I tried to get decent pictures which was difficult with the glare. If you need anything close up, a particular part of the board; I'll be more than happy to try again.
I tested the +5 and got nothing out of it.
Also I just noticed there seems to be a patina around the hot side of the underside of the board, like it was burnt.
Thanks again!...
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Re: Sceptre 32 inch , PSU problem?
I'll post pictures once I get back to it and opened up again. Hopefully tonight.
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Sceptre 32 inch , PSU problem?
Hello all, I've been reading the basics documents and have a Sceptre 32 inch with no power, no lights nothing. The PSU is a meg meet mp116.
I'm trying to figure out what to test first, all I have is a multimeter. I know I should first check the +5V rail because that is always on so long as the unit is plugged in.
I didn't see any obviously blown capacitors, possibly some bulging ones? but I don't have an ESR meter to check.
My question is, is there anything else I could probe on the PSU to make a definitive conclusion that it's the PSU?
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