TH-P50G15A - 6 Blinks- Bad TNPA4782

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

diode mode red lead on 5, then probe 6 & 7 with blk = 0.577, 0.574

red on #1 blk on 2 = 1.482, reverse 1.983
red on #3 blk on #4 0.830 reverse 1.454

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

I got another, opto pc461, right in the middle between the 2 fet drivers, diode mode red lead on 5, then probe 6 & 7 with blk = 0.535

red on #1 blk on 2 = 1.45, reverse 1.7
red on #3 blk on #4 0.745 reverse 1.35

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

I'm getting pretty much the same values.

end farest from ic521, 1.787,0.629, nearest 0.612, OL

q531 farest from ic501 charges to 1.793, 0.45 and keeps rising (finally stopped at 0.625)

nearest goes OL, 0.626

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

yes, caps. can bite. I've done that and had one zap me 3 times before it was discharged. worked on it straight after power up. wife thought it was funny.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

last one for now, really frustrating this is.

diode mode q551 I'm measuring across pins as shown in both polarities of the leads

end farest from ic521, 1.711,0.617, nearest OL,0.597

q531 farest from ic501 charges to 1.71, 0.37 and keeps rising

nearest charges and goes OL, 0.602

I'll have to quit for bed

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Yep R869 has continuity to the gate of Q604. Also measuring from the top of R613 and Q604 G gives me around 42k ohms.

D618 I basically soldered it upright with the wire connected to the top of the diode (white band) and other end of wire to the end of R611.

R521, and R522 are marked 1000, measuring 100 ohms both.

D652 measures 0.482, OL

Rechecked and resoldered some of the ICs, a trace came off from IC521, but looking on the datasheet it seems to be NC so I don't think it should be a problem.


I just noticed that C691 (The big electrolytic cap near Q661) won't dissipate its charge. I left the board over night and this morning still got a little shock from it.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Here you go, and yes R451 and R441 measure 5.6 ohms

picture#1

confirm from blob of solder on underside of r869 has continuity to Gate of missing Q604

D618, I can't make out the diode at all. I see the hard wire in the air. How's that set up? ids the white band of the diode soldered to that wire?

Picture #2

double check there's no bridges or little balls of solder between the pins, 10 & 11 looks sus but not clear

R521,522, what marking is on them? Do they measure 100 ohms

Pic 4 , check pins 2,3 for any dags or bridge ic773

D652 in front of Q660 did that check out?

I've attached how I rebuilt the track for D618 using some used braid

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Here you go, and yes R451 and R441 measure 5.6 ohms

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

and ic773

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Also close ups of ic521 including q551 and ic501 please

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Heres what I got on mine, seems pretty much the same.

q451

g(red)
- E(blk)0.654,
- c(blk)1.086

g(blk)
- E(red)1.065,
- c(red) OL
E(red)
-C(blk) 0.480

E(blk)
- C(red) OL

Q441

g(red)
- E(blk)0.661,
- c(blk) OL

g(blk)
- E(red)1.002,
- c(red) OL
E(red)
-C(blk) OL

E(blk)
- C(red) OL

thanks, that's comparable.

Can you zoom in on D618 and illuminate?

R451,441, do they measure 5.6 ohms

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Heres what I got on mine, seems pretty much the same.

q451

g(red)
- E(blk)0.654,
- c(blk)1.086

g(blk)
- E(red)1.065,
- c(red) OL
E(red)
-C(blk) 0.480

E(blk)
- C(red) OL

Q441

g(red)
- E(blk)0.661,
- c(blk) OL

g(blk)
- E(red)1.002,
- c(red) OL
E(red)
-C(blk) OL

E(blk)
- C(red) OL

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

here's some diode readings

q451

g(red)
- E(blk)0.608,
- c(blk)1.041

g(blk)
- E(red)0.998,
- c(red) OL
E(red)
-C(blk) 0.47

E(blk)
- C(red) OL

Q441

g(red)
- E(blk)0.604,
- c(blk)charges and goes OL

g(blk)
- E(red)0.992,
- c(red) OL
E(red)
-C(blk) 1.94

E(blk)
- C(red) OL

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Are you able to put up some hi res shots of the board just so I can get an eyeball . thanks.

[tom66]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

If its only going to 45V then the ckt is only being charged by the resistors to Vsus, I would check if the gate drivers are working (check their 5 & 16V supply)

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Yep I'm stumped... The only thing I noticed is the MID voltage is too low, peaking at around 45V. So I guess there has to be a problem with the FET and drivers? (IC521 I guess) Replaced some extra parts, and even some from your image but still no process... ugh I hate these boards -.-

Don't quit. There's only so many parts on the board. that's what i tell myself. All I know is I went from 145v to 45v and then fixed and that was with a blow up and fried buffers to boot.

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Yep I'm stumped... The only thing I noticed is the MID voltage is too low, peaking at around 45V. So I guess there has to be a problem with the FET and drivers? (IC521 I guess) Replaced some extra parts, and even some from your image but still no process... ugh I hate these boards -.-

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Might just be my meter, I've always had trouble measuring resistances of anything in the 200K or Meg range. Never actually had to.

I don't where to steer you but this image I've done my best from memory what I replaced(believe) between the 2 boards I did. Not all of these were necessarily bad but most were

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Might just be my meter, I've always had trouble measuring resistances of anything in the 200K or Meg range. Never actually had to.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

on diode mode im getting 0.535, and 1.105

yep, so close enough, weird how our meters handle resistance differently in cct