Philips 37PF7321/98 cannot turn on

[john_doe]

Re: Philips 37PF7321/98 cannot turn on

now recheck usual voltages at G D S and at 1305 and also check the pad to the right of the cut

Gate is 9v
Drain is 5v
Source is 5v

Pad to right of cut is 85v

[bammbammfran]

Re: Philips 37PF7321/98 cannot turn on

looks like you are going to have to replace that transistor with the old one.
I wish you would have mentioned the transplant !!

85v ?? WTF
I'll look into that in the morning

[john_doe]

Re: Philips 37PF7321/98 cannot turn on

looks like you are going to have to replace that transistor with the old one.
I wish you would have mentioned the transplant !!

85v ?? WTF
I'll look into that in the morning

Very sorry about that. I will put it back right away.

[john_doe]

Re: Philips 37PF7321/98 cannot turn on

Old transistor on board.

With pin 7 out from 11 pin plug and trace cut, the voltage of Gate is about 6v, Source and Drain are 5v. All 3 pins of 1305 are 5v.

Pad to right of cut is still 85v.

When I jump ground to Gate, the relay clicks and the TV screen lights up. That means I can turn on and off the screen by touching ground to Gate.

[bammbammfran]

Re: Philips 37PF7321/98 cannot turn on

now we need to try to find out where the hell 85 volts is coming from.
may be leaking from high power side ?
start with checking the pins on the optocoupler at 7501
also mark anything that is showing over 14v on that quarter of the board


basically back track from that 85v pin
you'll see in my picture that I started tracing, but there is a couple parts like where the pin traces T-off that I am not sure if it goes that way
if you run into a component where it changes voltages, make a not

[john_doe]

Re: Philips 37PF7321/98 cannot turn on

now we need to try to find out where the hell 85 volts is coming from.
may be leaking from high power side ?
start with checking the pins on the optocoupler at 7501
also mark anything that is showing over 14v on that quarter of the board


basically back track from that 85v pin
you'll see in my picture that I started tracing, but there is a couple parts like where the pin traces T-off that I am not sure if it goes that way
if you run into a component where it changes voltages, make a not

I blown fuse 1315 twice. I am out of fuse to test further. Don't know where is the short. I will get 10 fuse tomorrow.

[bammbammfran]

Re: Philips 37PF7321/98 cannot turn on

that is the one on the power supply ??
did you blow it twice between today and yesterday or was one of those time when you did it a few days ago ?

[john_doe]

Re: Philips 37PF7321/98 cannot turn on

that is the one on the power supply ??
did you blow it twice between today and yesterday or was one of those time when you did it a few days ago ?

The other day I blown one. Just a couple of minutes ago, I blown two at 1315 fuse.

It was ok earlier after I put back the old transistor. I suspect I shorted the pin 7 wire of the 11 pin plug. Pin 7 wire was dangling and may accidently touch other part.

You think can pin 7 with 5v blow the fuse on the power supply board?

[bammbammfran]

Re: Philips 37PF7321/98 cannot turn on

hook that pin back up
I do not think the it would blow that fuse since that fuse is handling 340volts to the standby board
you might just have accidentally grounded the standby ?

[john_doe]

Re: Philips 37PF7321/98 cannot turn on

Since I don't have power now, what else can I check?

[john_doe]

Re: Philips 37PF7321/98 cannot turn on

now we need to try to find out where the hell 85 volts is coming from.
may be leaking from high power side ?
start with checking the pins on the optocoupler at 7501
also mark anything that is showing over 14v on that quarter of the board


basically back track from that 85v pin
you'll see in my picture that I started tracing, but there is a couple parts like where the pin traces T-off that I am not sure if it goes that way
if you run into a component where it changes voltages, make a not

"Back track from that 85v pin" means I should trace from the pink or blue line of your pic?

[bammbammfran]

Re: Philips 37PF7321/98 cannot turn on

"Back track from that 85v pin" means I should trace from the pink or blue line of your pic?

the 85 volts is showing right now at the solder pad to the right of the yellow cutout trace which starts as a light blue line and goes in two directions.

It can partly be traced with an ohm meter, but I think it would be easier to track it with the 85volts active
so without a fuse, that won't be doable

the orange rectangular fuse at 1500 on the standby could have been stolen for temporary use but it is probably not rated high enough in amps ???

[john_doe]

Re: Philips 37PF7321/98 cannot turn on

the 85 volts is showing right now at the solder pad to the right of the yellow cutout trace which starts as a light blue line and goes in two directions.

It can partly be traced with an ohm meter, but I think it would be easier to track it with the 85volts active
so without a fuse, that won't be doable

the orange rectangular fuse at 1500 on the standby could have been stolen for temporary use but it is probably not rated high enough in amps ???

Being a noob like me, I think I better get the proper fuse.

[bammbammfran]

Re: Philips 37PF7321/98 cannot turn on

on the standby board near the large transformer and on the low voltage side: there is a diode at 6140 that looks like it leads to the positive pin of capacitor at 2140 that might be worth checking voltage at
see what that voltage at that cap is and what that cap is rated for voltage wise

[bammbammfran]

Re: Philips 37PF7321/98 cannot turn on

I started retracing from a different part of the board and it looks like the last picture that I posted is incorrect at the pink T
this one should be more correct
Still tough to see some stuff and I am not 100% sure if the T in the pink line At the pink circle marked with a pink B is correct
green is ground
red is 5volt
pink appears to go to or from the transistor gate
I lose track on the right side at that one diode at white A

[john_doe]

Re: Philips 37PF7321/98 cannot turn on

I started retracing from a different part of the board and it looks like the last picture that I posted is incorrect at the pink T
this one should be more correct
Still tough to see some stuff and I am not 100% sure if the T in the pink line At the pink circle marked with a pink B is correct
green is ground
red is 5volt
pink appears to go to or from the transistor gate
I lose track on the right side at that one diode at white A

I added some tracing at white A.

The thinner pink line at the pink circle is not touching the thicker pink line.

[john_doe]

Re: Philips 37PF7321/98 cannot turn on

Put in new fuse at 1315 and switch on main power from wall. Fuse blown sky high.

Check the hot section of the standby board and found it has shorted.

There is continuity from pin 1 and pin 2 of 1306. Also from pin 1 of 1306 to as far as all pins on hot side of transformer. Even the transistor 7102 has continuity to 1306.

Is the board fried?

[bammbammfran]

Re: Philips 37PF7321/98 cannot turn on

take out one end of 5104 and recheck 1806 power plug pins
then check resistance at all 3 pins to each other on 7102

[bammbammfran]

Re: Philips 37PF7321/98 cannot turn on

I added some tracing at white A.

The thinner pink line at the pink circle is not touching the thicker pink line.

ok on the thin pink which means there ia a direct line from the capacitor by the main transformer all the way to the gate. only thing in the way is a diode that should be blocking that voltage. so that diode need to be check to see if it only allows resistance in one direction

so , at the transistor that I marked with the white A the trace that goes under that transistor is from the single pin side up to the 471 resistors right side ?
If that is the case, then we have to figure out where the top left pin of that transistor goes. the 253x white numbers cover the traces

FYI: At the diode at 6149- the top K pin goes to 5 volts at the 9065 jumper
and the jumper below that goes to the 0 resistor and also gets 5 volts and that feeds 5 volts to the 1 and 2 pins at the 1305 plug

[bammbammfran]

Re: Philips 37PF7321/98 cannot turn on

is 8105 cooked by the 7106