PS-42Q97HD, not starting every time :( HELP !!!!

[jczarniak]

Hi,

After switching OFF and ON from the power socket (sometimes a few times) TV is starting fine.

Checked a few voltages:
When TV struggle to switch on I've got:
instead of 18V - 11.3V
instead of 12V - 11.4V
Va=33.5V

After switching OFF and ON from the power socket (sometimes a few times) TV is starting fine and:
18V test point - 18.5V
12V - 12.4
Va - 63.5V etc...

TV works fine, stays on as long I want.
Help, please.

[ReeceyBurger123]

Re: PS-42Q97HD, not starting every time HELP !!!!

Have you checked for cold solder joints ?

[sordids999]

Re: PS-42Q97HD, not starting every time HELP !!!!

+1 mate

[jczarniak]

Re: PS-42Q97HD, not starting every time HELP !!!!

Have you checked for cold solder joints ?

Hi,
Yes I did, didn't found anything.
When TV is ON stays on forever
Unplugging its power cord and plugging it back in, its the only solution which I found so far.
Need to do it sometime a few times.

[dick_barton]

Re: PS-42Q97HD, not starting every time HELP !!!!

A repair kit has the following components so you could check the following parts out.

F801S
FS801S
QS801
QS802
DS803
DS804
RS812
RS814
ICS801

[jczarniak]

Re: PS-42Q97HD, not starting every time HELP !!!!

A repair kit has the following components so you could check the following parts out.

F801S
FS801S
QS801
QS802
DS803
DS804
RS812
RS814
ICS801

All them parts looks OK.

[ReeceyBurger123]

Re: PS-42Q97HD, not starting every time HELP !!!!

Hmm this model Psu is known for bad caps, have you an esr meter ? If not does heating the Psu with a hairdryer help it come on faster ?

[ReeceyBurger123]

Re: PS-42Q97HD, not starting every time HELP !!!!

A repair kit has the following components so you could check the following parts out.

F801S
FS801S
QS801
QS802
DS803
DS804
RS812
RS814
ICS801

Lol DB re-read the thread it does come on after a sec.

[dick_barton]

Re: PS-42Q97HD, not starting every time HELP !!!!

I realise it's the parts list for a faulty psu but considered it may be worthwhile checking the components.
Have the resistors changed value, check the components/solder joints around the IC for example.
It was just a thought although as you say it is often capacitors that cause this problem.

[sordids999]

Re: PS-42Q97HD, not starting every time HELP !!!!

Hi,
Yes I did, didn't found anything.
When TV is ON stays on forever
Unplugging its power cord and plugging it back in, its the only solution which I found so far.
Need to do it sometime a few times.

have u actually reflowed any joints or just looked for cold solder joints ?

[jczarniak]

Re: PS-42Q97HD, not starting every time HELP !!!!

have u actually reflowed any joints or just looked for cold solder joints ?

All suspected (and not also) joints has been re flowed.

A few new observations:
when TV is cold (has been switched off for 10 hrs) is switching ON straight away, works fine, stays ON etc...
When switched OFF after about 15 minutes of work, blue light which should be ON all the time (setup in menu) is like dimmed and comes back on after 10-15 minutes.
No chance to switch the TV ON, need to wait for good 10-15 minutes.

[flocko]

Re: PS-42Q97HD, not starting every time HELP !!!!

Please make yourself clear, when you say the set is off do you mean unplugged from wall socket, or in standby.Replaceing the small caps (50v) on hot side of the supply would be a good place to start from

[ReeceyBurger123]

Re: PS-42Q97HD, not starting every time HELP !!!!

You need to isolate the Psu first, heat it and follow what I said.

[jczarniak]

Re: PS-42Q97HD, not starting every time HELP !!!!

Just found the burn mark under zener diode ZDB803 (already removed on the picture)
Could it be a reason of all my problems with that power supply?

Can't find replacement anywhere - MTZJ30C
Can I use any equivalent, please?
Thank you.

[dick_barton]

Re: PS-42Q97HD, not starting every time HELP !!!!

Zener Diodes Zener 500mW 2,5% 30V

Data sheet available from:


http://eu.mouser.com/ProductDetail/T...8wxQLQMw%3d%3d

CPC, RS or Farnell will probably supply them or its equivalent.

[jczarniak]

Re: PS-42Q97HD, not starting every time HELP !!!!

Zener Diodes Zener 500mW 2,5% 30V

Data sheet available from:


http://eu.mouser.com/ProductDetail/T...8wxQLQMw%3d%3d

CPC, RS or Farnell will probably supply them or its equivalent.

Thanks a lot.
What you thing about this one, please:

http://uk.rs-online.com/web/p/zener-diodes/0812572/

Thank you.

[dick_barton]

Re: PS-42Q97HD, not starting every time HELP !!!!

The tolerance is twice the value but same working voltage and higher power dissipation so worth a try. May be worth your while checking around that circuit to see if anything else has failed and caused the zener to overheat.

Have you got a Maplins near you?

[jczarniak]

Re: PS-42Q97HD, not starting every time HELP !!!!

The tolerance is twice the value but same working voltage and higher power dissipation so worth a try. May be worth your while checking around that circuit to see if anything else has failed and caused the zener to overheat.

Have you got a Maplins near you?

Yes, 5 minutes drive

[jczarniak]

Re: PS-42Q97HD, not starting every time HELP !!!!

Yes, 5 minutes drive

Something like that?

http://www.maplin.co.uk/p/bzx85c-30v...er-diode-qf64u

[sordids999]

Re: PS-42Q97HD, not starting every time HELP !!!!

Have u tested the diode ?
and i would certainly do what flocko said start testing the caps etc