Samsung S42AX-YB04 Plasma TV stuck in standby

[tom66]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

No, did any of us say that?
Check voltage from pin 2 to pin 3. OR voltage across CB808 (one only.)

[Mikeyboy2007]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

No, did any of us say that?
Check voltage from pin 2 to pin 3. OR voltage across CB808 (one only.)

sorry mate :/ il check voltage across pin 2 to 3> black probe on one red on the other ?

[Alastair E]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

No--Its not that part. You have the STD_5V

[tom66]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

The STBY is unstable though.

Either:
- the controller is operating in low power mode (and the ripple is normal)
- or there's a bad startup cap, controller or other issue (and the ripple is abnormal preventing the main board starting properly)

@mikey Yes that is how to test it.

[Alastair E]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

--No need to check the volts across CB808, that circuit is working--You have the STD_5V

(You checked that before--Its in yer list of voltage readings....)

[Mikeyboy2007]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

No--Its not that part. You have the STD_5V

yeah mate i had the STD5v leading to the Av board but there was no cable in the STD5v leading to the control board

[Alastair E]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

Allegedly--that voltage is varying by only 0.1V--which could have been a user-made error by poor connection of meter probe....

[Mikeyboy2007]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

ok i will now test pin 2 to 3 on the 7 legged chip. how do i know which pin is n and 3 ? meaning there is 4 pins on 1 side and 3 on the other so would pins 2 and 3 be the one on the 3 legged side with the space in between them ?

[tom66]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

Only need to check voltage across CB808. They're electrically the same. What was the result?

[Mikeyboy2007]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

was boucing around a little, held probes straight and firm. but volatges ranged from 15.4 - 17.9

[tom66]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

The IC requires a min 16V to start up. So it would appear to be OK, but I would be suspicious of it.

I would prefer to check the supply with a 22 ohm 2W resistor to see if it regulates better under load. Any chance you can source one? Or a similar value 18~33 ohms minimum 1W (will get hot) but ideally 2W.

[Mikeyboy2007]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

no, i can order one from ebay though ? would these suit ?

http://www.ebay.co.uk/itm/2W-Metal-F...item20ce8eebfb

[tom66]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

That would be fine -- Maplin stock them too.

[Mikeyboy2007]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

where would i put that though tom, sorry to sound like a d**khead just new to all this kinda stuff, tryin to learn too much too fast but appreciate the help. i have attached a picture of what CB808 is on the board as it looks different from a resistor >?

[Mikeyboy2007]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

cant seem to find a 22 ohm 2W resistor on maplins website :/

[tom66]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

You're putting it across the STBY voltage, not on the primary side. And not as part of a repair, because we still don't know what's wrong -- it's part of a diagnosis.

Check Maplin code W22R. (For tests only.)

[Mikeyboy2007]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

W22R on maplins site returns 3 Watt Wirewound Resistor would that be correct

[tom66]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

Yes. Watts (power dissipation) is a more than or equal rating...

[Mikeyboy2007]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

will try get one today and give it a try, came across a guy on ebay a few months back when i had to repair a power board on a LG LCD tv, the guy also does cap repair kits for this board including start up caps so is this a common problem with these boards

[tom66]

Re: Samsung S42AX-YB04 Plasma TV stuck in standby

I'm thinking that; the unsteady voltage makes me suspect that capacitor. However, I want to rule it out (or in) first.