Soniq (australian brand) 32" - screen doesn't always start up

[psmedley]

Re: Soniq (australian brand) 32" - screen doesn't always start up

Touched up the obviously dull looking joints on the PSU and main board - unfortunately nothing changed in terms of the TV's behaviour

[selldoor]

Re: Soniq (australian brand) 32" - screen doesn't always start up

Ok - id try the wood/plastic stick test. You can tap or push gently on
the componnents when the tv is on but not working to see if it comes on
or when it is on to see if it goes off. Start on the main board - not the power supply.

[psmedley]

Re: Soniq (australian brand) 32" - screen doesn't always start up

Hi Selldoor,

didn't have any luck with heating... I had the meter probing VA whilst I was heating different parts of the mainboard - nothing changed I have a ESR meter coming from ebay, so when it arrives, I'll test all the caps on the mainboard - they LOOK ok but ya never know

When I tried heating using a hair dryer, I heated the component side of the board - should I also try heating the back of the board?

Tapping/moving the components on the main board with the TV in the non-working state didn't make any different. I've just re-read your note, and you suggest also trying the inverse case to try and make it fail when it is working - I'll try that next.

[psmedley]

Re: Soniq (australian brand) 32" - screen doesn't always start up

Bugger - tapping the main board or PSU with the TV working didn't change anything either. Unless there are any other pearls of wisdom, I'll wait for my ESR meter to turn up then will test all the caps on the main board and psi and see if that shows up anything.

I really appreciate everyone's input so far!

[psmedley]

Re: Soniq (australian brand) 32" - screen doesn't always start up

Update: the ESR meter I got from ebay showed up - for reference see: http://www.ebay.com.au/itm/261006730010#ht_2934wt_1141

It confirms the two caps I changed are bad - ESR of >2.5 and 1.5 for the 470uF, 25V caps I changed from the main board and PSU respectively vs a reference value of 0.15.

In the process I noticed that I had somehow managed to install a 1000uF 10V cap in place of a 470 uF 25V one - only excuse is the replacements looked the same!! I changed the cap over hoping this was the issue - unfortunately it didn't help. The other caps on the main board and PSU appear ok with the ESR meter - so maybe fixing this board just isn't meant to be - for my skillset anyway.

[psmedley]

Re: Soniq (australian brand) 32" - screen doesn't always start up

One other thing I noticed today is some sometimes after I get the TV to power on - it's asking for a channel rescan as it seems to have forgotten the saved channels. Not sure if this provides any clues or not as to what might be wrong?

[vinceroger69]

Re: Soniq (australian brand) 32" - screen doesn't always start up

does that esr meter check the capaicitor uf readings as well just wonder if a capacitor is low on the uf scale although the esr is reading ok if this can happen? just a thought.
this is a good one imo
http://www.ebay.co.uk/itm/New-ESR-an...item4ab70f6aa9

[psmedley]

Re: Soniq (australian brand) 32" - screen doesn't always start up

This one just shows the resistance. I've since ordered the ESR meter shown in your link direct from Mike for $US75 including postage to Australia - just waiting for it to arrive

[vinceroger69]

Re: Soniq (australian brand) 32" - screen doesn't always start up

thats good then thats what i am doing hes going to send me a meter to the uk at a very good price. hope fully you will find its just a bad capacitor on your supply but i was thinking your supply has a few transformers on it i wonder if where the transormer wire windings that contact the pin that comes through the rear of the circuit board if one of these joints could be bad as you wont see its bad untill you remove the transformer from the board and look it that makes sence? i think the transformer winding is wrapped around the pin the soldered?

[psmedley]

Re: Soniq (australian brand) 32" - screen doesn't always start up

Hi All,

Measured some caps on the power supply today - found 3 that look suss...

C202 - 470uF 50V - measures overflow (infinite??) vs ref value of 0.15 - UPDATE - measures 0.0 once removed
C208 - 47 uF 25V - measures 1.22 vs ref value of 1.0
C914 - 47 uF 25V - measures 2.6 vs ref value of 1.0

Will replace these and see what happens

[psmedley]

Re: Soniq (australian brand) 32" - screen doesn't always start up

Unfortunately, it didn't help

[tom66]

Re: Soniq (australian brand) 32" - screen doesn't always start up

What is the voltage across the 400-450V caps when it doesn't start up and when it does?

[psmedley]

Re: Soniq (australian brand) 32" - screen doesn't always start up

What is the voltage across the 400-450V caps when it doesn't start up and when it does?

What's the best method to do this? I propped up the PSU board on some cardboard and the TV wouldn't even switch on - presumably as it wasn't earthed?

I went through the caps on the main board again, and found 3x 220uF 10V caps that are at best borderline. Reference value 0.4 Ohms, I measured 0.42, 0.38, 0.32 - so I might try replacing these.

[tom66]

Re: Soniq (australian brand) 32" - screen doesn't always start up

There are sometimes test points on the top of the board.

[psmedley]

Re: Soniq (australian brand) 32" - screen doesn't always start up

I don't see any test points.... BUT since replacing most of the caps on the PSU board, VS_ON activates most of the time now and the screen powers on.

It doesn't always become functional - sometimes, it still seems to 'hang' and the power toggle button won't turn the TV off, so perhaps the problem is partly related to the power supply, and also related to problems with the main board.

Given the main board caps show a few with with high ESR, I'll take my chances and order some caps to recap that too.

[tom66]

Re: Soniq (australian brand) 32" - screen doesn't always start up

Hmm. I suspect a cold joint somewhere.

[psmedley]

Re: Soniq (australian brand) 32" - screen doesn't always start up

Well, I replaced several caps on the main board that tested in-circuit with high ESR using rusmike's tester and.....

I think I've had some success - I've just turned the TV on/off successfully 3 times in a row!!

Will continue to monitor but seems like I might be on a winner now

[maz]

Re: Soniq (australian brand) 32" - screen doesn't always start up

Started new thread.

[selldoor]

Re: Soniq (australian brand) 32" - screen doesn't always start up

Advice re above

[psmedley]

Re: Soniq (australian brand) 32" - screen doesn't always start up

Update: TV is still working fine.

A question however - is it normal for capacitors to measure lower resistance once they're removed than in-circuit?

Several caps I replaced on the main board measured significantly lower ESR once removed - ie they were close to 0.6 ohms in-circuit, but ~0.3 Ohms once removed.