32" Dynex DXL3210A Won't Power On

[budm]

Re: 32" Dynex DXL3210A Won't Power On

It is my guess since fixed regulator will usually has 1.2, 1.8, 2.5, 3.3V
That 1122 is what makes me think it is the 1.2V reg.

I think it is the same as this one:
http://www.mouser.com/Search/Product...4GeXac6g%3D%3D


The other one I found with 1122 series regulator are these, but they have 5 pins.

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

So would the problem still be in the main board or the power supply?
Also, how do you test if a transistor or a mosfet is defective?

[budm]

Re: 32" Dynex DXL3210A Won't Power On

It looks like the main board problem since it consatnly sedn out the PS_ON signal to turn on the power supply even when the TV is not turn on.
Transistor can be test with meter that has Diode test function.
MOSFET is normally open connection device, you can check for short but cannot tell if it has bown open circuits, you will need to build a tester for that.
Unless anyone else here has seen this problem before with this model, you may want to wait and see if anyone else can chime in.

[selldoor]

Re: 32" Dynex DXL3210A Won't Power On

I removed the fuse from the inverter board, and measuring it now gives me 4.2 Ohms, may be a bad fuse? Do you know the specs of this fuse? Photo below.

This looks like it may be a golden king resettable fuse so normal test does not apply? cant see a data sheet.

http://www.tradevv.com/chinasuppliers/goldenkinghk

To test mosfets/transistors for shorts see retiredcaps' guide
https://www.badcaps.net/forum/showthread.php?t=10419
Start at post 19 - whole thing is worth reading if you have not read it.

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

Does anyone happen to have a service manual for this set?

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

Just received my esr meter, checked all the caps and none seem to be bad.
So far the fuses on each board are working, caps are working, regulators on main are in spec, and the voltages on the ps output connector are there. Except the run power and power_on voltage is present constantly before the power button is pressed.

Can you [carefully] measure the voltage on the large rubycon capacitor in the power supply? It should be about 160v.

Does what happens with the standby supply voltage when you press the power button?

There's no reading on this capacitor, should it be there during standby?
There doesn't seem to be much voltage measurement on the primary side of the ps.

[selldoor]

Re: 32" Dynex DXL3210A Won't Power On

What voltage do you get at the mains fuse- the cap must have worked at some time post six
you had a picture.

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

When I meant no reading I meant measurements near 0V on the largest cap. On th main board, the fuse measures 5.27V on both ends of the fuse

[selldoor]

Re: 32" Dynex DXL3210A Won't Power On

Sorry I meant the Mains fuse the glass one where the power lead comes in.
Measure with care meter on AC600v should be 120v?

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

oh how do you measure AC voltage?

Also when measuring the capacitance of a cap, what measurement would it be considered bad?

[selldoor]

Re: 32" Dynex DXL3210A Won't Power On

oh how do you measure AC voltage?

If it was me doing it Id set my meter on 600vAC You might have 200vAC
and that will do as in US. Black probe on the N mains lead pin -( you can see it on the board) then with the red probe touch each end of the fuse and report the result.

Also when measuring the capacitance of a cap, what measurement would it be considered bad?

Someone else may have to advise as I dont have an esr meter. It can vary
depending on the cap a 100uf 5% could be 96 - 104
a 100uf 10% could be 91 - 109. But the cap may still be faulty which is why you are measuring the esr - didnt you get any instructions with it?

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

I'm getting about 119.0v on both ends of the fuse.

All the caps I've measured give 0.10 ohms or less esr, but some of the capacitance seems off. 1000uf cap I measured about 820uf, and 2200uf cap measured about 2020uf, so not sure if it's faulty or not.

[selldoor]

Re: 32" Dynex DXL3210A Won't Power On

I'm getting about 119.0v on both ends of the fuse.

.

Good - I have been looking for the picture of the back of the power supply
so I could verify where you are checking the voltage on the BIG Cap.
I cant see one - can you post one - its unusual to get to page3 without?

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

heres the back of the power supply board.

[selldoor]

Re: 32" Dynex DXL3210A Won't Power On

Ok so to test the Voltage on the BIG cap Meter on 600vDC
the two pins are on the back fo the powerboard - in your picture if you look at the top it says bottom between A and C. Straight below where it says bottom there are two big joints- The top one has a + beside it. (is that where you have been testing?)
Apply power to the board and very carefully put your black probe on the lower joint and the red probe on the upper joint with the + beside it.

[budm]

Re: 32" Dynex DXL3210A Won't Power On

The main power supply must be working, otherwise you will not have 24vDC OUTPUT.

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

Okay I got it, it reads 160.2v I was measuring relative to ground before that's why.

Well if it is the main board I'm completely stumped, trying to look for a component that prevents the PON until turned on. Sounds like a short somewhere but don't know where to start. All the regulators are within spec on the main board.

[selldoor]

Re: 32" Dynex DXL3210A Won't Power On

Hi - Couple of things to check - any caps you replaced check that they are the right way round (I Know they should be as in post11 the set came on) and check your soldering -wiggle the cap on the top and look at the joint underneath.

When you repaired a ground pin was that on the power board
or the main board - perhaps you could mark the underside pics of the psu and main board showing which are the Pon and Bon pins -and which pin you repaired. I see there are two similar connectors with a Bon do they both have leads and where do they go to.
If the set is together an overall picture showing the boards in position and the leads might help us.
I know its old ground but seem to be running out of ideas.
Having said that I cant see that any diodes have been checked?

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

The Ground Pin i reflowed was on the PSU. After the TV went off and wouldn't turn on, I reflowed the rest of the connecting pins and almost all the joints on the Secondary side of the PSU.
I did check some diodes and they appear good, but i'll remove them and check them out of circuit just to make sure.

Here are some photos of all the connectors on the PSU and mainboard.

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

What components on the main board are simple to test?