Dynex DX-LCD32-09 wont turn on. Lights for half second.

[lookimback]

This is a different Dynex than the one I fixed yesterday. I thought I was going to have an easy one because I could have swapped boards to figure out which one to focus on. No such luck. Inverter board is different in this one. Its only 1 sided, transformers are different, that fuse that was bad on the other one, doesn't seem to be present in this one.

Visual observation: inconclusive

Beginning pin testing now.

Starting with the power board.

Top connector

PON. 2.4v
Gnd. OK
5v 5.15v
Gnd. OK
Gnd. OK
16v. 15.5v
16v. 15.5v
Gnd. OK
5v. 5.09v
Gnd. OK
9v. 9.09v
Gnd. OK
32v. 32.37v

Middle connector

PON. 5.166v
PWM. 3.39v
Gnd. OK
Gnd. OK
Gnd. OK
24v. 23.75v
24v. 23.75v

Bottom connector

PON. 5.166v
PWM. 3.39v
Gnd. OK
Gnd. OK
Gnd. OK
Gnd. OK
Gnd. OK
24v. 23.75v
24v. 23.75v
24v. 23.75v
24v. 23.75v
24v. 23.75v

Can't check voltages across PFC without flipping the power board and I don't think its necessary. Voltages all seem correct. Getting P/ON signal from main. 24v is present so power board is coming on. I was pretty sure it was an inverter problem when I first plugged it in. Certain of it now. I'm just trying to develop a protocal I will follow on every set I work on.

Beginning testing on inverter board now.

PWM. 3.38v
PON. 5.16v
Pin 4. 3.23v
Gnd. OK
Gnd. OK
Gnd. OK
Gnd. OK
Gnd. OK
24v. 23.75
24v. 23.75
24v. 23.75
24v. 23.75
24v. 23.75

Voltages all seem correct. P/ON signal present.


Beginning testing resistances on transformers now. Since the pins are not numbered I'll call the top left (connector side) pin 1 and go clockwise to 8. From what I can tell from the resistances, testing should be across pins 1 and 8, and, 4 and 5.

T7
1-8. 966 ohms
4-5. 975 ohms

T6
1-8. 974 ohms
4-5. 968 ohms

T5
1-8. 977 ohms
4-5. 973 ohms

T4
1-8. 971 ohms
4-5. 973 ohms

T3
1-8. 969 ohms
4-5. 1090 ohms

T2
1-8. 968 ohms
4-5. 974 ohms

T1
1-8. 951 ohms
4-5. 956 ohms

At this point I'm thinking maybe T3 is bad. Maybe T1 as well. I'm going to post this now to get feedback. Meanwhile, I'll look for a service manual or at least a data sheet for the PWM IC.

[ben7]

Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

T3's readings do seem a tad high.

[lookimback]

Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

Over 100 ohms higher than the rest. Yes, I think that may be it.

[budm]

Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

I agree that T3 dose look bad.

[lookimback]

Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

I'm going to look for a replacement. I looked into just replacing the board but its $60-$70. I'll look and see what a new transformer will cost.

[lookimback]

Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

Wish I could pull one from a different board just to see if it is the problem. I have some with the same number of pins. Footprint probably different. If the resistances are the same, could I just solder wires to it and the board just to test it?

[budm]

Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

Sometime it is cheaper to buy a board so you will have spare transformers, more likely the other will fail too, if you can find the board real cheap or if the transformer can be had for less than $5 then you can see which way will be cheaper. If you going to sell the TV then buying the transformer will be cheaper than buying the board.

[lookimback]

Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

…more likely the other will fail too

Other what? I have to open it back up and get the numbers from the transformer. I forgot to do that while I had it open last night.

[budm]

Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

Other transformers. I did that before, replace one transformer, the a few month later another one failed, I should have bought replacement board to have spare parts from the old board.

[lookimback]

Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

These are both the exact same inverter boards. One is from an Element and is about $40. The other is from a Dynex and is about $70.

http://m.ebay.com/itm/251279072662?nav=SEARCH&sbk=1

http://m.ebay.com/itm/190882564273?nav=SEARCH&sbk=1

Transformer number is 2874015400. Its about $9 plus shipping.