Hitachi 42hdf39 no display

[mpobanion]

I received a non working Hitachi 42hdf39 (circa 2006). I'm not the original owner so I don't know the history. It is a hybrid Plasma TV/computer monitor. The TV side has S-video, composite, component and HDMI inputs. The "PC" side has a single VGA input.

SETUP
=====

- known working VGA cable, 15 pin male to male
- known working laptop with VGA output
- known working AC power surger protector
- laptop plugged into Hitachi PC side with known working VGA connections
- remote control has fresh known working batteries
- known working DVD player and composite cable plugged into TV side

SYMPTOMS
========

- press power button and Hitachi LED will not turn green, and there is no picture at all. No flash of the screen, nothing. LED stays off.
- pressing the OSD menu on the TV or remote shows nothing
- pressing the source button on the TV or remote control does not display any picture
- I cannot be sure what the "source" is because there is no OSD display or menu
- The screen is entirely blank and stays that way.
- Questionable Capacitor 3300uF 100v Nippon Chemi-Con KMH 105C 30mm* 40mm snap-in Radial bloated top




MEASUREMENTS
============

- power supply board DC 0V with DMM
- inverter board gets 0V DC with DMM
- all fuses sound continuity with DMM
- DC voltages are
(CN61) 120V 1L 3W
(CN10) 1+0V 5+0V 6+0V
(CN11) 1+0V 3+0V 4+0V 10 +0V
- I have no ESR meter, but all caps look visibly okay except one that *might* have been slightly bloated which I changed. All the original caps are real Nippon Chemi-con KMH 105C.
- all front panel buttons test okay (no shorts)

NOTES
=====

- the cap I changed looks slightly bloated and I replaced it with a United Chemicon.

- I think the problem lies somewhere on the PSU board possibly the DC rectifier. I suspect that for one reason.

It looks like there is a A/C sine wave through out PSU board checked @ + & - D/C output on the chip this might be the choke point. I saw this with O-scope

- Datasheet for 42hdf39 is at

http://www.eserviceinfo.com/download.php?fileid=31806

NEXT?
=====

So I'm looking for suggestions on how to proceed or test points.

If the suggestion is to recap PSU board, I can, albeit 2006 circa.

[retiredcaps]

Re: Hitachi 42hdf39 no display

So I'm looking for suggestions on how to proceed or test points.

Great detailed description!

Now where are the pictures?

I'm a bit confused with your description on the DC voltage measurement.

Do you get mains voltage across the large filter capacitor? If yes, what is the reading?

[PowerAmpFreak]

Re: Hitachi 42hdf39 no display

I'm a little interested HOW you hooked up your scope across the powersupply. Remember that if measurements has to be made on PRIMARY side of the psu, then you should have your scope supplied through an isolating transformer. Also, primary measurements does NOT use chassis as reference since this is the cold (secondary) ground, which is also connected to earth.
Also a word of caution, the power supplies in plasma TV's use high potentials (especially in the PFC front end across the big bulk cap/caps, which will in best case just provide you with a nasty experience)

[PlainBill]

Re: Hitachi 42hdf39 no display

I'd like to echo what retiredcaps said about the pictures. The Service Manual for this set leaves a lot to be desired.

I suggest an over-all picture of the back of the set, plus an over-all picture of the power supply.

A couple of points to cover. Is there any clicking sound when you try to turn the TV on?

On the power supply there are several points to check CAREFULLY! With the TV plugged in you should see line voltage across CN51 pins 1 and 3. Also, you should see about 5VDC from CN11 pin2 (gnd) to pin 10 (5V stby). When you try to turn the TV on check for a change in voltage on CN11 pin 7 (AC-off).

PlainBill

[mpobanion]

Re: Hitachi 42hdf39 no display

I can get pictures any particular one first?


(CN61 connector a/c power) 120V wire 1 Line in and Neutral DMM
(CN10 board inter-connect to sus board etc. to other boards) wire 1 on plastic connector and so on wire 3 +0Vdc wire 5 +0Vdc wire 6 +0Vdc
(CN11 )wire 1 +0V wire 3 +0Vdc wire 4 +0Vdc wire 10 stdby +0Vdc

There is no main filter voltages.

Thanks

[retiredcaps]

Re: Hitachi 42hdf39 no display

I can get pictures any particular one first?

Yes, the pics that PlainBill asked for in post #4.

I forgot my standard picture monologue ...

1) Post clear focused pictures AFTER reading

https://www.badcaps.net/forum/showthread.php?t=1868

2) Please do not post pictures inline as they slow down loading of pages.

3) Take your boards to a window on a sunny day, turn flash off, and use macro mode. Take a top down view of all your boards (front and back). Make sure the photo is legible so that we can read the PCB printing clearly. A shutter speed of 1/125 or faster will produce nice clear focus pictures. Try to get a photo that is 2000x2000 resolution or as close as possible.

4) Here is an example of the pictures we want.

https://www.badcaps.net/forum/showpos...94&postcount=1

[PlainBill]

Re: Hitachi 42hdf39 no display

I can get pictures any particular one first?


(CN61 connector a/c power) 120V wire 1 Line in and Neutral DMM
(CN10 board inter-connect to sus board etc. to other boards) wire 1 on plastic connector and so on wire 3 +0Vdc wire 5 +0Vdc wire 6 +0Vdc
(CN11 )wire 1 +0V wire 3 +0Vdc wire 4 +0Vdc wire 10 stdby +0Vdc

There is no main filter voltages.

Thanks

I prefer an over-all shot of the entire TV so I can possibly identify the source of the plasma panel (most TV manufacturers don't manufacture their own panels). In this case, a single shot covering the entire power supply would be beneficial.

To repeat what retiredcaps said, your terminology when reporting voltages is confusing. If we can't communicate clearly, there is little point in continuing. For example, I asked

Also, you should see about 5VDC from CN11 pin2 (gnd) to pin 10 (5V stby). When you try to turn the TV on check for a change in voltage on CN11 pin 7 (AC-off).

You replied with

(CN11 )wire 1 +0V wire 3 +0Vdc wire 4 +0Vdc wire 10 stdby +0Vdc

Now I THINK that you are telling me that all pins in CN11 read 0 volts. I only hope that you measured from pin 2 or other appropriate ground point.

Now, if you did indeed measure the voltages correctly, there is 120 VAC into the power supply, and 0 VDC out of the standby supply. That is good news, the usual design call for standby power to be present whenever the TV is plugged in. Even better news, the standby supply is fairly straightforward to troubleshoot.

I don't think that a total recap of the power supply is in order, but certainly good clear pictures of the top and bottom of the power supply would be useful.

PlainBill

[mpobanion]

Re: Hitachi 42hdf39 no display

I was replying to fast and did not refresh my screen to see other info first #1 PowerAmpFreak this was after RetiredCaps and PlainBill had already started to help so that post came under PlainBill. Sorry about that.

Thanks so much for three different people helping


More History

There has a major storm in area after that TV did not turn on again the following day
The TV did not have any surge protection just plugged straight into a/c outlet.

When I received the TV the stdy LED (red) was present, after tuning TV on with remote relay sound could be heard then would turn off and than LED (green), but no display.

After continued troubleshooting and replacing the first cap (3300uF 100v) which was bloated then the other two main filter caps not bloated with higher rated (330uF 450v) to save some time from a local supplier figuring they might be the problem. Instead of the (270uF 400v) thinking that the increase in uF and extra 50volts would not matter. I turned on the TV and the relays did not click like before and the TV LED's were not present.

I found and replaced a MOSFET transistor on main PSU that the middle leg was shorting to the back of metal on the under side board discoloration (light brown) leading to a GND wire. The middle leg was getting so hot that it shortened the length and made a pit on trace I did my best to fix, not sure if it made a difference. Anyways, do I just give this one up as a learning lesson or could it possibly be saved?

Do I still continue with pictures?

Thanks

[retiredcaps]

Re: Hitachi 42hdf39 no display

Do I still continue with pictures?

Yes, don't make us ask 5 times!

[PlainBill]

Re: Hitachi 42hdf39 no display

I was replying to fast and did not refresh my screen to see other info first #1 PowerAmpFreak this was after RetiredCaps and PlainBill had already started to help so that post came under PlainBill. Sorry about that.

Thanks so much for three different people helping


More History

There has a major storm in area after that TV did not turn on again the following day
The TV did not have any surge protection just plugged straight into a/c outlet.

When I received the TV the stdy LED (red) was present, after tuning TV on with remote relay sound could be heard then would turn off and than LED (green), but no display.

After continued troubleshooting and replacing the first cap (3300uF 100v) which was bloated then the other two main filter caps not bloated with higher rated (330uF 450v) to save some time from a local supplier figuring they might be the problem. Instead of the (270uF 400v) thinking that the increase in uF and extra 50volts would not matter. I turned on the TV and the relays did not click like before and the TV LED's were not present.

I found and replaced a MOSFET transistor on main PSU that the middle leg was shorting to the back of metal on the under side board discoloration (light brown) leading to a GND wire. The middle leg was getting so hot that it shortened the length and made a pit on trace I did my best to fix, not sure if it made a difference. Anyways, do I just give this one up as a learning lesson or could it possibly be saved?

Do I still continue with pictures?

Thanks

The power supply found in a plasma TV is very complex. There are a number of outputs that must come up in a specific order, and with a limited delay between each output. This is almost impossible to troubleshoot without a schematic, other than by replacing any defective components found. There is also a power factor correction circuit that is simpler, but equally arcane. However, the standby supply is usually quite simple, and usually can be repaired fairly easily. Or I note that there are several power supplies available on eBay.

PlainBill

[mpobanion]

Re: Hitachi 42hdf39 no display

Thanks for being patient here are those pictures.

[PlainBill]

Re: Hitachi 42hdf39 no display

Thanks for being patient here are those pictures.

Well, they are pictures, but they don't really help. Retiredcaps gave some advice above.

The second picture is almost good enough. A higher resolution would help. The maximum allowed here is 2000 x 2000 pixels, try to come as close as possible. Every pixel counts when I am trying to trace a circuit.

Also, I need a picture covering all of the power supply, again at something close to 2000 x 2000 pixels. I notice in the shot of the bottom, the AC power connector is in the lower right. When you take the picture of the top it makes it much easier for me if the power supply is oriented so the AC connector is in the lower left. That way if I am trying to identify a component located near the top right, it will be on the top left in the other picture.

PlainBill

[mpobanion]

Re: Hitachi 42hdf39 no display

Hi
The digital camara i have can only capture 1280x960 Fine 1/125 shutter speed in Macro mode with flash disabled (off) the entire board fills the LCD screen, I hope these are better. I know every pixel counts, i can eye it and bring in tightly.

Thanks

[PlainBill]

Re: Hitachi 42hdf39 no display

Hi
The digital camara i have can only capture 1280x960 Fine 1/125 shutter speed in Macro mode with flash disabled (off) the entire board fills the LCD screen, I hope these are better. I know every pixel counts, i can eye it and bring in tightly.

Thanks

Those are excellent pictures, now the failure is at my end. The power supply appears to be a Murata product. I spent more time than I care to remember troubleshooting one of them and wound up buying a replacement.

The transformer at the bottom center in the picture of the top appears to be for the standby supply. The one in the lower left corner of the same picture is for the power factor correction circuit. I suspect the 'daughter board' just below the medium sized brown 450 Volt filter cap is the SMPS controller.

Checking the voltage across that cap (with power on, careful) would be useful. If it reads 1.4 x line voltage (or 165 VDC in the US) the most likely suspect is the SMPS controller.

PlainBill