Hitachi 46F500 power surge

[ryan74]

Major power surge blew this tv and first thing I noticed was a bad main fuse 125V. 6A and what I think is a ZNR Transient/Surge Absorber ZNR V10241U.
I dont know anything about surge absorbers.

Nothing seems burnt on power board but the surge must have melted the solder on the absorber, it pulled right out of board with no heat. there are 2 other 125V. 5A. buss fuses that are fine.

Im going to replace the absorber and fuse but I was wondering if the surge would have MOST LIKELY stoped at the absorber when it blew. I will order 2 just in case.

[johnboy1313]

Re: Hitachi 46F500 power surge

I don't have an answer for you, just a question. Were the absorbers in the circuit before or after the blown fuse?

[tom66]

Re: Hitachi 46F500 power surge

If you're lucky that's where the damage stopped. Hopefully it didn't come in through any of the video inputs and fry something on the main board.

[ryan74]

Re: Hitachi 46F500 power surge

I don't have an answer for you, just a question. Were the absorbers in the circuit before or after the blown fuse?

After.

Part seems to be obsolete and Im having trouble reading the last part on it, it is a little burnt.
ZNR
V10241U
?CD
Im not sure of the manufacturer/replacment.

[budm]

Re: Hitachi 46F500 power surge

You do not have to replace the MOV yet, if nothing else is damaged, the TV should power back up OK. I would suggest using 150W lamp in place of the fuse, if the lamp stays brightly lit when power caord is plugged into the outlet, that will indcate you still have shorted out circuits in the TV. The TV will work without the MOV, the MOV is put AFTER the fuse so when the first surge comes along, the fuse will blow so if there is a second surge the TV will not be exposed to the second surge.
By the way, that is 150V (code 241, Max allowable =150VAC/200VDC ) MOV, it looks like either 10mm or 14mm diameter. You can get it from Mouser or Digikey.
14mm:
http://www.digikey.com/product-detai...41K-ND/2799114

[ryan74]

Re: Hitachi 46F500 power surge

I called digikey and they said they didnt have anything to replace that part.
Mouser gave me this.
http://www.mouser.com/ProductDetail/...nLmFzxP794I%3d

on my way to town to pick up a 150w bulb unless fuses are cheaper.

[ryan74]

Re: Hitachi 46F500 power surge

The boards were filthy so I cleaned them and replaced fuse and have MOV removed.
Set powered on and I could see the lamps start to glow red green blue untill they shut off after 5sec. set remained powered(red front led).
The power board has 5 led on it and 1 is red. see pics

--Edit-- seems to be working. I have cable hooked up and it has pic and sound.
Is there a reset or factory mode?
all i have is the attached pdf

[tom66]

Re: Hitachi 46F500 power surge

I think this is a CRT rear-projection TV. Must be heavy! Nice 1080i set but how's the convergence?

[ryan74]

Re: Hitachi 46F500 power surge

yes it is crt rear projection. weighs over 100lbs.
Im such a amateur Im not sure what convergence is.. I havent read up on it yet.

[tom66]

Re: Hitachi 46F500 power surge

Convergence is basically how well aligned the red, green and blue tubes are. It's pretty normal for them to drift after some time. Usually adjustment is possible from user menu or service menu.

[ryan74]

Re: Hitachi 46F500 power surge

I just read a bit about it.
thought I would take a couple pics from about 4ft away.

-Edit- which part would be best? the digikey or mouser.
http://www.mouser.com/ProductDetail/...nLmFzxP794I%3d

http://www.digikey.com/product-detai...41K-ND/2799114

If it doesnt matter ill go with digikey. they are faster and cheaper shipping.
the original part diameter is 10mm

I found this also same as mousers part
http://www.digikey.com/product-detai...41K-ND/2407562

[ryan74]

Re: Hitachi 46F500 power surge

I was looking inside to see how dirty the mirror was and saw something odd on red lamp.
it looks like a thin strip of electrical tape.
Is windex ok inside on lamps and mirror?

[ryan74]

Re: Hitachi 46F500 power surge

I ran this tv about 72hrs. testing before selling on sunday.
Three days later I get a call it has wavy lines on right side of screen.
I go to look at it and he said it just shut off and wont turn on.

It attempts to power on but shutsdown right away.
I took tv back
back to troubleshooting

-Edit-
I removed the board and when I plug it in it makes noise around what I think is a relay(pic 2).
After 5-10 sec noise stops and led's light up on board.
Its not a chirp or squeel but more of a vibrating buzzing sound

[ryan74]

Re: Hitachi 46F500 power surge

(above)I suspect a bad cap but who knows.

I was looking inside to see how dirty the mirror was and saw something odd on red lamp.
it looks like a thin strip of electrical tape

I think this has something to do with calibration from what I have read on other sites.

[ryan74]

Re: Hitachi 46F500 power surge

I removed the power board and when I plug it in, it makes noise from the relay in pic above. this is probly from a bad relay or voltage issue. I have bad luck locating fet's and leaking caps that havent completely failed so I would like to verify correct voltage at relay.

Any tip for troubleshooting or schematic?
Im not possitive it is a power supply issue but pretty sure and I dont have service manual/schematics.
The power board is stamped
DP2X
#JK08024-A

the next numbers are smeared in black ink
DP23A/32AB
IDICT29C04

[tom66]

Re: Hitachi 46F500 power surge

Any time you suspect the power supply, first rule is, "thou shalt check voltages." Basically all a PSU does is give you voltage rails. Are they there or not? If they're there, look elsewhere, otherwise, consider the PSU.

[ryan74]

Re: Hitachi 46F500 power surge

I noticed voltages printed on bottom of board so I checked each pin.
Most were 13v while the relay made noise then went up to 20v and the led's turned on board.
The 10v was only 3v.
I also noticed when power is applied to board I only get 55v at main fuse.
Seems to be low voltage overall.
The varistor I replaced looks ok but I may pull it and see what happens if I power up the board.

Any tips as to what I should check now?

Edit- I swear I was reading 20v off ground pins also. I may have to recheck that.

[tom66]

Re: Hitachi 46F500 power surge

The transformer outputs are ac, you cannot measure them with dmm.

You need to measure the output voltages on the connector.

Leaky caps don't cause this problem, high ESR maybe, board uses very good ones though, so it is unlikely.

[ryan74]

Re: Hitachi 46F500 power surge

The readings I took were ac. Can you explain why that cannot be measured with a digital multimeter?

The cap question was partialy unrelated to this post. I just threw the question in.

I will have to take pics and post results of connector voltage. Theres a few connections and I dont know which to test.

[plc]

Re: Hitachi 46F500 power surge

Pardon me friends. I have this same board from a Hitachi television. I'm wondering if I can get a point in the right direction.

Here are my set's symptoms:

Unit worked flawlessly for about a month
Unit was working with a slight buzz just before it stopped working
Unit now turns on, audio pops, but no tubes light up
Any media player turning on will turn on the set
Remote will turn unit on
Remote will not turn unit off
All LEDs on board light except D928, which checks on a DMM

I am inclined to believe that whatever power source which powers the imaging and audio section of the digital board is not sending power.

I am inclined to believe that a relay has failed
S901 and S902 conduct across the coil side
S903 and S905 do not conduct across the coil side

I am at the limit of my TS understanding

Thanks for any help
Philp