Riddled TV Repair Forum

Frankie · Joined: 26 Feb 2011 Posts: 11 Location: Tampa, FL

Hitachi 57" CRT RPTV
Model 57F59A
Chassis DP65G

Hey guys and girls, I'm sure you hear it constantly, but first time poster here with a broken TV that needs some help. I'm familiar with working on electronics as I'm a tube amplifier hobbyist, but I really don't even know where to start trying to diagnose this TV. I also don't want to start poking around until I understand the capacitor discharge method for this thing. I've been whacked by a tube amp before, that's no fun!

Okay, so onto the problem, I have a Hitachi 57F59A CRT RPTV here that won't display anything. The set powers on, I can hear the relay click, I can hear the audio amplifier working (it just hisses, I don't hear any actual signal), the LED on the front illuminates, but I can't get anything on the screen. None of the buttons on the remote or on the front of the TV bring up the menu or channels or anything.

I pulled the back panel and checked the 3 fuses on the board on the right hand side; they all tested for continuity on my meter. What I did notice is that there's a diagnostic panel inside the TV showing the location of an LED on that board. No matter what the LED isn't lit, I don't know if that's relevant.

So yeah, that's where I'm at now. I got the set open, I got my meter, I got my toolbox, I even got my soldering iron nearby... I just don't know where to start. Help! And thanks in advance.

Also, here are some pictures I took of inside the set. They're high res, but still crappy cell phone pics, so I'm just posting links to them in case you're on a slow connection.

http://www.cowboymafia.net/frankie/tv/1.jpg
http://www.cowboymafia.net/frankie/tv/2.jpg
http://www.cowboymafia.net/frankie/tv/3.jpg
http://www.cowboymafia.net/frankie/tv/4.jpg

Also, I got me a service manual and I've stepped down through the diagnostic.

I've got 5V at D949, I can hear the relay click, I have 115V at D945, so I visually inspected the components in order. Everything looks okay, but Q777 (on the right) looks a little misshapen/cracked. Here's a picture:

Is that part supposed to look like that or did it blow out? None of the other components on the heat shield have the bulge in the back like that. Or is Q777 that big brown deal and I'm looking at the wrong part? That bulge might not even be a bulge, it could be a reflection. It's pretty hard to see in that thing! Heeeelp! Very Happy

Google

Frankie · Joined: 26 Feb 2011 Posts: 11 Location: Tampa, FL

I should also add that prior to it just taking its football and going home, sometimes the TV would lose one color. I'd have to turn it off, wait 10-30 seconds, and turn it back on and it'd be fine. This normally happened when the kids were on a video game bender, so the TV would be on for a while before this happened. Bad IC? Blown capacitor? I eyeballed and re-eyeballed all the caps on the board, I don't see anything visually cooked and I don't want to haphazardly start probing things, I might cause even more damage. Again, thanks in advance for any help!

Frankie · Joined: 26 Feb 2011 Posts: 11 Location: Tampa, FL

One more thing to add, the heat sink nearest the AC plug gets warm, but all of the other ones are ice cold when the set is powered on in its current state. Not sure if that matters, but hey, the sticky said to be as detailed as possible so I'm trying to be. Very Happy

murfy888 · Joined: 02 Mar 2011 Posts: 6 Location: philippines

Check CRT socket. Does heater filament light up? Can you read any G2 voltage? Check or replace CRT socket... I think this is the problem..

Frankie · Joined: 26 Feb 2011 Posts: 11 Location: Tampa, FL

Murfy, I think you called it! This set has 3 CRT's, and I should be seeing red filaments in them much like a vacuum tube in a guitar amplifier, right? None of them are lit, not even a faint glow in the dark, so I assume you may have found the problem. Do you know what to check off hand? I'm going to dive into the schematic right now and see if I can make heads or tails out of the heater runs.

Google

Frankie · Joined: 26 Feb 2011 Posts: 11 Location: Tampa, FL

T902 appears to feed the heaters for the CRT's, and it's not really giving me any of the expected voltages. I'm seeing -300vdc or so at those E test points, not +24, +28, etc... Should I assume T902 needs to be replaced? I also tested I908 as per the service manual it directly feeds the heaters, and it's giving me large negative voltages too of ~90vdc, not the expected +6-+24vdc as indicated in the manual.

JTS1957 · Joined: 21 Jan 2009 Posts: 2393 Location: Far, Far Away

REFERENCING what? Hot ground, Cold ground?

doyed · Joined: 05 Apr 2011 Posts: 1 Location: Mexico

I'm in the same trouble with the same tv model.I can see the heaters on,the fly back is working,audio ampliefer is workink two,but no any raster on screen. I traced R,G,B signal out from jugla IC(TA1360AFG)and singnal is OK, vertical IC and pincushion IC's (STK's)normal voltage.the led diagnosis doesen't work to me
¿anyone has another idea?

Tony M · Joined: 01 May 2011 Posts: 1 Location: seattle wa

Frankie, if you get this please reply with your findings on the rptv no picture issue. I am curious and share the same concern on my TV.

Rockstar · Joined: 26 Oct 2008 Posts: 43

Check the vertical Ic for crack solder joints I had 2 Hitachi hd rear projection tvs that had the no picture or sound and flyback transformer didnt have the static sound of starting up.