Hitachi 43fdx01b no picture after convergence repair

[Smitlivan]

Hi, I could use some help if you will. I'm very frustrated at the cost of new tv's so I thought I would repair the convergence by purchasing the kit. The vertical blue was bowed to the right and unadjustable. I ordered the repair from Vance Baldwin, replaced the parts last night and now the screen is blank. There is sound and once in a great while you can see fuzziness and adjustment lines but for the most part it's blank. I can here tsst sounds and clicking inside the unit but can't tell where it's coming from. I didn't hear that noise prior to replacing the parts. I have gone over and over the process and can't for the life of me figure what went wrong when I had video before I started. This is the first time any repair has been done on this unit.

Any advise?

Thanks in advance.

[lcaillo]

You likely have something disconnected or connected poorly. You need to go over all connections and verify them.

[Smitlivan]

We just finished going through the connections and found nothing. Each time we hear that "Rice Krispies" sound, the video works but it doesn't stay. It sounds like the noise is coming from the black component that looks like it has spark plug wires attached to it.

[lcaillo]

Sounds like high voltage connections in the flyback transformer are loose or maybe you cracked the board around the flyback(that black component). Also check the focus lead, the red wire going up to the focus block in the front of the set. You may have pulled it loose where it plugs into the back of the focus block. This has about 10kV on it and the anode leads going into the flyback have about 30kV on them, so please be very careful.

[Smitlivan]

Thank you for your expertise. How long before the flyback transformer is fully discharged?

[lcaillo]

The flyback does not generally hold a charge, the crts do. If you handle the anode leads, discharge them to the chassis through about a 10K resistor. There may still be a chage on the other end of the crt however, as the caps on the crt board hold a good bit of energy for a while.

[Smitlivan]

We found nothing wrong with the connections. Reflowed the solder joints in one area of the board and now have video, colors are great but the power doesn't stay on even though the red power light is lit and the sides of the picture are bowed. Power only stays on for a few seconds.

[lcaillo]

Are the top and bottom bowed as well as the sides? Do you have +/- supplies to the convergence ICs? When is turns on do all of the green LEDs illuminate in the set? Does one go off before the others?

[Smitlivan]

Only the left side of the picture is bowed. I looks like it may be needing an alignment as some of the words are off the screen on the right side. When you first turn the tv on both the Green and Red leds illuminate but the red will fade imediately to nothing and there is no picture or audio.
However, a quick cycling of the power button will bring up the video and audio along with both LEDs (green and red) for just a few seconds (15 to 20) then the power supply reduces the power to the board and the red LED fades to nothing at which point we lose audio and video.

[Smitlivan]

We did adjust the convergence manually and the picture is about perfect but I was wondering to make it easier to solder the joints to remove the board completely so is it safe to assume the following? found it on the web ...... (Regarding the large red leads on the transformer (the large black blocky thing in the middle of the board)... in order to remove them, you need to push them down, and rotate them a quarter turn to allow them to be removed vertically... It's hard to describe, but once you get one of them off, you'll see what I mean. (the thin red wire you can just remove vertically, it's a normal connector)).

[lcaillo]

I generally do not remove the board. It is sometimes hard to get the anode leads out without damaging them, and if you do not get them seated properly it is easy to cause arcing and burn the contacts in the flyback. Nothing wrong with doing it that way, but you can loosen the wires and stand the board up enough to get to the solder side without removing the board on almost ever Hitachi that I have serviced, which number in the hundreds.

Is the set not shutting down now?

[Smitlivan]

It is shutting down but it takes a little longer now for that to happen. It still has a convergence problem but is intermitant. The picture will shake a little bit too but not that often. I did disconnect all the wires except for the flyback, stood the board up on it's side and resoldered all the leads that looked suspect to problems. Could the IC's that I replaced for the convergence problem be causing the issue I'm having now? The color is absolutely beautiful until the convergence starts acting up. The picture still seems a little to far to the right because the "L" in Animal and the "T" in Planet does not show on the screen but I don't know how to fix that. It is set in Normal mode not Zoom.

[lcaillo]

You may have a problem in the DCU. If the pix is offset, check for d.c. on the inputs to the convergence amps. You should have no more than a couple of hundred millivolts of offset. You could have a bad IC. Did you check the resistors carefully?

[Smitlivan]

Thank you for your help .... we really appreciate! We checked all the parts visually but didn't find anything and we will certainly check the inputs on the amps but can you tell me - What is the DCU?

[lcaillo]

Digital Convergence Unit. This is the module inside the shielded box toward the front of the set. The resistors need to be checked with a meter, with the connections to the yokes unplugged.