Question about Hitachi 61HDX98B 61" Rear Projection Television
TV comes on and displays the OSD menus. If left alone, power will stay up on the TV. All leds and power supply voltages check correct. When an antenna connection is selected, the video will display for 10 to 20 seconds without any audio then the video blanks out and the power on light goes out. All of the power supply and deflection chassis leds stay lit. A few seconds after that, the power supply crowbars and shuts down. Using the audio test function in the OSD menu (no video input), there is no sound and after a few seconds, the shut down sequence occurs. The DM-1 control module should blink the power led twice when AC power is plugged in, but I do not see this. I removed the main chassis and power supply, checked both with an ESR meter, checked for shorts on the deflection board, used a lighted magnifier to check for cold/cracked solder joints, re-soldered any that even looked dull and repaired a solder bridge on the -13V drive transistor. Any help would be greatly appreciated.
Are you still working on this one? It's been more than 2 months, so I thought someone should check in. If it still isn't working after the last advice given here, can you give us an update of the current status, so we can see if there's any other suggestions to be made?
Posted on Sep 07, 2007
An expert who has achieved level 3 by getting 1000 points
If your PS waveform drops out it could be your 130v regulator (photo coupler) IP05 Hitachi p/n#2000465... The load would change when simply displaying an OSD to then creating a full screen raster. And something beyond that could be loading it - like the vertical IC601. Do you have a full vertical deflection when you select antenna?
Posted on Jun 27, 2007
There are bad capcitors in the control board, there are bad tact switches on the control board,or the CRTs are leaking fluid onto the printed circuit boards Good Luck
Posted on Jun 25, 2007
How did you check what I wrote for you. There is no way to fix it magicly. You will need to check what i wrote .
Unplug the front control boardwith the front panel control switch on it, and make sure the remote sensor is disconnected.
Check and/or replace the opticoupler
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The repair manual only shows a block diagram for the DM-1
control module, no schematic or parts list. The manual refers to the DM-1 as a "non-repairable front end module" and it contains the main microprocessor, the ntsc & atsc decoders, the osd generator and video and audio demodulation. I made a visual check and there is no fluid leak evidence on any of the circuit boards below the CRTs.
I had clicked on the "another solution" before I added my comments, sorry.
Removed the front control panel module, checked the caps with my ESR meter, all checked good. Ohm checked the diodes and transistors in circuit, no shorts. Remote control functions correctly, panel switches function correctly. Scoped the power on signal from the DM-1, it goes low at the same time the video blanks out. Appears that the DM-1 is not working properly or is detecting some other problem. Had a similar problem with this set while still under warranty and the service guy that Hitachi sent out replaced the activation plug-in card.
Have been trying to scope blanking and shutdown signals, but it is very difficult to get at connector pins to see what is causing the shutdown.
I have full screen video when the antenna is selected, but no sound. When the problem first started, I had sound and video for a few minutes before it blanked and shutdown. Will scope the 130V B+ and other voltages to see if any are dropping when the video is selected.
Monitored B+ while switching from OSD to video, no change in value (130V DC). Monitored other voltages with the same result. All leds remain on (not blinking) as described in the service manual until the power supply shutdown occurs.
Dyllan,
I determined that the problem had to be coming from the DM-1 tuner assembly. Sent it to PTS for testing and repair. They got the same symptoms that I was seeing and, after working on it for 2 weeks, declared it unrepairable. Rather than invest another $700 or so to replace the module and be stuck with 10 year old technology (no hdmi, no component video, etc.), I decided to replace the set. Thanks for checking back on this.
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