Question about Televison & Video
One switching tv on, no light comes on. Is this a power supply problem? Many Thanks for your help.
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Posted on Jan 02, 2017
this is the raw research for this that I have found. It seems like the most likely culprit for this is the stk chips on the convergence board (JVC didn't put nearly enough heat sink compound on should be a small layer all the way across they put on a couple dabs) I hear tale you can check this out by disconnecting the convergence board and turning on the set . only go after the convergence board from the front (behind the speaker grill is another panel, the convergence card is right behind there) there is a sneak circuit which will kick in possibly destroying at least the dvi input and mabie more if the set is powered on with the back removed and you didn't put a jumper in the right place or cover over a hole in the back of the dvi module (supposidly to keep people from hacking movies, like there arn't easier ways to do that if you really wanted to). if that doesnt fix it then I have found several other possibilities but I am now a few hundred miles from the tv that I was working on so havent had a chance to try this out:
No. The CRT driver ICs are prone to shorting and cause this symptom (I just had one with those very symptoms and the green CRT driver IC was shorted). Disconnecting the CRT board does not clear the short on the board. Often then is a small burn mark on the CRT board under the affected IC (but not always). The IC should be a TDA6111Q. Be sure to note the proper position
of the IC as it should face with the letters TOWARD the heat sink!!!!
Larry, Check the CRT driver ICs on each of the CRT boards.
Bob Waterman, CET® #RI-28
Master Technician License #9109
Service Manager / Parts Manager
Gemini Computer, TV, & Security Alarms
Hi Guys, I don`t see many JVC`s and don`t have the print for this AV48WP30, went out this morning and as customer claimed on phone when you plug set in and turn on it makes a loud thump thump in both speakers 20-30 times then relay clicks, the thump stops, and blue idiot light on front goes dim/bright, dim/bright, have to unplug set to start this same scenario over again. Never develops HV or audio, Will order the service manual today, but would like to know if anyone has seen this before (should say "heard" this before)
I would disconnect each crt board and hv lead one at a time and try. Have seen several bad tubes on that model. The only other problem I have seen on that set is bad convergence amps, however that doesn't cause shutdown.
From Tech Repair CD:
JVC\AV48WP74\just went click*click*click when turned on Video drive IC (IC1101) on the red CRT module
shorted. It looked like bad solder on the B+ was the cause
Frequently Used Top Five Repair Parts by symptom code
MODEL NUMBER : AV48WP30 - TV
SYMPTOM CODE : DEAD
TOP FIVE PARTS :
Above from JVC Web site, also I have seen shorted video drive IC's on the crt boards short and cause this symptom. Try unplugging the 200 volt source to the crt boards and see it the set powers up and stays on. There is a B+ relay which supplies 130 Volts to the horizontal output circuit. Is this relay energizing? I takes about five seconds after the power is turned on for it to energize. If a short is detected on the 130 volt line the blue power lamp on the front will do what you describe and the relay will pulse on and off. (David)
Non-functional Digital Input
1. Power off the unit
2. Disconnect the digital input if it is connected
3. Remove the rear cover
4. On the digital input module, using a shorting pin (PC type) or a
jumper, short Pin 1 and Pin 2 of the
5. Power on the unit
6. Unplug the unit and remove the shorting pin or the jumper
7. Re-attach the unit’s rear cover
8. Power on the unit, and input the digital source
Posted on Dec 06, 2007
In a large number of failures with these symptoms it's usually the HOT (horiz. output trans. Q522, which is a 2sd2499) and the regulator (Str30134), together with fuse F902 (Gma 1.25a). Not an expensive repair or that complicated if you're fairly good with electronics and know how to solder correctly. Otherwise take it in and have it repaired professionally - it's worth it...
Posted on Dec 07, 2007
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It sounds like your switching power supply or you High Voltage power supply has malfunctioned. These sections control all power to the TV and can produce the situation you are describing. If you do not have a background in electronics, I would suggest that you have a TV repairperson come over and check your TV out.
I say this because there are voltages in a TV set that can kill, so caution is needed.
I hope this helps
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