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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
Hitachi 42PD4200

 
 


Cornboats
New User

Oct 8, 2010, 8:56 AM

Post #1 of 8 (1758 views)
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Hitachi 42PD4200 Can't Post
Trying to fault find this set. Led goes back to red in 60 seconds. Service manual gives no waveforms on and off each board .
The Y-sus has 5 pots for set-up adjustment . No mention of thse in the manual.
Are there any engineers out there who can remember working on one of these and can throw any light on troubleshooting this one please let me know.Pirate



darstr
User


Oct 12, 2010, 3:18 PM

Post #2 of 8 (1738 views)
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Re: [Cornboats] Hitachi 42PD4200 [In reply to] Can't Post
Crazy Other than the led going to red . . . .what is the set doing? Picture or no picture? Sound or no sound? Do you hear relays click at all? This would help out.


Cornboats
New User

Oct 12, 2010, 4:31 PM

Post #3 of 8 (1734 views)
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Re: [darstr] Hitachi 42PD4200 [In reply to] Can't Post
Hi.
FS1 had blown on the Zsus board. I metered out as much as I could but couldn't find anything wrong so replaced the fuse.
The set goes to green then after 30 secs back to red. I checked all voltages from psu (MPF7414).
The VA & VS votages were a couple of volts on the high side so I brought them back down to spec.
I was going to use an oscilloscope to see if any waveforms are missing but theres no info in the manual.

Many thanks for taking an interest, any help is welcome.


darstr
User


Oct 12, 2010, 4:37 PM

Post #4 of 8 (1733 views)
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Re: [Cornboats] Hitachi 42PD4200 [In reply to] Can't Post
Crazy You are on the right track. If you can, check all the transistors and fet's on the z sus. You might be able to fix it at component level that way, but if not I would almost bet if change the z sus, you will be fine. I think the reason your vsus is a little high is because the zsus board is not giving a load back to the power supply. So just remember when you get it running to readjust that voltage. Good luck


Cornboats
New User

Oct 12, 2010, 7:59 PM

Post #5 of 8 (1726 views)
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Re: [darstr] Hitachi 42PD4200 [In reply to] Can't Post
I'll did a few checks on it but if you think its this board I'll take it out and do a component by component check.
You'll never guess whats happened now. I've lost both Va (65V) and Vs (190V) voltages. It can't be the transformers on the cpu because they are fed from separate ones. I've checked impedance on connectors to make sure continuity between boards. Now I'm stuck.
It must be something I've done. All other voltages are present on the cpu. does the power protection shut down these lines I wonder?
Any ideas would be most welcome.Frown


darstr
User


Oct 12, 2010, 8:14 PM

Post #6 of 8 (1725 views)
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Re: [Cornboats] Hitachi 42PD4200 [In reply to] Can't Post
Crazy Yes they do. There is a lot of handshaking going on. Do get your VS to come back you need to unplug the connector that connects the logic board with your digital board. should be about 7 pins i think. count to three and plug it back in. then power the set back up. Every time the set shuts down while you are testing, you will need to do that, or the set will not fire back up.


Cornboats
New User

Oct 14, 2010, 1:50 PM

Post #7 of 8 (1713 views)
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Re: [darstr] Hitachi 42PD4200 [In reply to] Can't Post
Hi.Darstr.
Following your reponse I tried unpluging 7 wire from logic board (This is a small L shaped board that plugs into larger board which has inputs for arial, scart etc.) and digital board( This is a screened board which has input plugs for computer and audio.)
I unpluged whilst set was mains off and whilst on red standby but neither would allow me to get va up.
I gave up on that one for the time being and decided to remove the Zsus for component fault finding.

All diodes fuses and fets tested ok but I then turned to the IPM.
Ref LG V6 Trouble shooting.
When each 4 TEST Diode value is over 0.4V =OK. Reverse = infinity
1) Gnd+, Sus-out- =.376
2) Sus-out +,Vs - = short
3) ER-DN -,ER-COM + = .493
4). ER-COM - ,ER-UP + =.581
The above polarity was reversed and 1,3,4, tested infinity but 2 was short.

I'll try and get a zsus board but in the meantime have you ever stripped down an IPM? Is it worth doing to find the fault?


darstr
User


Oct 14, 2010, 4:35 PM

Post #8 of 8 (1710 views)
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Re: [Cornboats] Hitachi 42PD4200 [In reply to] Can't Post
Crazy No I have not, but don't really think this will be needed to do.

 
 
 


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