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yareth
Joined: 01 May 2009
Posts: 8
Location: Venezuelan and Canada
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| Posted: Fri May 01, 2009 4:43 am Post subject: Diodes broken in HV board of projector DTV-852 runco. |
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Hi, i need to know the type of diode and ohms amount of the resistor of the HV board in DTV-852 Runco or Zenith pro900x. The following components is broken :
D4924, D4927, D4925, D4926, R4936 and R4937.
I need the Diagram and the parts list.
Thanks to all for help given.
Yareth.
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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yareth
Joined: 01 May 2009
Posts: 8
Location: Venezuelan and Canada
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| Posted: Fri May 01, 2009 5:14 am Post subject: |
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Thanks, but i checked them but there are not part list and diagram eschematics of circuit of Diode D4924 D 4927 D4925 D4926 and resitors R4936 R4937 .
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WTS
Joined: 08 Mar 2006
Posts: 1276
Location: Calgary
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| Posted: Fri May 01, 2009 3:34 pm Post subject: |
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How do you know the diodes are broken? If you've taken them out there should be numbers on the diode body, what are they"
What's wrong with the resistors are they burnt?
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Thanks
Walter
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yareth
Joined: 01 May 2009
Posts: 8
Location: Venezuelan and Canada
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| Posted: Fri May 01, 2009 5:57 pm Post subject: |
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They blew up, dissintegrated.
Thanks.
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WTS
Joined: 08 Mar 2006
Posts: 1276
Location: Calgary
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| Posted: Fri May 01, 2009 7:31 pm Post subject: |
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Really, damn, I don't have any schematics for those units. I would assume Curt does.
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Thanks
Walter
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jkruger
Joined: 24 Oct 2007
Posts: 2435
Location: Carlsbad, CA
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| Posted: Fri May 01, 2009 7:54 pm Post subject: |
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If you have blown up components on that board it has more problems. You may want to have a pro look at it. (Curt)
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Fri May 01, 2009 8:17 pm Post subject: |
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I'm also guessing that the HV transformer might be arcing internally or be shorted. I've got a few good HV boards left. Haven't had those diodes short out before without something else being wrong on those boards, usually the HV transformer.
Zenith has discontinued all support and parts for CRT units.
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yareth
Joined: 01 May 2009
Posts: 8
Location: Venezuelan and Canada
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| Posted: Fri May 01, 2009 9:54 pm Post subject: |
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In my case the flyback or hv transformer are operating just the burned diodes .
Only i need the parts list of this model to find the equivalents or replacements, i have done this task in other tv models.
thanks.
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stefuel
Joined: 07 Mar 2006
Posts: 3353
Location: Green Harbor MA USA
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| Posted: Sat May 02, 2009 5:33 pm Post subject: |
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How do you read the value of a diode. for instance, black body with a siver bar on one end and 400 near the bar and 412 on the other end.
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Chip
A Barco is only a AmPro with training wheels
Card carrying member of the AVS chain gang.
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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stefuel
Joined: 07 Mar 2006
Posts: 3353
Location: Green Harbor MA USA
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| Posted: Sun May 03, 2009 5:09 am Post subject: |
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OK, I have a situation in a heating control. It has 14 1N4007 rectifier diodes. Four of them have shorted. I don't have any 1N4007's but I do have plenty of 1N4004's. They are basically the same but the 4007's have a 1,000 volt capacity and the 4004's are 600 volt capacity. The most voltage they will ever see is 120 volts. Is there any reason why I should not substitute with the 4004's?
_________________
Chip
A Barco is only a AmPro with training wheels
Card carrying member of the AVS chain gang.
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yareth
Joined: 01 May 2009
Posts: 8
Location: Venezuelan and Canada
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| Posted: Mon May 04, 2009 3:55 pm Post subject: |
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ok. but only i need the diagram of HV board .
Thanks....
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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| Posted: Mon May 04, 2009 6:29 pm Post subject: |
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| stefuel wrote: | | OK, I have a situation in a heating control. It has 14 1N4007 rectifier diodes. Four of them have shorted. I don't have any 1N4007's but I do have plenty of 1N4004's. They are basically the same but the 4007's have a 1,000 volt capacity and the 4004's are 600 volt capacity. The most voltage they will ever see is 120 volts. Is there any reason why I should not substitute with the 4004's? |
Please correct me if I'm wrong...
Reverse Voltage
When a reverse voltage is applied a perfect diode does not conduct, but all real diodes leak a very tiny current of a few ľA or less. This can be ignored in most circuits because it will be very much smaller than the current flowing in the forward direction. However, all diodes have a maximum reverse voltage (usually 50V or more) and if this is exceeded the diode will fail and pass a large current in the reverse direction, this is called breakdown.
Could you not just put two IN4004 diodes in parallel to replace each IN4007 ?
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RogueChili
Joined: 31 Mar 2008
Posts: 162
Location: Westfield, MA
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| Posted: Mon May 04, 2009 7:09 pm Post subject: |
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parallel ? three in series will triple the PRV rating however would also decrease the output by an additional two diode drops; not advisable.
Something to consider, the voltage at the diode is dependent on the circuit type. It is possible the diode could see over 600 volts in an inductive switching circuits.
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Tom.W
Joined: 09 Mar 2006
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Mon May 04, 2009 7:32 pm Post subject: |
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Just order the right parts....Damn'it !!!!!!!!!!!
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Tom.W
Joined: 09 Mar 2006
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WTS
Joined: 08 Mar 2006
Posts: 1276
Location: Calgary
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| Posted: Tue May 05, 2009 1:13 pm Post subject: |
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Chances are you could use the 1N4004 and have no problems. I'd have to look at the circuit but I'd use them.
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Walter
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yareth
Joined: 01 May 2009
Posts: 8
Location: Venezuelan and Canada
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| Posted: Sun Jun 07, 2009 1:16 am Post subject: |
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| WTS wrote: | | Chances are you could use the 1N4004 and have no problems. I'd have to look at the circuit but I'd use them. |
thanks, i used 1n4007 and two resistor 10 ohm each on the R4937 and R4936 the projector power on for 5 minutes but the circuit power off .
Yareth . 
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