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erikmilan
Joined: 30 Apr 2013
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 Posted: Wed May 01, 2013 12:33 am Post subject: Philips TV Vertical Output Problem |
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Hi, i have a small MR1430 Phillips TV thats having problems with its vertical output... When i turn on the TV there's a thin horizontal line across the screen and there's no sound output either.
The first thing i did was to replace the L7830 Vertical IC for a new one but the symptoms are still the same, when i measure the volts on each pin of the IC there's no output or input whatsoever.
I dont have a lot of expertice on TV electronics but the yoke is also making very quiet poping noices.
Does anyone have a service manual for this thing or some repairing tip ?
Thanks ! |
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jts1957
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| Posted: Wed May 01, 2013 6:01 am Post subject: |
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pin 6 should have approx. 24 volts dc vcc
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erikmilan
Joined: 30 Apr 2013
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| Posted: Wed May 01, 2013 2:18 pm Post subject: |
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| jts1957 wrote: | | pin 6 should have approx. 24 volts dc vcc |
Thanks, im not picking up any volts reding from pin 6 or any of the others.
There's no input and/or output on the new replacement IC, i dont think the problem is on the IC either because the old one showed the same symptoms. |
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jts1957
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| Posted: Wed May 01, 2013 9:37 pm Post subject: |
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Assuming TV DOES turn On & Off at your command with No Vert deflection: D445 cathode 24vdc?
R445 1 ohm?
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erikmilan
Joined: 30 Apr 2013
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| Posted: Thu May 02, 2013 12:22 am Post subject: |
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| jts1957 wrote: | Assuming TV DOES turn On & Off at your command with No Vert deflection: D445 cathode 24vdc?
R445 1 ohm? |
The TV does turn on & off with the remote and the switch... I broke R445 when i tried to pull it from the board, it had a very fragile condition. I need to replace R445 to get the volts reading on D445 right ?
By the way, i pulled D445 from the board too to test it... it seems ok but the reading on direct polarity shows 6 ohms. Its that OK ?, i think its a Germanium Diode. |
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jts1957
Joined: 24 Nov 2008
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| Posted: Thu May 02, 2013 2:22 am Post subject: |
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R445 1 ohm .5 watt
Yes, you need the resistor to read a voltage from cathode of diode to chassis ground. (Tuner cover.)
D445 SILICON (NTE 580 should work if memory serves).
With a DVM on 'Diode Test' should read infinite with probes connected in one polarity and 'a reading' in the other polarity.
Also while in there replace C432 100ufd 200volt. They fail in ALL NAP sets sooner or later.
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erikmilan
Joined: 30 Apr 2013
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| Posted: Thu May 02, 2013 3:23 am Post subject: |
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| jts1957 wrote: | R445 1 ohm .5 watt
Yes, you need the resistor to read a voltage from cathode of diode to chassis ground. (Tuner cover.)
D445 SILICON (NTE 580 should work if memory serves).
With a DVM on 'Diode Test' should read infinite with probes connected in one polarity and 'a reading' in the other polarity.
Also while in there replace C432 100ufd 200volt. They fail in ALL NAP sets sooner or later. |
Ok, i will replace everything... I think NTE 580 it's to big for the circuit since its a 3amp diode, maybe a `1N4004 or 1N4007 could do the trick ?
Also i just noticed that theres a small component near the 110V input of the board, its called N401... It looks like a small transparent bulb with 2 conductors on the inside, do you have any idea what kind of component that is ?, the pins got loose and are on a really bad shape. |
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jts1957
Joined: 24 Nov 2008
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| Posted: Thu May 02, 2013 4:31 am Post subject: |
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Original diode IS bad?
See if you can make out any markings on your original. MUST be fast recovery. 15khz at flyback. 1N4000 series diodes you mention are for 60/120 Hz.
N401 Sounds like a neon lamp used as 'spark/surge' protection on DAG line.
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