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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 7th Sep 2019, 10:17 pm   #1
delaitt
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Default Philips EL8100 troubleshooting

Evening

I'm repairing a Philips EL8100 video monitor

many thanks to Brian for the schematic. much appreciated.

The schematic can be found at this previous post

It appears there is no high voltage to the CRT.

There is no pulse at the base of TS23 (transistor to high-voltage transformer)

I have the correct signals at the emitter and collector of TS17

However there is no signal at the base or emitter of TS19

I also don't seem to have the correct polarised voltage at the base of TS19. I hardly have -1V at the base of TS19 and approx -6V at the centre point between GR2/GR3 (the 2 x diode)

Would you recommend some suggestions for troubleshooting?

Thanks

Thierry
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Old 8th Sep 2019, 10:46 am   #2
delaitt
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Default Re: Philips EL8100 troubleshooting

The schematic in pdf can be found here

The voltage at the collector of TS20 is close to zero volt whilst the other side of R76 (1K) is at -9V. I unsoldered R76, tested R76 it and it is ok. after that the voltage came back at the collector of TS20 and could hear the HT transformer kicking in. I switched it off tried again and same thing voltage at the collector of TS20 is close to zero volt.

any hints you would recommend?

Thanks

Thierry
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Old 8th Sep 2019, 12:47 pm   #3
Maarten
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Default Re: Philips EL8100 troubleshooting

Try heating the case of TS20 with a soldering iron. Add a bit of tin and remove soldering iron as soon as it flows. If you don't want to repeat treatments like that once every so often, flush or replace all TO7 cased transistors. This looks like a case of tinwhiskers to me.
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