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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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16th Nov 2019, 8:29 pm | #1 |
Pentode
Join Date: Jan 2016
Location: Crewkerne, Somerset, UK.
Posts: 119
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Philips 1400 projection TV
i posted the type number on here last week but got no replies
i have since found it is a variation of the philips 1400 the problem i have is no raster low eht i have checked voltages around the grid which when the protection circuit is activated if one of the timebases fail goes to 160 volts which cuts off the bias to the crt well this voltage varies between 38-90v when the brightness control is adjusted so i am assuming the timebases are working. the speaker emits an awfull squeel i can here line whistle. but the eht is almost non existent and iirc the ht4 voltage is low. i have never seen one before i have the circuit diagram for it anyone have any experience of faults on this model or any help much apprefciated thanks in advance Simon
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Keep the soldering iron warm and never give up or you will kick yourself. BVWS MEMBER |
17th Nov 2019, 6:35 pm | #2 |
Octode
Join Date: Feb 2007
Location: Harrow, London, UK.
Posts: 1,483
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Re: Philips 1400 projection TV
Hi Simon
This Philips model was also badged Stella ST1481 and as with the Philips little on this site. However should you search Projection TV protection circuits, quite a few threads appear. I'm afraid that you will need to trawl through them to both get members recommendations and contact details. See also Philips 699 projection TV. The EY51's and associated capacitors plus the same in the protection circuit crops up. I am sure I've seen more information somewhere and I'll get back to you with details. Chris |
17th Nov 2019, 8:20 pm | #3 |
Octode
Join Date: Feb 2007
Location: Harrow, London, UK.
Posts: 1,483
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Re: Philips 1400 projection TV
More links
Emerson 609 Antiqueradio post. Riders Service Manual. Noreleco North American Philips projection same as European version together with protection circuits. Philips TD2312, TX1714A, VE2600 |
17th Nov 2019, 10:57 pm | #4 |
Dekatron
Join Date: May 2003
Location: Edinburgh, UK.
Posts: 3,273
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Re: Philips 1400 projection TV
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18th Nov 2019, 9:57 am | #5 |
Octode
Join Date: Jul 2006
Location: Solihull, West Midlands and Beaford, Devon
Posts: 1,626
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Re: Philips 1400 projection TV
Hi Simon.
Although I'm not really in favour of "blanket changes" of caps, I think I'd be inclined to replace almost any of those black pitch Philips caps in the tube protection circuit (first) and then the EHT oscillator. I seem to recall that the TG1400A circuit is very similar to the 6027A so this may help in the absence of a manual. The red books will almost certainly have the circuit but if you can't find it then you can download a copy from here : http://www.oldtechnology.net/documentation.html (Number 34 in the list.) One last thing which occurs to me is to make sure you don't have any leaky smoothing / reservoir caps as this will cause the HT to become low. It may be worth disconnecting and then re-forming them slowly. You can normally expect good results if you don't try and rush the re-forming process. Give it a good few hours (the longer the better in my experience) with a high value series resistor. Don't forget to disconnect them from the rest of the set of course. Thanks Simon. Kind regards. From Mike.
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G7TRF Last edited by Mikey405; 18th Nov 2019 at 10:13 am. |
18th Nov 2019, 10:11 am | #6 |
Octode
Join Date: Jul 2006
Location: Solihull, West Midlands and Beaford, Devon
Posts: 1,626
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Re: Philips 1400 projection TV
In the way of a PS:
If the tube protection and EHT circuits are working correctly then you may still have no picture if the frame circuit is not working but this can easily be checked with a 'scope. The little frame blocking oscillator transformers can be very delicate in these sets and are frequently found to be open circuit. Also those nasty black pitch caps going leaky can upset the scan or oscillation and cause no (or low) frame scan and this will, of course, cause the tube protection circuit to operate.
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G7TRF |
18th Nov 2019, 11:25 am | #7 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
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Re: Philips 1400 projection TV
Note that the HT supply to the 25kv EHT unit is voltage doubled by V21 a PZ30. Lots of pitfalls for the unwary with projection receivers. As Mikey has mentioned, all of the black Philips caps will be faulty by now. Check any resistors particularly the ones in the EHT unit with a value exceeding 100k for value. They tend to drift upwards but 20% tolerance is acceptable.
When you have the EHT working you should be able to hear the characteristic 'whine' from the can. If the screen is blank, on switching off you should get a large decaying 'blob' on the screen as the EHT fades. Keep the brightness turned back if you suspect the EHT is present but no screen illumination can be seen. A timebase collapse or spot will burn the screen almost instantly. Fortunately there appears to be quite large numbers of MW6-2 tubes still around. The best action I feel is: Get the H.T. supplies correct then sort out the EHT unit. The oscillator transformer is the same as the one fitted in the line oscillator. John. |