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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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22nd Aug 2005, 10:18 am | #1 |
Octode
Join Date: Nov 2003
Location: Bath, Somerset, UK.
Posts: 1,805
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Pye V14 LOPT substitution
All signs pointed to a shorted turn in the EHT winding. The heater of the EY86 would not light although the line oscillator was OK, with the cap of the EY86 removed, the winding still got hot, the pitch had been running from the winding. Not to be outdone, I looked for a replacement winding. I had saved the LOPT from an early seventies Hitachi B/W portable. After dismantling the donor LOPT, it was evident that the winding would fit on the Pye unit. After fitting the replacement winding onto the Pye LOPT, the set was powered-up and I was greeted with a bright raster. When you see these early portables going for a pound at the car boot, remember they can prove to be a lifesaver for the old timers.
Neil |
26th Aug 2005, 10:52 am | #2 |
Retired Dormant Member
Join Date: Jul 2003
Location: S. W. Midlands, UK.
Posts: 36
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Re: Pye V14 LOPT substitution
How convenient that the "new" overwind was physically and electrically compatible. With the differences between valve and solid state circuitry, crt deflection angle, higher eht requirements of modern crts, scan coil design, line scan power etc., things must be adding up the right way. I wonder if you were able to check whether the resulting eht voltage is within spec for the crt?
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26th Aug 2005, 11:49 am | #3 |
Octode
Join Date: Nov 2003
Location: Bath, Somerset, UK.
Posts: 1,805
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Re: Pye V14 LOPT substitution
I havent actually checked the EHT yet, although I have a probe for doing so. I felt that it would be a fair assumption that the EHT would be in a similar ball park with the replacement winding. Surprisingly, the Pye V14 manual gives no indication of the EHT that is applied to the tube. Interestingly, the line output stage of the "All Transistor" donor set used an NEC version of the EY86. This is in a similar vein to the Perdio Portarama which also claimed to be "All Transistor" but had the same arrangement.
Neil |
26th Aug 2005, 12:35 pm | #4 |
Octode
Join Date: Jan 2003
Location: Birmingham, West Midlands, UK.
Posts: 1,268
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Re: Pye V14 LOPT substitution
I guess the EHT can't be too far away from where it should be otherwise you'd have a lot of under or over scan as well as brightness difficulties.
TTFN, Jon |
26th Aug 2005, 2:16 pm | #5 |
Retired Dormant Member
Join Date: Dec 2003
Location: Solingen, Germany
Posts: 727
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Re: Pye V14 LOPT substitution
Hi,
this is not critical. You can vary the EHT by connecting the coil to the plate of the line output valve or the katode of the diode. The problem is to find an eht coil which is ok. I ordered some NOS and they are all defect.. In the "modern" coils moist comes is and can not get out. I tried to make an open coil, but 12KV was the maximum. There is not much space in the ferrite cores. Kind regards Darius |