Pye V14 LOPT substitution - UK Vintage Radio Repair and Restoration Discussion Forum

newlite4 · 22nd Aug 2005, 10:18 am

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

turret_tuner · 26th Aug 2005, 10:52 am

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?

newlite4 · 26th Aug 2005, 11:49 am

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

Duke_Nukem · 26th Aug 2005, 12:35 pm

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

oldeurope · 26th Aug 2005, 2:16 pm

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

22nd Aug 2005, 10:18 am	#1
newlite4 Octode Join Date: Nov 2003 Location: Bath, Somerset, UK. Posts: 1,805	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 Attached Thumbnails

26th Aug 2005, 10:52 am	#2
turret_tuner Retired Dormant Member Join Date: Jul 2003 Location: S. W. Midlands, UK. Posts: 36	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?

26th Aug 2005, 11:49 am	#3
newlite4 Octode Join Date: Nov 2003 Location: Bath, Somerset, UK. Posts: 1,805	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
Duke_Nukem Octode Join Date: Jan 2003 Location: Birmingham, West Midlands, UK. Posts: 1,268	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
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	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