Pye Cw17 Crt - UK Vintage Radio Repair and Restoration Discussion Forum

The teleman · 14th May 2009, 9:35 pm

Hi Guys , At the moment i am working on a PYE CW17 restoration but have come to a stop , The crt heater has a short so i need to replace it ( see crt wanted ) the type fitted is a MW 43-80 but have had no luck in obtaining one ,but i do have several AW 43-80 crt`s , would it be possable to use this as an alternative ? if so , what modifications would need to be done ? Thanks Chris ..

P.s if anyone has a MW43-80 crt to sell me i would be greatful , Thanks again .

Mikey405 · 14th May 2009, 10:26 pm

Hi Chris.

I'm probably barking up the wrong tree here as I really have no specific knowledge of these tubes but the first one sounds like a magnetically focussed tube and the second an electrostatically focussed tube. (Like the different tubes used in the all-but identical Bush TV56 and TV66.) I guess that, given an extra source of focus-potential voltage, you could happily swap them over. (Removing all the magnetic focussing paraphernalia of course.) I'm not telling you this through any even remote expertise or experience, just thoughts from the top of my head really.

(Prepares to be shot dopwn in flames...)

Kind regards.

From Mike.

Heatercathodeshort · 15th May 2009, 9:49 am

Hello Chris,
Mike is spot on here. The AW43-80 will replace the MW43-80 easily. The gun assembly is the same other than the addition of a focus electrode. You will need to remove the focus magnet assembly and if my memory is correct this also includes the picture centering shuffle plates. The AW43-80 should focus with the focus pin earthed. Its not at all critical and if very slightly out of focus may need to be connected to H.T. A usual supply is available around the tube base. You will require a picture centering device. This looks like a massive ion trap magnet and fits just behind the scan coils. Any one will be suitable providing it is for a 70 or 90 degree electrostatic focus tube.
Something I have not tried is to simply slip the AW tube into the set and see if the focus magnets will focus the beam. It may well do so after you have adjusted the ion trap of course. Hope this helps. Regards, John.

The teleman · 15th May 2009, 2:00 pm

Hi Guy`s , Thanks for the info, I will try the AW 43-80 as it is first to see what happens & i will let you know if it works , Ceers , Chris.

jayceebee · 15th May 2009, 7:38 pm

Hi Chris, As an experiment I replaced an MW43-64 with an AW43-80Z in a Philips 1756U many many years ago and it gave quite acceptable results ISTR, even with no connection to the focus pin or centering magnets. Also the fact that the replacement was a 90 degree not 70 degree I dont remeber any problems with underscan either.
John C

The teleman · 16th May 2009, 5:30 pm

Hi Guy`s, The CRT transplant worked o.k. ! I had to remove the old focus unit & add a 2meg preset from the boost line to chassis for the focus potential . I did try with the old focus unit but the AW 43-80 has a slightly shorter neck than the MW43-80 so no room for the ion trap. Anyway the sets working ok at last , Cheers , Chris..

chipp1968 · 16th May 2009, 7:57 pm

Is that the "designer pye set " from the mid 50s ? Tube loooking good

FERNSEH · 16th May 2009, 11:59 pm

Quote:

Originally Posted by jayceebee

Hi Chris, As an experiment I replaced an MW43-64 with an AW43-80Z

I have an AW43-80Z which I intend someday to fit into a really good set. A set like the Pye CTL58F or the Ferguson 305T.
The AW43-80Z uses the gun assembly from the 110 degree AW43-88. No ion trap required

The CW17 was one the range of Pye products called the "contemporary" series. The cabinet stylist was Robin Day. He was not the TV broadcaster.

DFWB.

14th May 2009, 9:35 pm	#1
The teleman Pentode Join Date: Dec 2007 Location: County Durham, UK. Posts: 243	Pye Cw17 Crt Hi Guys , At the moment i am working on a PYE CW17 restoration but have come to a stop , The crt heater has a short so i need to replace it ( see crt wanted ) the type fitted is a MW 43-80 but have had no luck in obtaining one ,but i do have several AW 43-80 crt`s , would it be possable to use this as an alternative ? if so , what modifications would need to be done ? Thanks Chris .. P.s if anyone has a MW43-80 crt to sell me i would be greatful , Thanks again .

14th May 2009, 10:26 pm	#2
Mikey405 Octode Join Date: Jul 2006 Location: Solihull, West Midlands and Beaford, Devon Posts: 1,626	Re: Pye Cw17 Crt Hi Chris. I'm probably barking up the wrong tree here as I really have no specific knowledge of these tubes but the first one sounds like a magnetically focussed tube and the second an electrostatically focussed tube. (Like the different tubes used in the all-but identical Bush TV56 and TV66.) I guess that, given an extra source of focus-potential voltage, you could happily swap them over. (Removing all the magnetic focussing paraphernalia of course.) I'm not telling you this through any even remote expertise or experience, just thoughts from the top of my head really. (Prepares to be shot dopwn in flames...) Kind regards. From Mike. __________________ G7TRF

15th May 2009, 9:49 am	#3
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Pye Cw17 Crt Hello Chris, Mike is spot on here. The AW43-80 will replace the MW43-80 easily. The gun assembly is the same other than the addition of a focus electrode. You will need to remove the focus magnet assembly and if my memory is correct this also includes the picture centering shuffle plates. The AW43-80 should focus with the focus pin earthed. Its not at all critical and if very slightly out of focus may need to be connected to H.T. A usual supply is available around the tube base. You will require a picture centering device. This looks like a massive ion trap magnet and fits just behind the scan coils. Any one will be suitable providing it is for a 70 or 90 degree electrostatic focus tube. Something I have not tried is to simply slip the AW tube into the set and see if the focus magnets will focus the beam. It may well do so after you have adjusted the ion trap of course. Hope this helps. Regards, John.

15th May 2009, 2:00 pm	#4
The teleman Pentode Join Date: Dec 2007 Location: County Durham, UK. Posts: 243	Re: Pye Cw17 Crt Hi Guy`s , Thanks for the info, I will try the AW 43-80 as it is first to see what happens & i will let you know if it works , Ceers , Chris.

15th May 2009, 7:38 pm	#5
jayceebee Heptode Join Date: Jun 2007 Location: Durham, County Durham, UK. Posts: 640	Re: Pye Cw17 Crt Hi Chris, As an experiment I replaced an MW43-64 with an AW43-80Z in a Philips 1756U many many years ago and it gave quite acceptable results ISTR, even with no connection to the focus pin or centering magnets. Also the fact that the replacement was a 90 degree not 70 degree I dont remeber any problems with underscan either. John C

16th May 2009, 5:30 pm	#6
The teleman Pentode Join Date: Dec 2007 Location: County Durham, UK. Posts: 243	Re: Pye Cw17 Crt Hi Guy`s, The CRT transplant worked o.k. ! I had to remove the old focus unit & add a 2meg preset from the boost line to chassis for the focus potential . I did try with the old focus unit but the AW 43-80 has a slightly shorter neck than the MW43-80 so no room for the ion trap. Anyway the sets working ok at last , Cheers , Chris.. Attached Thumbnails

16th May 2009, 7:57 pm	#7
chipp1968 Rest in Peace Join Date: Jul 2006 Location: Somerset, UK. Posts: 2,356	Re: Pye Cw17 Crt Is that the "designer pye set " from the mid 50s ? Tube loooking good