30th May 2021, 7:30 pm | #21 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
|
Re: HMV 1920 made in 1960.
Hi John,
The HMV is up against stiff opposition, my Pye V600A displays a superb picture and it also has the 23SP4 tube, and like the HMV it was made late 1960. I believe KB was the first in the UK to market a TV set with the 23" "square corners" CRT. It would seem the 23" tube arrived in the UK before the 19" tube. Wasn't Mazda the first in the UK with the 19" 114 degree CME1901? DFWB. |
30th May 2021, 8:06 pm | #22 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,147
|
Re: HMV 1920 made in 1960.
Yes I think it was David. The Mullard AW59-90 was a very close second but was a much better tube life wise than the CME1901! I can't recall ever having seen a good one but there must be one out there. John.
|
31st May 2021, 9:57 pm | #23 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
|
Re: HMV 1920 made in 1960.
Good progress today. The FM tuner is working after more work done on the tuner module.
Discovered that the fine tuner control has to be moved to the right to engage with the tuning gears. I was of the opinion that the fine tuner was a push and turn control. Now I have a picture with bad frame linearity. After replacing four capacitors in the frame timebase the linearity is greatly improved, although more work needs to be done to secure better results. The CRT is past it's best for sure but the contrast control has limited effect. More video drive will help to improve matters. An improvement can be gained by replacing the 3.9Megohm resistor R66 which is connected to the slider of the contrast control and the vision AGC circuits. It's most likely the resistor has gone high value. Will return to the set tomorrow to fix the low contrast fault. DFWB. |
1st Jun 2021, 12:17 am | #24 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,902
|
Re: HMV 1920 made in 1960.
Dust? That valve near the middle sneezed so hard that it cracked itself and let air in.
David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
1st Jun 2021, 12:40 am | #25 |
Heptode
Join Date: Jun 2006
Location: Ware, Hertfordshire, UK.
Posts: 988
|
Re: HMV 1920 made in 1960.
That was quick work!
I'm sure the CRT will improve after a few hours use. Cheers Andy
__________________
www.youtube.com/user/andyvalve100 |
1st Jun 2021, 11:06 am | #26 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
|
Re: HMV 1920 made in 1960.
Replaced R66 this morning. Improved contrast ratio but there's no getting away from the fact the CRT has low emission. Tube heaters are slightly underrun with 6.18V measured across pins 1 and 8.
So do I give the tube a boost? Nothing to loose but only solution really is find another tube. Never going to find a 23SP4, it was unobtainable in late sixties and the recommended replacement was the Mazda CME2306 or Brimar A59-13W. All three are bonded faceplate tubes. An alternative is the Rimband III A59-23W. DFWB. Last edited by FERNSEH; 1st Jun 2021 at 11:27 am. |
1st Jun 2021, 1:33 pm | #27 |
Pentode
Join Date: Dec 2009
Location: Chatteris, Cambridgeshire, UK.
Posts: 176
|
Re: HMV 1920 made in 1960.
The CRT could be a candidate for this more gentle mode of reactivation....
https://www.radios-tv.co.uk/communit...ation-updated/ But you probably know about this, so hope I am not teaching grandmother to suck eggs.
__________________
Andrew |
1st Jun 2021, 2:52 pm | #28 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
|
Re: HMV 1920 made in 1960.
Hi Andrew,
Many thanks for your research. I've printed the tube re-gen topic and will read it later today. I'm sure what is certain the tube has never been reactivated before and the set was taken out of service when either the vision IF amplifier valve went down to air or the failure of the mains dropper resistor. Good chance there might be plenty active cathode oxide material remaining to make a bright picture again. DFWB. |
1st Jun 2021, 6:38 pm | #29 |
Nonode
Join Date: Jun 2008
Location: Coningsby, Lincolnshire, UK.
Posts: 2,820
|
Re: HMV 1920 made in 1960.
I’ve had good results with the non destructive reactivation, I’ve got my Murphy V180C running (finally!) and I’ve fitted what was a clapped out Mazda CRM-121A, or so it seemed, it was very dull to begin with, but after a short go at the above it came up, but I still needed the lights out, and if the brightness or contrast were turned up I’d get fly back lines, I put up with it, running the set daily for an hour or 2, and over the last few months of running the picture has gotten brighter, I can now view the set in a fairly well lit room! It’s still not as good as a new tube, but it’s useable! Maybe the tube in your HMV will wake up over time?
Regards Lloyd |
1st Jun 2021, 7:46 pm | #30 |
Dekatron
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 5,422
|
Re: HMV 1920 made in 1960.
Hi.
That is one good looking set. Full of features into the bargain. Needs a good blow out with an air line to make it look like new inside. Lets hope we can get a CRT for it.
__________________
Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member |
3rd Jun 2021, 6:43 am | #31 |
Hexode
Join Date: Jan 2007
Location: Beckenham, London, UK.
Posts: 373
|
Re: HMV 1920 made in 1960.
What an amazing find David. I guess the reactivation decision is a hard one with a relatively rare type/manufacturer
|
3rd Jun 2021, 11:09 am | #32 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
|
Re: HMV 1920 made in 1960.
Hi Steve,
The 23SP4 tube was made in the USA by Sylvania and was fitted many TV sets including Pye group models and Thorn brands such as Ferguson and HMV. The adoption of this tube in late 1960 gave those manufactures a marketing edge over their competitors which were still fitting the rather round looking 17" and 21" 110 degree tubes. Kolster-Brandes might have been the first UK manufacturer to employ the new 23" tube in the RV70 "Consort". The Brimar tube was the type C23AG. DFWB. |
3rd Jun 2021, 11:59 am | #33 | |
Dekatron
Join Date: Sep 2003
Location: Near Swindon, North Wiltshire, UK.
Posts: 3,622
|
Re: HMV 1920 made in 1960.
Quote:
Sylvania-Thorn Colour Television Laboratories Ltd, Great Cambridge Road, Enfield, Middx (new in 1954). Joint venture to develop all aspects of colour TV. In 1959, they made a range of germanium power transistors in the UK. In 1961, they were advertising instrument CRTs. This joint venture seems to have petered out by 1966. In 1959, Sylvania was taken over by GTE (General Telephone & Electric Corp). It was later known as GTE Sylvania Inc. Sylvania delta gun colour CRTs (made in Belgium - IIRC) and chroma delay lines did occasionally appear (fitted in manufacture) in UK made colour TVs. |
|
3rd Jun 2021, 1:29 pm | #34 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
|
Re: HMV 1920 made in 1960.
Another feature in the HMV 1920 is a light dependant resistor to control the contrast depending on the brightness of the room lighting. It tends to be overly effective which might be how the designer intended it to be or it might be fault condition.
DFWB. |
3rd Jun 2021, 1:43 pm | #35 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,340
|
Re: HMV 1920 made in 1960.
I can understand the attention needed and being given to the vision circuitry and tube regeneration side of this, but when fully working, I'd be interested to know just how good this set sounds. Sound quality on TV restorations is very rarely commented upon.
__________________
Edward. |
3rd Jun 2021, 3:03 pm | #36 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
|
Re: HMV 1920 made in 1960.
Apart from the 10 X 6 inch loudspeaker there has been no other initiatives to improve the sound quality. No negative feedback.
The output valve is a PCL83 in a circuit that is no different from other 600 series models. DFWB. |
3rd Jun 2021, 6:09 pm | #37 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,147
|
Re: HMV 1920 made in 1960.
That auto contrast nonsense was nothing more than a nuisance. I remember seeing sticking plasters taped over the light sensor. I remember the Sobell went into overload when you turned the lights on!
PCL83 David? I thought the 600 series employed the PCL82. Looks good so far. John. |
3rd Jun 2021, 7:17 pm | #38 | |
Octode
Join Date: Feb 2006
Location: Ilkeston, Derbyshire, UK.
Posts: 1,398
|
Re: HMV 1920 made in 1960.
Quote:
Steve Last edited by Colourstar; 3rd Jun 2021 at 7:24 pm. |
|
3rd Jun 2021, 8:18 pm | #39 |
Octode
Join Date: Mar 2006
Location: Co. Durham, UK.
Posts: 1,118
|
Re: HMV 1920 made in 1960.
I think David has seen one of those before...
|
3rd Jun 2021, 11:52 pm | #40 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
|
Re: HMV 1920 made in 1960.
Brigham wrote: I think David has seen one of those before...
That's right, I remember your KB QF80 well. Another good looking console set. https://www.vintage-radio.net/forum/...ad.php?t=73210 Hi Steve, Again, another very attractive console TV set from Kolster-Brandes. I've seen Mullard twin panel CRTs in KB sets. I don't think data for the A59-16W twin-panel CRT ever appeared in any Mullard publications. I have a trader service sheet for another UF series KB TV set. A special model because it is convertible to dual standard. Getting back to the HMV 1920. The PCL84 remote control amplifier valve was found to be faulty. The remote control now works but the handset has to be close to the set. HKS wrote: "PCL83 David? I thought the 600 series employed the PCL82. Looks good so far. John." Hi John, That's right, the Ferguson 606T and the HMV 1921 have a PCL82 for the sound output and yet the HMV 1920 has a puny PCL83 for the audio amplifier and output. DFWB. |