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Old 4th Jun 2021, 6:59 am   #41
Jac
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Default Re: HMV 1920 made in 1960.

Hi David,

On the site of Frank Philipse you can find the (Philips) data of the A59-16W:
http://www.frank.mif.pg.gda.pl/sheets/030/a/A59-16W.pdf

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Old 4th Jun 2021, 8:55 am   #42
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Default Re: HMV 1920 made in 1960.

Hi
Can a standard 23 inch CRT not be fitted with a Fenbridge cap?
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Old 4th Jun 2021, 10:28 am   #43
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Default Re: HMV 1920 made in 1960.

Jac wrote: "On the site of Frank Philipse you can find the (Philips) data of the A59-16W:"
Hello Jac,
I remember seeing Mullard twin panel CRTs but always considered the tubes to be re-branded Brimar or Mazda rather than made by Mullard or Philips.
Philips had registered their twin-panel CRT with an unique type designation A59-16W proving it was the companies' own design and not a direct copy of tubes made by other firms.

Murphy310 wrote: "Can a standard 23 inch CRT not be fitted with a Fenbridge cap?"
Hi Trevor,
Shouldn't be any difficulties but I'd imagine finding a Fenbridge cap will be almost impossible.
In the late sixties Mullard offered the "Inckit" as a replacement for 19" and 23" twin-panel CRTs. The CRTs offered were a 19" A47-26W or the 23" A59-23W along with all the necessary mounting components.
Ad the fitting charges it was expensive repair to what were becoming quite old sets so not many Inckits were sold.

DFWB.

DFWB.

Last edited by FERNSEH; 4th Jun 2021 at 10:33 am.
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Old 4th Jun 2021, 6:07 pm   #44
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Default Re: HMV 1920 made in 1960.

I can find final data on the A59-16W dated 1966 in the Philips 1967 data book.
The 1970 data book also mentions this type, but only as a maintenance type.
(It is not mentioned in other Philips data books I have.)

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Old 5th Jun 2021, 1:03 pm   #45
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I doubt if Philips would have ever considered twin panel CRTs for their TV sets and only offered the A59-16W as another source of supply of that type of tube to UK manufactures. Kolster-Brandes was the biggest user of the twin panel tube.
The HMV 1920.
The light dependant cell has a 100Kohm shunted across it. Today, that resistor was replaced with one of a 18Kohms. Might even consider reducing the value to 10K. Picture contrast is improved by a considerable amount.
I'm assuming the LDR is a Mullard ORP60. No markings on it.

DFWB.
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Old 5th Jun 2021, 4:51 pm   #46
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Default Re: HMV 1920 made in 1960.

Looks like an ORP12 David.
The ORP60 is like an OC71 devoid of paint I believe.
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Old 5th Jun 2021, 6:25 pm   #47
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Default Re: HMV 1920 made in 1960.

"The ORP60 is like an OC71 devoid of paint I believe."

Hi Trevor,
was that the OCP71?
https://www.radiomuseum.org/tubes/tube_ocp71.html

Correction: the light sensitive device in the HMV has been determined as an ORP12 cadmium- sulphide cell.

DFWB.
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Old 5th Jun 2021, 7:47 pm   #48
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From the Wireless & Electrical Trader September 3rd 1960. An extract from the the Radio Show technical review.
A description of the light operated automatic contrast control and the introduction to the new 23" cathode ray tubes including the bonded faceplate
CRT.

DFWB.
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Old 6th Jun 2021, 11:32 am   #49
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Default Re: HMV 1920 made in 1960.

Quote:
Originally Posted by FERNSEH View Post
I doubt if Philips would have ever considered twin panel CRTs for their TV sets and only offered the A59-16W as another source of supply of that type of tube to UK manufactures. Kolster-Brandes was the biggest user of the twin panel tube.

DFWB.
Yes Philips seem to do things their own way as usual . I had a 23" Philips with the convertible chassis, the one where you had to fit system switches, IF panel etc.
The tube appeared to be direct vision, but the set was too early for one of those tubes, in fact was an unprotected tube with a curved screen of fairly thick glass in front of it. Much less bulky and "clunky" than a twin panel screen. It had a mask like the early direct vision tubes that had the thick rimband. I am surprised other manufactures didn't use the same idea.

Pye / Ekco also used twin panel tubes for a while on the sets fitted with the 11U series chassis. In fact that chassis used a selection of different implosion guards from the flat plate glass screen to twin panel, hard plastic bubble and fenbridge guard. Maybe because the chassis had such a long production run?
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Old 14th Jun 2021, 12:38 pm   #50
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Default Re: HMV 1920 made in 1960.

This week I'll turn my attention to the remote control amplifier to find out why the handset will only work when it is close to the microphone.
It was claimed the remote control would work up to twenty feet from the TV set.

DFWB.
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Old 14th Jun 2021, 4:20 pm   #51
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Hello David, It is possible that the ultrasonic receiver on the front of the TV has gone weak. I seem to remember early sonic remotes from the colour era slowly becoming faulty and reducing the range. J.
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Old 14th Jun 2021, 5:02 pm   #52
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Default Re: HMV 1920 made in 1960.

There's a veritable rogue's gallery of suspect caps in there David, Suflex aside, but you never know they may be innocent! Maybe the PCL84 is feeling it's age.

What does the preset pot do? Is it some kind of sensitivity control?

Steve
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Old 14th Jun 2021, 7:22 pm   #53
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Wink Re: HMV 1920 made in 1960.

If you want an EF80, I think I can spare one
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Old 14th Jun 2021, 9:56 pm   #54
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Default Re: HMV 1920 made in 1960.

Heatercathodeshort wrote:
"Hello David, It is possible that the ultrasonic receiver on the front of the TV has gone weak. I seem to remember early sonic remotes from the colour era slowly becoming faulty and reducing the range. J."
Hi John,
there's lots of components in the remote control amplifier possibly needing replacement and the microphone isn't above suspicion either.

Colourstar wrote: "What does the preset pot do? Is it some kind of sensitivity control?"
Hi Steve,
in a sense it is. The control is the relay current adjustment.. According to the information in the 1961/62 Radio and Television servicing book the adjustment procedure is as follows. "Check that HT voltage is correct, not too high or not too low as a result of mains tap setting or a receiver fault.
With the receiver fully warmed up turn the control fully clockwise and press down the relay armature with a fully insulated tool. The armature should "hold on".
Turn the control slowly anti-clockwise until the relay armature lifts.
Prod the armature a number of times and check that it does not hold down.
If it tends to hold, the control must be further turned further anti-clockwise to ensure the relay does not remain in the closed position."


Bob_Moss wrote: "If you want an EF80, I think I can spare one"

Hi Bob,
thanks for your kind offer, but although I could not find an EF80 at home where the HMV is kept and being serviced there was plenty EF80s in the shop. In fact one was found with the correct production date, late 1960.

DFWB.
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Old 21st Jun 2021, 1:11 pm   #55
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Reference to the remote control amplifier circuit on post No.50.
The voltage across across relay current control R304 is 3.38 volts irrespective of the position of the control knob. Wiper not making contact with the track.

DFWB.
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Old 21st Jun 2021, 11:17 pm   #56
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Replaced the 500ohm relay current control R304.
Now it is possible to activate the relay by turning the control fully clockwise. The tuner motor will then rotate, turn the control back until the motor stops. Then carry out the instructions described in post No. 54. The remote control handset will activate the motor up to a distance of ten feet but it's function is erratic and not easy to use. Still more work to done.

DFWB.
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Old 22nd Jun 2021, 5:49 am   #57
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Default Re: HMV 1920 made in 1960.

Hi, but you are making tremendous progress !
what an unusual set to be working on !
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Old 22nd Jun 2021, 7:46 pm   #58
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Dragonser wrote: "Hi, but you are making tremendous progress !
what an unusual set to be working on !"

Hi Peter,
this is a model I've been on the lookout for many years after seeing the the information in the 1961/62 R & T servicing book. I'm particularly interested in early cordless remote control systems. An other set I'm after is the Dynatron model with the three button remote control handset.
The basic TV chassis is similar to the Ferguson 636T and is known to be reliable but the remote control system in the HMV is a bit difficult to tame. The 1961 Murphy ultrasonic system is better and offers two functions, channel changer and sound muting.
No other BRC brand employed the ultrasonic remote control system, the Ferguson 705T "Senator" has a wired remote control.
Was a DER rental set ever made with the same ultrasonic system as the HMV?
So it's good fun working on this set now but what would have been like if one was asked to repair such a set in the early sixties? Bear in mind the HMV is actually heavier than many colour TV sets. It is heavier than a 25" G6.

DFWB.
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Old 27th Jun 2021, 12:12 pm   #59
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The HMV 1920 is proving to be an excellent set but that can't be said for the remote control system, it's hopeless! Sometimes it can work well but from time to time the RC system just goes erratic, either not responding to the remote control handset or with a single click from the handset the tuner goes into constant rotation and can be only be stopped by turning the relay current control down.
This remote control system was not used in any other Thorn group models, Ferguson, Ultra, Marconi and Philco. Philco employed the "SelectaFlash remote control system which worked very well. The remote handset was a torch.
The Ferguson Senator 705T used a cable remote control.
I'll keep faith with the HMV's remote control but modifications will be necessary in order it works properly. That circuit arrangement in which the triode section of the PCL84 operates a reflex 45Kc/s amplifier and also as the DC relay driver is suspect. A separate relay driver valve perhaps? That's how Murphy did it in the remote control versions of the V659.

DFWB.
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Old 27th Jun 2021, 12:43 pm   #60
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That is really odd David. I can't believe anyone paying the price for this model would put up with all that madness. It must have worked OK at some time. John.
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