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Forum 135

B&W TV Pye FV1.

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Till Eulenspiegel
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The Pye FV1 is now in the workshop. The good news is the set is restorable. The cabinet will need attention, the original lacquer is in poor condition and will be stripped off. Particular care will be taken to preserve the Pye emblem on the cabinet top.

The underside of the chassis is in surprisingly good condition. No evidence of any servicing work has been carried out during the life of the receiver. All the valves are the originals, no replacements fitted. Judging by the type of EF80 pentodes I'd guess the set was made in 1952.

FV1 20230215

 Till Eulenspiegel.

 
Posted : 15/02/2023 1:01 pm
slidertogrid
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It certainly looks nice and clean under the chassis. What is the top of the chassis like?

Nice and safe from the upcycle brigade now!   

 
Posted : 15/02/2023 2:12 pm
Cathovisor
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Posted by: @till

No evidence of any servicing work has been carried out during the life of the receiver. All the valves are the originals, no replacements fitted.

I too looked at that and thought "that's never had a hand upon it". Very impressive - I wonder if it worked reliably enough that when ITV came along it was simply replaced with a newer receiver?

I hate to say this but it almost seems a pity to restore it to working order, such is the originality of the set.

 
Posted : 15/02/2023 3:05 pm
Till Eulenspiegel
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I hate to say this but it almost seems a pity to restore it to working order, such is the originality of the set.

Perhaps if the waxie TCC capacitors are restuffed to retain some semblance of originality. My other FV1 has had very little work done to it throughout the time its been in my possession. Coming up for sixty-three years.

The top side of the chassis isn't so nice but it'll clean up.

FV1 20230216

 Till Eulenspiegel.

 

 
Posted : 15/02/2023 5:42 pm
slidertogrid
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Yes, I have seen worse! Those square valve screening cans always seem to be rusty on Pye sets. One thing that did strike me about the underside view of the chassis is how tidy and well laid out it is. Quite unlike the usual Pye 'knitting'! Almost as tidy as a Bush! 

 
Posted : 15/02/2023 6:35 pm
colourmaster reacted
Till Eulenspiegel
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At least the Pye emblem on the top of the cabinet has been saved.

FV1 Pye

 Till Eulenspiegel.

 
Posted : 16/02/2023 11:42 am
Lloyd reacted
Till Eulenspiegel
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The line output transformer is receiving the warming up treatment.                                                                                                                                                                                                       The PL38 line output valve was replaced in 1957. Valve has the date code B7G.

FV1 LOPTx

Till Eulenspiegel.

 
Posted : 16/02/2023 5:47 pm
Doz, slidertogrid and Lloyd reacted
irob2345
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This chassis deserves the re-stuffing of the paper caps. Here's how I do it:

Cover a baking tray with cooking paper and put it on the bottom shelf in the oven.

Hang all the waxies by their leads from a rack above the tray.

Cook for about 15 mins at 200 degrees C. or until the sleeves melt off the innards and fall onto the tray. Sometimes they need a little coaxing.

While still warm, wipe the sleeves clean with a rag.

Slide new poly cap (with lengthened leads if necessary) inside the sleeves.

Seal the ends with hotmelt glue.

The finished job looks just like a brand new paper cap!

 
Posted : 17/02/2023 12:07 pm
Lloyd reacted
Cathovisor
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What about the electrolytics though? Everyone talks about how they do "waxies" (a term I really dislike) but I have seldom seen a satisfactorily-rebuilt electrolytic - in fact I have seen some right horror stories on this very forum.

 
Posted : 17/02/2023 2:59 pm
crustytv
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Posted by: @cathovisor

I have seldom seen a satisfactorily-rebuilt electrolytic - in fact I have seen some right horror stories on this very forum

Conversely, there have been some incredible ones too, such as the ones manufactured 10-years ago now, by the pre-war master Brian Cuff.

I also remember in that same thread the unbelievable work and effort he invested into make the missing I.Ft's.

https://www.radios-tv.co.uk/community/brian-cuff-pre-war-memorial-archive/recreating-the-gec-8161-mirror-lid-tv/paged/9/#post-49360

https://www.radios-tv.co.uk/community/brian-cuff-pre-war-memorial-archive/recreating-the-gec-8161-mirror-lid-tv/paged/11/#post-53125

Forum 136

Forum 137

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Posted : 17/02/2023 4:12 pm
Lloyd reacted
Till Eulenspiegel
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The CRT in this TV receiver is a rebuilt MW31-74 from a firm called the Grandelek company. Any memories of this firm?

Grandelek CRT

 Till Eulenspiegel.

 
Posted : 17/02/2023 6:13 pm
Till Eulenspiegel
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As a result of corrosion almost every section of the mains dropper resistors are open circuit. The circuit diagram of the FV1 doesn't have mains dropper resistive values, but the circuit diagrams of the models FV2C and FV4C do. The attachment is the power supply section of the FV4C. The FV2 has the Mullard metal cone CRT type MW41-1 and the FV4C a Mullard MW36-24. Note the bi-filar windings in the heater chain. The booster diode is a Mullard PY80 which doesn't have sufficient heater cathode insulation so the extra windings on the line output transformer compensate for the this. It's possible the PY81 wasn't available when the FV1 was in the design stage.

FV1 Power Supply

 Till Eulenspiegel.

 
Posted : 18/02/2023 12:30 pm
Cathovisor
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Posted by: @till

The booster diode is a Mullard PY80 which doesn't have sufficient heater cathode insulation so the extra windings on the line output transformer compensate for the this. It's possible the PY81 wasn't available when the FV1 was in the design stage.

I believe that was indeed the case, Till - I think there's a Bush set that does this too, IIRC the TUG26.

 
Posted : 18/02/2023 2:08 pm
Till Eulenspiegel
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Hi Mike, I'll take a look at the Bush TUG26 circuit diagram to confirm this. I was told that there was a Bush TV set in which the boost diode derived it's heater supply from a winding on the line output transformer in a similar manner as certain post-war Continental Philips TV receivers.                                                                                                                               A special diode was made for the purpose, the EA40. EA40 (hupse.eu)

Till Eulenspiegel.

 
Posted : 18/02/2023 3:30 pm
Cathovisor
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I seem to recall this method is covered in Spreadbury.

 
Posted : 18/02/2023 4:29 pm
Cathovisor
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Implementation of the bifilar LOPT windings for the PY80 in the Bush TUG26 and TUG34; note, the TUG34A does not do this as it has a PY81.

 

Forum 138

 
Posted : 18/02/2023 5:49 pm
Till Eulenspiegel
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Radiomuseum states that the PY81 was introduced in 1951. Possibly too late for the Pye FV1 and Bush TUG26. In the event of failure of the bi-filar windings there's nothing to stop replacement of the PY80 with the PY81.

PY 81, Tube PY81; Röhre PY 81 ID3375, Damper, booster, flyba | Radiomuseum

Till Eulenspiegel.

 
Posted : 18/02/2023 8:40 pm
Cathovisor
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Posted by: @till

In the event of failure of the bi-filar windings there's nothing to stop replacement of the PY80 with the PY81.

Assuming the failure mode isn't shorted turns in those windings, of course.

 
Posted : 19/02/2023 4:18 pm
Till Eulenspiegel
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Posted by: @cathovisor

Assuming the failure mode isn't shorted turns in those windings, of course.

That's right of course.  The restoration of this set will take some time and I'm no hurry to finish the job. How about allowing some engineering licence and do one of two modifications to set?  For example try out a different sync separator circuit.  In the 1960 Practical Television TV receiver the Mazda 6F33 valve was used as a Miller integrator to separate the frame sync pulses. The circuit exploits the G3 characteristics of the Mazda 6F33. The valve was used for all sorts of interesting applications.                                                                                                  6F33, Tube 6F33; Röhre 6F33 ID18697, Vacuum Pentode | Radiomuseum

Olympic TV sync Sep

 Till Eulenspiegel.

 

Mod note:
Fixed broken the quote. When, editing a quote please do not remove the codes (userid & Postid) the forum inserts

 
Posted : 19/02/2023 9:35 pm
Cathovisor
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Posted by: @till

How about allowing some engineering licence and do one of two modifications to set? 

Your set of course David, but again I would be inclined to say that given its originality perhaps another FV1 could be found to experiment on, rather than this one?

 
Posted : 20/02/2023 12:18 am
slidertogrid reacted
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