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Old 12th Mar 2013, 7:11 pm   #1
FERNSEH
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Default Pye FV1: no sound

After the fun I've had with Masteradio it's time to do what might well be a nice easy repair. The sound has gone off on my Pye FV1, and to think I've only owned the set for 53 years!
I'd reckon the sound output transformer primary has gone OC. Let's find out.

The FV1 employs a high slope pentode type PL33. The output from the detector and noise limiter goes straight into grid of the valve, there is no AF amplifier. Later models: The 16" version, the FV2 employs a PL83 as the sound output, a valve really intended for use as a video amplifier.
A 14" model, the FV4 employs the ECL80 triode-pentode as the AF amplifier and output.

DFWB.
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Old 12th Mar 2013, 7:39 pm   #2
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Default Re: Pye FV1: no sound

Now what have you found David? Ah, the Pye FV1.
There used to be dozens of these at jumble sales when I was a lad for a shilling a piece. I used to remove the blue anodized model number plate from the rear of the chassis and hang them from the picture rail in my bedroom/den. They used to extend to the skirting board! Very popular model and was Pye's first five channel model. [Five Vision One]
I would say output transformer for sure. If you need one I have a couple that will match to the PL33. It could be an O/C R35A, the bias resistor on the anode of the noise limiter EB91 but this usually results in low very distorted sound.
If you want to bring it up to date a bit I have a transistor amplifier complete, removed from a scrap Hacker Hunter radio. You are welcome to either but I reckon you will go for the transformer.
The chassis looks very clean and the performance is outstanding. Pye produced the excellent F124 tuner to convert it to I.T.A. It plugged in with valve base adaptors, brilliant. Regards, John.
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Old 12th Mar 2013, 9:34 pm   #3
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Default Re: Pye FV1: no sound

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Originally Posted by Heatercathodeshort View Post
Now what have you found David? Ah, the Pye FV1.
Pye produced the excellent F124 tuner to convert it to I.T.A. It plugged in with valve base adaptors, brilliant. Regards, John.
Hi John, Don't worry, this is the set I acquired way back in 1960.
The set was converted to receive Tyne-Tees-Television (a brilliant Geordie TV station) shortly after I got the set by using a GEC BT304 two band adaptor. The set sat on a special plinth which was made for certain GEC TVs.
The IFs were same as those of the Pye, 34.5Mc/s vision and 38mc/s sound, almost the same as the later industry standard frequencies of 34.65Mc/s and 38.15mc/s.
I guess if I can't get the sound to work I could chop up a Hacker Hunter for it's audio amplifier. Better still, why use a Hacker Black Knight?

DFWB.
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Old 12th Mar 2013, 11:26 pm   #4
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Default Re: Pye FV1: no sound

Period advert for the GEC BT304 Band 3 converter.

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Old 12th Mar 2013, 11:39 pm   #5
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Default Re: Pye FV1: no sound

The primary of the output transformer is OC.

DFWB.
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Old 13th Mar 2013, 9:14 am   #6
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Default Re: Pye FV1: no sound

The axe hangs over the Hacker Hunter David but if you want the output transformer, let me know. John.
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Old 13th Mar 2013, 2:32 pm   #7
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Default Re: Pye FV1: no sound

Found this sound output transformer, ex Regentone radio set, matches the EL41 which was the successor to the EL33.
The Hacker Hunter is safe for the time being.
Pictures of two early versions of the EF80 valve. First production was in Holland where the valve was designed by Philips. The other EF80 is a UK made version, produced about 1952.

DFWB.
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Old 13th Mar 2013, 2:54 pm   #8
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Default Re: Pye FV1: no sound

The EF80 went through quite a few internal design changes. Pye continued to put their distinctive metal shields around them, rather over the top due to the EF80's internal screening. That transformer looks quite adequate. I'll put the Hunter back in the condemned cell. John.
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Old 14th Mar 2013, 1:47 pm   #9
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Default Re: Pye FV1: no sound

Hi John,
That's the sound sorted, but last night a frame TB fault appeared but when I tried out the set this morning the fault had disappeared. This set fixes itself.
The Hacker Hunter is on standby if the sound ever goes off again.
The picture is a design for a hotel and flats in Hove, Brighton. It never got built. too ambious evidently.

DFWB.
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Old 14th Mar 2013, 3:34 pm   #10
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Default Re: Pye FV1: no sound

Hi David, what is the purpose of the EB91? Malc
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Old 14th Mar 2013, 4:42 pm   #11
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Default Re: Pye FV1: no sound

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Hi David, what is the purpose of the EB91? Malc
Hi Malc,
One half of the EB91 (V4A) functions a series noise limiter. Normally the valve is conducting and the audio passes though. When interference spikes come along the time constant of C21A and R1C is too long to react to the short duration pulses, thus the interference is blocked.
The interesting thing is that although the max audio is 10Kc/s the sound IF bandwidth is much greater than that, it can be up to 100Kc/s. This actually preserves the interference splikes and having a wide bandwidth allows for tuner drift.

DFWB.
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Old 14th Mar 2013, 5:59 pm   #12
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Default Re: Pye FV1: no sound

The spikes have to be preserved right up to the noise limiter for it to work efficiently. It's a bit like having the grass pointing straight up for the cutter to crop the top off.
Noise limiters did work incredibly well especially in fringe areas where with the aid of a pre amplifier, quite large numbers of FV1's worked very well. J.
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Old 14th Mar 2013, 6:05 pm   #13
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Default Re: Pye FV1: no sound

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Originally Posted by Heatercathodeshort View Post
The spikes have to be preserved right up to the noise limiter for it to work efficiently. It's a bit like having the grass pointing straight up for the cutter to crop the top off.Noise limiters did work incredibly well especially in fringe areas where with the aid of a pre amplifier
Hi John,
What an excellent analogy.
David.
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