Pye Fenman II

[zenitht]

Just starting to take a look at this set recently acquired, I've noticed that although there is some life on FM albeit low volume, there is nothing on MW or LW just white noise.
I would be very grateful if someone could help me prioritise where i should start (replace all the Hunts Capacitors?) or be a bit more strategic.

You help would be very much appreciated as its a set I have been after for some time and want to make it work again to its best ability so i can keep it and enjoy it.

Thanks
Graham

[Nickthedentist]

I would carefully clean and exercise the wavechange switch to start with.

But yes, I would aim to change all those troublesome Hunts caps, ideally on a one-by-one basis, testing the set after each replacement to ensure you've not done something daft, and to see what effect replacing each cap has.

[zenitht]

Thank you for your reply

[Aub]

Even when it's all working well, you'll find that it's not so sensitive on medium and long waves, unless you have a good length of wire for an aerial.

Good luck with it.

Aub

[Edward Huggins]

The Pye Labs team put all their design expertise into the FM tuner section. One might reasonably assume that the AM section received the same degree of attention. Regretably it did not - it is just a fairly standard Superhet. However, the AM does benefit of course from the good AF stages that follow.

[Boulevardier]

Have you got the service sheets for this set - they are available at top right of all these forum pages? There are two available - the Pye sheet and the Trader sheet. It's quite a complex circuit for a domestic set, and the schematics aren't easy to follow. Just a warning based on my own experience - the Pye and Trader sheets are laid out differently (the Pye sheet keeps valve elements - eg, triode + pentode - that are in the same envelope together on the schematic; the Trader sheets sets them out according to function and splits the elements in the same envelope across the schematic). They also use completely different numbering systems for the components. This can make it very confusing and frustrating if you're cross-referencing from one schematic to the other - which you may want to do sometimes as they occasionally give different levels of information. Personally, I find the Trader sheet more easy to follow for most purposes.

Mike

[Cobaltblue]

I would concentrate your efforts on the Audio output stage and power supply in the first instance.

This set has a push pull output stage and if you damage the output transformer or mains transformer they may not be cheap to replace or rewind.

These are pretty decent sounding sets when restored and loud.

If you have not already got the service sheet you can get it here:

https://www.service-data.com/product...40/6574/m15140

Cheers

Mike T

[Nickthedentist]

Originally Posted by Cobaltblue

I would concentrate your efforts on the Audio output stage and power supply in the first instance.

This set has a push pull output stage and if you damage the output transformer or mains transformer they may not be cheap to replace or rewind.

Very good advice. There are two small grid coupling capacitors which you need to change; cheap and relatively easy to do.

[zenitht]

Thank you, yes I have Trader Service Sheet 1285

[zenitht]

Thank you. Please could you identify the Grid Coupling Capacitors ....C & C

[Cobaltblue]

On the Trader sheet

C77 and C78, while I am there I would look at C76 as well

Cheers

Mike T

[zenitht]

Huge thanks to everyone for your extremely helpful advice

[Boulevardier]

Do let us know how you get on...

Mike

[stevehertz]

Originally Posted by Boulevardier

Have you got the service sheets for this set - they are available at top right of all these forum pages? There are two available - the Pye sheet and the Trader sheet. It's quite a complex circuit for a domestic set, and the schematics aren't easy to follow. Just a warning based on my own experience - the Pye and Trader sheets are laid out differently (the Pye sheet keeps valve elements - eg, triode + pentode - that are in the same envelope together on the schematic; the Trader sheets sets them out according to function and splits the elements in the same envelope across the schematic). They also use completely different numbering systems for the components. This can make it very confusing and frustrating if you're cross-referencing from one schematic to the other - which you may want to do sometimes as they occasionally give different levels of information. Personally, I find the Trader sheet more easy to follow for most purposes.

Mike

You make a good case for just using the Trader sheet. Why confuse things using two, very differently laid out schematics?

[Cobaltblue]

I forgot to say use good quality capacitors at least 400V 0.047μF

These will sometimes be listed as 47nF same thing.

C76 is just a puffer (small value in pF region) likely ceramic unlikely to be faulty unless physically damaged but you don't know what's happened in the past

Cheers

Mike T

[Cobaltblue]

Originally Posted by stevehertz

You make a good case for just using the Trader sheet. Why confuse things using two, very differently laid out schematics?

Are you suggesting the manufacturer should not draw it as they wish? or are you suggesting that Paul should only offer the Trader Sheet where it's available?
In house Drawing offices have always had their own styles and conventions they were not universal. I always struggle with some US circuit diagrams, they seem "upside down".

Cheers

Mike T

[Boulevardier]

Originally Posted by stevehertz

Why confuse things using two, very differently laid out schematics?

Agreed - I have always stuck with the Trader sheet. But, just sometimes, I've found that there's more info on the Pye sheet - e.g, the latter gives a much more comprehensive breakdown of valve electrode voltages, etc. And then you have the problem of translating the Pye valve numbering to the Trader numbering - can get a bit mind-twisting. Same difficulty with the waveband switch contacts numbering. You just need to be a bit mentally nimble!

Mike

[Aub]

Out of curiosity, who produced the trader sheet, one particular trader or an association of traders and who decided how the schematic should look?

Cheers

Aub

[Boulevardier]

Originally Posted by Aub

Out of curiosity, who produced the trader sheet, one particular trader or an association of traders and who decided how the schematic should look?

Cheers

Aub

The Trader service sheets were produced by Wireless & Electrical Trader, and, as Cobaltblue says, anyone producing these can do so in any format they wish. Presumably WET traced the schematic out for themselves – a huge amount of work. I just found that the Trader format, where components are laid out more or less by their function in the circuit, was more user-friendly than the Pye format where components were more laid out more by their physical proximity (switches on the same wavechange wafer all grouped together even where adjacent switches are used in completely different parts of the circuit; valve “elements shown side-by-side – even though e.g. the triode is used in a completely different part of the circuit from it’s “co-dwelling” pentode). Instead, Trader put switches and valve elements in their natural circuit-function location, and provides charts showing the functions of each valve and how each switch operates in different waveband positions.
It's horses for courses and take your pick which one you find easiest to work with.
Mike

[stevehertz]

Originally Posted by Cobaltblue

Are you suggesting the manufacturer should not draw it as they wish? or are you suggesting that Paul should only offer the Trader Sheet where it's available?
In house Drawing offices have always had their own styles and conventions they were not universal. I always struggle with some US circuit diagrams, they seem "upside down".

Cheers

Mike T

I'm not "suggesting" anything really Mike. My comment is to be taken at face value, use the Trader sheet. That's what I do. On the rare occasions that I also have the manufacturer's data, I may dip into it to eke out some more info, but only if required. Because in general, cross referencing component numbers from two different documents is a recipe for introducing mistakes, so I stick to the Trader sheet. In any case, I have noticed that manufacturer's data tends to be idiosyncratic, whereas Trader sheets have a 'housestyle' that is both logical (aimed at the 'hands on' repairman) and also familiar to most of us as the commonest source of data, our 'go to' source.