PAM 720 Transistor

[PJL]

Local fb marketplace has provided a sorry looking 1957 PAM 720 for just £2. It needs cosmetic work as both the front and back cloth have shrunk and frayed, the handle leather has worn, but it does look complete with no previous battery leaks. It seems to have original Newmarket transistors so probably unlikely to work!

[PJL]

I have serial no TK 1754 so probably an early one and not covered by the service sheet for the 720 but I have looked at the Pye P123BQ service sheet and that looks like an identical layout so I will have a go at getting it going.

[60 oldjohn]

Originally Posted by PJL

I have serial no TK 1754 so probably an early one and not covered by the service sheet for the 720 but I have looked at the Pye P123BQ service sheet and that looks like an identical layout so I will have a go at getting it going.

My experience of the Pye variant is, clean the battery contacts, put a set of batteries in, turn up the volume and listen to R4. Most of my Pye sets have a pre tuned LW, most sets left set to LW.
Do not try to move any of the transistors, the legs are very brittle any more than just looking at them will cause them to break. When applying power for the first time allow time for the caps to reform.

John.

[FIXITNOW]

mine came as part off a job lot and powered up just fine

[Pamphonica]

Both my Pam 720s, provided by a very kind fellow forum chap worked fine on arrival. One is rather sad, missing the tuning knob. The front cloth is not too badly shrunk, but the back has big gaps now. Hardy things, though, aren't they?
I tried 3D-printing a knob but they are transparent plastic and printed ones look wrong (opaque, even with clear filament). Maybe I'll find one somewhere.
Of course we may all be sitting on a goldmine - who knows!
-Jeremy

[PJL]

The owner advised it had not been used for 40 years and not a squeak after adding batteries. As you can see shrinkage and dirt are a major issue!

[60 oldjohn]

I wonder if the owner cleaned the battery terminals before inserting the batteries. Check for a voltage on the leads from the battery holder. Batteries may be a little different shape to what were around in 1957 making more difficult to make contact with the brass contacts.

John.

[PJL]

There was voltage but it disappeared on turning on. I cleaned the battery connections properly and it WORKS...

[PJL]

Which is a bit of a disappointment as I now need to try to improve its looks!

[music-centre]

Amazing how these early transistor sets always seem to work OK, wish the later ones were as reliable

[PJL]

I have taken it to bits and concluded the 'dirt' is down to it being covered with shellac, not sure if this was done during manufacturing or later but I favour the former. I also found repairs on a couple of the plastic knobs.