[DonaldStott]

Spent the afternoon circuit tracing and feel that I have now got to grips with my two “mystery” electrolytic capacitors and one of the “mystery” tubular capacitors – these had been replaced before the set came into my hands and were causing confusion. There is still the issue of one “unknown” tubular capacitor but more on that later.

Forgive the slow rate of progress, only my second restoration, but this has really helped me understand what might be going on: -

C29 - Electrolytic capacitor 32 μF 275 V (H.T. line smoothing) – replaced with 47 μF, 450 V.

The +ve end is connected to Pin 5 (Cathode) on V5 (Mullard CY31).

The +ve end is also connected to the Output Transformer.

The –ve end is connected to an earth screw on the chassis.

The –ve end is also connected to the –ve end of C27 (see below).

The –ve end is also connected to the enclosure of the on/off switch/volume control – this connection is not shown on the circuit diagram – see first picture below??


C27 - Electrolytic capacitor 16 μF, 275 V (H.T. line smoothing) – replaced with 15 μF, 400 V.

The +ve end is connected to Pin 4 (g3 – Screen Grid) on V4 (Mullard CL33).

The +ve end is also connected to R18 (10,000 Ω 2 W – H.T. Line smoothing).

The –ve end is connected to the earth screw as detailed above.


C30 - Tubular capacitor 0.1 μF 500 V (Mains R.F. by pass) – replaced with an RS capacitor with the markings .1 / 20 1500V.

This is connected to the on/off switch/volume control (S3) and to the right hand tag (when viewed from underneath) on the mains connector – is this the LIVE connection?? See second picture below.


Unknown tubular capacitor – this is a 0.047 μF 1500 V which connects the earth tag on the mains connector to the chassis. This is not shown on the circuit diagram – see third picture below??

Once I get past this stage hopefully most everything else is a standard restoration (if there is such a thing?) in terms of waxy caps, out of tolerance resistors, chassis cleaning, rewiring etc. etc. Might need some help with the wiring associated with the two large aluminium coil enclosures?? Looking forward to tackling the metallised valve coatings further down the line and the cabinet is also in need of some attention.

So any help with the above items would be most welcome – thanks in advance.