[Ed Stone]

‘Mullard’ – yes, chances are you know that Mullard made tubes in the UK, actually, some of the best tubes made. But Mullard, a subsidiary of the Dutch firm Philips for most of its life, also made other electronic components, as well as a range of radios. A recent Ebay purchase placed a 1950 vintage Mullard Type MAS 277 (similar to Philips Model 500A) on my workbench.

The set was in quite good, working condition on arrival, really needing only cleaning of the chassis top and underneath plus a polish to render it ‘acceptable’ to me. On checking it out, I noticed that someone had already changed-out the electrolytics (quite recently I would say) and one paper cap (strangely for a horrible waxy Dublier paper unit) – the rest of the capacitors were all-original, as were the resistors. The new electrolytics are a really tight fit under the chassis and whoever did it had not mounted the tagstrip correctly, so they were making a poor ground to the chassis – I soon fixed that by inserting the mounting screw from the other side (a bit awkward) and screwing it into the tapped chassis hole. The paper capacitors, black wax encapsulated, were probably the biggest and ugliest I have ever seen (resemble sections of dog stools modelled in school crayon wax). One, on the top of the chassis, a 0.022uF, 1000v unit, had several cracks right through to the capacitor element. The others were not cracked, and the set was actually working quite well with these fitted, but I decided they just had to go! Much more space under the chassis after that (before and after photos attached). For some reason the anode lead from the output stage was screened to the output transformer using a nasty rubber-insulated wire with a metal strip wound around it – the rubber was decomposing and about to short to the screening – so I replaced it (it would be curtains to the output transformer if that shorted-out).

The tuning gang was loose on its mounting bushes – the rubber had shrunk and gone soft with age (strange – it usually goes hard) – so I replaced the bushes with neoprene grommets cut to fit (fiddly and time-consuming, but worth the effort). I also tidied-up the wiring with some cable ties.

The socket for the tuning eye had been modified – on closer inspection it has the voltage doubler mod in the tube socket (2 diodes, 2 electrolytics) to give 12v heater voltage for the 1629 eye tube that had been fitted in lieu of the original EM34.

As I was re-assembling the set I ended-up having to re-string the drive cord as a speaker wire became tangled-up in it when re-fitting the dial pointer to the cord. Then I dropped a screw from one of the dial-lights onto the chassis: I removed the EZ40 rectifier to access where the screw fell and when re-inserting the tube the glass locating spigot on the tube (B8G base) broke off – end of the EZ40… luckily I had a spare!

All I did with the cabinet was a little touch-up with stain-pens and then polished, washed/Novus’ed the knobs, wiped the scale with lukewarm slightly soapy water and stuck a small felt pad on the pointer where it slides along the glass.

It’s a pretty impressive-sounding radio (and not a bad looker for a ’50’s set).

Finally I checked alignment and found it was close-enough to not tweak anything (for now anyway).

Click on a photo for a larger version.

Ed

Download DSC00189 [1024×768].JPG. (Caution: This file may not be virus scanned.)

Download DSC00186 [1024×768].JPG. (Caution: This file may not be virus scanned.)

Download DSC00164 [1024×768].JPG. (Caution: This file may not be virus scanned.)

Download DSC00168 [1024×768].JPG. (Caution: This file may not be virus scanned.)

Download DSC00145 [1024×768].JPG. (Caution: This file may not be virus scanned.)

[Ed Stone]

Some more photos

Download IMG_0097 [1024×768].JPG. (Caution: This file may not be virus scanned.)

Download IMG_0098 [1024×768].JPG. (Caution: This file may not be virus scanned.)

Download DSC00180 [1024×768].JPG. (Caution: This file may not be virus scanned.)

Download IMG_0092 [1024×768].JPG. (Caution: This file may not be virus scanned.)

Download DSC00162 [1024×768].JPG. (Caution: This file may not be virus scanned.)

[Author]

Posts