1954 Philips 141U 5 valve AC/DC MW/LW transportable radio

[howard]

Hello again,

This is another set I've been looking out for some time and quite a few turn up on Ebay and sometimes command quite good prices but this one, working condition unknown, I got for just £16. These are pretty little sets in their reddish brown bakelite cases and their one-piece perspex grille and dial cover which lights up when switched on. On arrival it was very dirty, some of the gold paint around the front and rear had worn away, but there were no scratches or cracks at all on the main part of the case nor on the perspex front, but the brass screws and knob trims were badly tarnished and there is a small crack either side of one of the screw holes in the top right corner of the rear panel where someone had overtightened the screw. Worryingly it rattled when gently shaken, so I took off the back cover to find bits of capacitor deposited on the bottom inside so I then removed the bottom cover to find that the mains bypass capacitor had exploded and one or two other black pitch caps had chunks missing from them too. It was very dusty inside and the chassis a touch spotty with rust but overall it wasn't bad at all. There was evidence that it had had work done on it in the past, it had a Radiospares dropper fitted and a mixture of brands of valves. During the chassis restoration I worked from the Philips 141U manufacturers service sheet which is on Paul Stennings DVD, or from here for £1.99 ....

http://www.service-data.com/section.php/5739/1

Chassis restoration
I removed the chassis from the case although just about everything in this set is accessible with just the covers off ...
- back and bottom covers removed (8 screws)
- perspex front removed (4 screws and washers)
- knobs removed (2 long grub screws)
- 2 chassis screws removed inside
- the chassis then slid out the back (the pointer needed to be guided though the slot along the front)
- the loudspeaker was removed (loosen 2 screws/clamps)
The chassis was then free from the case.

I cleaned all the dust off the chassis, then cleaned it with white spirit, and cleaned all the valves/valve pins/bases, the waveband switch etc with Servisol 10. I then replaced the 0.033uF mains bypass capacitor with a Maplins metallised paper RFI class X2 capacitor (£0.32p), the 0.01uF audio coupling capacitor and and a couple of other damaged capacitors with Vishay polyester caps, fitted a new mains plug with a 3 amp fuse, plugged it in, switched on and away it went. It hummed a bit and after a short time it sounded distorted and strangely the volume control didn't work properly, at minimum it was still at half volume and the volume only started to increase at around half way. So I then replaced the rest of the black capacitors with new polyesters and then tried swapping its valves with NOS ones to see if any improvements could be made in its sound quality. The UY41, UCH42 and UF41 were all fine but when the UBC41 was changed, a big improvement was evident, the volume control started working correctly, much of the hum had gone and also the distortion had gone. I also swapped the UL41 for another used one, both sounded the same so I left the original one in place and then took the set over to Ron Bryan to check it over.

The grid voltage on the UL41 was checked and was found to be a staggering 13 volts (a new one will measure around 30 millivolts) so that was well and truly knackered ! A new UL41 borrowed from Ron's DAC90A was fitted and that measured fine and the sound quality was better too although there was still a bit of hum audible at low volume. Another known good UBC41 was tried but that made little difference to the hum so a cap was bridged across each of the 50+50uF smoothing capacitors and that didn't make any difference either. The 4.7M ohm UBC41 grid leak resistor was checked and was found to have gone up to over 10M ohms so that was changed and the UL41 150 ohm cathode resistor was checked and that was found to have gone down to around 100 ohms so that too was replaced and the latter reduced the hum a touch and we then decided that the hum was now acceptable.. When I got home I fitted my last used UL41, the grid voltage to that measured around 150 millivolts which is OK. The set works very well now, picking up everything on both MW and LW and sounding good.

Cosmetic restoration
- The inside and outside of the case was cleaned with B&Q upholstery cleaner brushed on with a toothbrush and then rinsed off with water and quickly dried with a towel and allowed to dry.
- the remains of the gold painted coachline around front and back was removed with Nitromors and white spirit
- the case was polished with Brasso and the coachlines repainted
- the brass knob trims were removed, the tarnish polished off and they were then revarnished
- the perspex front and the knobs were care fully cleaned with a damp cloth, the outer surface of the front was polished with Brasso and the knob trims were stuck back on with EvoStik
- the pointer was rusty so that was sanded down, masked off and resprayed with matt white paint

It took four days to restore this little set and it has come up nice and from the front looks pristine. There is a tiny crack in the rear cover across the corner screw hole and one of the original brass screws has been replaced but even so it looks good from the back too. When working in a darkened room, its lit up perspex dial looks fabulous and it sounds good too for a small portable, although its perspex front does tend to buzz a bit at times, and its case does get very warm.

My thanks to Ron for his help in fixing this set.

Howard

[dallaslaff]

Hi Howard, Well done another super restoration. I don't think I've seen this set before, the styling reminds of a fifties Juke box.
Les

[howard]

Hello Les,

Yes indeed I think some folk call the fronts on these 'jukebox' fronts. I've seen a few of these appear on ebay so they're not that uncommon. I suspect Philips sold a lot of them back in 1954 as they were budget sets and very decorative too.

I've managed to get some pics in daylight now of the back and inside.

Howard

[Tim]

Another splendid job Howard. You really aught to do these professionally you know!

Archetypal fifties look those, sort of ugly and cute at the same time.

[Tazman1966]

Not really to my taste but beautifully restored none the less - and well written up. Thanks for sharing it with us Howard

[kalee20]

Good work, excellent write-up too, thanks for sharing this with us!

Originally Posted by howard

the UL41 150 ohm cathode resistor was checked and that was found to have gone down to around 100 ohms so that too was replaced

That's interesting, I've not yet come across a resistor going low in value. Would account for the original UL41 getting a hammering.

Incidentally, did you try microwaving the old UL41? Nothing to lose as it's already leaky. And isolate any unused pins on the UL41 valveholder, which Philips may have used as convenient anchoring tags. I just hate the idea of discarding any UL41's, there a limited resource...

[howard]

Hello kalee,

We've found that high-value resistors ie: 1M and above tend to go high, and low-value resistors tend to go low. Both these resistors were way out of spec.

Is it safe to put metallic objects in a microwave oven ? This UL41 was well and truly knackered, I'd be amazed if it could have been recovered. I usually buy secondhand UL41s which aren't leaking but I have to admit to have just ordered one secondhand UL41 and a NOS Mullard UL41 cos I've used up my entire stock. I'm told that the UL46 is a good reliable substitute for the UL41, exactly the same valve but built for use in TV sets so it's more robust in construction.

http://www.r-type.org/exhib/aaa0376.htm

Howard

[Tim]

Originally Posted by kalee20

That's interesting, I've not yet come across a resistor going low in value.

We were told at college this never happens. Of course WE know different.......
I have found this before, but only a few times. Nearly all on output valve cathode resistors in Philips sets funnily enough.Well done for finding it Howard.

Originally Posted by howard

I'm told that the UL46 is a good reliable substitute for the UL41, exactly the same valve but built for use in TV sets so it's more robust in construction.

Yes, that's right, I have done it. Of course the prices of UL46's will now rise.
A Mazda 10P13 is worth considering in some sets with low anode current.I think I used one in a DAC10 before now.Looks more authentic than a conversion, and hopefully quite cheap.

[kalee20]

[QUOTE=howard;238375]

Originally Posted by kalee20

Is it safe to put metallic objects in a microwave oven ? This UL41 was well and truly knackered, I'd be amazed if it could have been recovered

Well, I wouldn't put one in an ultra-new, expensive, microwave oven. But I often make cocoa in mine, with a stainless steel spoon still in the mug, and it hasn't blown up yet!

I'd certainly put a UL41 in my oven, with just half a cup of water nearby, to absorb standing waves. After all, the oven enclosure is itself metal.

If the UL41 is really knackered, there's no point. But I'd check emission by shorting the grid directly to chassis (which will overcome any internal leakage between pins). If the current (or voltage across the cathode bias resistor) is then normal-ish, I'd certainly try zapping the internal leakage deposits somehow!

[julie_m]

Originally Posted by kalee20

That's interesting, I've not yet come across a resistor going low in value.

Carbon composition resistors can fail low-resistance: they consist of a mixture of very-conductive and not-so-conductive particles. If they overheat, the resistive rod can soften and the particles separate, possibly creating a highly-conductive path.

Metal-film, carbon-film and wirewound resistors are presumed only ever to fail open-circuit for the purposes of an FMEA.

[geofy]

Originally Posted by kalee20

That's interesting, I've not yet come across a resistor going low in value.

I think it has something to do with high value have more carbon so tend to go even higher whereas low value have less carbon and more of the conductive stuff whatever that might be so tends to go lower, and of course it is then a runaway situation as more current is passed.

Another excellent restoration

[chipp1968]

pretty set , I dont have many 50s valve sets about 5 i think ,But I would have that , alsofancy an ultra coronation set. Philips like painted lines in bakalite for some reason

[howard]

Originally Posted by chipp1968

pretty set , I dont have many 50s valve sets about 5 i think ,But I would have that , alsofancy an ultra coronation set. Philips like painted lines in bakalite for some reason

I think this GB Philips 141U and the similar German Philips Philettas are pretty sets, they are tiny too so take up very little space. And in a darkened room their fronts light up and they look amazing.

Howard

[howard]

Hello again,

I've fixed one last 'feature' of this Philips set, it was drifting off station while warming up, even within a minute from switch-on it was obviously drifting and wouldn't settle down for around 10 minutes. That's not usually a feature of Philips sets so I fitted another used UCH42 and it doesn't drift at all now

Howard

[batterymaker1]

Pretty set--I always liked them from that era--when they used translucent plastic for the dial and grille.