Pye P114BQ 'Jewel Case' 1955 - UK Vintage Radio Repair and Restoration Discussion Forum

Phil G4SPZ · 17th Jan 2015, 1:10 am

I'd always rather fancied one of these battery portables, so when a friend offered me a cosmetically-good non-worker in exchange for a restored Avo 8, I agreed to the swap. The repair turned out to be far from straightforward though...

After repairing some leads and battery connections, the set was dead despite drawing approximately the right current from the batteries, so having had problems with valveholders on several battery sets, I looked closely and found that the DL96 output valve's holder had a cracked contact. This was in pin 2, which is the anode, so no wonder the set was silent. I didn't have an identical replacement B7G PCB-mounting valveholder, but I managed to unsolder and remove the faulty valveholder and extract the broken pin, replacing it with one taken from a similar type. A bit fiddly, but it worked fine and the audio stages and the IF stage were working well after that.

However, the local oscillator was well and truly stalled. A couple of resistors had gone high in value, so I replaced those but it still wouldn't work. I substituted the valve for a known good one, to no avail, so I then tried the old trick of tuning to 200kHz long wave and injecting RF at 670kHz from my signal generator into the DK96's first grid, pin 4. Radio Four burst forth, so I knew the mixer and IF stage were basically OK.

The coil, band switches and the other components around the oscillator circuit seemed to be in order, so I resorted to bridging capacitors and soon found the culprit, C13, 580pF (see attached diagram). It was completely open-circuit, and when I unsoldered and removed it, one of its wire leads stayed behind! I had a 560pF in stock, and this restored normal operation.

I used to think that silvered mica capacitors were generally above suspicion, but this is one of several duff SM caps that I've had to replace recently, so you can't trust the little devils can you?

This set has a very nice tone and like all battery portables, it is very sensitive. I'm currently cleaning the cabinet and will post a couple of pictures later.

kalee20 · 17th Jan 2015, 9:58 am

Interesting write-up!

The DL96 will have taken a bit of a hammering. With the anode disconnected, all the cathode current (which wouldn't change much) would have gone to the screen grid causing over dissipation. However, in low-power valves it would not do much harm apart from possibly liberating some gas.

Did you have to replace 'that' capacitor?

Phil G4SPZ · 17th Jan 2015, 10:36 am

Thanks Kalee, and yes, I did replace 'that' capacitor as a matter of course but I forgot to mention it! It's a 0.01uF waxy.

Good point about valves being harmed by an o/c anode connection. As you say, the effect on total HT current is masked by the increased screen current. I always monitor both HT and LT currents when servicing this type of set, as it can quickly show up problems. Fortunately I only operated it for a few seconds in this condition - it sounds good enough, so I guess the valve survived the ordeal.

Phil G4SPZ · 17th Jan 2015, 1:16 pm

Pictures, as promised.

As you can see, the innards are far from pristine, and the cabinet could do with more effective cleaning! However, having once ruined the front of a Sky Queen cabinet by using foam cleaner to remove the 'grime', I have come to the conclusion that this fake 'lizard-skin' finish covering darkens naturally with age, and it's difficult if not impossible to restore to its as-new state. So nowadays I just clean it using baby wipes to get the surface muck off, then back off.

So, please, don't get the impression that this has been a 'restoration'! I posted the story more to highlight the electronic faults that were repaired.

Phil

yesnaby · 17th Jan 2015, 2:12 pm

Hi,

This was my first ever radio, bought by my parents at the age of 10. Still have it.

Michael

17th Jan 2015, 2:22 pm

Nice reproduction (I assume!) batteries too.

Phil G4SPZ · 17th Jan 2015, 3:54 pm

Ah, I can't claim credit for the batteries...

I do make replica batteries, but the ones in the picture are actually an original B126 and an AD35, which I found found inside another set, refilled with PP3s and D-cells respectively.

17th Jan 2015, 5:32 pm

Quote:

an original B126 and an AD35

That is a handy (and lucky) start.

Brian R Pateman · 17th Jan 2015, 6:19 pm

A nice refurbishment Phil. Like you I've always tended to assume that Silver Micas are usually above suspicion.

I've always liked this style of set and the Pye offerings are among my favourites. They are nice performers too.

I must get mine off the "to do" pile before too long.

batterymaker1 · 19th Jan 2015, 12:25 am

Those are wonderful sets. I always get compliments whenever I have it playing. Pye designed some beautiful portables, and this is no exception.

17th Jan 2015, 1:10 am	#1
Phil G4SPZ Dekatron Join Date: Apr 2005 Location: Bewdley, Worcestershire, UK. Posts: 4,748	Pye P114BQ 'Jewel Case' 1955 I'd always rather fancied one of these battery portables, so when a friend offered me a cosmetically-good non-worker in exchange for a restored Avo 8, I agreed to the swap. The repair turned out to be far from straightforward though... After repairing some leads and battery connections, the set was dead despite drawing approximately the right current from the batteries, so having had problems with valveholders on several battery sets, I looked closely and found that the DL96 output valve's holder had a cracked contact. This was in pin 2, which is the anode, so no wonder the set was silent. I didn't have an identical replacement B7G PCB-mounting valveholder, but I managed to unsolder and remove the faulty valveholder and extract the broken pin, replacing it with one taken from a similar type. A bit fiddly, but it worked fine and the audio stages and the IF stage were working well after that. However, the local oscillator was well and truly stalled. A couple of resistors had gone high in value, so I replaced those but it still wouldn't work. I substituted the valve for a known good one, to no avail, so I then tried the old trick of tuning to 200kHz long wave and injecting RF at 670kHz from my signal generator into the DK96's first grid, pin 4. Radio Four burst forth, so I knew the mixer and IF stage were basically OK. The coil, band switches and the other components around the oscillator circuit seemed to be in order, so I resorted to bridging capacitors and soon found the culprit, C13, 580pF (see attached diagram). It was completely open-circuit, and when I unsoldered and removed it, one of its wire leads stayed behind! I had a 560pF in stock, and this restored normal operation. I used to think that silvered mica capacitors were generally above suspicion, but this is one of several duff SM caps that I've had to replace recently, so you can't trust the little devils can you? This set has a very nice tone and like all battery portables, it is very sensitive. I'm currently cleaning the cabinet and will post a couple of pictures later. __________________ Phil Optimist [n]: One who is not in possession of the full facts

17th Jan 2015, 9:58 am	#2
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,088	Re: Pye P114BQ 'Jewel Case' 1955 Interesting write-up! The DL96 will have taken a bit of a hammering. With the anode disconnected, all the cathode current (which wouldn't change much) would have gone to the screen grid causing over dissipation. However, in low-power valves it would not do much harm apart from possibly liberating some gas. Did you have to replace 'that' capacitor?

17th Jan 2015, 10:36 am	#3
Phil G4SPZ Dekatron Join Date: Apr 2005 Location: Bewdley, Worcestershire, UK. Posts: 4,748	Re: Pye P114BQ 'Jewel Case' 1955 Thanks Kalee, and yes, I did replace 'that' capacitor as a matter of course but I forgot to mention it! It's a 0.01uF waxy. Good point about valves being harmed by an o/c anode connection. As you say, the effect on total HT current is masked by the increased screen current. I always monitor both HT and LT currents when servicing this type of set, as it can quickly show up problems. Fortunately I only operated it for a few seconds in this condition - it sounds good enough, so I guess the valve survived the ordeal. __________________ Phil Optimist [n]: One who is not in possession of the full facts Last edited by Phil G4SPZ; 17th Jan 2015 at 10:41 am. Reason: Afterthought

17th Jan 2015, 1:16 pm	#4
Phil G4SPZ Dekatron Join Date: Apr 2005 Location: Bewdley, Worcestershire, UK. Posts: 4,748	Re: Pye P114BQ 'Jewel Case' 1955 Pictures, as promised. As you can see, the innards are far from pristine, and the cabinet could do with more effective cleaning! However, having once ruined the front of a Sky Queen cabinet by using foam cleaner to remove the 'grime', I have come to the conclusion that this fake 'lizard-skin' finish covering darkens naturally with age, and it's difficult if not impossible to restore to its as-new state. So nowadays I just clean it using baby wipes to get the surface muck off, then back off. So, please, don't get the impression that this has been a 'restoration'! I posted the story more to highlight the electronic faults that were repaired. Phil Attached Thumbnails __________________ Phil Optimist [n]: One who is not in possession of the full facts

17th Jan 2015, 2:12 pm	#5
yesnaby Octode Join Date: Jul 2005 Location: Newport, Gwent, UK. Posts: 1,623	Re: Pye P114BQ 'Jewel Case' 1955 Hi, This was my first ever radio, bought by my parents at the age of 10. Still have it. Michael

17th Jan 2015, 2:22 pm	#6
Guest Guest Posts: n/a	Re: Pye P114BQ 'Jewel Case' 1955 Nice reproduction (I assume!) batteries too.

17th Jan 2015, 3:54 pm	#7
Phil G4SPZ Dekatron Join Date: Apr 2005 Location: Bewdley, Worcestershire, UK. Posts: 4,748	Re: Pye P114BQ 'Jewel Case' 1955 Ah, I can't claim credit for the batteries... I do make replica batteries, but the ones in the picture are actually an original B126 and an AD35, which I found found inside another set, refilled with PP3s and D-cells respectively. __________________ Phil Optimist [n]: One who is not in possession of the full facts

17th Jan 2015, 6:19 pm	#9
Brian R Pateman Nonode Join Date: Jun 2005 Location: Western Lake District, Cumbria (CA20) - UK Posts: 2,136	Re: Pye P114BQ 'Jewel Case' 1955 A nice refurbishment Phil. Like you I've always tended to assume that Silver Micas are usually above suspicion. I've always liked this style of set and the Pye offerings are among my favourites. They are nice performers too. I must get mine off the "to do" pile before too long. __________________ Brian

19th Jan 2015, 12:25 am	#10
batterymaker1 Heptode Join Date: Apr 2006 Location: Indianapolis, Indiana, USA. Posts: 674	Re: Pye P114BQ 'Jewel Case' 1955 Those are wonderful sets. I always get compliments whenever I have it playing. Pye designed some beautiful portables, and this is no exception. __________________ Just playing with high voltage....