UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Radio (domestic)

Notices

Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

Closed Thread
 
Thread Tools
Old 22nd Mar 2020, 1:50 pm   #1
JonSnell
Hexode
 
JonSnell's Avatar
 
Join Date: Oct 2019
Location: Weymouth, Dorset, UK.
Posts: 473
Default PYE P114BQ restoration

I was asked to restore this lovely piece of kit for a friend and thought some of you may be interested.
The unit was dead and all filaments in the valves were open circuit which means only one thing ... wrong battery connected. 90volts on 1.5volt heaters ... they are very bright for a few milliseconds then dead.
I ordered a set of valves from various suppliers in the UK and ensured they were all Mullard NOS valves.
Fitting the new valves and connecting the LT and HT batteries there was a very weak sound.
I looked at the schematic, took a few voltage measurements with my AVO Model 8, (as the drawings used an AVO for measurement) to find the cause.
If anyone is interested, I will go into it deeper and show the fault finding process.
Attached Thumbnails
Click image for larger version

Name:	IMG_3583.jpg
Views:	190
Size:	69.2 KB
ID:	201391   Click image for larger version

Name:	IMG_3584.jpg
Views:	166
Size:	61.9 KB
ID:	201392   Click image for larger version

Name:	IMG_3587.jpg
Views:	178
Size:	61.5 KB
ID:	201393   Click image for larger version

Name:	IMG_3588.jpg
Views:	189
Size:	66.5 KB
ID:	201394  
JonSnell is offline  
Old 22nd Mar 2020, 2:02 pm   #2
AC/HL
Dekatron
 
AC/HL's Avatar
 
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,637
Default Re: PYE P114BQ restoration

Yes please, and members will also be interested in details of your replacement batteries.
AC/HL is online now  
Old 28th Mar 2020, 10:39 am   #3
JonSnell
Hexode
 
JonSnell's Avatar
 
Join Date: Oct 2019
Location: Weymouth, Dorset, UK.
Posts: 473
Default Re: PYE P114BQ restoration

The wireless came to me through a friend that recommended my services.
When the PYE arrived it was totally dead, no life and reasonable battery voltage. As I quizzed the owner about why the batteries were made up of 10 X PP3 in series for the HT supply and four C Cells in parallel for the LT supply I noticed an instant problem; Choc Block connectors that screw down the old plugs, that used to fit the batteries, ( the original batteries had either an offset three pin socket for HT or a polarised two pin socket, (one pin larger than the other). These plugs were stuffed into the ChocBlocks and the wrong batteries had been unfortunately connected causing open circuit heaters in all valves.
Where do I find a set of valves ... and where to find a service manual or at least service information.
V1 is a DK96, a chap in Israel had one. V2 is a DF96, Spain. V3 is a DAF96, UK supplier of NOS components along with V4 a DL96.
These are all "Bright Emitter" valves or directly heated as they are known now.
I gave the customer the price for valves, he agreed and two weeks later I had them in my possession.
Now, to batteries.
The B126 and AD35 have not been made for many decades but there was life in the copies supplied. They were dry cells in a cardboard printed box to look like the real thing.
I double checked the battery wiring, the negative terminal of the HT goes to the chassis and the positive LT also. The others run through a push off switch located on the radio front board inline with the edge of the lid meaning when the lid was closed the switch turned off the supplies. Clever!
Having fitted the valves and the batteries we had no sound.
A look for a service sheet for the P114BQ was impossible to find but I remembered an old friend had many Trader Service Sheets and number 1253 dated 16th June 1956 was the one.
I set up my oscilloscope and looked at the grid of V1, local oscillator and it was oscillating. There is life here after all.
Tuning Long Wave to about 1500Metres I saw modulation on Anode 2, the diode, of V3.
Looking for interference noise, hum/crackle at the loudspeaker inputting a 1kHZ sine wave on the grid of V4, output pentode, the 1kHZ arrived and faded out at the probe charged up the odd volt or so. R12 the 4M7 resistor was over 32M, replacing the resistor and PYE sprung back into life.
Good news but how to stop it happening again was the burning question.

The LT battery was the problem. Connection wise.
I thought to place a 2.5mm DC connector from the wireless to the battery will stop the possibility of it happening again, the valves alone were over £70!
Then I thought if I used a 4Ah re chargeable cell 1.2volts is adequate for the heaters, that will solve a problem.

So a 2.5mm DC socket was fitted to the battery pack that contained the Lion cell, a 2.5mm plug to the wireless and I modified a Lion charger with a 2.5mm plug to recharge the battery that is housed in the AD35 box. The HT battery has a 3 pin miniature Bulgin connector fitted, of the type fitted to 24volt Weller Soldering Irons.

I hope you found this useful and I look forward to the next repair.

Last edited by Station X; 28th Mar 2020 at 10:59 am. Reason: Forum rule B.8.
JonSnell is offline  
Old 28th Mar 2020, 11:17 am   #4
CambridgeWorks
Nonode
 
CambridgeWorks's Avatar
 
Join Date: Jun 2010
Location: Spalding, Peterborough, Cambridgeshire, UK.
Posts: 2,851
Default Re: PYE P114BQ restoration

the valves alone were over £70!
Bit late now, I know, but should have put a wanted here first.
You might have got several sets for that price.
Rob
__________________
Apprehension creeping like a tube train up your spine - Cymbaline. Film More soundtrack - Pink Floyd
CambridgeWorks is online now  
Old 28th Mar 2020, 11:33 am   #5
Cobaltblue
Moderator
 
Cobaltblue's Avatar
 
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,823
Default Re: PYE P114BQ restoration

Hi Jon and welcome to the forum.

I have a soft spot for these post war battery sets myself the the PYE is a nice looking example.

If you join the BVWS you will get a copy of the Trader sheets on CD Rom as part of your membership created by non other than our own Paul owner of this Forum.

As you will also no doubt have spotted top right you can get most service sheets on a one off basis or purchase Pauls DVD.

Question about the LiON cell I thought these had a nominal terminal voltage of 3.6ish volts how did you reduce it 1.2V or did you use an NiMH which has around a 1.2V terminal voltage.

I must admit first thing I do on any of these battery sets is check for OC fils (very common) then any resistor above 470K gets checked, replace the grid coupling cap if it paper then fault find.

Hope we hear from you some more on other restros.

Cheers

Mike T
__________________
Invisible airwaves crackle with life or at least they used to
Mike T BVWS member.
www.cossor.co.uk
Cobaltblue is online now  
Old 28th Mar 2020, 11:36 am   #6
JonSnell
Hexode
 
JonSnell's Avatar
 
Join Date: Oct 2019
Location: Weymouth, Dorset, UK.
Posts: 473
Default Re: PYE P114BQ restoration

My apologies, you are quite correct, I meant NiMh. Typo.
Sorry for any confusion. I will try and change it.
JonSnell is offline  
Old 28th Mar 2020, 12:30 pm   #7
JonSnell
Hexode
 
JonSnell's Avatar
 
Join Date: Oct 2019
Location: Weymouth, Dorset, UK.
Posts: 473
Default Re: PYE P114BQ restoration

Quote:
Originally Posted by robinshack View Post
the valves alone were over £70!
Bit late now, I know, but should have put a wanted here first.
You might have got several sets for that price.
Rob
I restored this wireless before I found this forum but will look further afield next time.

Luckily the customer paid for the repair parts.
JonSnell is offline  
Old 29th Mar 2020, 12:21 pm   #8
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
Default Re: PYE P114BQ restoration

Not being picky but...bright emitter valves were used pre-1925 and had tungsten filaments, to get any emissions from them they needed to be lit up like a lightbulb. Oxides were subsequently used in dull emitter valves.
PJL is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 5:17 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.