Philips radio identification (1960s?) - UK Vintage Radio Repair and Restoration Discussion Forum

callisto · 18th Aug 2007, 1:39 am

I have just found an old Philips Radio with 4 valves and would like to restore it (my first attempt at such an old radio). However, it does not have a part number other than "MK 36701" which doesn't seem to match the coding of other Philips radios, I suspect it is a serial number. There is clearly an emblem missing from the cardboard back plate of this set.

I have some photos here:
Front

Inside

The valves are:

UCH81
UBF89
UCL82
UY85

Can anyone identify it? The closest matches I have are B2G81U (1959) and B2G25U (1960?). Except the 25U has a 700 ohm Speaker and this radio has a 5 ohm with a transformer so is probably more like the 81U, but the case is different.

I think the LW/MW switch is the original, while the power on/volume pot is a replacement (and dangerous too - being nothing more than a spikey metal object connected to a metal shaft and a live chassis!)

The radio will not power on - and looking at the replacement switch its obvious why - the live lead on the secondary switch connection is free from the PCB.

Andy

Phil G4SPZ · 18th Aug 2007, 10:47 am

The Vintage Wireless Database at http://www.classaxe.com/wireless/data/sets/ shows several similar sets, but not identical, and I can't see anything in "Radio Radio!" that matches it. Hopefully someone more familiar with late Philips sets can help further.

Phil

paulsherwin · 18th Aug 2007, 11:26 am

I don't recognize it either, but Philips made a number of similar radios in the early 60s in all their various international plants. They don't normally need mass capacitor replacement like earlier sets but the smoothing electrolytics may be shot.

Thhere are detailed descriptions of the repair of similar sets here:

http://www.vintage-radio.com/recent-...ps-b2g81u.html
http://www.vintage-radio.com/recent-...ilips-95u.html
http://www.vintage-radio.com/recent-...la-st113u.html

Paul

paulsherwin · 18th Aug 2007, 1:56 pm

The printed circuit layout looks very like th B2G81U.

Paul

Sideband · 18th Aug 2007, 9:27 pm

It's probably a B2G81U as suggested or something very similar. I once had the Stella equivalent of it but scrapped it due to the PCB being conductive giving it an uncontrollable hum and a very unhappy output valve! The valve lineup is identical. Some of these sets had an 800 ohm speaker and no output transformer. Others, like mine, had a 3 ohm speaker and an output transformer mounted under the chassis.

There are plenty of these about in one form or another. I still have the chassis...well most of it so I may be able to provide some spares if you need them. I think it still has the volume control/switch and if memory serves, there is a short plastic extension fitted to it to reduce the diameter of the spindle to fit the Philips knobs.

Rich.

Paul Stenning · 18th Aug 2007, 9:57 pm

It's not a B2G81U but it looks like the same chassis so the B2G81U service data should be fine for servicing.

Normal problems with these are leaky or worn out smoothing electrolytic capacitors, open-circuit sections on the dropper resistor, and the PCB becoming slightly conductive around the output valve which causes hum. My restoration of a B2G81U here http://www.vintage-radio.com/recent-...ps-b2g81u.html may help (this had the PCB and electrolytic problems).

callisto · 19th Aug 2007, 8:58 pm

Well I got hold of a BG2G25U service sheet and everything looks very similar except for the 800 ohm loudspeaker arrangement.

The heater dropper resistors (R3,R4) are ok, as is R2, and all the valve heaters came on. Unfortunately R1 is open circuit. The circuit diagram I have shows it as 1K, whereas marked on the dropper is 600 ohm. I think I will bridge it with a 1K 10W wirewound from Maplin.

In the meantime I have desoldered the "drilectric" cap C1/C2 and am attempting to reform it. Unfortunately the best DC supply I have is 30V so I can't do it at the rated 275V but will try it anyway. So far so good - after an hour the voltage across the resistor is only 0.725 and slowly dropping. I'll leave it overnight and do the other one in the morning.

18th Aug 2007, 1:39 am	#1
callisto Retired Dormant Member Join Date: Aug 2007 Location: Liverpool Posts: 3	Philips radio identification (1960s?) I have just found an old Philips Radio with 4 valves and would like to restore it (my first attempt at such an old radio). However, it does not have a part number other than "MK 36701" which doesn't seem to match the coding of other Philips radios, I suspect it is a serial number. There is clearly an emblem missing from the cardboard back plate of this set. I have some photos here: Front Inside The valves are: UCH81 UBF89 UCL82 UY85 Can anyone identify it? The closest matches I have are B2G81U (1959) and B2G25U (1960?). Except the 25U has a 700 ohm Speaker and this radio has a 5 ohm with a transformer so is probably more like the 81U, but the case is different. I think the LW/MW switch is the original, while the power on/volume pot is a replacement (and dangerous too - being nothing more than a spikey metal object connected to a metal shaft and a live chassis!) The radio will not power on - and looking at the replacement switch its obvious why - the live lead on the secondary switch connection is free from the PCB. Andy Last edited by Station X; 18th Aug 2007 at 1:54 pm. Reason: Second link fixed.

18th Aug 2007, 10:47 am	#2
Phil G4SPZ Dekatron Join Date: Apr 2005 Location: Bewdley, Worcestershire, UK. Posts: 4,748	Re: Philips radio identification (1960s?) The Vintage Wireless Database at http://www.classaxe.com/wireless/data/sets/ shows several similar sets, but not identical, and I can't see anything in "Radio Radio!" that matches it. Hopefully someone more familiar with late Philips sets can help further. Phil __________________ Phil Optimist [n]: One who is not in possession of the full facts

18th Aug 2007, 11:26 am	#3
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,943	Re: Philips radio identification (1960s?) I don't recognize it either, but Philips made a number of similar radios in the early 60s in all their various international plants. They don't normally need mass capacitor replacement like earlier sets but the smoothing electrolytics may be shot. Thhere are detailed descriptions of the repair of similar sets here: http://www.vintage-radio.com/recent-...ps-b2g81u.html http://www.vintage-radio.com/recent-...ilips-95u.html http://www.vintage-radio.com/recent-...la-st113u.html Paul

18th Aug 2007, 1:56 pm	#4
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,943	Re: Philips radio identification (1960s?) The printed circuit layout looks very like th B2G81U. Paul

18th Aug 2007, 9:27 pm	#5
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,571	Re: Philips radio identification (1960s?) It's probably a B2G81U as suggested or something very similar. I once had the Stella equivalent of it but scrapped it due to the PCB being conductive giving it an uncontrollable hum and a very unhappy output valve! The valve lineup is identical. Some of these sets had an 800 ohm speaker and no output transformer. Others, like mine, had a 3 ohm speaker and an output transformer mounted under the chassis. There are plenty of these about in one form or another. I still have the chassis...well most of it so I may be able to provide some spares if you need them. I think it still has the volume control/switch and if memory serves, there is a short plastic extension fitted to it to reduce the diameter of the spindle to fit the Philips knobs. Rich. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

18th Aug 2007, 9:57 pm	#6
Paul Stenning Administrator Join Date: Dec 2002 Location: Cardiff Posts: 9,071	Re: Philips radio identification (1960s?) It's not a B2G81U but it looks like the same chassis so the B2G81U service data should be fine for servicing. Normal problems with these are leaky or worn out smoothing electrolytic capacitors, open-circuit sections on the dropper resistor, and the PCB becoming slightly conductive around the output valve which causes hum. My restoration of a B2G81U here http://www.vintage-radio.com/recent-...ps-b2g81u.html may help (this had the PCB and electrolytic problems). __________________ Paul Stenning Forum Admin/Owner and BVWS Webmaster

19th Aug 2007, 8:58 pm	#7
callisto Retired Dormant Member Join Date: Aug 2007 Location: Liverpool Posts: 3	Re: Philips radio identification (1960s?) Well I got hold of a BG2G25U service sheet and everything looks very similar except for the 800 ohm loudspeaker arrangement. The heater dropper resistors (R3,R4) are ok, as is R2, and all the valve heaters came on. Unfortunately R1 is open circuit. The circuit diagram I have shows it as 1K, whereas marked on the dropper is 600 ohm. I think I will bridge it with a 1K 10W wirewound from Maplin. In the meantime I have desoldered the "drilectric" cap C1/C2 and am attempting to reform it. Unfortunately the best DC supply I have is 30V so I can't do it at the rated 275V but will try it anyway. So far so good - after an hour the voltage across the resistor is only 0.725 and slowly dropping. I'll leave it overnight and do the other one in the morning.