Philco Model 444 Peoples Set Advice Sought. - UK Vintage Radio Repair and Restoration Discussion Forum

DoctorWho · 16th Jun 2007, 5:26 pm

I'm in the process of restoring a Philco 444 and I am working from Trader Sheet 146 and/or 655, both use the same numbering for components etc.

I replaced all of the condensers, inclusing those in the condenser blocks, I check the set between each condenser change to ensure that nothing had been overlooked.

When finished the set worked but with distortion, uncontrollable volume and severe buzzing when not tuned to a station.

The set looked untouched for decades, and was full of dust, so has not been "got at" in recent times.

I found a small piece of wire had been soldered between the junction of L11/R9/C9 across to the junction of R13/V3 Top Cap. I removed this, as it does not appear to be original according to the circuit diagram (if I had read this correctly?) and so I removed it, and now the volume control works correctly.

The set now works and picks up stations on both wavelengths, but there is still distortion on the set, most noticable when music is being played.

The set also overloads with a very long aerial when tuned to a local station and so a shorter aerial seems to work better with this set.

Any advice on what may be the cause would be very much appreciated.

The Philco 80 rectifier valve had an open circuit heater, and the dial lamp was also open circuit. I borrowed an '80' valve from another set just to work on it, so I will order one of these for this set.

Any advice on the cause of the distortion, and what bes to do to rectofy it would be very much appreciated.

Thanks in advance for any help.

All the best,

Peter.

ukcol · 16th Jun 2007, 5:51 pm

Hi Peter,
Overloading on strong signals sounds like the AGC is not working correctly. The AGC voltage is fed back to V1 and V2 via R8 (2 meg ohms). Since you have done a capacitor change, R8 would be a good starting point.

DoctorWho · 16th Jun 2007, 10:37 pm

Thanks Colin, I'll investigate that tomorrow and let you know what I find.

Just out of interest, any ideas why the link I mentioned above would have been added in the past as it made the volume control completely inoperable?

Thanks again for the help, any further advice/suggestions appreciated.

The other thing I did notice was that wax had been dripping out of the mains transformer a little, not masses of it, but enough to notice. The transformer is running only very slightly warm, so I'm presuming that it is likely to be alright? At least hopefully so. Is this normal as I've not seen this on another set before. There is no sign of burning anywhere and I have indeed changed all of the condensers, inclduing the condenser blocks.

All the best,

Peter.

Steve_P · 16th Jun 2007, 11:00 pm

Yes, change that and see what happens.

People did/do all sorts of things to keep a set working! Just leave it out and fix it properly. Anyone who can fix a certain TV set should have no trouble!!

The transformer should be OK, but keep an eye on it.

Right. Back to this radio. I took the back off and yelled something very rude - so came on here...

Cheers,

Steve P

DoctorWho · 17th Jun 2007, 11:00 am

Thanks Steve, I much prefer to keep the circuitry original, I just couldn't understand how someone could use the set at full volume all of the time!

I have been through and checked the resistors, 4 were a bit high, including R8, and so all the high value ones were replaced.

The audio is now pretty good, but there is still some distortion, most noticable when music is being played, speech sounds pretty good actually. It does still seem to work best on a short aerial.

I traced the circuitry through either side of R8 and everything reads as it should, coils all seem intact, condensers have been replaced and resistors are the correct value.

Interesting, when the computer is unplugged (in a different room) the volume goes up on the set!!

It's now useable, and the sound is acceptable, it would just be nice to get rid of the slight distortion and also stabilse the signal.

Thanks again for the help,

Peter.

Steve_P · 17th Jun 2007, 6:52 pm

Computer power supplies and old radios don't mix. It's the computer, not the radio.

If speech is OK but music isn't.... R14 ?

Also... is this off air or from an internal RF Modulator? And I hope the C11 distortion (or that 'modification') hasn't meant that the O/P valve is slightly damaged?

Cheers,

Steve P

DoctorWho · 17th Jun 2007, 8:21 pm

You're probably right about the computer PSU, it's much better with the PC unplugged!

I'll check R14. I have an idea that the output valve is not easy to find, as it's the only 7-pin 6 volt heater valve, is that right? I hope this isn;t the problem.

I only use off-air for daily listening, we tune in to the BBC Radio Devon transmitter and so receive a nice strong signal.

I'll check further along the lines you've suggested and let you know what I find.

Thanks again,

Peter.

DoctorWho · 19th Jun 2007, 2:13 am

Well R14 is very slightly lower in value, but not enough to worry about I don't think, literally just a few ohms. I haven't yet replaced it, but I can do so easily.

Is this likely to be the problem, or should I order a replacement output valve?

Thanks for the help,

Peter.

flyingtech55 · 19th Jun 2007, 9:39 am

Hi Peter

Is the 'speaker OK. If it's been running at high volume for some time it may have distorted the voice coil. I know you said it's OK on speech but sometimes slight distortion only shows up on certain types of sounds.

HTH

TimR

DoctorWho · 19th Jun 2007, 11:22 am

Thanks for your advice Tim, you certainly may well be right.

I decided to do something last night which I would not normally do, but I wanted to get the best possible performance out of the set, and so, having already replaced all of the condensers, and all of the high value resistors, i replaced the rest of the resistors (there are not that many in this set otherwise I would not have even considered doing this), so now all of the condensers and resistors are pretty much spot on the original specification.

The set does sound pretty good actually, but it does still seem that when the set has been on for a little while, and when music is being played, very slight distortion can be heard. It is now only slight, so it could easily be lived with.

I suspect having gone this far that the set is probably as good as it will get without either a replacement output valve or a speaker. I'd like to keep the rest of the set as original as possible, and, to be honest, the sound quality is pretty good, on speech it's perfect, and so I may just keep it like that.

If I were to decide to look at it again would it be advisable to approach the output valve or teh speaker first as the most likely culprit?

Steve_P · 19th Jun 2007, 11:51 am

The speaker first. Or...

Let the set go cold. Switch on and go straight to Music. Does it sound OK at first but come in as the set warms up. If it is, the O/P valve could be running into grid current.

Cheers,

Steve P

DoctorWho · 19th Jun 2007, 5:51 pm

Well this certainly seemed the case when I was running the set earlier on, it started off very good but the distortion came in after a short while, so you may well be right about the valve. I wonder if the bodge found in the set caused this? I'll have to see if I can track down a replacement valve.

Thanks again for the help,

Peter.

Paul Stenning · 19th Jun 2007, 5:57 pm

Can you connect a different speaker to the set to prove the point? It does sound like a valve problem to me though.

DoctorWho · 19th Jun 2007, 7:08 pm

Good idea Paul, that was just too simple for me to think of it, thank you

I'll give it a try and report back.

mickjjo · 19th Jun 2007, 7:11 pm

Hi Peter, It may be worth resoldering the grid cap connection on the output valve, These are notorious for going high resistance or intermittent due to the solder oxidising in the cap due to the heat. The PENDD61 is unique to these sets and very hard to find now. You can use a PENDD4020 or AC2/PENDD by adding a resistor in series with the heater as these are 4 volt valves.

Regards, Mick.

DoctorWho · 20th Jun 2007, 1:04 pm

Thanks Mick, I'll certainly try that. I have sent an enquiry about a replacement valve, so now I'll just have to see what comes of that. I did test the top cap with a test meter and it didn;t show any resistance, but I haven't tried re-soldering it.

Interstingly the distortion is there right away when using a longer aerial. it's most odd!

DoctorWho · 20th Jun 2007, 1:48 pm

Quote:

Originally Posted by mickjjo

You can use a PENDD4020 or AC2/PENDD by adding a resistor in series with the heater as these are 4 volt valves.

Regards, Mick.

If I took this option then what value resistor would I need to put in series with the heater? What current rating as well?

mickjjo · 20th Jun 2007, 2:35 pm

Hi Peter, The AC2/PENDD heater is rated at 4 volts, 2 amps, so Ohms law says a 1 ohm wire wound resistor with at least a 2 watt rating should be fine. (The PENDD4020 is only suitable for the AC/DC version of the 444 by the way).

.

There is a bit of information on the Philco sets and the PENDD61 here:-

http://www.classicwireless.btinternet.co.uk/philcoa.htm

Regards, Mick.

DoctorWho · 20th Jun 2007, 7:26 pm

Mine is the AC only version. Thanks for clarifying about which resistor to use, if I need to go down that avenue then I'll try this.

DoctorWho · 3rd Jul 2007, 12:07 pm

The set is now up and running perfectly. A NOS original output valve was obtained and the speaker given a good clean and the centre nut adjusted, it's now sounding superb.

Thanks again for the help.

Peter.

16th Jun 2007, 5:26 pm	#1
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Philco Model 444 Peoples Set Advice Sought. I'm in the process of restoring a Philco 444 and I am working from Trader Sheet 146 and/or 655, both use the same numbering for components etc. I replaced all of the condensers, inclusing those in the condenser blocks, I check the set between each condenser change to ensure that nothing had been overlooked. When finished the set worked but with distortion, uncontrollable volume and severe buzzing when not tuned to a station. The set looked untouched for decades, and was full of dust, so has not been "got at" in recent times. I found a small piece of wire had been soldered between the junction of L11/R9/C9 across to the junction of R13/V3 Top Cap. I removed this, as it does not appear to be original according to the circuit diagram (if I had read this correctly?) and so I removed it, and now the volume control works correctly. The set now works and picks up stations on both wavelengths, but there is still distortion on the set, most noticable when music is being played. The set also overloads with a very long aerial when tuned to a local station and so a shorter aerial seems to work better with this set. Any advice on what may be the cause would be very much appreciated. The Philco 80 rectifier valve had an open circuit heater, and the dial lamp was also open circuit. I borrowed an '80' valve from another set just to work on it, so I will order one of these for this set. Any advice on the cause of the distortion, and what bes to do to rectofy it would be very much appreciated. Thanks in advance for any help. All the best, Peter.

16th Jun 2007, 5:51 pm	#2
ukcol Rest in Peace Join Date: May 2003 Location: Harlaxton, Lincolnshire, UK. Posts: 3,944	Re: Philco Model 444 Peoples Set Advice Sought. Hi Peter, Overloading on strong signals sounds like the AGC is not working correctly. The AGC voltage is fed back to V1 and V2 via R8 (2 meg ohms). Since you have done a capacitor change, R8 would be a good starting point.

16th Jun 2007, 10:37 pm	#3
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Philco Model 444 Peoples Set Advice Sought. Thanks Colin, I'll investigate that tomorrow and let you know what I find. Just out of interest, any ideas why the link I mentioned above would have been added in the past as it made the volume control completely inoperable? Thanks again for the help, any further advice/suggestions appreciated. The other thing I did notice was that wax had been dripping out of the mains transformer a little, not masses of it, but enough to notice. The transformer is running only very slightly warm, so I'm presuming that it is likely to be alright? At least hopefully so. Is this normal as I've not seen this on another set before. There is no sign of burning anywhere and I have indeed changed all of the condensers, inclduing the condenser blocks. All the best, Peter.

16th Jun 2007, 11:00 pm	#4
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Philco Model 444 Peoples Set Advice Sought. Yes, change that and see what happens. People did/do all sorts of things to keep a set working! Just leave it out and fix it properly. Anyone who can fix a certain TV set should have no trouble!! The transformer should be OK, but keep an eye on it. Right. Back to this radio. I took the back off and yelled something very rude - so came on here... Cheers, Steve P __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

17th Jun 2007, 11:00 am	#5
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Philco Model 444 Peoples Set Advice Sought. Thanks Steve, I much prefer to keep the circuitry original, I just couldn't understand how someone could use the set at full volume all of the time! I have been through and checked the resistors, 4 were a bit high, including R8, and so all the high value ones were replaced. The audio is now pretty good, but there is still some distortion, most noticable when music is being played, speech sounds pretty good actually. It does still seem to work best on a short aerial. I traced the circuitry through either side of R8 and everything reads as it should, coils all seem intact, condensers have been replaced and resistors are the correct value. Interesting, when the computer is unplugged (in a different room) the volume goes up on the set!! It's now useable, and the sound is acceptable, it would just be nice to get rid of the slight distortion and also stabilse the signal. Thanks again for the help, Peter.

17th Jun 2007, 6:52 pm	#6
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Philco Model 444 Peoples Set Advice Sought. Computer power supplies and old radios don't mix. It's the computer, not the radio. If speech is OK but music isn't.... R14 ? Also... is this off air or from an internal RF Modulator? And I hope the C11 distortion (or that 'modification') hasn't meant that the O/P valve is slightly damaged? Cheers, Steve P __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

17th Jun 2007, 8:21 pm	#7
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Philco Model 444 Peoples Set Advice Sought. You're probably right about the computer PSU, it's much better with the PC unplugged! I'll check R14. I have an idea that the output valve is not easy to find, as it's the only 7-pin 6 volt heater valve, is that right? I hope this isn;t the problem. I only use off-air for daily listening, we tune in to the BBC Radio Devon transmitter and so receive a nice strong signal. I'll check further along the lines you've suggested and let you know what I find. Thanks again, Peter.

19th Jun 2007, 2:13 am	#8
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Philco Model 444 Peoples Set Advice Sought. Well R14 is very slightly lower in value, but not enough to worry about I don't think, literally just a few ohms. I haven't yet replaced it, but I can do so easily. Is this likely to be the problem, or should I order a replacement output valve? Thanks for the help, Peter.

19th Jun 2007, 9:39 am	#9
flyingtech55 Octode Join Date: Nov 2005 Location: Ayrshire, UK. Posts: 1,096	Re: Philco Model 444 Peoples Set Advice Sought. Hi Peter Is the 'speaker OK. If it's been running at high volume for some time it may have distorted the voice coil. I know you said it's OK on speech but sometimes slight distortion only shows up on certain types of sounds. HTH TimR

19th Jun 2007, 11:22 am	#10
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Philco Model 444 Peoples Set Advice Sought. Thanks for your advice Tim, you certainly may well be right. I decided to do something last night which I would not normally do, but I wanted to get the best possible performance out of the set, and so, having already replaced all of the condensers, and all of the high value resistors, i replaced the rest of the resistors (there are not that many in this set otherwise I would not have even considered doing this), so now all of the condensers and resistors are pretty much spot on the original specification. The set does sound pretty good actually, but it does still seem that when the set has been on for a little while, and when music is being played, very slight distortion can be heard. It is now only slight, so it could easily be lived with. I suspect having gone this far that the set is probably as good as it will get without either a replacement output valve or a speaker. I'd like to keep the rest of the set as original as possible, and, to be honest, the sound quality is pretty good, on speech it's perfect, and so I may just keep it like that. If I were to decide to look at it again would it be advisable to approach the output valve or teh speaker first as the most likely culprit?

19th Jun 2007, 11:51 am	#11
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Philco Model 444 Peoples Set Advice Sought. The speaker first. Or... Let the set go cold. Switch on and go straight to Music. Does it sound OK at first but come in as the set warms up. If it is, the O/P valve could be running into grid current. Cheers, Steve P __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

19th Jun 2007, 5:51 pm	#12
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Philco Model 444 Peoples Set Advice Sought. Well this certainly seemed the case when I was running the set earlier on, it started off very good but the distortion came in after a short while, so you may well be right about the valve. I wonder if the bodge found in the set caused this? I'll have to see if I can track down a replacement valve. Thanks again for the help, Peter.

19th Jun 2007, 5:57 pm	#13
Paul Stenning Administrator Join Date: Dec 2002 Location: Cardiff Posts: 9,072	Re: Philco Model 444 Peoples Set Advice Sought. Can you connect a different speaker to the set to prove the point? It does sound like a valve problem to me though. __________________ Paul Stenning Forum Admin/Owner and BVWS Webmaster

19th Jun 2007, 7:08 pm	#14
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Philco Model 444 Peoples Set Advice Sought. Good idea Paul, that was just too simple for me to think of it, thank you I'll give it a try and report back.

19th Jun 2007, 7:11 pm	#15
mickjjo Rest in Peace Join Date: Jul 2004 Location: Dartford, Kent, UK. Posts: 1,661	Re: Philco Model 444 Peoples Set Advice Sought. Hi Peter, It may be worth resoldering the grid cap connection on the output valve, These are notorious for going high resistance or intermittent due to the solder oxidising in the cap due to the heat. The PENDD61 is unique to these sets and very hard to find now. You can use a PENDD4020 or AC2/PENDD by adding a resistor in series with the heater as these are 4 volt valves. Regards, Mick.

20th Jun 2007, 1:04 pm	#16
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Philco Model 444 Peoples Set Advice Sought. Thanks Mick, I'll certainly try that. I have sent an enquiry about a replacement valve, so now I'll just have to see what comes of that. I did test the top cap with a test meter and it didn;t show any resistance, but I haven't tried re-soldering it. Interstingly the distortion is there right away when using a longer aerial. it's most odd!

20th Jun 2007, 2:35 pm	#18
mickjjo Rest in Peace Join Date: Jul 2004 Location: Dartford, Kent, UK. Posts: 1,661	Re: Philco Model 444 Peoples Set Advice Sought. Hi Peter, The AC2/PENDD heater is rated at 4 volts, 2 amps, so Ohms law says a 1 ohm wire wound resistor with at least a 2 watt rating should be fine. (The PENDD4020 is only suitable for the AC/DC version of the 444 by the way). . There is a bit of information on the Philco sets and the PENDD61 here:- http://www.classicwireless.btinternet.co.uk/philcoa.htm Regards, Mick.

20th Jun 2007, 7:26 pm	#19
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Philco Model 444 Peoples Set Advice Sought. Mine is the AC only version. Thanks for clarifying about which resistor to use, if I need to go down that avenue then I'll try this.

3rd Jul 2007, 12:07 pm	#20
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Philco Model 444 Peoples Set Advice Sought. The set is now up and running perfectly. A NOS original output valve was obtained and the speaker given a good clean and the centre nut adjusted, it's now sounding superb. Thanks again for the help. Peter.