Philips 634A 'speaker rattle. - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

wheresthetubes · 16th Dec 2009, 1:55 pm

When I've done everything but throw the kitchen sink at a radio, and it still won't behave, I draw a line in the sand and sell the thing. Mind you I've only done this once. Two cars can roll off a production line, one after the other, yet one could go 60,000 miles before encountering problems, whilst the other could be in and out of the mechanics from day one. I think its the same with radios. You just got to be lucky most of the time amd hope the one you buy won't make you

. Luck of the auction I suppose. If it were me with this Philips I'd off-load it and get another, or the other way round. Then I'd have a

chipp1968 · 16th Dec 2009, 7:47 pm

No i dont this I will be off loading it just yet. cost quite a bit and its a craker of a Wireless ,cabinet and chassis in good nik . I suspect there is a fault somwhere that needs tweeking

Ian B · 16th Dec 2009, 10:56 pm

The volume control is probably a special Philips wire wound effort. Pots of this kind (not just Philips) in my experience often wear in one area corresponding to the normal listening level. This often leads to a break in the winding, but careful fiddling with the control can make the wiper bridge the break - until it's disturbed again. Sometimes it's possible to repair by replacing the resistance winding with one from another pot of similar value.

Ian Blackbourn

chipp1968 · 16th Dec 2009, 11:04 pm

I wondered if it was the pot itself , but not sure ,it could be a combo of things , would this explain it being very quiet below the problem area ?
On my HMV 907 there was a problem with the vol pot that as you say was in a certain area , just where i wanted to put the volume !! obviously so did eveyone previously , though its much improved after switch cleaner and plenty of use . With the philips it not noisey though , just the volume hardly increases most of the way then jumps into overloading

PJL · 17th Dec 2009, 12:11 am

This set uses the rare SD4 valve so does have a diode detector. It has a 'normal' volume control but typical Phillips idiosyncracies with a bizarre bias arrangement.

After that I would do a few checks with your meter, HT volts, SD4 anode volts, anode current of the PM24A which you will have to break the circuit to measure. PM24A's don't seem that reliable and a few I have are low emission or have grid leak problems.

chipp1968 · 18th Dec 2009, 2:24 pm

I may get time over christmas to look at it but i recon othet stuff will take presidence.

Does anyone have a pic of what the pull out station card looked like ? Missing on mine but i assume it was slotted into the rarther substantial rebates undernieth

16th Dec 2009, 1:55 pm	#21
wheresthetubes Retired Dormant Member Join Date: Jul 2009 Location: Reading, Berkshire, UK. Posts: 135	Re: Philips 634A 'speaker rattle. When I've done everything but throw the kitchen sink at a radio, and it still won't behave, I draw a line in the sand and sell the thing. Mind you I've only done this once. Two cars can roll off a production line, one after the other, yet one could go 60,000 miles before encountering problems, whilst the other could be in and out of the mechanics from day one. I think its the same with radios. You just got to be lucky most of the time amd hope the one you buy won't make you . Luck of the auction I suppose. If it were me with this Philips I'd off-load it and get another, or the other way round. Then I'd have a

16th Dec 2009, 7:47 pm	#22
chipp1968 Rest in Peace Join Date: Jul 2006 Location: Somerset, UK. Posts: 2,356	Re: Philips 634A 'speaker rattle. No i dont this I will be off loading it just yet. cost quite a bit and its a craker of a Wireless ,cabinet and chassis in good nik . I suspect there is a fault somwhere that needs tweeking Attached Thumbnails

16th Dec 2009, 10:56 pm	#23
Ian B Hexode Join Date: May 2006 Location: Arlesey, Bedfordshire, UK. Posts: 401	Re: Philips 634A 'speaker rattle. The volume control is probably a special Philips wire wound effort. Pots of this kind (not just Philips) in my experience often wear in one area corresponding to the normal listening level. This often leads to a break in the winding, but careful fiddling with the control can make the wiper bridge the break - until it's disturbed again. Sometimes it's possible to repair by replacing the resistance winding with one from another pot of similar value. Ian Blackbourn

16th Dec 2009, 11:04 pm	#24
chipp1968 Rest in Peace Join Date: Jul 2006 Location: Somerset, UK. Posts: 2,356	Re: Philips 634A 'speaker rattle. I wondered if it was the pot itself , but not sure ,it could be a combo of things , would this explain it being very quiet below the problem area ? On my HMV 907 there was a problem with the vol pot that as you say was in a certain area , just where i wanted to put the volume !! obviously so did eveyone previously , though its much improved after switch cleaner and plenty of use . With the philips it not noisey though , just the volume hardly increases most of the way then jumps into overloading

17th Dec 2009, 12:11 am	#25
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Philips 634A 'speaker rattle. This set uses the rare SD4 valve so does have a diode detector. It has a 'normal' volume control but typical Phillips idiosyncracies with a bizarre bias arrangement. After that I would do a few checks with your meter, HT volts, SD4 anode volts, anode current of the PM24A which you will have to break the circuit to measure. PM24A's don't seem that reliable and a few I have are low emission or have grid leak problems.

18th Dec 2009, 2:24 pm	#26
chipp1968 Rest in Peace Join Date: Jul 2006 Location: Somerset, UK. Posts: 2,356	Re: Philips 634A 'speaker rattle. I may get time over christmas to look at it but i recon othet stuff will take presidence. Does anyone have a pic of what the pull out station card looked like ? Missing on mine but i assume it was slotted into the rarther substantial rebates undernieth