Paillard 70TR - UK Vintage Radio Repair and Restoration Discussion Forum

Richardgr · 7th Jul 2021, 8:07 pm

I acquired this set when restoring a Paillard 768. Both are pre-war Swiss radios, that look to be based on more upmarket USA models. The 768 is from '35, and the 70TR from '36 or '37 and it is amazing how different they are, although the chassis are similar in layout. The 70TR is quite a lot more modern in its approach, so shows at what a rapid speed consumer electronics was changing back them. The tubes lineup is (from the aerial) 6K7, 6L7, 6C5, 6K7, 6G7 and 2A3, with an 80 in the power supply and a 6G5 magic eye.

Link to Radiomuseum:
Paillard 70TR

I have drawn out much of the schematic so I can reproduce it, which I plan to do when it is complete.

I have covered some of my travails with this radio in seperate threads on the Paillard 768, and also ...
Mallory Bias Cell
... since this radio uses a small button cell for the bias of the detevtor/driver tube (6Q7).

I replaced the biass cell with an LR44 (described in the thread) so bias is slightly greater at 1.5V instead of 1V.

I have managed to get the radio working - photos to follow - but the main issue I have is very low gain. I will add some more data later, but was wondering what are the normal first steps to investigate a 'quiet' radio.

I have had it working with a bluetooth adaptor in the gramaphone pickup, and the sound is surprisingly good, and the loudspeaker is completely quiet on no signal, so I was very pleasantly surprised. However the volume has to be up quite high to get a reasonable volume from the Bluetooth (which I presume if 1V RMS line output), and when in radio ode the staic from the radio waves is a lot quieter than it should be.

Can it all be the 6Q7, or can I investigate other causes?

I traced the 6Q7 on the uTracer as part of the investigation, and it is attached. It is weaker than the factory data sheet, so I was considering how I could eliminate that from the investigation.

Richardgr · 7th Jul 2021, 9:01 pm

Some photos of progress.
Photo 1: The case is not particularly attractive and has some damage on the veneer. I'm sure its mother would love it, but not sure anyone else would.
Photo 2: Quite a compact chassis for such a large cabinet.
Photo 3: Underside before cap replacement.
Photo 4: Caps replaced, bias cell revitalised, and an earthed power lead added
Photo 5: Sweet music, toe-tapping owner not pictured.

7th Jul 2021, 8:07 pm	#1
Richardgr Heptode Join Date: Oct 2019 Location: Täby, Sweden Posts: 702	Paillard 70TR I acquired this set when restoring a Paillard 768. Both are pre-war Swiss radios, that look to be based on more upmarket USA models. The 768 is from '35, and the 70TR from '36 or '37 and it is amazing how different they are, although the chassis are similar in layout. The 70TR is quite a lot more modern in its approach, so shows at what a rapid speed consumer electronics was changing back them. The tubes lineup is (from the aerial) 6K7, 6L7, 6C5, 6K7, 6G7 and 2A3, with an 80 in the power supply and a 6G5 magic eye. Link to Radiomuseum: Paillard 70TR I have drawn out much of the schematic so I can reproduce it, which I plan to do when it is complete. I have covered some of my travails with this radio in seperate threads on the Paillard 768, and also ... Mallory Bias Cell ... since this radio uses a small button cell for the bias of the detevtor/driver tube (6Q7). I replaced the biass cell with an LR44 (described in the thread) so bias is slightly greater at 1.5V instead of 1V. I have managed to get the radio working - photos to follow - but the main issue I have is very low gain. I will add some more data later, but was wondering what are the normal first steps to investigate a 'quiet' radio. I have had it working with a bluetooth adaptor in the gramaphone pickup, and the sound is surprisingly good, and the loudspeaker is completely quiet on no signal, so I was very pleasantly surprised. However the volume has to be up quite high to get a reasonable volume from the Bluetooth (which I presume if 1V RMS line output), and when in radio ode the staic from the radio waves is a lot quieter than it should be. Can it all be the 6Q7, or can I investigate other causes? I traced the 6Q7 on the uTracer as part of the investigation, and it is attached. It is weaker than the factory data sheet, so I was considering how I could eliminate that from the investigation. Attached Thumbnails

7th Jul 2021, 9:01 pm	#2
Richardgr Heptode Join Date: Oct 2019 Location: Täby, Sweden Posts: 702	Re: Paillard 70TR Some photos of progress. Photo 1: The case is not particularly attractive and has some damage on the veneer. I'm sure its mother would love it, but not sure anyone else would. Photo 2: Quite a compact chassis for such a large cabinet. Photo 3: Underside before cap replacement. Photo 4: Caps replaced, bias cell revitalised, and an earthed power lead added Photo 5: Sweet music, toe-tapping owner not pictured. Attached Thumbnails