Bill's Quad woes cont. - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

Bufo Bill · 18th May 2020, 7:55 pm

Sorry that should be R19, not R22.
Bill.

Bufo Bill · 20th May 2020, 5:42 pm

Quick update: got the last resistors in and everything works, but still low volume on pick up. Will start on Capacitor replacement soon hopefully, thanks for sticking with me!
Bill.

PJL · 20th May 2020, 11:44 pm

Valve circuits are usually quite tolerant of resistor value changes although in a hi-fi amp it is worth getting them right. It's the capacitors that are more likely to cause major performance problems.

Techman · 21st May 2020, 1:04 am

I'm a bit surprised at you going for the resistors first. I absolutely agree that the problem is far more likely to be caused by the capacitors - famous last words!

cathoderay57 · 21st May 2020, 8:57 am

Agree with Post #44. If you're cranking up the volume of the QC2 to nigh on 50% the output should be ear-splitting. The QC2 is basically half a Quad22 and on my Quad22 a comfortable listening level is about 2 on the volume cursor, using a moving magnet cartridge. I should think replacing the caps should make a marked improvement.

sparkymike · 21st May 2020, 11:31 am

I agree with previous post. I have my Quad 22 on 2 to 3 position. I don't think I have ever used it on 4 or 5, let alone 6 . I think the speakers and ears would suffer at that level !!
Mike.

Bufo Bill · 21st May 2020, 12:26 pm

Thanks guys, half way through the caps right now, I will remember to start there with my next project, whatever that may be. Showing I'm a bit green at this I guess!
Cheers from Bill.

stevehertz · 21st May 2020, 1:43 pm

Quote:

Originally Posted by Bufo Bill

PJL, the capacitors have not all been replaced, C13 and C16 are the original Hunts caps.

Cheers from Bill.

Cue Jaws' 'shark moving in' sound effect!! Change them, just change them.

Bufo Bill · 21st May 2020, 4:40 pm

Changed and working now. I tested both EF86 in the quad, and whatever was going on destroyed the one and impaired the other. So volume is back to no. 5 on the control. Will order another EF86 and see if we get anywhere with that. Suggestions welcome if there is something I have missed.
Cheers from Bill.

PJL · 21st May 2020, 4:50 pm

Now we know the components are good, you need to measure the voltages on the valves (anode, cathode, grid 1 and grid 2) and post the results here. That will tell us if they are worn out. It may not be the EF86.

Bufo Bill · 21st May 2020, 7:09 pm

Hi, EF86 measurements
Anode Pin 6: 83.0 VDC
Cathode pin 3: 1.54 VDC
Grid 1 Pin 9: 0 VDC
Grid 2 Pin 1: 70.1 VDC
Just to be sure I did it right, I measured all to chassis ground, and measured on the valve base pins.
Cheers from Bill.

PJL · 21st May 2020, 8:22 pm

The EF86 voltages look good so it is probably OK. Now measure the cathode, grid and anode of both halves of the ECC83.

Bufo Bill · 21st May 2020, 8:47 pm

Ecc83
A1 Pin 1: 3.2mVDC
A Pin 6: 3.1mVDC
K1 Pin 3: 2.8mVDC
K Pin 8: 0
G1 Pin 2: 3 VDC
G Pin 7: 1.24 VDC
Cheers from Bill.

PJL · 21st May 2020, 9:17 pm

I think you must have made a mistake with your voltage measurements as it would not be working with these values. Have another go.

Bufo Bill · 21st May 2020, 9:18 pm

Yeah, it looks weird, I will retest.
Bill.

Bufo Bill · 21st May 2020, 9:42 pm

Silly mistake; transposed the pins back to front,
A1 132 VDC
K1 302.1 VDC
A 131.1 VDC
K 3.1 VDC
CHECKED CATHODE K1: SIMILAR RESULT!
Bill.

Bufo Bill · 21st May 2020, 10:00 pm

PJL, I made another mistake in post #56: It was anode pin 6 that was high not cathode pin 3. I have a bit of a headache so will leave it for tonight, sorry. Clearly not supposed to be measuring voltages right now.
Thanks for your patience.
Bill.

PJL · 21st May 2020, 10:04 pm

No problem, you must have put a few hours in on this, have a break!

Bufo Bill · 22nd May 2020, 1:14 pm

Hi again, what should my next move be?

Herald1360 · 22nd May 2020, 1:35 pm

Redo the voltage measurements?

18th May 2020, 7:55 pm	#41
Bufo Bill Heptode Join Date: Jan 2016 Location: Wolverhampton, West Midlands, UK. Posts: 777	Re: Bill's Quad woes cont. Sorry that should be R19, not R22. Bill.

20th May 2020, 5:42 pm	#42
Bufo Bill Heptode Join Date: Jan 2016 Location: Wolverhampton, West Midlands, UK. Posts: 777	Re: Bill's Quad woes cont. Quick update: got the last resistors in and everything works, but still low volume on pick up. Will start on Capacitor replacement soon hopefully, thanks for sticking with me! Bill.

20th May 2020, 11:44 pm	#43
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Bill's Quad woes cont. Valve circuits are usually quite tolerant of resistor value changes although in a hi-fi amp it is worth getting them right. It's the capacitors that are more likely to cause major performance problems.

21st May 2020, 8:57 am	#45
cathoderay57 Nonode Join Date: Oct 2017 Location: Bristol, UK. Posts: 2,388	Re: Bill's Quad woes cont. Agree with Post #44. If you're cranking up the volume of the QC2 to nigh on 50% the output should be ear-splitting. The QC2 is basically half a Quad22 and on my Quad22 a comfortable listening level is about 2 on the volume cursor, using a moving magnet cartridge. I should think replacing the caps should make a marked improvement.

21st May 2020, 11:31 am	#46
sparkymike Octode Join Date: Dec 2006 Location: Colchester, Essex, UK. Posts: 1,076	Re: Bill's Quad woes cont. I agree with previous post. I have my Quad 22 on 2 to 3 position. I don't think I have ever used it on 4 or 5, let alone 6 . I think the speakers and ears would suffer at that level !! Mike.

21st May 2020, 1:04 am	#44
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Bill's Quad woes cont. I'm a bit surprised at you going for the resistors first. I absolutely agree that the problem is far more likely to be caused by the capacitors - famous last words!

21st May 2020, 12:26 pm	#47
Bufo Bill Heptode Join Date: Jan 2016 Location: Wolverhampton, West Midlands, UK. Posts: 777	Re: Bill's Quad woes cont. Thanks guys, half way through the caps right now, I will remember to start there with my next project, whatever that may be. Showing I'm a bit green at this I guess! Cheers from Bill.

21st May 2020, 4:40 pm	#49
Bufo Bill Heptode Join Date: Jan 2016 Location: Wolverhampton, West Midlands, UK. Posts: 777	Re: Bill's Quad woes cont. Changed and working now. I tested both EF86 in the quad, and whatever was going on destroyed the one and impaired the other. So volume is back to no. 5 on the control. Will order another EF86 and see if we get anywhere with that. Suggestions welcome if there is something I have missed. Cheers from Bill.

21st May 2020, 4:50 pm	#50
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Bill's Quad woes cont. Now we know the components are good, you need to measure the voltages on the valves (anode, cathode, grid 1 and grid 2) and post the results here. That will tell us if they are worn out. It may not be the EF86.

21st May 2020, 7:09 pm	#51
Bufo Bill Heptode Join Date: Jan 2016 Location: Wolverhampton, West Midlands, UK. Posts: 777	Re: Bill's Quad woes cont. Hi, EF86 measurements Anode Pin 6: 83.0 VDC Cathode pin 3: 1.54 VDC Grid 1 Pin 9: 0 VDC Grid 2 Pin 1: 70.1 VDC Just to be sure I did it right, I measured all to chassis ground, and measured on the valve base pins. Cheers from Bill.

21st May 2020, 8:22 pm	#52
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Bill's Quad woes cont. The EF86 voltages look good so it is probably OK. Now measure the cathode, grid and anode of both halves of the ECC83.

21st May 2020, 8:47 pm	#53
Bufo Bill Heptode Join Date: Jan 2016 Location: Wolverhampton, West Midlands, UK. Posts: 777	Re: Bill's Quad woes cont. Ecc83 A1 Pin 1: 3.2mVDC A Pin 6: 3.1mVDC K1 Pin 3: 2.8mVDC K Pin 8: 0 G1 Pin 2: 3 VDC G Pin 7: 1.24 VDC Cheers from Bill.

21st May 2020, 9:17 pm	#54
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Bill's Quad woes cont. I think you must have made a mistake with your voltage measurements as it would not be working with these values. Have another go.

21st May 2020, 9:18 pm	#55
Bufo Bill Heptode Join Date: Jan 2016 Location: Wolverhampton, West Midlands, UK. Posts: 777	Re: Bill's Quad woes cont. Yeah, it looks weird, I will retest. Bill.

21st May 2020, 9:42 pm	#56
Bufo Bill Heptode Join Date: Jan 2016 Location: Wolverhampton, West Midlands, UK. Posts: 777	Re: Bill's Quad woes cont. Silly mistake; transposed the pins back to front, A1 132 VDC K1 302.1 VDC A 131.1 VDC K 3.1 VDC CHECKED CATHODE K1: SIMILAR RESULT! Bill.

21st May 2020, 10:00 pm	#57
Bufo Bill Heptode Join Date: Jan 2016 Location: Wolverhampton, West Midlands, UK. Posts: 777	Re: Bill's Quad woes cont. PJL, I made another mistake in post #56: It was anode pin 6 that was high not cathode pin 3. I have a bit of a headache so will leave it for tonight, sorry. Clearly not supposed to be measuring voltages right now. Thanks for your patience. Bill.

21st May 2020, 10:04 pm	#58
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Bill's Quad woes cont. No problem, you must have put a few hours in on this, have a break!

22nd May 2020, 1:14 pm	#59
Bufo Bill Heptode Join Date: Jan 2016 Location: Wolverhampton, West Midlands, UK. Posts: 777	Re: Bill's Quad woes cont. Hi again, what should my next move be?

22nd May 2020, 1:35 pm	#60
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: Bill's Quad woes cont. Redo the voltage measurements? __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O