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Old 22nd May 2020, 1:59 pm   #61
Bufo Bill
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Default Re: Bill's Quad woes cont.

Ecc83
Pin 1 Anode1: 132 VDC
Pin 3 Cathode1: 1.28 VDC
Pin 2 Grid1: 0 VDC
Pin 6 Anode: 311 VDC
Pin 8 Cathode: 3.2 VDC
Pin 7 Grid 3.2 VDC
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Old 22nd May 2020, 2:29 pm   #62
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Default Re: Bill's Quad woes cont.

There is a problem on the 6/7/8 triode as the grid is the same as the cathode and the anode is very high.

Can you check cathode resistor R31 (2.2K), anode resistor R30 (50K), R28 (1.5M) and has C18 (0.01uF) been replaced? This is from Quad Drawing 11171, if you are using trader 1427 then it's R22, R23, R21 and C14.

PS: C14 is a little Hunts capacitor soldered directly to the V2 socket.

Last edited by PJL; 22nd May 2020 at 2:43 pm.
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Old 22nd May 2020, 2:54 pm   #63
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Hi PJL, R30 measures 58k, the c18 is 0.01uF, but I must have misread the MM with R31, I have in my notes 2.7k, but checking again it is actually 27k.
Bill.
Edit: replaced cap yesterday so no problem there.

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Old 22nd May 2020, 3:31 pm   #64
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Default Re: Bill's Quad woes cont.

Quote:
Originally Posted by PJL View Post
There is a problem on the 6/7/8 triode as the grid is the same as the cathode and the anode is very high.

Can you check cathode resistor R31 (2.2K), anode resistor R30 (50K), R28 (1.5M) and has C18 (0.01uF) been replaced? This is from Quad Drawing 11171, if you are using trader 1427 then it's R22, R23, R21 and C14.

PS: C14 is a little Hunts capacitor soldered directly to the V2 socket.
Cue Jaws 'shark moving in' sound effect! Change it, just change it!
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Old 22nd May 2020, 3:38 pm   #65
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Default Re: Bill's Quad woes cont.

We'll have to leave it there for a bit chaps, I don't have a suitable resistor replacement to hand.
By the way, the volume on/off pot has developed a little delay in clicking into off position . . . a sign of worse to come?
Cheers from Bill.
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Old 22nd May 2020, 4:38 pm   #66
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R28 on the Quad drawing measures 1.85 MOhm.
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Old 22nd May 2020, 5:27 pm   #67
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Not perfect but R28 should be OK. I am a bit concerned about the grid voltage though as it should be near zero, measure pin 7 and pin 8 again.
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Old 22nd May 2020, 7:17 pm   #68
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Default Re: Bill's Quad woes cont.

Hi, managed to find a 2.2 kOhm resistor, pin 6 (Anode) now measures 255 VDC.
PIN 7: 5-6 mVDC
PIN 8: RESULT TO FOLLOW
We seem to have more volume, but not very clear fidelity, but need to test more. Back after dinner!
Bill
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Old 22nd May 2020, 7:55 pm   #69
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It's very likely the frequency response will be different with all the new components but should now be working as Quad intended.
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Old 22nd May 2020, 8:57 pm   #70
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Gave it a good test, and we have an excellent result! Volume is good for gentle strings (Vivaldi's violin concertos for example) at No. 3 volume, and serves just as well for Fela Kuti and the Afrika 70! Hurrah! Thanks for all the help guys, but a special thanks to PJL for your patience. You were my rock!
Cheers from Bill.
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Old 23rd May 2020, 9:20 am   #71
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Congratulations on your first successful restoration and all done without a single disaster.
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Old 23rd May 2020, 9:51 am   #72
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Nice work Bill, good job. Now you can dig deep into your pockets and buy another Quad II and a Quad22 and do it all again in stereo!
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Old 23rd May 2020, 1:39 pm   #73
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Thanks PJL! Couldn't have done it without you.
I can't imagine how you would ever work on a 22; double the components in the same space? No thanks, I had to use all my wits not to melt wires etc without that . . .
But stereo does sound tempting!
Cheers guys, all the best.
Bill.
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