Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Quickie => Topic started by: aragorn723 on January 25, 2015, 12:15:32 PM
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Hi,
I was working on the Quickie today swapping out the 150uf caps, and now one side doesn't work. Tried switching tubes, and putting in fresh batteries, but one channel is still out. Been trying to find the PJCCS CD to do some continuity checks, but can't find it anywhere. Help!
Dave
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Are there any voltages that are out of spec?
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don't know, I can't find the PJCCS manual :P The only thing I can find is the original quickie 1.1 manual.. Guessing the voltages/resistance values would be different from that. Should I do some resistance measurements first? (just need to know what the points, are supposed to be). Thanks,
Dave
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You can take voltage measurements and compare them against the standard Quickie manual, as they should be pretty close.
-PB
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ok, so it is safe to skip the resistance measurements?
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here are the voltage readings (voltages are with the pjccs but against the spec of the quickie 1.1 without pjccs):
1,6 30.5v, 19.9v spec 29v
2,7 2mv,1.9mv spec 38v
4,9 223mv, 1.4v spec 2-3v
5,10 0,0 spec 0,0
RD 1.8v spec 4v
RC 2.96v spec 4v
The caps installed in place of the 150uf are 220uf, 4v, black gates. Thanks,
Thanks,
Dave
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here are pjccs voltage readings (did some searching on the forum to find the points):
spec measurement
IA/IB 37-38v 30.25v/30.25v
A6/B6 9-21V 18.8v/19.74v
A5/B5 2V -.5mv/-.7mv
Looks like there is something wrong with A5/B5. Could it be the difference between using the stock caps and 220uf? The new caps are electrolytic as well-the negative poles are on terminals 5 and 10. Also, I checked continuity between A5 and the negative D battery terminal, and between B5 and the other D battery terminal, and both were good. What else could be wrong?
Dave
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Try putting the old caps back.
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only one problem, i had to cut the leads to get the caps out (the leads were wrapped into the terminals pretty good).. Guess I need to order some new ones, is that an email to the queen? Do you think one of the new caps was blown by a turn-on transient of more than 4v? I measured the voltage across the stock caps before the swap (was ~1.5v) but maybe there is a swing of more than 4v when the Quickie is turned on?
Dave
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You can run the Quickie without that cap and measure the voltages again.
-PB
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Did you check the polarity of those caps?
I had lots of problem when building my quickie the first time.
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Hi Bonzo,
Yes, the banded side was installed the same way as stock. The odd thing was that one side worked but not the other.
Dave
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I'd suggest that if the stock caps have leads on them you can swap them back in using alligator clip jumpers.
If you don't have any jumpers go to Radio Shack and buy some. They are a very handy thing to have. I have a number of them right now working on zeroing in on my tweeter level control.
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Hi Grainger,
I'll have to give that a try.. Got a bunch of those lying around. Thanks,
Dave
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You can run the Quickie without that cap and measure the voltages again.
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Thanks for all the responses. I guess the first thing to do is take out the black gates. After that:
1) check voltages at A5/B5 without the 150uf cap
2) check voltages with the 150uf caps in with alligator jumper clips
Hopefully the numbers will be good!
Wish I knew why the numbers were out of whack though, its good to have a root cause on these things :)
Dave
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Hi,
The numbers with and without the 150uf caps are about the same:
IA/IB 30.1v / 30.1v
A6/B6 29.97v / 19.7v
A5/B5 1.82v / 1.40v
Looks like something funny on the A6?? Any thoughts?
Dave
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You now have bias voltage at least. What are your battery voltages?
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Hi Paul,
The 9v batteries are at 7.5v each, and the D batteries are at 1.5v each. Thanks,
Dave
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Your 9V batteries are dead.
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What about A6? That voltage is 29.97 and should be 9-21. A5/B5 are a little low. Is there another issue here? Can the Quickie be safely run this way, or should I still be troubleshooting?
Dave
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I would put in a fresh set of 9V batteries, then remeasure your voltages.
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With new batteries:
IA/IB 36.76v/36.5v
A6/B6 36.3v/23.54v
A5/B5 1.869v/1.795v
Dave
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Back on the first page, I see you did not have this problem; both plates were at a suitable voltage. From that I conclude the PJCCS is, or at least was, working correctly. If the PJCCS were shorted on the A6 side during the preceeding page+ of discussion, you would get these measurements. Not saying that's the problem, just trying to get some perspective.
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Hi Paul,
Any suggestions where a short could be? Maybe by accident during probing (an accidental bridge from pin to pin on the socket tube maybe?) One thing worth noting, the only joints I touched were the connections for the bias caps. I tried to pull the original caps out without using a solder removal tool, and heated it up quite a few times to do this (probably not the right thing to do). Could it be that the 1k got thermally overstressed and that's why the cathode voltage is off? (Would this impact A6 potentially too?)
Thanks,
Dave
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Sorry, the last note was quick without looking closely.
A5 and B5 are the correct value, indicating that the current source is working properly. If you swap the tubes, do you get the same result? It may be a weak tube, or one not yet run in.
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Hi Paul,
Here are the voltages with swapped tubes:
35.6v / 35.62v
35.48v / 21.7v
1.86v / 1.73v
Thanks,
Dave
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This makes no sense to me! Must be missong something.
Try swapping the PJCCS outputs that go to A6 and B6 - if it's not the tubes, it must be the plate load (?)
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Just want to make sure i got this right-desolder a6, and jumper that wire to b6, then desolder b6, and jumper that wire to a6? Thanks,
Dave
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Sorry, I didn't look at the manual so that wasn't clear. I want to move the PJCCS wires to test whether the current source is at fault.
In the manual, OA goes to A2 and OB goes to B6 (pins 2 and 6 both go to the tube plate). Just swap those, OA to B6 and OB to A2. Check voltages at A2/6, B2/6, A5, and B5. Better check A3 and B3, too - these are the grids and should measure near zero volts but let's be sure.
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gonna check later today. I borrowed a capacitor checker too, so that will give another data point on whats up with those.
Dave
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Hi Paul,
These are the measurements with the pjccs outputs moved.
A2/A6 21.39v/21.4v
B2/B6 22.74v/22.74v
A5 1.697v
B5 1.712v
A3 0v
B3 0v
Thanks,
Dave
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Here are the capacitance measurements for the 150uf caps:
90uf
85uf
Is that normal to be that far off 150uf?
There are the measurements for the 220uf caps:
110uf
110uf
Dave
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Well, the problem seems to have gone away.
Are you still hearing only one channel?
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I haven't tried hooking it back up yet, looks like it would be safe to do that now. The one thing that I did besides disconnecting the PJCCS outputs was disconnect A6 (from one of the posts further up), and after realizing that was the wrong wire, re-soldered it (it comes from the terminal strip on the A side). Maybe it was just a marginal solder joint.
Dave
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Hi,
Just tested the Quickie, and both sides work! Guessing I should probably solder the pjccs wires back in (to their original locations). What about the black gate caps, think i can put those back in too? It definitely sounds better with them (there was a little bit of a grainy sound without having any caps in that location).
Dave
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Dave,
Do that one step at a time. Swap the PJCCS back first. Then after verifying it works put the BG caps back.
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The PJCCS does not care which side is which, but I would restore it just so that next time there's a question, you know the wiring matches the manual.
Yeah, put the caps back - making sure they are oriented correctly.
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Thanks everyone, its good to go 8)