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chris_d
Winston Wolf
Joined: Wed Jun 16, 2010 7:32 pm Posts: 11362 Location: ruining everything.
Yes/No: No
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Re: The workbench thread
With normal-ish voltages, i would check the output jacks solderings, and then head straight for the pots, suspecting either a bad one(or one with a solder blob dropped into it) or just a not great solder joint. Can you control the tone of the faint signal? Also, you have tested the rotation of all of the controls to ensure that you haven't merely wired one or more backwards or something silly, as well?
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Tue Dec 07, 2010 8:53 pm |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
Those are the next things I'm going to check properly. The tone controls seem to work although there isn't much signal to go on. It's not Impossible that I've wired them backwards though.
I may be able to borrower an oscilloscope and function generator from work which will help a lot.
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Tue Dec 07, 2010 9:17 pm |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
The guy I could have borrowed an o-scope off wasnt in today so I'm going to jump the output of the 1st stage to the input of the output (via R12) to see if that makes anything happen. I can pull all the relay switching out the circuit as I wired to a socket rather then straight to the relay pins. This will bypass all the other stages and pots/switching so it'll tell me if its an in/out problem if nothing else. Of course other problems could exist too.
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Wed Dec 08, 2010 2:00 pm |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
Looks like I made noob error number 3: jacks wired the wrong way There may be more afoot but that wasnt a good start This is why you shouldnt solder past 11 kids
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Wed Dec 08, 2010 2:30 pm |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
The clean channel passes signal now! Its not all that clean and if the mid and bass dials are on 0 it passes nothing so I've fucked something up there. Nothing from the lead but i'll work on the clean fist as if i've made a cock up it's likely i've repeated it. I have wired the MV backwards though
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Wed Dec 08, 2010 2:54 pm |
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knope
The guy from the place with the thing. The one with the stuff.
Joined: Thu Jul 08, 2010 8:37 pm Posts: 1400
Yes/No: No
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Re: The workbench thread
Ouch... seems like I'm going to have to switch my OCD to overdrive while I put mine together... I just made a small purchase, but I'm still have a long way to go $$$ wise Good lucking debugging!
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Wed Dec 08, 2010 3:11 pm |
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chris_d
Winston Wolf
Joined: Wed Jun 16, 2010 7:32 pm Posts: 11362 Location: ruining everything.
Yes/No: No
Less/More: More
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Re: The workbench thread
Out of curiosity, what did you source the tonestack circuit from?
_________________ STOP FIXING ROCK RECORDS.
START YOUR OWN RELIGION TODAY.
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Wed Dec 08, 2010 3:27 pm |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
laney vh100r
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Wed Dec 08, 2010 3:36 pm |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
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Wed Dec 08, 2010 3:44 pm |
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chris_d
Winston Wolf
Joined: Wed Jun 16, 2010 7:32 pm Posts: 11362 Location: ruining everything.
Yes/No: No
Less/More: More
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Re: The workbench thread
Aye, i just got it from schematic heaven. I wonder why they did it that way with the mid control? I will have to look at it a bit more later when i have some more time to do so. What is it that you like about the sound of that channel?
_________________ STOP FIXING ROCK RECORDS.
START YOUR OWN RELIGION TODAY.
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Wed Dec 08, 2010 4:29 pm |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
It's nice and chimey but in a different way. It works well in a high powered amp without sounding sterile.
The mid is odd. If I knew how to work spice I'd model it to see how it affects the tone.
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Wed Dec 08, 2010 5:10 pm |
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chris_d
Winston Wolf
Joined: Wed Jun 16, 2010 7:32 pm Posts: 11362 Location: ruining everything.
Yes/No: No
Less/More: More
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Re: The workbench thread
It is like they just couldn't decide if they wanted to wire it the Fender way or the Vox way... so they just wired them both up at the same time. Electrically, i guess it is maybe more Voxy in the way it would behave, but i don't really know.
_________________ STOP FIXING ROCK RECORDS.
START YOUR OWN RELIGION TODAY.
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Wed Dec 08, 2010 6:03 pm |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
I never even noticed the vox part! Its a great clean for a high gainer.
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Wed Dec 08, 2010 8:46 pm |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
A ha! I have took off the relay switching and manually jumped to the output. The clean channel works and the pots work as you'd expect. Its very clean and glassy - could do with more bass. apparently this is an issue with split input stage amps but the large bypass cap should have taken care of that. needs tweaking
The MV is very sensitive. The signal off the clean may be too hot.
The lead is very quiet and doesnt overdrive. This may be because of the 470k resistor going into the gain pot and the wiper then having a probably superfluouss 68k grid resistor. I'll remove those to see what happens. Could just be that my switching circuit is a bag of dicks. Probing with a sine wave shows the signal pre v2b tp be much weaker than what goes into the TS of the clean.
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Thu Dec 09, 2010 4:28 pm |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
Turned out it was a bad join to the input of the gain pot! It lives! It lives! I need to play with the interstage attenuation levels on the lead channel as it isnt gainy enough. Currently getting a moderate crunch with the lead controls dimed so it needs to be hotter. I may bring the 3rd stage cathode resisitor down to 10k too. Overall its bright and it needs taming a litte and the bass content needs to go up on both channels.
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Fri Dec 10, 2010 7:01 am |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
Also I'm going to get a 5V regulator later so I can fix the switching. I bought a 6V regulator by accident and 6.3V rectified wont give enough juice to power it so it only outputs ~3.5V and the relays need a minimum of 4V to switch.
For the lead I may up the second stage anode resistor to 220K to get more swing to clip the 3rd stage with.
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Fri Dec 10, 2010 9:49 am |
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chris_d
Winston Wolf
Joined: Wed Jun 16, 2010 7:32 pm Posts: 11362 Location: ruining everything.
Yes/No: No
Less/More: More
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Re: The workbench thread
Regarding the regulator, i don't know if that makes sense? 6.3v rectified should give you just shy of 9vdc before the regulator? Which should be tons for bringing down to 6VDC?
_________________ STOP FIXING ROCK RECORDS.
START YOUR OWN RELIGION TODAY.
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Fri Dec 10, 2010 11:40 am |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
The heater winding is pretty close to its max so its only pumping 7.5 to the regulator which isn't enough for a 7806 it would seem
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Fri Dec 10, 2010 11:52 am |
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chris_d
Winston Wolf
Joined: Wed Jun 16, 2010 7:32 pm Posts: 11362 Location: ruining everything.
Yes/No: No
Less/More: More
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Re: The workbench thread
Ah. I see. Yarp. Looks like it will want at least 8v. What transformer are you using again?
_________________ STOP FIXING ROCK RECORDS.
START YOUR OWN RELIGION TODAY.
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Fri Dec 10, 2010 12:00 pm |
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Zozobra
Henry Kissinger
Joined: Tue Jul 13, 2010 7:00 am Posts: 1105
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Re: The workbench thread
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Fri Dec 10, 2010 12:04 pm |
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