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Tap Tempo Tremolo Again

Started by Guybrush, March 11, 2014, 12:41:35 AM

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Guitarmageddon

Since you're only a cap and a pull down resistor from the output,
a) the problem has to be there (1M shorting straight to ground- wrong value or bad resistor [I've never actually seen one tho])
b) It's pretty easy just to wire this part off-board.

My guess, and I know from bitter experience, is that the board is damaged. I've found these multilayer boards have no tolerance for de-soldering of any kind. 
Spud knows tone!

Captain Cod at
www.codtone.com

Guybrush

Quote from: Guitarmageddon on May 08, 2014, 10:33:25 PM
Since you're only a cap and a pull down resistor from the output,
a) the problem has to be there (1M shorting straight to ground- wrong value or bad resistor [I've never actually seen one tho])
b) It's pretty easy just to wire this part off-board.

My guess, and I know from bitter experience, is that the board is damaged. I've found these multilayer boards have no tolerance for de-soldering of any kind.

Ahh ok. Please could you mark on the photo which cap and resistor you mean? I'm crap at following schematics.

Guitarmageddon

The cap is the 1uf at points 12 & 13 on my old illustration, and the resistor is the 1M to it's left.
You will have continuity to ground at the 1Ms top end, but shouldn't at the other or from either end of the cap.
Spud knows tone!

Captain Cod at
www.codtone.com

Guybrush

Great stuff. I will check later today.

Thanks again!

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Guybrush

Checked both components and there's no ground connection other than the top side of the resistor. Maybe one of them is bust. I'll have a look at removing them but it might just be easier for me to connect the output (and a capacitor) to the gain pot lug as I mentioned above.

Would there be any downside to me doing this? What do the resistor and cap I am bypassing add to the circuit?

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midwayfair

Quote from: Guybrush on May 09, 2014, 02:24:55 PM
Would there be any downside to me doing this? What do the resistor and cap I am bypassing add to the circuit?

The resistor is a pull-down, to prevent pops. The capacitor is extremely important: It's the decoupling capacitor to remove DC. If you simply put the output to your amp, you have 4.5V of DC instead of the normal 0DC. If you plug it into an amp without an input cap, that's more than enough DC to destroy a tube (and possibly a lot more). It might work for your amp -- most modern production amps have an input cap -- but you don't want to risk plugging it into something else and destroying the amp.

Guybrush

Cheers Jon.

I guess I could simply wire the resistor and cap off board between the pot lug and output?

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Guitarmageddon

Yep, attach the cap to the gain pot, it's other end is the output and will go to your stomp switch, 1M there output to ground.
Spud knows tone!

Captain Cod at
www.codtone.com

Guybrush

Worked a treat! Thank you so much for all your assistance. And thanks to everyone else who has also helped.

If it wasn't quarter to one in the morning here in the UK I'd be cranking my amp and blasting out How Soon is Now by the Smiths with my now fully working trem!

The neighbours are in for treat in the morning! ;-)

Thanks again.

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