Archibald volume issue *FIXED*

[jimilee]

So, the hi-pot cuts the volume when I turn it up. Is anyone else experiencing this, or should I dig deeper?


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[jeffwhitfield]

Yeah, that's not normal. I don't recall that happening with mine. Might check the resistors and caps around that pot (R13, R14, C9, & C10) to make sure they're the correct values. Also, is the pot itself an A500k?

Does it matter what the Lo is set on? Or does it cut out regardless of what the Lo is set on?

[jimilee]

Yeah, that's not normal. I don't recall that happening with mine. Might check the resistors and caps around that pot (R13, R14, C9, & C10) to make sure they're the correct values. Also, is the pot itself an A500k?

Does it matter what the Lo is set on? Or does it cut out regardless of what the Lo is set on?

Pot is correct, values in the EQ section are correct. Lo pot acts like it's supposed to without affecting the hi pot. That's what has me stumped.

Edit: It was the Jfet in the buffer, it was affecting it no matter the setting. I replaced the j201 and it works fine now. Thank you for your help!


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[jeffwhitfield]

Oh wow! Good to know! That would definitely do it alright.

[jimilee]

Oh wow! Good to know! That would definitely do it alright.

Funny story, I noticed a blown 470uf before the transistor. Blew the whole bottom right out of it.  Think it may have happened when I briefly plugged in a 15v tip positive dc adapter. Ooops!


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[mauman]

Oh wow! Good to know! That would definitely do it alright.

Funny story, I noticed a blown 470uf before the transistor. Blew the whole bottom right out of it.  Think it may have happened when I briefly plugged in a 15v tip positive dc adapter. Ooops!

Yeah, that 470 uF power cap is not protected from reverse polarity, is it?  An inline 1N5818 between the DC jack and the PCB would do it. 

[Derpinador]

yeah... been there done that but to the 18v version of Callo.. I was at 1st wondering if you used a C instead of A taper pot but should have left a minimal signal at  near full turn. Also wouldn't suprise me if the same inverted polarity jolt toasted that 201.

[jimilee]

yeah... been there done that but to the 18v version of Callo.. I was at 1st wondering if you used a C instead of A taper pot but should have left a minimal signal at  near full turn. Also wouldn't suprise me if the same inverted polarity jolt toasted that 201.

It toasted it proper.


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