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Projects => Tech Help - Projects Page => Topic started by: jimilee on July 11, 2022, 06:23:39 PM

Title: Archibald volume issue *FIXED*
Post by: jimilee on July 11, 2022, 06:23:39 PM
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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Title: Re: Archibald volume issue
Post by: jeffwhitfield on July 12, 2022, 07:04:04 PM
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?
Title: Re: Archibald volume issue
Post by: jimilee on July 12, 2022, 08:13:07 PM
Quote from: jeffwhitfield on July 12, 2022, 07:04:04 PM
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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Title: Re: Archibald volume issue *FIXED*
Post by: jeffwhitfield on July 13, 2022, 12:01:11 AM
Oh wow! Good to know! That would definitely do it alright. :P
Title: Re: Archibald volume issue *FIXED*
Post by: jimilee on July 13, 2022, 03:19:21 AM
Quote from: jeffwhitfield on July 13, 2022, 12:01:11 AM
Oh wow! Good to know! That would definitely do it alright. :P
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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Title: Re: Archibald volume issue *FIXED*
Post by: mauman on July 13, 2022, 03:40:22 AM
Quote from: jimilee on July 13, 2022, 03:19:21 AM
Quote from: jeffwhitfield on July 13, 2022, 12:01:11 AM
Oh wow! Good to know! That would definitely do it alright. :P
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. 
Title: Re: Archibald volume issue *FIXED*
Post by: Derpinador on July 13, 2022, 08:47:44 PM
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.
Title: Re: Archibald volume issue *FIXED*
Post by: jimilee on July 13, 2022, 09:39:28 PM
Quote from: Derpinador on July 13, 2022, 08:47:44 PM
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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