Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: clarkleach on December 27, 2021, 08:23:05 pm

Title: Hoffman AB763-Twin BOM/Schematic question
Post by: clarkleach on December 27, 2021, 08:23:05 pm
I was going through the BOM, putting together a price to retrofit a '65 TRRI, and noticed what I think is an error.  If it is not can someone explain?
The BOM lists C26 as "not used" in the notes column.  According to the schematic, this is the feedback coupling for the tremolo oscillator.  Surely it would not oscillate without it.  Right?
Title: Re: Hoffman AB763-Twin BOM/Schematic question
Post by: SILVERGUN on December 27, 2021, 08:40:19 pm
It is always helpful to post links to the info you are referencing.
Title: Re: Hoffman AB763-Twin BOM/Schematic question
Post by: clarkleach on December 27, 2021, 08:47:20 pm
Quote from: SILVERGUN on December 27, 2021, 08:40:19 pm
It is always helpful to post links to the info you are referencing.
https://el34world.com/schematics.htm#Hoffman_AB763_Two_Channel_ (https://el34world.com/schematics.htm#Hoffman_AB763_Two_Channel_)
Title: Re: Hoffman AB763-Twin BOM/Schematic question
Post by: sluckey on December 27, 2021, 08:50:13 pm
Trust the schematic.
Title: Re: Hoffman AB763-Twin BOM/Schematic question
Post by: pdf64 on December 28, 2021, 04:36:14 am
Quote from: clarkleach on December 27, 2021, 08:23:05 pm
I was going through the BOM, putting together a price to retrofit a '65 TRRI, and noticed what I think is an error.  If it is not can someone explain?
The BOM lists C26 as "not used" in the notes column.  According to the schematic, this is the feedback coupling for the tremolo oscillator.  Surely it would not oscillate without it.  Right?
Correct, the ‘not used’ seems to be in error.
Title: Re: Hoffman AB763-Twin BOM/Schematic question
Post by: EL34 on December 28, 2021, 08:00:53 am
Quote from: clarkleach on December 27, 2021, 08:23:05 pm
I was going through the BOM, putting together a price to retrofit a '65 TRRI, and noticed what I think is an error.  If it is not can someone explain?
The BOM lists C26 as "not used" in the notes column.  According to the schematic, this is the feedback coupling for the tremolo oscillator.  Surely it would not oscillate without it.  Right?


The BOM line was probably copied and pasted and the not used did not get erased
The schematic is correct
Title: Re: Hoffman AB763-Twin BOM/Schematic question
Post by: clarkleach on December 28, 2021, 12:50:56 pm
Quote from: EL34 on December 28, 2021, 08:00:53 am
... The schematic is correct
Is there a document available with turret spacing dimensions?
This would be helpful in selecting components.