Advent 300 Receiver Question

[stellavox]

Hi folks,

Working on this receiver and notice that the output offset on one channel is what I believe to be too high (50mv) versus the other channel's 5mv.

Schematic here:

https://davidreaton.com/wp-content/uploads/2016/08/Advent-300-newer-Amplifier-schematic.pdf

Notice that it uses a number of differential pairs in the inputs and was wondering if I should remove a few of them, and try to match the gains of transistors in input of the "offending" output section channel to lower the offset - or could you suggest another way to lower this.

And while we're at it - can you suggest any other tweaks

THANKS

Charles

 

[JonSnell Electronic]

There is only one differential pair per amplifier; Q300 - 303.
50mV is a good reading. 500mV is too high.

 

[rayma]

Working on this receiver and notice that the output offset on one channel
is what I believe to be too high (50mv) versus the other channel's 5mv.

Agreed, the offset is just fine, and mine works great without any work since new.
Clean the pots and switches, and you'll be good.

 

[Impunity]

I just acquired one of these Advent 300's. It looks like it might have an issue as the 3A fuse is blown so I wont be plugging it in until I've gone through a test procedure to find where the short is.
It's a neat little receiver though and I'm keen to get it cranked up.

Regards John

 

[rayma]

Mine sounds very nice, and has a good but low power amplifier. The phono stage is well designed
for the time. It has cheap parts, though. Clean all the switches and controls while the cover is off.

 

[planet10]

From experience, bw careful, it is easy to break the chip that drives the tuner part.

dave