1176 LN Question concerning Output Hiss

[frejo89]

Hey @all

Maybe you can help my here. I got an 1176 from a friend of mine - he ask me to have a closer look to it.

It creates a strong, well audible hiss noise coming from the output - In increases with the amount of the dialed output. The other controles do not have any influence on that. Audio-Signal is very low.

Any clue, what to check, or what can be the problem most likely?

the pcb description is the following:
V2.2
1176LN REV D
(c) 2013 MNATS

thanks in advance !

Jonas

 

[kidb]

Could be transistors, going off the rev d schematic (urei vintage) could be Q1,2,3 or 14. I’d verify voltage first, measure resistors, test transistors, assuming you don’t have an oscilloscope to trace signal?

 

[frejo89]

Could be transistors, going off the rev d schematic (urei vintage) could be Q1,2,3 or 14. I’d verify voltage first, measure resistors, test transistors, assuming you don’t have an oscilloscope to trace signal?

ok, thanks for your answer.
no, unfortunately I do not have an oscilloscope here

voltages measures at first were ok..
But changing transistors is no big deal at all. so thank you for this hint

Any concern to swap the 2N3391A to some 2N5089s ?
supposing they are lower-noise

 

[kidb]

Not familiar with the 2n5089 but assuming it is a good replacement no issue with trying it!