artifactaudio
Member
- Joined
- Jan 19, 2018
- Messages
- 5
Working on a 1176 Rev D with an issue I haven’t ran into before.
Unit calibrates, works fine, but over time (aka, with heat) gain reduction goes away. Engineer who it belongs to complains that as the session goes on, the “compression” effect goes away and it just sounds like the “dry” effect.
Unit will operate within spec, but when I put a heat gun on the board (namely near the input amp section) I can recreate this issue. Interestingly, when the signal gen is disconnected DC voltages don’t seem to fluctuate much with heat. This makes me think what’s actually happening is heat is making the input level drop.
Leaky cap? Failing fet? Wanted opinions before I pull out the parts cannon as I’m feeling a little lost! Tested basically all caps and couldn’t find any leakers.
Also if anyone knows where the hairball Rev D test points correspond to the MNAT’s schematic, that would be super helpful.
Unit calibrates, works fine, but over time (aka, with heat) gain reduction goes away. Engineer who it belongs to complains that as the session goes on, the “compression” effect goes away and it just sounds like the “dry” effect.
Unit will operate within spec, but when I put a heat gun on the board (namely near the input amp section) I can recreate this issue. Interestingly, when the signal gen is disconnected DC voltages don’t seem to fluctuate much with heat. This makes me think what’s actually happening is heat is making the input level drop.
Leaky cap? Failing fet? Wanted opinions before I pull out the parts cannon as I’m feeling a little lost! Tested basically all caps and couldn’t find any leakers.
Also if anyone knows where the hairball Rev D test points correspond to the MNAT’s schematic, that would be super helpful.
