Hello!
I have some trouble with a modded Audioanalyse PA-90 integrated amp: the right side runs much hotter than the left side and is almost untouchabe.
For those interested, let me introduce Audioanalyse first. They were a French company founded in the early 1970's and continued to make amplifiers until mid eighties when they went bankrupt. Although AA made beautiful amps (the PA-90 has been on display in the NY museum of modern arts, don't know when though) they were notoriously badly constructed. Plastic snap-in binding posts, messy soldering and wiring (in my opinion) and more often than not they ran too hot: as a result of that most of the survivors now have fried pcb's.
A dutch company named Duson eventually bought Audioanalyse and continued to produce and revise them, this time with a higher production standard. Unfortunately to no avail: Duson is also long gone.
The above and some images were all google told me (apparently that is still possible!). Lacking sufficient knowledge of electronics I now need help
.
Here are picture-links of the original PA-90:
- Top open: http://i43.tinypic.com/30b0fh0.jpg
- Advert: http://1.bp.blogspot.com/-2MOWeKiYY...hXK2l25npCs/s1600/audioanalyse+reklame+87.jpg
The specimen I accidentally managed to buy 2 years ago gradually broke down on me, and I have been gradually patching it up. I removed the input selector boards (chip-based...?) and the opamp/pre-stage that had all sorts of bass / treble / cutoff mumbojumbo. This cleaned up the sound considerably but left me with one dysfunctional looking amp. Then the pot started to fail and I decided to revise the chassis. Welded new back and faceplate in place, cleaned pcb's and fitted some proper connectors and an alps pot. Had some issues with an accidental ground-loop but that's sorted now.
I've attached some pictures:
- The amp as it is now.
- The new front, homemade volume knob, fuse and power-switch that I still need to install.
- The tiny pots I suspect being responsible for bias correction (If that's why it runs too hot left).
So: any advice? Please let me know if I should post more pictures, unfortunately I couldn't find a circuit schematic. Thanks!
I have some trouble with a modded Audioanalyse PA-90 integrated amp: the right side runs much hotter than the left side and is almost untouchabe.
For those interested, let me introduce Audioanalyse first. They were a French company founded in the early 1970's and continued to make amplifiers until mid eighties when they went bankrupt. Although AA made beautiful amps (the PA-90 has been on display in the NY museum of modern arts, don't know when though) they were notoriously badly constructed. Plastic snap-in binding posts, messy soldering and wiring (in my opinion) and more often than not they ran too hot: as a result of that most of the survivors now have fried pcb's.
A dutch company named Duson eventually bought Audioanalyse and continued to produce and revise them, this time with a higher production standard. Unfortunately to no avail: Duson is also long gone.
The above and some images were all google told me (apparently that is still possible!). Lacking sufficient knowledge of electronics I now need help
Here are picture-links of the original PA-90:
- Top open: http://i43.tinypic.com/30b0fh0.jpg
- Advert: http://1.bp.blogspot.com/-2MOWeKiYY...hXK2l25npCs/s1600/audioanalyse+reklame+87.jpg
The specimen I accidentally managed to buy 2 years ago gradually broke down on me, and I have been gradually patching it up. I removed the input selector boards (chip-based...?) and the opamp/pre-stage that had all sorts of bass / treble / cutoff mumbojumbo. This cleaned up the sound considerably but left me with one dysfunctional looking amp. Then the pot started to fail and I decided to revise the chassis. Welded new back and faceplate in place, cleaned pcb's and fitted some proper connectors and an alps pot. Had some issues with an accidental ground-loop but that's sorted now.
I've attached some pictures:
- The amp as it is now.
- The new front, homemade volume knob, fuse and power-switch that I still need to install.
- The tiny pots I suspect being responsible for bias correction (If that's why it runs too hot left).
So: any advice? Please let me know if I should post more pictures, unfortunately I couldn't find a circuit schematic. Thanks!