EDIT: FIXED!
thanks to Douglas Blake and Osvaldo de Banfield.
turned out to be C14 which has dried up resulting in a too short delay in the protection circuitry.
Original post:
Hey folks,
i recently brought a Thule IA100 back to life after it severely burned up on both channels, charred pcb, missing tracks etc.
It is a old rev.6 pcb without the load sharing resistors on the transistors. and some bodges. nasty
https://i.imgur.com/UW5KVrl.jpg
https://i.imgur.com/tmOQSl2.jpg
https://i.imgur.com/bNuyfHl.jpg
https://i.imgur.com/oNyvKj9.jpg
how it looks after fixing it (i added heatsinks later on):
https://i.imgur.com/CfHSXqK.jpg
https://i.imgur.com/fU2Ksds.jpg
took quite a while and lots of parts, but its now working again...
sort of
i still have a big problem with it.. when i turn it on or enable it from standby (relay klicks) it does a loud pop on my speakers.
about 10Vp for a few milliseconds, exactly the same with and without load attached.
its exactly the same on both channels.
i allready disconnected the Preamp (i wonder why people like it so much its just few analog switches and a volume IC..) and the problem persisted. it must be in the power amp stage.
it runs fine after that, but the initial pop may hurt sensitive speakers.
i allready replace the main filter caps and all other capacitors.
i checked connections and measured for broken components (had a broken resistor in the initial repair)
i traced down the STBY signal from the front panel to the protection circuit which sends it via STBY 1 and 2 to the power amplifiers.
All of this did work correctly.
when in standby it draws 10W, when turned on its about 20W.
i just cant figure out whats going on.
its gotta be something both channels use.. theres the rectifier, filtering and protection relay / circuitry.
The problem looks like this
Signals look fine (note: no load attached)
https://i.imgur.com/EfrNwIq.png
https://i.imgur.com/9rbmmag.png
https://i.imgur.com/6sYDD13.png
schematics (of rev7 which is almost the same) found here
https://elektrotanya.com/thule-audio_spirit_ia100_schematics.pdf/download.html
thanks to Douglas Blake and Osvaldo de Banfield.
turned out to be C14 which has dried up resulting in a too short delay in the protection circuitry.
Original post:
Hey folks,
i recently brought a Thule IA100 back to life after it severely burned up on both channels, charred pcb, missing tracks etc.
It is a old rev.6 pcb without the load sharing resistors on the transistors. and some bodges. nasty
https://i.imgur.com/UW5KVrl.jpg
https://i.imgur.com/tmOQSl2.jpg
https://i.imgur.com/bNuyfHl.jpg
https://i.imgur.com/oNyvKj9.jpg
how it looks after fixing it (i added heatsinks later on):
https://i.imgur.com/CfHSXqK.jpg
https://i.imgur.com/fU2Ksds.jpg
took quite a while and lots of parts, but its now working again...
sort of
i still have a big problem with it.. when i turn it on or enable it from standby (relay klicks) it does a loud pop on my speakers.
about 10Vp for a few milliseconds, exactly the same with and without load attached.
its exactly the same on both channels.
i allready disconnected the Preamp (i wonder why people like it so much its just few analog switches and a volume IC..) and the problem persisted. it must be in the power amp stage.
it runs fine after that, but the initial pop may hurt sensitive speakers.
i allready replace the main filter caps and all other capacitors.
i checked connections and measured for broken components (had a broken resistor in the initial repair)
i traced down the STBY signal from the front panel to the protection circuit which sends it via STBY 1 and 2 to the power amplifiers.
All of this did work correctly.
when in standby it draws 10W, when turned on its about 20W.
i just cant figure out whats going on.
its gotta be something both channels use.. theres the rectifier, filtering and protection relay / circuitry.
The problem looks like this

Signals look fine (note: no load attached)
https://i.imgur.com/EfrNwIq.png
https://i.imgur.com/9rbmmag.png
https://i.imgur.com/6sYDD13.png
schematics (of rev7 which is almost the same) found here
https://elektrotanya.com/thule-audio_spirit_ia100_schematics.pdf/download.html
Last edited: