Hi guys,
I've just picked up a Sony XM4525 car amplifier; a 2 channel bridgeable amp with discrete circuitry (mosfet) from around 1996,45Wx2.
It's pretty much mint, but as you do, I opened it up to make sure all looked OK inside and to check the bias, and noticed a mod I can't fathom.
A previous owner has connected an Elna Silmic Fine Gold 220uF cap bypassed with a 0.1uF polypropylene cap across the 'power' inputs. The job is really nicely done with neatly heat shrinked leads and neat soldering which makes me think they knew what they were doing.
Can anyone explain what this might be meant to do?
Cheers
Stuey
I've just picked up a Sony XM4525 car amplifier; a 2 channel bridgeable amp with discrete circuitry (mosfet) from around 1996,45Wx2.
It's pretty much mint, but as you do, I opened it up to make sure all looked OK inside and to check the bias, and noticed a mod I can't fathom.
A previous owner has connected an Elna Silmic Fine Gold 220uF cap bypassed with a 0.1uF polypropylene cap across the 'power' inputs. The job is really nicely done with neatly heat shrinked leads and neat soldering which makes me think they knew what they were doing.
Can anyone explain what this might be meant to do?
Cheers
Stuey
I thought a bit harder about this and considered there may have been a service bulletin which required the additions (while acknowledging it most likely wouldn't have specified those caps), and found one about power supply noise on the speakers. I haven't purchased it, but found the text of it which said that if you're getting this issue, there is a cap which has been installed reversed polarity. The fix is to replace, with the note that the silk screening on the board is incorrect. Although it notes 'up to serial number X' and mine is after that number, I had a look at that specific cap and its + lead shows continuity with the - from an adjacent cap, which suggests mine has the issue.
I have to think that someone may have had the problem but not known about the fix, adding the subject caps on the inputs.
When I have time I'll have to have a proper look, as the bulletin appears to suggest the noise occurs if the cap shows failure (presumably leaks or explosion); mine looks fine.
I have to think that someone may have had the problem but not known about the fix, adding the subject caps on the inputs.
When I have time I'll have to have a proper look, as the bulletin appears to suggest the noise occurs if the cap shows failure (presumably leaks or explosion); mine looks fine.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.