Hi!
I just read this thread after seeing your pics of your aleph 5...
And I just want to contribute something similar to what you did to you Sony...
I took an old Marantz Receiver from my Dad (built in 78, a SR 2000), and ripped out it's heart (the amp), without the receiver and pre-amp part.
The transformator did hum quite a lot, and after agreeing with some friends that electrolytics get bad when the amp is not powered often enough (which it wasn't for four years), I started replacing ALL electrolytics.
First of all I exachanged the PSU caps... well, I went a little bit over the top with the replacement, I took 8700 uA BHC SlitFoil, and only by exchanging them, the change was dramatic...
The hum of the transformator was almost completely gone, and the amp did not get as warm as before.
Next I exchanged all remaining electrolytics with Panasonic FC (except 1uF / 50 V, which isn't available as Panasonic FC, so I took Elna Cerafine for that), and the sound is pretty amazing. Now I plan to exchange the (pretty standard) rectifiying diodes with ultra fast switching TO220 ones...
I still think the sound blows my self made GainClones away, so now I have to wait for completion of my DoZ to compare it to that...
After this experience I am pretty sure that I will buy some old (good) amps again so time in order to refit them with new and better parts...
If nothing is really broken in an old amp, exchanging electrolytics (and maybe pots / diodes) can sometimes produce wonderful, better-than-new products...
Bye,
Arndt
I just read this thread after seeing your pics of your aleph 5...
And I just want to contribute something similar to what you did to you Sony...
I took an old Marantz Receiver from my Dad (built in 78, a SR 2000), and ripped out it's heart (the amp), without the receiver and pre-amp part.
The transformator did hum quite a lot, and after agreeing with some friends that electrolytics get bad when the amp is not powered often enough (which it wasn't for four years), I started replacing ALL electrolytics.
First of all I exachanged the PSU caps... well, I went a little bit over the top with the replacement, I took 8700 uA BHC SlitFoil, and only by exchanging them, the change was dramatic...
The hum of the transformator was almost completely gone, and the amp did not get as warm as before.
Next I exchanged all remaining electrolytics with Panasonic FC (except 1uF / 50 V, which isn't available as Panasonic FC, so I took Elna Cerafine for that), and the sound is pretty amazing. Now I plan to exchange the (pretty standard) rectifiying diodes with ultra fast switching TO220 ones...
I still think the sound blows my self made GainClones away, so now I have to wait for completion of my DoZ to compare it to that...
After this experience I am pretty sure that I will buy some old (good) amps again so time in order to refit them with new and better parts...
If nothing is really broken in an old amp, exchanging electrolytics (and maybe pots / diodes) can sometimes produce wonderful, better-than-new products...
Bye,
Arndt
Jan Didden
the guys from www.schaltungsdienst.de sent me at last the service manual.
It is just like you told me.
Everything is there, all the regulations components, substitution semiconductors.
All I needed for fixin' the amp (except for the glue hint and the cold spray trick on the caps)
It costed €16 with pp. I really spent less with the help of you guys, but the service manual helped me to understand a little more about the amp.
If you like I can post the schematics, to see what we were talking about all this time 😉
Thanks again,
the guys from www.schaltungsdienst.de sent me at last the service manual.
It is just like you told me.
Everything is there, all the regulations components, substitution semiconductors.
All I needed for fixin' the amp (except for the glue hint and the cold spray trick on the caps)
It costed €16 with pp. I really spent less with the help of you guys, but the service manual helped me to understand a little more about the amp.
If you like I can post the schematics, to see what we were talking about all this time 😉
Thanks again,
PedroPO said:
Posting them could bring new life into this threat but what about copyrights?
🙂
Hugo
I'll post only the amp part without any reference to the semiconductor names.
If it were so confidential, www.schaltungsdienst.de could not sell it (fotocopies in fact). Maybe it has lost its copyrigths after 20 years or so.
Do you think I would be in trouble or the forum?
What you think?
If it were so confidential, www.schaltungsdienst.de could not sell it (fotocopies in fact). Maybe it has lost its copyrigths after 20 years or so.
Do you think I would be in trouble or the forum?
What you think?
sony
Hi Pedro,
I have been away from the forum some time, but just noticed the last couple of posts.
This offset still is bothering me at least, I hate loose ends. So, let's have the schematic. Since we use it not commercially, just for troubleshooting, we use it for the purpose it was made, should not be any problems.
Jan Didden
Hi Pedro,
I have been away from the forum some time, but just noticed the last couple of posts.
This offset still is bothering me at least, I hate loose ends. So, let's have the schematic. Since we use it not commercially, just for troubleshooting, we use it for the purpose it was made, should not be any problems.
Jan Didden
Cradle22,
Not to get too far off the subject, but 1uf 50V FC caps are indeed available...I'm staring at a pile of 'em now.
PedroPO,
Just post it. 😎
Not to get too far off the subject, but 1uf 50V FC caps are indeed available...I'm staring at a pile of 'em now.
PedroPO,
Just post it. 😎
Why not just replace the input pairs on both channels? I'd suggest someting like a 2SC2547... It is possible that the problems you have experianced with the amp have damaged or degraded the current ones.
My purpose of all this was to repair the amp - not improving it.
The amp is a 20 year old bastard from Sony.
I did it for the challenge. If I can make a Aleph 5 I can also repair an old amp ! (well, with a little help from my friends 😉)
I made a side by side test with a 5W SOZ.
The Sony is really outdated 🙁 the bass, in the middle position is awful. too strong and over ressonant - I believe that is due to a "built in loudness" as is said on the service manual). I cannot listen to it without a little bass correction.
It reminds me that SOZ is a great amp!!! 😀
The amp is a 20 year old bastard from Sony.
I did it for the challenge. If I can make a Aleph 5 I can also repair an old amp ! (well, with a little help from my friends 😉)
I made a side by side test with a 5W SOZ.
The Sony is really outdated 🙁 the bass, in the middle position is awful. too strong and over ressonant - I believe that is due to a "built in loudness" as is said on the service manual). I cannot listen to it without a little bass correction.
It reminds me that SOZ is a great amp!!! 😀
Agreed. But if you want to get rid of the DC offset, why not throw a couple of $0.50 transistors in there?
PedroPO said:
Try injecting a square wave and look at the output with a scope.
All bass & treble in middle position, loudness off. You won't believe your eyes with old amps like this.
A few weeks ago, I repaired an old Carad amp.
Every channel had his tone pots.
I had to turn all bass & treble pots far from their middle position to get a more or less flat square wave.
I wonder if new commercial amps still have the same problem?
I think commercial brands did this on purpose, so people could say: Look and hear how good it sounds even when everything is flat.
/Hugo – doesn’t like tone controls
Simplifying
The SOZ is also simpler.
Why don't you bypass all the filtering stages in the Sony's feedback? Things may start sounding better then.
Carlos
PedroPO said:
The SOZ is also simpler.
Why don't you bypass all the filtering stages in the Sony's feedback? Things may start sounding better then.
Carlos
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