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CA-F1 on the bench

Hyperion said:
...I note on the schematic for the main filter capacitors it says 'Note C601 & C602 = 1000µF, 63V, (Japan Model 2200µF, 63V)'. As you will note above they are now 3300µF, 63V as this is my rebuild spec' :king: other capacitors (with careful consideration) have received similar treatment, a restore methodology copied shamelessly from Ben, @Leestereo :thumbsup:...
Click to expand...

You're more than welcome to "copy and distribute"...it's said that "imitation is the sincerest form of flattery", consider me flattered.
 
@Hyperion It might just be photo glare, but it certainly looks like one or more cap has its shrink pulled back, indicating expansion (bulging or vent rising). If true in real life, I'd replace those even if tested okay.

I *think* you've already replaced these but figured I'd mention just in case.
 
I am finally getting close to finishing this,

Here is a picture of the completed restoration

IMG_3045a.jpg

You'll be able to see quite a few WIMA films used to replace electrolytics, there are also 6 mounted on the track side, as I used two 4.7µF in parallel to create a replacement for the original 10µF electrolytics, as I was unable to fit either a 10µF Wima or both 4.7µF on the top-side. You'll also notice some replaced resistors, the usual electrolytic replacements, and three relays.

Along the way I found damaged MM Head Amp OP transistors, (their replacements were also getting extremely hot, so I tweaked the bias a bit ;) ), and a single damaged JFET in the MC Head Amp, I solved this by replacing it, luckily the damaged one was a 2SK163, (with an intermittent near short circuit between gate and source), with the single 2SK163 used elsewhere in the unit. The two sets of six 2SK163 are supposed to be matched, and in turn they are matched to two sets of six 2SJ44's. So, as the manufacturing code on the single 2SK163 was the same as for the matched sets of six I used it as a replacement, making the assumption that it was a match for the others. I used another much more common JFET for the much less critical (non-audio) spot vacated by the 2SK163. ;)

The power supply is now very stable, settling quickly and accurately to +/-40 Volts, the unit is also very quiet, I am able to turn it up to full volume (even with MM or MC selected) - still with the covers off, and just hear some faint noise in the speakers with the AU-919 being used by me as the power amp during testing. As part of the restore I also performed the 'Martin Kuhne' modification to the MM head amp, (originally used and described in his AU-X1 restore). With the same excellent result as before, it has eliminated the very drifty DC offset that is a feature of this design.

How does it sound?
It really is excellent, very nice to listen to indeed, a fitting partner for the BA-F1 owned by the same AK member (and reconditioned by me). :)

I still have to refit the internal MC Head Amp cover, and the external covers, and give it a final clean and check over - then it's done. :thumbsup:
 
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@Hyperion What did you use to replace the 10uF capacitors on F-2992 (C39, C40) and F-2993 (C31, C32) with? Looks like you used WIMA MKSII?
Did you change the value then? 4.7uF?
 
Hyperion said:
there are also 6 mounted on the track side, as I used two 4.7µF in parallel to create a replacement for the original 10µF electrolytics, as I was unable to fit either a 10µF Wima or both 4.7µF on the top-side.
Click to expand...

Magnus Back said:
@Hyperion What did you use to replace the 10uF capacitors on F-2992 (C39, C40) and F-2993 (C31, C32) with? Looks like you used WIMA MKSII?
Did you change the value then? 4.7uF?
Click to expand...
 
I was wondering if it is a possibility to use the place for the film capacitor that they have in the Japanese model for the second 4,7 uF?

Screenshot_20230110-172918_Moon+ Reader.jpg
 
@Hyperion, just saw this old thread, and had two comments-
Really nice work on a nicely laid out chassis, and, I, too, am shamelessly using @Leestereo’s rule-of-thumb about increasing the value on local bypass caps. It just makes SO much sense to stiffen the supply rail(s) throughout these units, as Ben suggests. Increasing this capacitance in a distributed way can only result in cleaner power delivered to all of the subcircuits, and cleaner output to the speakers.
 
Just some helpful hints for those trying to maximize the sound quality of their ca-f1. It's a great sounding preamp but you would never know that if it's still built to it's U.S. version stock spec, even recapped. The key to much improved sound quality is found right in the service manual and on the circuit boards themselves. If you don't appreciate my easter egg hunt, just message me and I will fill you in. The amp goes from and rolled off and lacking width and depth to the quality that this era of sansui is known for.

Beyond that, I was able to fit a Shindengen Schottky rectifier (leg bending required). I also replaced the SD and SB finals in each amp section with faster parts.
 
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Hi, I’m the current owner of a Sansui BA-F1, that you worked on, some 6(?) years ago, as posted on here….
It’s a bit of a long story but I now have 2 matching CA’s to go with it.
The first, I bought from Germany as restored.
The second (bought purely for the rack ears), is a unrestored JDM model, which I considered selling, once I removed the “ears”.
Only recently, did I have a look inside the “restored” item, only to discover what (even to my untrained eyes) looks like a bit of a mess, as I don’t know what the Black Flag capacitors have been replaced with (see photo)
I need to decide if I should get you (possibly?) to restore one or the other (or possibly both, lol)
Any advice would be greatly appreciated: Mark.IMG_2963.jpeg
 

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Drayton mon said:
Hi, I’m the current owner of a Sansui BA-F1, that you worked on, some 6(?) years ago, as posted on here….
It’s a bit of a long story but I now have 2 matching CA’s to go with it.
The first, I bought from Germany as restored.
The second (bought purely for the rack ears), is a unrestored JDM model, which I considered selling, once I removed the “ears”.
Only recently, did I have a look inside the “restored” item, only to discover what (even to my untrained eyes) looks like a bit of a mess, as I don’t know what the Black Flag capacitors have been replaced with (see photo)
I need to decide if I should get you (possibly?) to restore one or the other (or possibly both, lol)
Any advice would be greatly appreciated: Mark.View attachment 3743451
Click to expand...
See top centre and bottom right of photo
 
Drayton mon said:
Hi, I’m the current owner of a Sansui BA-F1, that you worked on, some 6(?) years ago, as posted on here….
It’s a bit of a long story but I now have 2 matching CA’s to go with it.
The first, I bought from Germany as restored.
The second (bought purely for the rack ears), is a unrestored JDM model, which I considered selling, once I removed the “ears”.
Only recently, did I have a look inside the “restored” item, only to discover what (even to my untrained eyes) looks like a bit of a mess, as I don’t know what the Black Flag capacitors have been replaced with (see photo)
I need to decide if I should get you (possibly?) to restore one or the other (or possibly both, lol)
Any advice would be greatly appreciated: Mark.View attachment 3743451
Click to expand...
That doesn't look fully restored. Some transistors and diodes look replaced but the electrolytic capacitors are original.
 
Drayton mon said:
I need to decide if I should get you (possibly?) to restore one or the other (or possibly both, lol)
Click to expand...
Unfortunately I am currently having an extended rest from working on other people's units, with the strong possibility I will not start again.

Drayton mon said:
Any advice would be greatly appreciated
Click to expand...
I am happy to try and answer any queries you may have.
 
This pod of resistors is likely functional but not a good way to execute a reliable long term 'restoration' IMO.
Screenshot_20260416-092406.png
 
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