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Old 6th September 2007, 05:25 PM   #1
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Unhappy Help Schematic and condensator

Hello at all,
I'd like to have your help about a problem that I have with my audio equipment.

I have (or better, at the moment "had") a solid state amplifier Soundcraftsmen A100 amplifier.

Due to an unknown event, now one of the channel doesn't work. I've opened the case and I discovered that two caps in the power section have gone...

It was a good friend, and I really love how this amplifier sounds; so I want to repair it.

The two "help requests" are:

1) I tried to find the service manual with the schematics without result; I asked also to a couple of schematics website, but they do not have the schematic. Can you help me?

2) Now I need to replace the four electrolitic condensator inside; what do you suggest as best electrolitic caps? what you suggest? What I have to look for when I evaluate the caps available in my country/shops?

My audio system is composed by: an old Mitsubishi preamp strongly modified in every part; a Pioneer CD player PD 73 modified in power, op amps, caps, case, cables; kworks cables (power and signal); Sonus Faber Extrema and Guarneri Homage, Ars Aures F1 and MI as loudspeakers.

This amp managed perfectly all these loudspeakers... especially Estrema, that I know they are not really easy to interface.

Thanks in advance for all your help.

Giuseppe
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Old 10th September 2007, 02:49 PM   #2
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...neither in this forum I get help....

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Old 10th September 2007, 02:54 PM   #3
Netlist is offline Netlist  Belgium
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As for the schematic, Soundcraftsmen are not easy to find but I think a little Googling could reveal something although not necessarily free.

Capacitors in the power supply: What's written on them and what makes you think they are 'gone'?

/Hugo
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Old 11th September 2007, 01:37 PM   #4
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Quote:
Originally posted by Netlist
As for the schematic, Soundcraftsmen are not easy to find but I think a little Googling could reveal something although not necessarily free.

Capacitors in the power supply: What's written on them and what makes you think they are 'gone'?

/Hugo
Hello, thanks for your reply.

I've "googled" all around, but I didn't get any result; I mean, I've founded some company that sell schematics and service manuals, but the results were always the same: "no, we do not have the schematic" or no reply.
Also I tried to look in Google groups, but also there I wasn't lucky.

Regarding the caps, when one of the channels stopped working, I opened the amplifier and two of the four caps were hot and looked like "inflated".
The others seemed ok. Ok, I can test through a multimeter if the caps are ok or not, but... I think they are broken.

Regarding what it's written on the caps, if I'm not wrong the brand is Nichicon and the value ... I don't remember.

I'll check.

Thanks.

BR

Giuseppe
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Old 11th September 2007, 04:09 PM   #5
Netlist is offline Netlist  Belgium
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In that case, the cap is definitely bad.
Replace them all, (two or maybe four) and do your amp a favor and replace the bridge rectifier too.
For this kind of job, you don't need a schematic.

/Hugo
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Old 14th September 2007, 08:03 AM   #6
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Hello Hugo,
for real, upgrading the bridge rectifier was one of the thing I wanted to do.
in the post you can find a picture of the caps I have to replace; the inflated part in in the bottom of the caps.
They are not Nichicon as I wrote. I didn't recognize the brand.
Anyway, on the caps there is written:

CTP FSNKK7 44764
9202 5000 MFD 63V

Ok, 5000 MFD 63V it's easy to understand... but what about the brand and quality?
Also, in changing the caps I've also some constarints given by the small form factor of the amplifier...

what do you suggest to replace that caps and rectifier?

I put the picture of the rectifier in the next post.

Thanks a lot.

Giuseppe
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File Type: jpg caps.jpg (87.4 KB, 103 views)
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Old 14th September 2007, 08:05 AM   #7
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The rectifier: PX KBPC 2502 144

What do you think about it?
Should I change it?
What do you suggest?

Thanks.

Giuseppe
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File Type: jpg bridge.jpg (68.6 KB, 92 views)
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Old 14th September 2007, 09:10 AM   #8
Netlist is offline Netlist  Belgium
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From the picture I would not consider them bad caps.
Please take them out and show a picture of the bottom.
The brand could be BC components.

As for the rectifier, it's a 25A 200V standard bridge rectifier.

/Hugo
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Old 14th September 2007, 09:55 AM   #9
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Is the rectifier good enough or it's better if I upgrade it?

This amplifier, is small, but with it's very low CRF and High damping factor, it's "punchy" and energic driving the loudspeakers (in particular the Extrema). Of course, not really powerful, but at my listening level it's ok.

Regarding caps, the rubber "inflated" part is only at bottom.
The metallic part on top doesn't seem "inflated".

BC components? Never heard before. Are there good?

I'want really to extract the maximum performance from the amplifier (if I can fix it).

I'm new to this huge and full of ideas forum, and I can imagine my questions can seem "wasting time" question because surely discussed before.
I was used to modify my hifi equipment, for 15 years I stopped modifying equipment for various reason. Now, I have this problem and, of course I'm "out of the games".
And I'm looking for an help.



Thanks.

Giuseppe
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Old 14th September 2007, 10:10 AM   #10
Netlist is offline Netlist  Belgium
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Before doing any mods, why not try to fix that one channel?

BC has good caps and if they work good I would not replace them, neither would I touch the rectifier.
Check the rail voltages. If both + and - are ok and the ripple is fine, your PSU is in good shape.

/Hugo
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