Fisher SA-100

adnick

adnick

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Picked up a a new to me Fisher SA 100, outside is not bad, some paint chipping and a few rust bubbles.

Had time to take the bottom off and check capacitors/resistors. The thing looks like it was not used much, extremely clean, and original looking. Some plating gone in a few spots, but not bad.

To my surprise, this is the first amp that I really found nothing wrong, even the power supply 50 UF that’s close to the resistors, looks good and measures 60uf (many show signs of heat damage).

That capacitor was the only one, capacitors/resistors found that was off much at all....

Checked all the ground connections with an ohm meter, ( thanks to Dave G. For all his posts) and they are also good. Planned on a stock restoration first and then decide on EFB II or ?

Don’t have a set of replacement tubes for the 7189s yet, so will have to wait a few days before trying it out.

I’ll post the next question in the Fisher forum, but does anyone have a match for the Fisher brown paint?

Some Pics,

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The Sovtek EL84M (or whatever the cyrillic-writing Russian military version is) would likely be the best choice for this amp.

I would not trust any of the electrolytics unless you have the ability to test them for leakage at their actual operating voltages.
Lots of caps test good for ESR and leakage at a few volts,but when you apply the many-hundreds-of-volts they actually operate at in circuit, pop goes the weasel:eek:
 
arts said:
The Sovtek EL84M (or whatever the cyrillic-writing Russian military version is) would likely be the best choice for this amp.

I would not trust any of the electrolytics unless you have the ability to test them for leakage at their actual operating voltages.
Lots of caps test good for ESR and leakage at a few volts,but when you apply the many-hundreds-of-volts they actually operate at in circuit, pop goes the weasel:eek:
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Appreciate your input ...

Andy
 
+1 on the Sovtek EL84M's and Arts' advice on restoration. These are terrific amps and worth some time and $ to get them in shape for long-term, reliable service. Good luck with it!
Dave

EDIT P.S.: Search in this forum to find an excellent thread Dave Gillespie posted on upgrades and restoration of the SA-100.
 
Dave451 said:
+1 on the Sovtek EL84M's and Arts' advice on restoration. These are terrific amps and worth some time and $ to get them in shape for long-term, reliable service. Good luck with it!
Dave

EDIT P.S.: Search in this forum to find an excellent thread Dave Gillespie posted on upgrades and restoration of the SA-100.
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Yes, appreciate the pointer, have read most of that and book marked it....

VR
Andy
 
Are you planning any changes to the power supply? My own SA-100 has sat in my to-do pile for a very long time for that very reason. When it was still (relatively) serviceable,it was astonishing just how much heat it generated due to the power supply.
My plan was to design a solid state remedy to this fiasco, but you know how that goes....never enough time,blah blah blah.
Every time I see an SA-100,boy,do I feel guilty. I really liked that little amp,probably one of my best sounding ever.
 
arts said:
Are you planning any changes to the power supply? My own SA-100 has sat in my to-do pile for a very long time for that very reason. When it was still (relatively) serviceable,it was astonishing just how much heat it generated due to the power supply.
My plan was to design a solid state remedy to this fiasco, but you know how that goes....never enough time,blah blah blah.
Every time I see an SA-100,boy,do I feel guilty. I really liked that little amp,probably one of my best sounding ever.
Click to expand...

Arts:

Initially no circuit changes, will move the power supply cap away from the side resistors however and change some of the large wire wound resistors.

Implementing some of the clever changes that Heyraz made to his relatively stock SA-100, he did an outstanding job,...

After looking at it closely, my opinion is that the bottom cover is too close to the electronics and doesn’t allow enough air flow.

One SA-100 I looked at had been so hot it completely discolored the copper plating, it looked burned like smoke damage, so I passed on that one.

My plan is to raise it up high, Ordered some 1.75 inch isolation feet which I’m going to mount on the four corners and try running it without the bottom cover.


After my test run I’ll decide if I’m going to do something like Dave’s EFB II

Time to put yours back into service (-;

VR
Andy
 
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The SA-100 is a special amp, plenty of threads on these and EFB is supposed to really bring out the best in them. I have one that I restored stock, and another I have started a restoration on and it will have all the latest mods when finished. The riveted grounding points are problematic on these, only choice is to either create a ground buss throughout or find a way to get the rivets tightened up.
 
RS Steve said:
The SA-100 is a special amp, plenty of threads on these and EFB is supposed to really bring out the best in them. I have one that I restored stock, and another I have started a restoration on and it will have all the latest mods when finished. The riveted grounding points are problematic on these, only choice is to either create a ground buss throughout or find a way to get the rivets tightened up.
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You have 2 (-:

Had a hard time finding one, and all you guys all seem to have them, guess that’s why there’s not many for sale....

Anyone using the center channel, if s how have you implemented it’s use?
 
Yes I’m envious of that 400-C....

BTW: For those that are about to refresh their SA-100, Hayseed Hamfest can custom build a can capacitor, just order one myself 40 600v 10 450v 10 450v 40 600v for $40

No affiliation

Andy
 
arts said:
Really!?!? You guys just wanna make me feel miserable,don't ya? I've got a 400-c in the to-do pile as well. :oops:
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If I had a 400c I’d be working on it (-;

Not gonna happen unless one ends up at my local thrift store )-:

On the bright side, I’ve had some great success on my PAS 2 with mostly original boards ( a few changes)

Went to a high end volume control, and implemented CurcioAudio’s Selector Switch modification, using a high end switch, and Dynacodesign tone, loudness and filter components, Erhard Audio power supply and Dynakitparts transformer, rca upgrade...

Completely got rid of pops and clicks when using the selector, hum is gone, and no crosstalk, or ghosting of any kind, very happy with the results.
 
Yea, I’m muddying the water (-;

Back to the SA-100, and I’ll ask this question again to regain focus.

Anyone have experience using the center channel? If so how was it implemented and what kind of results ensued?


VR

Andy
 
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