Help Saving 400-CX SA-100 and 100-R Tuner

Discussion in 'Fisher' started by moondogtn, Oct 10, 2017.

  1. moondogtn

    moondogtn AK Subscriber Subscriber

    Messages:
    437
    Location:
    Pleasanton, TX
    Dave, I haven’t checked the can cap but just assumed it should be replaced? I’ve been doing some reading and it seems the EFB would definitely be a worthwhile addition. Should I do it now or get it running first?
    I’d like to get this amp prepared for a longer, productive life.

    So, I will do some more reading to see what all this entails. I’ve read threads by notdigital and ronton3. I think there was another that I was looking for but can’t find it. I’ll look again later.
    I’ll get back here once I get it sorted out so that I can ask more relevant questions.
    As always, thanks for help and suggestions.

    Bill
     

     

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  2. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
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    EFB is definitely worth doing since a significant ancillary reason is that the unit will no longer be a cooker! All those heat throwing wirewounds would be eliminated with the mod. Of course, the primary reasons for the mod are laid out in Dave's thread.

    BTW: My opinion FWIW is that you should get it working first. Once you iron out the kinks, then you can enhance its performance with modification.
     
  3. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    21,440
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    ALWAYS Repair, get it working, THEN Modify or update it.
     
  4. moondogtn

    moondogtn AK Subscriber Subscriber

    Messages:
    437
    Location:
    Pleasanton, TX
    I haven’t given up just been busy. I was finally able to spend some time with the SA-100 this evening. I replaced the small electrolytics. I used the axial te series by sprague.
    50uF 50 volts like for like and the 25 uF 6 volt I used 25 uF 16 volts.
    I don’t have a can cap just yet but will get one ordered. I’ll probably use Tom at Hayseed unless someone knows of a drop in replacement.

    Just doing a preliminary visual, I noticed some wiring that may have gotten hot. I tried to capture this in first two attached pictures. Is this normal for this amp?
    Last two are before and after replacing caps.

    Bill
     

    Attached Files:

  5. moondogtn

    moondogtn AK Subscriber Subscriber

    Messages:
    437
    Location:
    Pleasanton, TX
    I was looking and notice that several folks have used this cap with success. Which is preferred? Cost is about the same for either option. https://www.tubesandmore.com/products/capacitor-ce-mfg-525v-40402020uf
    I saw a post stating that some modification may be required using the CE cap.

    I could also have Hayseed bump voltages slightly if it is a good idea?

    Thanks.

    Bill


    Bill
     
  6. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    I prefer Hayseed just for the Temp ratings. 105*C rating on Hayseed. 55*C on the Mallory copy from AES. The caps at AES aren't bad, but their temp rating is low.
     

     

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  7. moondogtn

    moondogtn AK Subscriber Subscriber

    Messages:
    437
    Location:
    Pleasanton, TX
    Larry, thanks. I let them know to bump up voltages to 525 or so. Should have it ordered today. I plan to try and work on soldering all the grounding tabs this evening.

    Bill
     
  8. moondogtn

    moondogtn AK Subscriber Subscriber

    Messages:
    437
    Location:
    Pleasanton, TX
    I was able to get all of the tabs grounded except one. Pic is prior to new cap being installed. It reads fine on meter but may go ahead and try to do it but I need to remove transformer leads to do it.

    I’m using a good Weller with a chisel tip. This chassis is a brute to heat up.
    Any tips?

    I’m dreading the removal of that can cap. It will take some heat to few up that tab soldered to the chassis. I also have hakko 808 gun that may help.
    If I break the wafer, I’ll have to drill out and mount new one but noticed that those rivers don’t go all the way through the chassis.

    One step at a time....

    Bill
     

    Attached Files:

  9. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
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    Location:
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    Usually 2 irons or guns on either side will heat up a chassis joint in good time. When/if you have to replace the wafer, you can use 4x40x5/8" machine bolts.
     
  10. heyraz

    heyraz AK Subscriber Subscriber

    Messages:
    1,751
    Location:
    Long Branch, NJ
    I used a 140 watt Weller gun, flux, braid and a lot of patience.
    I applied heat only to the underside because I didn't want to damage the topside's paint finish.
    Flux is messy, but I couldn't have done the job without it. I dipped the braid in flux, put the braid against the area to be de-soldered and applied heat to the top of the braid. The solder moved quickly from the chassis into the braid maybe 1/2 inch at a time. I snipped off the loaded braid and repeated the process until all was clean.
     

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