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500c Rundown and Refurb Questions

Discussion in 'Fisher' started by Csermonet47, Apr 18, 2017.

  1. Tcomisky

    Tcomisky AK Subscriber Subscriber

    Messages:
    3,051
    Location:
    Lawrenceville, NJ

    I found a few 10k's in my bin. I found a few nice ones that will work.

    For the price of a stamp I could send you one, up to you.

    IMG_3027.JPG
     
  2. Tcomisky

    Tcomisky AK Subscriber Subscriber

    Messages:
    3,051
    Location:
    Lawrenceville, NJ
    Here's where I put the bias resistor pot. My 500C already had the selenium rectifier changed out to a silicon bridge, so I just left it.. although, I probably should clean up the sloppiness.

    I ended up ordering the Hayseed can caps as well. I WAS going to stuff the originals, but, my laziness got the better of me. :)


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  3. Csermonet47

    Csermonet47 New Member

    Messages:
    19
    Location:
    Atlanta
    I couldn't imagine restuffing the originals. I'm not sure how you could remove them without breaking tabs. The Hayseeds are nice though. Not the same style construction as the old ones, but I like having the new stuff so I don't have to worry about it. Thank you for the offer on the 10k. We can work out the details in private messages.

    I scored a really clean faceplate off eBay for a decent price that should be here next week. I have been running around so haven't been able to test voltages, but I should be back at it soon and see what areas need to be messed with.
     
  4. Tcomisky

    Tcomisky AK Subscriber Subscriber

    Messages:
    3,051
    Location:
    Lawrenceville, NJ

    There's a few threads on can re-stuffing on here, I've done it two different ways before. One way is to pry around the edge at the bottom, the other is to cut the bottom on a lathe then use a clamp. Both have merits.
    I always keep the old cans for this purpose.
     
  5. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,319
    Location:
    Glen Burnie Md.
    Csermonet47. Removing a CAN CAP isn't as hard as it seems. The worst part is getting the solder off the tabs and chassis so it can be pulled out. Some tabs have splayed end that grab the chassis and they bend back when you straighten out the tab itself. In this case twist the tab slightly past the slot then grab the whole tab at the chassis with a small pair of vise grips or 8" electricians plier and squeeze against the flat. The splayed tabs will flatten out and then you give them a slight squeeze along the edge. Twist the tab back so it's lined up with the slot. Do all 4 this way. Then grab the can cap and start rocking it in a circular motion and pulling at the same time. It'll pop out. For tabs without the splayed end just twist it so it lines up with the slot. Do all 4 tabs. Rock and pull. Then open up as noted in previous posts, empty out old guts and reload.

    Larry
     
  6. Csermonet47

    Csermonet47 New Member

    Messages:
    19
    Location:
    Atlanta
    I will keep that in mind if I restore another one in the future. I just broke the tabs and thew them in the trash.

    I brought my record player back from home and it sounds great. At least through the left channel. The right channel is gone. I suspect its that spotty volume pot but I will have to poke around to know for sure. The only thing that changed since it worked was I blew it out with compressed air and took the tubes out to wax the chassis. I switched some tubes around to see if that helps but I still got nothing.
     
  7. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,319
    Location:
    Glen Burnie Md.
    Make sure you have the correct tubes in the right sockets. Improper placement has ruined more than one day. Run a little Deoxit in all of the switches and pots, then finish them with Faderlube to replace some of the lubricant. Failure to use a lubricant will ruin the pots / switches very quickly.
     
  8. RORER_714

    RORER_714 New Member

    Messages:
    11
    Location:
    Brooks, Georgia
    Can you tell me how you cleaned the chassis? I have the block spots, not sure how or what to use?
    Thank you!
     
  9. Csermonet47

    Csermonet47 New Member

    Messages:
    19
    Location:
    Atlanta
    The right channel came back shortly after posting that it wasn't working. It is almost like the more hours I put on it, the better it runs. The scratchiness in the volume pot is almost completely gone now. The thing is dead silent with little to no hum and it really sounds great. I believe she just needs some cosmetic lovin' now.

    Just microfiber towels, brushes, all purpose cleaner, and water. Nothing too fancy. The black spots on mine are corrosion. I tried some naval jelly to try to remove them but it didn't help much and discolored to the plating so I would recommend avoiding it.
     
  10. Tcomisky

    Tcomisky AK Subscriber Subscriber

    Messages:
    3,051
    Location:
    Lawrenceville, NJ
    So, did you put the can caps in from Hayseed yet or did I miss that? I haven't received mine yet, I'm waiting on them because some of the new stuff is connected to them (b+, etc)
    Mine had significant hum prior to this so I'm assuming the cans may be the issue..

    And FYI: the 10K pot in place of the 5.6 resistor really helped. I set it for 5.6k prior to connecting anything and I was getting 18.89 V on pin 5, I adjusted it slightly and dialed it right in at 17.02 V.
    Yours went out in the mail yesterday
     
  11. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

    Messages:
    8,592
    Location:
    Ball Ground, GA
    T -- If you don't have the sampling resistors installed to measure the actual cathode current through each output tube, remember that as the line voltage is increased over that which the set was designed for, all the operating voltages increase: positive voltages go more positive, and negative voltages go more negative. Therefore, if the main B+ voltages have risen due to today's higher line voltages, but you have set the control grid bias voltage to a level based on yesterday's line voltages, it will mean that the tubes are most likely drawing excessive current now. It would typically be best to let the bias voltage be whatever it would be based on the original design (5.6K) and today's line voltages, and then when you can measure the actual current, make the necessary adjustments at that time. Invariably, unless your tubes are quite weak, most the time, the bias voltage is being adjust towards a more negative level, not less.

    Dave
     
    Tcomisky likes this.
  12. Csermonet47

    Csermonet47 New Member

    Messages:
    19
    Location:
    Atlanta
    Yes I threw them in when I replaced all the other caps. I got the Metalbone kit first too so I just worked around the cans until they arrived. Thank you again for sending that 10K pot. That should allow me to really dial in the bias adjustment.



    Thank you for the insight Dave. The power tubes are currently running a little hot at -19v. I am hoping to dial them back a bit once my 10k pot arrives. The power tubes tested pretty strong thankfully.

    My new face plate came in today so I threw it on real quick. Looks way better without that gaping hole in the front. Also found that both my dial bulbs work. One was just a little corroded on the contact points.
    [​IMG]

    [​IMG]

    I am really happy with how it is looking now. Only thing is that the eBay knob caps are pretty low quality. I will need to figure out something in the future but for now I think it is coming together nicely.
     
    AlTinkster92 and Tcomisky like this.
  13. Tcomisky

    Tcomisky AK Subscriber Subscriber

    Messages:
    3,051
    Location:
    Lawrenceville, NJ
    Thanks Dave, I was wondering if I should have waited to make the adjustment until all the mods were done.
     
  14. Tcomisky

    Tcomisky AK Subscriber Subscriber

    Messages:
    3,051
    Location:
    Lawrenceville, NJ
    My can caps showed up today..(they are a thing of beauty).. yup, that solved all the issues with this receiver. It's dead quiet now. Very happy so far.. still need to complete the coupling caps, and a few other things, but now I know I have a heathy PS.
     
    Last edited: May 19, 2017
  15. Csermonet47

    Csermonet47 New Member

    Messages:
    19
    Location:
    Atlanta
    Tcom- the 10k pot just got here. Thanks again! I will have to throw it in sometime this week. Glad the cans solved your problems. They are nice pieces.
     
  16. RORER_714

    RORER_714 New Member

    Messages:
    11
    Location:
    Brooks, Georgia
    Csermonet47, thank you! I mean't black, which is corrosion. I have tried a product from rustoleum (krust kudder) and seems to work after much scrubbing. I'm
    not sure what damage it will do to other components. Thanks very much. I'm south of Atlanta, maybe we can connect.
     
  17. Tcomisky

    Tcomisky AK Subscriber Subscriber

    Messages:
    3,051
    Location:
    Lawrenceville, NJ
    I finished mine this week. Matched with a pair of Klipsch Cornwalls, this thing is like butter.
    Intoxicating, smooth sound. No wonder these Fisher receivers have such a cult following. I'm impressed.


    IMG_0074.JPG
     
    AlTinkster92 likes this.

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