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Fisher 500-B - Help w/ Can Cap Replacement in Chicagoland Area

Discussion in 'Fisher' started by Ksebaski, Dec 5, 2018.

  1. Ksebaski

    Ksebaski New Member

    Messages:
    8
    I want to start by saying thank you to everyone who contributes to this site. I've never posted before but I've read a plethora of Fisher threads on AK.

    That said, I'm almost finished installing a Metalbone kit on my 500-B. It's an early model 500-B in which the output tubes are in front of the transformers (rather than behind).

    Looking ahead to additional restoration work I know I need to replace the remaining three can caps (I've already re-stuffed C79 and C88). The remaining can cap connections are in much tighter spaces with a larger number of connected components. For this reason I'm doubting my ability to adequately remove and reinstall those caps. While I'm open to Hayseed kits, I would prefer to restuff the original cap cans in order to preserve the original look of the receiver.

    I know I've seen posts in which AK members provide help themselves or recommend specific shops. For this reason, does anyone have recommendations on where I could get this done in the Chicagoland area? Also, any recommendations on what I should expect for the cost of the work?
     

     

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  2. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,895
    Location:
    Glen Burnie Md.
    It's not as bad as you think. Break out your camera and take LOTS of CLOSEUP Pics of the bottom of Each cap with the wiring on it. Make a drawing of each cap with the identifier marks on the bottom (outside the wiring tabs). Triangle, square, 1/2moon and blank. Note which wires go to which connection. DO ONE CAP AT A TIME, and tape/mark each wire as to which connection it comes off of. Do this for all the wires, resistors, diodes, etc. on each tab. I generally just install NEW Resistors on the new caps 1st (don't solder just yet.) then install the new cap to the chassis. Note the marking on each wire and mate it to it's TAB on the cap. Solder each TAB as it's finished. Make sure you Solder at least one of the Mounting tabs to the chassis.

    Having a shop do the work will cost an exorbitant amount of Money for labor, over and above the cost of the can's or individual caps. If you run into problems, take pictures and post them with a description of the problem. We're all here to help. 99.9999999999999% of us have been in your boat(leaky bottom and sharks circling). Save yourself the $$$$$ and do it yourself..
     
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  3. Tim D

    Tim D AK Subscriber Subscriber

    Messages:
    1,412
    Location:
    Melbourne, FL
    Let me be the first to welcome you to AK!

    Also, +1 for what Larry said......
     
  4. Ksebaski

    Ksebaski New Member

    Messages:
    8
    How did I know you all were going to say that. I've taken a bunch of pictures and began recording which additional parts I'll need (if I do cut out the originals in order to remove the can caps). It appears I'll 9 resistors and 1 small cap. Unfortunately I'm not very good with a schematic so I'm having trouble determining the required wattage for the resistors and cap. One 1.2K resistor is significantly larger than the others and the small cap just says .02/+80/-20. Any idea what the wattage is for the resistor and voltage for the cap? If I replace the two 180ohm 10w resistors, should I look for a particular type/brand? I've attached a picture and circled the 3 parts in question in green.

    Also, does anyone know if Jim McShane puts together custom packages for the can caps? If so I might try and see if he can just add the parts described above to the order.

    Fisher 500-B.jpg
     
    Last edited: Dec 5, 2018
  5. rufleruf

    rufleruf Poor Impulse Control Subscriber

    Messages:
    1,163
    Jim could probably put a kit together for you. If you want to order the parts on your own I think someone recently put a list up for a 500B recently

    For cans CE makes cans that look just like the originals, but you have to do some section matching, and they are $40 each I have a sheet at work where I figured out which ones and how to wire. Cost is probably slightly lower for Hayseed. Stuffing is probably $8 per can or less, but is some work - there are a few ways to approach it, but it's especially challenging if you want the stuffing to be undetectable from above. I have a new idea to make stuffing easier I will be trying out over my winter break.

    Do some searches for recent posts someone had some notes about higher wattage resistors for the resistors you mention above.
     
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  6. Tim D

    Tim D AK Subscriber Subscriber

    Messages:
    1,412
    Location:
    Melbourne, FL
    Matt,

    If you could point us to the list that would be really nice. I have a 500B in the queue.
     

     

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  7. rufleruf

    rufleruf Poor Impulse Control Subscriber

    Messages:
    1,163
    I'll try not to embarrass myself here. This is the parts list I put together for my next 500-B build. It will get an IBAM with test points and pots under the insulated can cover.

    This is how I will use CE cans. There are a few other ways to do this - maybe you have a better idea? I think this balanced cost and count. C84A and C78C will be swapped, and two 20uf sections combined in the new C78 to get 40uf. Note: I like the original appearance of the CE cans hence going with them instead of HH.
    500b cans plan.JPG
    For the other caps that should be replaced I am doing the "updated replacement". Still not sure what cap brand I will use - I ordered several types to try out. Russian PIOs are still somewhere on a boat. Recently got curious about jb caps from justradios.com and have a bunch of vintage to PIO to consider.

    mylar caps 500b.JPG
     
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  8. Tim D

    Tim D AK Subscriber Subscriber

    Messages:
    1,412
    Location:
    Melbourne, FL
    Thanks Matt. Nice list.
     
  9. Ksebaski

    Ksebaski New Member

    Messages:
    8
    Does anyone have a mouser parts list for caps who has actually restuffed can caps on a 500B? Specifically for C77, C78, and C84? I’d like to keep the original cans, but my fear is I’ll order caps and they won’t fit inside the cans.
     
  10. bhamham

    bhamham AK Subscriber Subscriber

    Messages:
    2,032
    Location:
    Austin
    Here's a possibility Ksebaski
    C77 - use 4 x 68uF/350v (original 50uF/250v)
    C78 - use 27uF/350v and 2 x 47uF/450v (original 20uF/300v - 40uF/400v - 40uF/450v)
    C84 - use a 47uF/500v and a 220uF/350v (original 40uF/500v - 200uF/250v)

    I think these will fit the cans but measure to make sure, Mouse part numbers on left

    647-UCY2H470MHD Nichicon Aluminum Electrolytic Capacitors - Radial Leaded 47uF 500 Volts 20% 1 $4.75 $4.75
    647-UVY2V221MRD Nichicon Aluminum Electrolytic Capacitors - Radial Leaded 350volts 220uF 22x50 20% 10LS 1 $4.05 $4.05
    647-UCS2W470MHD Nichicon Aluminum Electrolytic Capacitors - Radial Leaded 450volts 47uF 18X25 20% 2 $2.91 $5.82
    647-UCY2V270MPD9 Nichicon Aluminum Electrolytic Capacitors - Radial Leaded 27uF 350 Volts 20% 1 $1.15 $1.15
    647-UCS2V680MHD1TN Nichicon Aluminum Electrolytic Capacitors - Radial Leaded 68uF 350V 20% 4 $2.01 $8.04
     
  11. Ksebaski

    Ksebaski New Member

    Messages:
    8
    Thank you! That helps a lot.

    I think I can remove and reuse the small cap and the two 180Ohm 10W resistors in the image in post #4. The remaining 7 resistors that are attached the can caps are going to be removed and replaced. Any idea what watt resistors I should get? Are the 6 "normal" sized resistors 1/4W? 1/2W? Any clue what wattage the larger resistor between C84 and C78 is (the leftmost green circled item in the post #4 image)?

    One final question (for now), once I get all my new caps is there an easy way to match capacitor lead to cap base symbol (triangle, square, 1/2 moon, blank)? C77 is simple since they're all the same but C84 and C78 are a little trickier. AS I mentioned in an earlier post, I'm not particularly good with schematics, so a crosswalk would be really helpful. Something like: C78A: half moon, C78B: triangle, etc, etc
     

     

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  12. rufleruf

    rufleruf Poor Impulse Control Subscriber

    Messages:
    1,163
    If you look in the service manual it has default rating for resistors and each part that is not default has the rating stated.

    Re the question about matching symbols to ratings - the symbol to capacitance value decoder is stamped on the outside of the can. When I do it, I drill a small hole beside the connection tab and thread the positive lead of the discrete cap that is the value you are replacing through the hole beside the symbol and gets soldered to the existing tab that's sticking out.
     
    Last edited: Dec 7, 2018
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  13. Ksebaski

    Ksebaski New Member

    Messages:
    8
    Thanks! I've been starring at the inside of the receiver so long I forgot the symbols were stamped on the outside of the cans. I just put my mouser order in so I think I'm good to go. Now it's time to figure out how to fit the Russian K40Y coupling caps into the space I need them - those things are huge.

    It'll probably take a week or so to get my Mouser order and get everything installed, but I'll post a picture when I'm finished.
     
  14. Ksebaski

    Ksebaski New Member

    Messages:
    8
    Is there any potential issue with slightly extending the leads on the coupling capacitors? Since my output tubes are in front of the transformers, that while area is really crowded and given the size of the K40Ys, I’m essentially at maximum lead length to squeeze them in.
     
  15. bhamham

    bhamham AK Subscriber Subscriber

    Messages:
    2,032
    Location:
    Austin
    No it's OK to extend them but I would use some wire sleeving if there was some there originally.
     
  16. lopezluna

    lopezluna AK Subscriber Subscriber

    Messages:
    66
    Location:
    San Diego, California U.S.A
    Ksebaski, I just restored my Fisher kx-200 with the help of many of these great fellow AK members and the great dcgillespie. I also am not very good at reading schematics. I used this resistor chart to see what the values of certain resistors were and then I looked for them on the schematic. It helped me a lot so I hope it can help you too. resistor-120801103759-phpapp01-thumbnail-4.jpg
     

     

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  17. Rockyhill

    Rockyhill No marigolds in the promised land Subscriber

    Messages:
    3,200
    Location:
    Maine
    As I prepared to rebuild my 500B I also spent countless hours staring at the underside of this complex beast.I forced myself to learn how to read the schematic. Jim McShane's kit had a parts list with the description of the part and the Fisher schematic number. That made it "easier" to read the schematic. As I located each part in the chassis I highlighted it on the schematic. I labeled each part before they were removed using 3M blue tape marked with the part number. Then as I replaced the part with the new one I checked it off his list. For the can caps I agonized over them for weeks! I took many pictures and drew diagrams of how they were currently connected and what wires & components were connected to them. Jim's kit only included one drop-in replacement can. All the others were discrete parts. The two big 560uf/400 V caps (C84B, C88) are mounted topside. All the rest are under the hood. While it doesn't look original I don't care. I only made one error during the entire process and that was not tieing C79A & B together :-| Once I posted a picture of my work on this forum someone noticed that and let me know. I made the correction and it's been performing beautifully ever since. I added IBAM a year later. It was definitely worth the blood, sweat and tears!
     
    Last edited: Dec 8, 2018
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  18. Rockyhill

    Rockyhill No marigolds in the promised land Subscriber

    Messages:
    3,200
    Location:
    Maine
    These charts are invaluable. I also used an app on my phone - I plugged in the color bands and it tells you the value. You can also plug in the value and it displays the color bands.
     
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  19. Sam08861

    Sam08861 Well-Known Member

    Messages:
    562
    Location:
    Northwestern NJ

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