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500c Rundown and Refurb Questions

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

  1. Csermonet47

    Csermonet47 New Member

    Messages:
    19
    Location:
    Atlanta
    Does anyone have a scan of a large dial face? I was attempting to clean mine very gently (just water and a microfiber) and it wasn't gentle enough. The lettering has started to come off. Ideally I could print a new decal to put on there but I feel like this is a long shot.
     
  2. Tcomisky

    Tcomisky AK Subscriber Subscriber

    Messages:
    3,051
    Location:
    Lawrenceville, NJ


    I will follow along and do mine at the same time. Looking forward to your progress. I have pretty much everything I need already.
    Although, mine seems to have some issues out of the gate. Really bad hum, that get worse then you touch the chassis. It passed the DBT, but that's as far as I got. I'll pop the cover soon.
     
  3. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,183
    Location:
    NYNY
    Bummer!! Happens to many of us, me included. You might want to check in with RadioDaze.com Tough getting another original glass since the large number version wasn't that common.
     
  4. rufleruf

    rufleruf AK Subscriber Subscriber

    Messages:
    879
    Oof. I did that with my first 500C a few years ago. Supposedly Radiodaze will do custom graphics, you just need to get a scan to send to them I would guess.

    I have been using one of their repro glass dials for a few years, but just agreed to buy a basket case 500C with a nice original glass. Finally!
     
  5. Csermonet47

    Csermonet47 New Member

    Messages:
    19
    Location:
    Atlanta
    Thank you for the feedback.

    I emailed Radiodaze and it turns out they already make a large number dial glass. It is part #DG-279 if anyone was interested. I will likely start to address cosmetics once it is running properly.

    Got my Metalbone kit yesterday. Seems to be really nice. The documentation is awesome and everything is really organized. I am really impressed so far.

    I took care of the rectifier and bias caps last night. This is my first time doing an electronic work like this so I am I am pretty pleased with how clean it turned out:
    [​IMG]

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    I visited Rick from North GA Vintage Audio Repair (really nice guy) this morning and he tested some tubes for me and hooked it up to a variac and took it through the paces to make sure nothing was out of the norm. When I initially got the receiver, I would hear a hissing sound from the power tubes but that seems to have gone away so hopefully that is no longer an issue. I am thinking it was the rectifier going out or bad bias caps or a combination of the two.

    I was worried I would need new power tubes but all of them tested about 90% so I will keep running them until they die. I also put in the 3.3k resistor to hopefully reduce the strain on the power tubes but I will check voltages once everything has been replaced and see what needs attention.
     
  6. Tcomisky

    Tcomisky AK Subscriber Subscriber

    Messages:
    3,051
    Location:
    Lawrenceville, NJ


    That kit appears to have some very good quality parts. I broke down and ordered one after looking over the parts list and what I have on hand. That was the easiest cap order ever. Lol.
    I popped the hood and mine appears original?
    Did your yellow cardboard covered can capacitor under the chassis appear to be leaking too? Mine seems crushed by the clamps and looks "wet".

    Edit: I just read that the Metalbone kit doesn't contain the can caps? Does it include caps that mount under the chassis, or does it plan to Stuff the cans?


    IMG_9753.JPG
     
    Last edited: May 3, 2017
  7. Csermonet47

    Csermonet47 New Member

    Messages:
    19
    Location:
    Atlanta
    Tcom: My bias filter cap was crushed and looks like it has been wet at some point too. I would assume it was leaking. That is correct, the Metalbone kit does not come with the can caps. There is nothing included to restuff them or mount under the chassis. I have ordered new ones that are drop in replacements from Hayseed. They actually offer a bias can cap that fits in the original clamp too, but it was extra so I opted for the Nichicons. I think you will really like the kit! The documentation is really nice and so are the parts. Your 500c looks clean under there. It looks original to me with the exception of the rectifier, which you will be replacing anyways with the Metalbone kit.
     
    Last edited: May 3, 2017
  8. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,183
    Location:
    NYNY
    The stain on the cardboard cover is from sticky black adhesive used to adhere the cover to the metal can underneath. Nothing to worry about. The pinched effect of the clamps is 50+ years of pressure on what is essentially paper. Again, nothing to be concerned about. What matters most is the integrity of the caps in that can. In a typical restoration, they are changed as a matter of course as is illustrated in post 25.
     
  9. larryderouin

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

    Messages:
    19,314
    Location:
    Glen Burnie Md.
    Concur on the "WET" Stain. The adhesive is tar based, and the paper (cardboard) soaks up the leeching liquid from the tar. Nothing to worry about. If the cap itself WAS going to leak, it would do so at the terminal end at the vent in the center.

    Csermonet; I have a couple of concerns over your work. Specifically the purple lead from the rectumfrier to the 1st cap. That lead should be insulated (all the way to the cap) due to the shield tube for the power switch leads, and the 3.3K resistor from the 2nd 1/2 of the cap unit to the resistor body. (Replace the 3.3K with a 10K Bournes sealed pot which makes it now adjustable to an extent). Items tend to get pushed or bumped slightly and then something touches something else it ain't supposed to and then you're hunting down shorts (usually in the sock drawer unless you're a slob and they're hanging from the bathroom door).:D Other than those two concerns it looks very good! The pot will help you dial in the bias better than a single resistor. You'll need to tie the center lead to one of the outer leads and it becomes a variable resistor at that point. Basically with point to point, if it's a power lead it should be insulated (just my personal anal retentive vice). One more point. The Russian K-40y-9 and K42y-9 caps have uninsulated metal bodies. Highly recommended to at least apply a layer of electrical tape to the body or heatshrink. (provided you ever use them).

    You're doing good, keep going. Tcom. Follow along and write down the talking points. There will be an exam at the end of the rebuild.
     
    Tcomisky likes this.
  10. Csermonet47

    Csermonet47 New Member

    Messages:
    19
    Location:
    Atlanta
    Good point Larry. I took a study break and redid the rectifier. The more I get the hang of it, I realized it could have been done better. I curled loops into the rectifier pins so I could put the wires in them. I also redid that lead you pointed out. I will have to order one of those pots soon. I don't have any of those metal caps (that I am aware of) but if I do use them I will be careful. I think it looks much tidier/safer now:

    [​IMG]

    [​IMG]
     
  11. larryderouin

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

    Messages:
    19,314
    Location:
    Glen Burnie Md.
    Much BETTER and Safer. Just be careful around that 3.3K resistor or the 10K pot when you get it installed. You could extend the wires to the pot, and mount it on the bulkhead with some JBWELD, next to the antenna mount. That would help stabilize the pot, and the wire leads, plus get them away from the other "HOT" leads.
     
  12. Csermonet47

    Csermonet47 New Member

    Messages:
    19
    Location:
    Atlanta
    I have finished replacing all the capacitors for the amplifier path. I have attached pictures so if anyone sees something that needs to be changed please let me know. The only thing I am unsure of is the orientation of the Sonicaps. I did some research and some people say where the foil is facing doesn't matter, some people say it does. I am unsure if really makes a difference but if it does I can always flip some around.


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    It has been going smoothly so far but the most time consuming process is removing the old leads by far. Some of them are looped completely through and it makes it a pain to get them out.

    I plan on tackling the FM path and multiplex stuff next, which looks like it is extremely tight in some areas. The one under the FM filter is barely even visible. I was thinking I should remove the multiplex subchassis to get better access. Is this a good route to go?

    [​IMG]
     
  13. larryderouin

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

    Messages:
    19,314
    Location:
    Glen Burnie Md.
    Orient the Soni caps the same way in each pair. Shouldn't matter either way.

    You can undo the screws on top of the MPX unit, make some slack in the wiring going to it, and slide it out enough to change the caps or resistors. Leave the Filters in (the big red axial can looking things). If you mark all 7 or 8 wires leading to the MPX correctly (draw out a 3d image of the MPX unit (barebones)) you can remove the whole thing, make the changes and reinstall it. I wouldn't do it with out making a drawing 1st along with a lot of pictures pointing to the individual wires.
     
  14. Tcomisky

    Tcomisky AK Subscriber Subscriber

    Messages:
    3,051
    Location:
    Lawrenceville, NJ
    My kit arrived yesterday. The instructions are printed on very nice paper.
     
  15. Csermonet47

    Csermonet47 New Member

    Messages:
    19
    Location:
    Atlanta
    ^ It is a really well done kit. Good luck with the install!

    Well I am all done with installing the Metalbone kit and Hayseed cap cans. I also got a new power switch from Mark that I threw on. I also put on my knob caps except for one that I am missing. It is all buttoned up and ready for the variac this Friday. Lets hope there are no issues. Removing the multiplex chassis was definitely the way to go for those caps. I don't know how I would have done it otherwise. The Sonicaps are still flipped for now but I want to see what it does before changing them around. If anyone sees anything that looks off please let me know.

    [​IMG]

    [​IMG]

    The yellow cap on the bottom here is the only non ceramic or mica capacitor that wasn't included in the Metalbone kit. In his pictures it looks like his unit doesn't even have that cap so not sure what the deal is there. Any ideas?

    [​IMG]

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    [​IMG]
     
  16. ncwalz

    ncwalz AK Subscriber Subscriber

    Messages:
    72
    Location:
    Alberta, Canada
    Not sure, but I think what you are referring to is commonly referred to as a "couplet"; a precursor to an integrated circuit. Don't think it usually requires replacement.
     
  17. larryderouin

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

    Messages:
    19,314
    Location:
    Glen Burnie Md.
    He's talking about the Mustard cap at the bottom of that picture. It's just to the left of the MPX. It's a Film cap, not ceramic or mica. Looks like it might be C107, a .1uf film cap coming off pin 5 of the V7 tube thru a 1K resistor, thru the cap and to ground. Replace it with a .1uf 250v film cap.
     
  18. Csermonet47

    Csermonet47 New Member

    Messages:
    19
    Location:
    Atlanta
    Ok sweet. I will snag one next time I am putting in an order and throw one in.

    Everything seems to be working great. Some scratchiness in the volume pot and maybe some other stuff to work out but I won't really be able to diagnose for a little while. Also gonna need some festoon bulbs. Is there an incandescent alternative to the $30 NOS pairs on eBay? I am not really feeling the LED options.
     
  19. larryderouin

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

    Messages:
    19,314
    Location:
    Glen Burnie Md.
    I just get fuse lamps @ wjoe.com add 1/4" copper tubing to the ends. The only person that will know is you (unless you have a tendency to snitch on yourself!)
     
  20. Tcomisky

    Tcomisky AK Subscriber Subscriber

    Messages:
    3,051
    Location:
    Lawrenceville, NJ
    I have done this by drilling a 1/4" hole in a piece of wood, inserting the fuse lamp in one end, then filling the other side with solder. It works very well actually. I did that with a couple of Mcintosh MX110 and others. Saves a lot of money and the results are perfect. You can use LEDs for this too.
     

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