Meet my friend Rusty the Fisher KM-60 Tuner

Discussion in 'Fisher' started by Tim D, May 2, 2018.

  1. sgmlaw

    sgmlaw Well-Known Member

    Messages:
    651
    Saw this one late.

    OP, do yourself a huge favor and check those IF cans before you put too much elbow grease into this one.

    With that much surface corrosion, I would be very concerned about moisture damage to those internal film micas. They sit at the can bases, right near that rusty chassis. Once wet stuff gets in and eats ‘em up, you either have to break down the cans and install new discrete micas, or source replacements. Neither one is a fun prospect. Lots o work on what is already a project case.

    And the earlier comment about frozen cores is legit as well. You can’t tune an IF stage if the transformer core is welded in with corrosion.

    A shiny waxed chassis is small consolation for a tuner that can’t be aligned.
     

     

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  2. audmod01

    audmod01 Super Member

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    Tim;

    What are the active ingredients in Krud Kutter Rust Remover? I found the product list on the Rust-Oleum site, but it does not say what the ingredients are. I like that it says it not only removes the rust, but includes an ingredient that protects from further rust and preps the surface for painting.

    Joe
     
  3. Tim D

    Tim D AK Subscriber Subscriber

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    Joe,

    The label does not give a complete list of ingredients, but the warning label says it contains Phosphoric acid. It also says on the front that it is water based and a gel.
     
  4. Tim D

    Tim D AK Subscriber Subscriber

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    Here are some current pics. Going to find some time to replace more caps soon.

    IMG_0393.JPG IMG_5203.JPG IMG_7711.JPG IMG_9855.JPG
     
  5. Tim D

    Tim D AK Subscriber Subscriber

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    The thought about the IF cans is a scary one. Still I'm not sure how to verify the IF cans before I go further. My inclination is to push forward to see what happens. And I was worried about the cores on the IF cans being frozen, but I'm not the one that would do the detailed alignment. I could only do the touchup as detailed in the assembly manual. Worst case is that I end up with a parts unit and a lot of labor and "some" sunk money lost. I've got a pair of 12AT7's on the way for it and will be ordering some more parts before it will be ready to test. For me this is a fun hobby and failures are part of the learning. It isn't completely about the destination. For me the journey is important too. (See my tagline)

    I've also got a second Fisher KX-100/X-100-B amp in the queue. Learned a lot on the first one and will apply that learning to the second one. Moral is: I don't mind doing more than one.
     
  6. notdigital

    notdigital AK Subscriber Subscriber

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    My sentiments exactly!!!
     

     

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  7. audmod01

    audmod01 Super Member

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    Tim;

    As a preliminary move, test the primary and secondary windings of each IF transformer beginning with the one at the output of the Mixer tube in the front end. You should get measurements of an ohm or less. Check the schematic to be sure. The main thing is to make sure you do not have an open winding. If you have an IF core hex adjustment tool you can try moving both bottom and top slugs (if there are two in a given IF can) to see if they move easily. Do not force them. A 1/4 turn or less is enough and move it back to where it was before you moved it before going to another core. If both of those efforts show continuity and ease of movement of the cores, you are ahead of the game from this point forward.

    Thanks for the information on the phosphoric acid content. That is then the active ingredient. Another acid often seen used in control and contact cleaning is oelaic acid (which can be found in olive oil). Phosphoric acid is also found in coca-cola among others (don't try drinking strong phosphoric acid though!). Naval Jelly is another product that uses phosphoric acid as its primary cleaning agent. Scrubbing Bubbles uses various ammonia compounds. One thing to keep in mind about all these various cleaning compounds is not to mix them. Certain combinations can cause poisonous gasses to be emitted.
    Like you I use Q-tips and work on small areas for much of the cleaning that I do on chassis.

    Joe
     
  8. rufleruf

    rufleruf Poor Impulse Control Subscriber

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    This looks better than I was expecting. I've got a big bag of the tuning section cans if it turns out you need one.
     
  9. fred soop

    fred soop Super Member

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    2,065
    Careful turning those slugs. It doesn't take much to turn the entire coil and break off the wires rather than turning the slug. Ask how I know.

    1425
    [​IMG]
     
  10. audmod01

    audmod01 Super Member

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    Yes, the wires inside are usually very fine (30AWG or smaller). The slogs or cores should move easily. If not, stop and check back here with the group.
    Z5 External web 01.jpg
    Z5 Internal Parts web 01.jpg
    This shows details of a ratio detector transformer to give you an idea what a typical IF transformer looks like.
    Joe
     
  11. Tim D

    Tim D AK Subscriber Subscriber

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    Thanks for the offer Matt.

    I'll need to check that the cores are movable first and then it will be a while before I can power up and have a listen. Lotsa work to do to get to that point.

    Thanks to everyone for the guidance on the IF transformers. Will do.
     

     

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  12. Tim D

    Tim D AK Subscriber Subscriber

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    Trying to take the dial glass out to clean it. I’ve removed the 4 little metal retainers/screws but it isn’t coming out. I don’t want to force it. Is there a trick or do I have to take the lamp assemblies off with it as a whole?
     
  13. bhamham

    bhamham AK Subscriber Subscriber

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    Is it stuck on the rubber bumpers? Try an exacto knife or single edge razor but very carefully between the bumper and glass.
     
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  14. audmod01

    audmod01 Super Member

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    Ditto what bhamham said. The rubber pads do often stick to the back side of the glass due to age of the materials used. Be very careful in any cleaning of the back side of the glass. That is where the lettering is applied to the glass. Check the condition of the lettering. If it is not flaking off you are in good shape to clean it. I have had good success using just my breath against the glass followed by rubbing with an old T-shirt or something soft. It may require several attempts, but this method does not wet the surface excessively and consequently does not have a tendency to loosen the lettering from the glass surface. On the front surface of the glass you can use an ammonia based cleaner such as Windex, but apply the cleaner to the cloth or paper towel not to the surface of the glass. Allow the cleaner to soak into the cloth or towel so that it is not going to run all over the surface of the glass dial and get to the back side of the glass.

    Joe
     
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  15. Tim D

    Tim D AK Subscriber Subscriber

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    Will do. I guess that means that the glass is supposed to be separable. I'll give it a try tonight.

    Once I get it free I'll gently clean the stenciled side. I heard some use newspaper and water (gently, I guess).

    I've got the faceplate off and mostly cleaned. It had some old foam weather gasket material around dial glass opening - presumably to keep the light from bleeding out and to keep it from clanking around. The gasket was turning to dust and there was no resiliency left in the foam. I resorted to "Goo Gone" and a putty knife to remove the old material. I've got the face plate about 90% cleaned and will spend another 30 minutes finishing that up tonight.
     
  16. Tim D

    Tim D AK Subscriber Subscriber

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    I was going to restuff the can cap. It had Four 40uF (all grounded) sections. I cut the top off at the shoulder and pulled the guts out. The old terminals inside the can appear to be made of aluminum. I can't seem to solder to those legs inside the can. I got frustrated and ordered an exact match from Antique Electric Supply. It was a bit pricey, but it was a way to get me past that frustration. (When I did my cans from the KX-100 I didn't have that problem. Not sure why this can is different.
     

     

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  17. audmod01

    audmod01 Super Member

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    Tim;

    I hate when I run into aluminum terminals inside a can type electrolytic. I have formed the habit of saving old can electrolytics base phenolic insulators and terminals for re-use on other units I want to restore. That way I have a way around the few that have the aluminum internal terminals. Most of them have two layers of insulating phenolic wafers in the bottom and the terminals come up through the bottom layer and have part of the terminal folded over against the phenolic material while another part of the terminal continues up through the second phenolic layer to make connection to the leads from the electrolytic section. Those are the ones I save for future use. My technique for stuffing the old ones is to file off the bottom edge of the shoulder aluminum and remove the ring with grounding lugs. Then I apply heat from a gas flame (separate small burner or a propane torch) making sure that I keep the bottom of the can pointed to either side of myself. When it gets hot enough, the guts will pop out of the can. When I reassemble with new parts inside, I fold the bottom edge of the aluminum shoulder a small amount at a time working my way around the bottom to secure the bottom insulating wafers and ring terminals prior to re-mounting on the chassis. It is more work, but the end result is quite sturdy.

    Joe
     
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  18. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    Tim. DO NOT USE NEWSPAPER on the DIAL GLASS! Go with Joe's recommendation. On the Can cap, I just drill very small holes in the bottom next to each leg, and route the wire to the outside and wrap the leg, then solder. I haven't come across a can yet that had steel legs on the inside, usually aluminimum which don't take to soldering.
     
    Last edited: Jan 7, 2019
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  19. sgmlaw

    sgmlaw Well-Known Member

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    In a way, you are doing this backwards. I normally do all the electronics work on these first, and then save the beauty stuff for the end. It’s certainly ok to do it your way, but there is a small risk.

    Back when I was a young guy, a few of us restored cars. In that domain, you get all the structural and mechanical in order first, and you save the paint, trim, interior and other cosmetic for later. That way, you are not putting 20 coats of paint or a new interior into a ride that then then turns out to need a frame-off or a driveline pull.

    But you are right in that no matter what, you are gaining good restoration skills that you can carry with you for the rest of your days.

    And you seem to be having a lot of fun, and that is what matters most. By far.
     
  20. Tim D

    Tim D AK Subscriber Subscriber

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    Ordered a set of cheap plastic tools for the IF transformer cores to see if they are frozen. Should be here in a few days. I'll do the continuity check in a couple of days.

    I managed to get the dial glass to release from the rubber bumpers. I used an exacto knife and it was tedious while trying not to chip or crack the glass. It eventually released. I'm using the huff and buff method with my tee shirt. The stenciled side isn't too dirty, but the outside has years of stuff that is going to take some time to remove. So far the stenciling is perfect and it is cleaning up nicely. I'm confident that the stenciling won't be a victim.

    Looks like I might need one or both fuse lamps or some kind of replacement. I'll check continuity on both lamps tomorrow.
     

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