Fisher Medalist II (R-20?).. My first tube gear experience here...any hints? Service Manual?

Discussion in 'Fisher' started by TheLostBrain, Jul 26, 2017.

  1. TheLostBrain

    TheLostBrain Active Member

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    So, as my first foray into tube gear ever I went on a long shot and picked up a "project" (lord knows I really don't need another lol).

    So, picked up this:
    http://www.ebay.com/itm/THE-FISHER-MEDALIST-II-MONO-TUBE-AMPLIFIER-RECEIVER-CONSOLE/142456757864

    And these:
    http://www.ebay.com/itm/JJ-Tubes-EL84-6BQ5-Power-Tubes-Matched-Pair/192178253313

    I do have a pretty decent bench setup but have only done hobby-level work on solid-state gear so this is all new to me (both sound-wise and tech-wise).

    My guess is this thing does not work work and is dangerous so I plan to treat it accordingly.

    Any thoughts on bringing this up for testing?

    I'm sure I'll want to replace caps, etc. but is bringing it up for a test the same as solid state gear for the most part? Ex: Bring it up slowly on a variac, etc.?

    I guess I should look at some high voltage leads / probes for my meters?

    Also I don't have a tube tester I'm guessing this is something else that would be helpful at some point.

    As for speakers I have a pair of klipsch cornwalls and a pair kg4s so I'd imagine those will be fine efficiency wise.

    Anything else I should be thinking about here (aside from getting a different tube amp heh).

    Thanks

    PS anyone have a service manual for this thing?
     

     

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  2. audmod01

    audmod01 AK Subscriber Subscriber

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    TheLostBrain;

    Due to the age of the equipment and the way that capacitors in tube type equipment ages, the answer is no. Do not attempt to bring it up on a variac. The electrolytics in the power supply at the very least need to be replaced or rebuilt before powering up. Then attention to other capacitors in the set need to be addressed. In particular, coupling capacitors and bypass capacitors (bypass caps in B+ distribution bus lines). Older equipment with carbon compisition 1/2W resistors need to be checked for values that have changed beyond their tolerances. For service manual and other information on your unit see:
    http://www.fisherconsoles.com/provence medalist II.html
    Or you can access the fisher console site through the "Fisher Stickies" links.
    Larry Derouin is one of the Fisher console experts here, so I know he will be able to offer you some great help. Also for really technical help one of our great assets is Dave Gillespie. You will find many posts by each of them on this site.

    Best wishes!

    Joe

    Oops! I see after looking closer that there is no service manual or schematic listed under this model. However someone here may have a copy they can scan and Sam's service data is available on many Fisher products in a pinch.
     
  3. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    And Larry happens to have a 1958 Contemporary with an R-20 that's been rebuilt. Let me see what i can dig up on the rebuild. I do remember replacing the Main Caps with a pair of CE 40/40/40uf 525v Can's, which would be the least expensive option and they DO work well. I would also recommend that you get some 6bq5 retainers, to keep them from leaning. Not a whole lot underneath to replace. But I did replace the weak 5u4GA, 12ax7,and 6bq5's. All of these were original Fisher branded GE(Rectifier), and or Mullard (12ax7 and 6bq5's). Get some new RCA's for the input's.

    A 5U4GB is the better version of the ubiquitous 5U4 or 5U4GA. Cheap too. TUBES ARE NOT REQUIRED TO BE FISHER BRANDED!!! Any brand will do as long as it is working. Some brands ar better than others. I tend to GE tubes for RF/IF tubes.

    https://www.tubesandmore.com/products/capacitor-ce-mfg-525v-404040uf CAN CAPS

    http://audiokarma.org/forums/index.php?threads/c-800-contemporary-coming-home.697697/ Thread for mine. I did the can's after the thread ended.

    Cleaning! Brush off the heavy stuff with the Tuning capacitor at the top. Brush thru the fins lightly 1st before anything else. Brush off all dirt/dust. REMOVE ALL TUBES and covers (Mark each as you pull them off). Spray the whole chassis with SCRUBBING BUBBLES (Yeah the stuff used for bathtubs and showers!!) Let sit for a couple minutes and rinse with a damp cloth. Sit out in the sun while you make a run to Home Depot. Get a can of CRC QD ELECTRONICS CLEANER (Make sure the words "NON RESIDUE"! are on the can.) When you get back turn the chassis back on it's side, and with the tuning cap on top and the fins UNMESHED, spray the fins heavily getting them ALL ON BOTH SIDES! Then spray the rest of the chassis. LET it sit in DIRECT sun (bring it in at night to the garage) for 2 days.

    Replace the CAN CAPS, resistors that are out of spec and the other caps in the power supply. output coupling caps are replaced at the same time.

    The original speakers were Jensens, a 15" woofer, a 5" mid and slightly smaller tweeter. I would suggest 1 cornwall or one of the KG 4.5's as this is a mono unit.

    PM me with an e-mail address that can handle an 8meg zip file. I'll send you the Service manual. with schematic. It's marked up with circles around the tuning coils,etc so I could locate them for alignment. But it's nothing you need to worry about.

    Have fun with it.
     
    Last edited: Jul 26, 2017
  4. TheLostBrain

    TheLostBrain Active Member

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    Wow! Thank you both for the ALL the great info!

    That's everything I was looking for and more. :)

    It will be a bit before it comes in but I'll update this post w/ arrival and progress pics, etc.

    I'm guessing I should prob start keeping an eye out for a tube tester so I can verify them at home since this will probably be a an ongoing hobby. Although in the meantime, while I've never been, I do have two large vacuum tube stores within short driving distance to me here in Orlando, Fl. I'm guessing they'd be able to check them for me as well.

    Would you guys recommend something like this for "safer" testing considering the high voltages, etc.?
    http://www.extech.com/display/?id=14760

    I'm pretty sure I've seen the guy from Blue Glow Electronics use something very similar.

    Thanks again.
     
  5. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    Absolutely! You'll need them to do testing anyway. Safer than holding a probe while fighting the coffee jitters. If you DO use the Regular Probes, take the red one and heatshrink the metal pin except for the very tip. I do this with every probe set I have. And fit an alligator clip to the black probe for chassis clamping. Helps keep the "AW SH*T's" away and your hands out of the live voltage areas!
     
  6. TheLostBrain

    TheLostBrain Active Member

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    So 6 months later and it was still sitting on my shelf (still with it's original dust).

    On a whim decided to just take a "quick look" last night.

    ESR on the caps was OK... everything looked ok... so just said screw it and decided to bring it up on the variac.

    It works! Surprisingly filter caps are good enough that there is no hum to speak of (either by ear or on the scope).

    -AM pulled in stations just fine. Tuning eye works (although quite dim).
    -FM.. nothing really.. not sure if it needs antenna or something else needs work there.
    -Flipped it over to TV (aux) and played some sinatra and some classic spanish music from my iphone

    I can tell it needs the caps (and to make sure everything else is in spec) but all in all sounds very good.

    One thing I'm unsure of though... there are two windings on the output transformer... i *believe* one is 8 ohm and the other 16 but I have no idea which is which.
    They both work but I'd prefer to run the 8 ohm winding for my 8 ohm speakers. Anyone have any ideas?

    Also, if you any ideas on the tuning eye being so dim? Maybe it's just at the end of its life not sure.

    Want to say someone had provided my a schematic / service manual back in July but have no idea where that's at at this point.

    On a funny note... I had the unit into an 8 ohm dummy load when first bringing it up...and I could tell it was "working" because I could hear music playing from the unit itself.. I believe one or more of the ceramic caps wanted to be a speaker. ;)

     

     

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  7. TheLostBrain

    TheLostBrain Active Member

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    Ok found the info on the 8 vs 16 ohm outputs.

    Attached a shot from the schematic pointing it out. It's 8ohm center tap and is the "middle" pin on the speaker connector socket. Ground is the 2 pins that are bridged..and the last is the 16 ohm tap.

    Thanks to audmod01 above for posting the link to this site:
    http://www.fisherconsoles.com

    The page for the Medalist doesn't really have a lot of info...
    http://www.fisherconsoles.com/provence medalist II.html

    However, the c800 (which uses this same r-20 unit) has quite a bit more including the schematic:
    http://www.fisherconsoles.com/contemporary c800.html

    Direct link to schematic:
    http://www.fisherconsoles.com/schematics/FISHER R-20 SCHEMATIC.pdf



    Ok, if anyone can offer any thoughts on the dim "eye" tube that would be great.

    Thanks
     

    Attached Files:

  8. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    REPLACE the 6E5 Tube (the EYE Tube). www.abcvacuumtubes.com usually has new old stock tubes and the Eye tubes I've gotten from them have all been bright.
     
  9. TheLostBrain

    TheLostBrain Active Member

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    Wow, thanks. I just looked...can you believe they are actually right down the road from me... 15 minutes!? Small world!
     
  10. Sam Cogley

    Sam Cogley Last of the Time Lords Subscriber

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    You can read about my travails with repairing an R20 in an old thread about my C800 console. It's working well now.
     
  11. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    Last edited: Feb 13, 2018
    Sam Cogley likes this.

     

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  12. Sam Cogley

    Sam Cogley Last of the Time Lords Subscriber

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    I'm fairly sure the R-20 schematic was drawn by a drunk intern. It's accurate, but decidedly...non-standard. My headaches trying to figure it out are detailed in that thread. Specifically, the correct power supply notations are on page 4.
     
    Last edited: Feb 14, 2018
  13. TheLostBrain

    TheLostBrain Active Member

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    Well, I went over to abcvacuumtubes today and got to meet Stan.

    Nice gentleman, without my even asking he took the time to make sure he had some 6E5's on hand and tested to make sure it glowed bright before I headed over.

    Talk about tubes... they have em. When I say there were tubes everywhere I'm not exaggerating :) Tubes in the office space in the front, tubes in a room off to the side...and from what i could get a peek at a huge warehouse of them stacked to the ceiling!

    Will definitely be back may even pickup the caps from them didn't think of it at the time.

    Thanks for recommending them larryderouin... and thanks for recommending getting the new 6e5 - it's glowing bright as can be!

    B02V0925.jpg B02V0929.jpg B02V0935.jpg B02V0938.jpg
     
  14. TheLostBrain

    TheLostBrain Active Member

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    Ok, so I'm putting together a parts list but first taking an inventory of what we've got (that needs replacing) prior to finding suitable replacements.

    Bulbs
    2 x GE47

    Filter Caps
    2x 40uf 40uf 20uf (450v)

    Waxy Caps
    2x .01uf 400v
    2x .022uf 200v
    1x .0047uf 200v
    1x .047uf 200v

    Dry Electro Caps
    1x 50uf 25v
    1x 8uf 50v

    I'm kinda stumped on this one. I think it's a bumble bee...and at best I can make out it's .01uf?
    That seem right?
    IMG_0950.jpg
    how-to-read-bumblebee-cap.jpg

    I *think* it works out like this:
    1|0|000|20%|600
    10,000pF (MMFD)
    Which is .01uF 600v
    ...or 700v if the last strip is violet
    ...or 900v if the last strip is white


    Also, I wasn't sure on these little guys...I'm not sure what kind they are... any ideas?:
    IMG_0949.jpg


    For the waxy replacements abcvacuumtubes has both Metalized Polyester and Polypropylene in the suitable sizes. Is either of those better than the other in this particular application?

    IMG_0946.jpg

    Thanks!
     
  15. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    .01uf 600v is fine. Your e-lytic caps will be a 47uf 35v and a 10uf 50V. Go up on voltage 1 step on most lytics. The "8uf 50V" is in the Detector circuit for the tuner and doesn't see more than 30-40v so 50v is fine. as 8uf is a non starter anymore use a 10uf. Both of these can be Nichicon UKL series(low Noise) caps.
    When I did my R-20 I used 2 50-50 / 500v JJ caps from AES and got the clamps for them. Then mounted a 20uf for each can underneath on a terminal strip soldered to the back wall. Mount the terminal strip away from the inputs and speaker outputs and close to the incoming power cord. Cost is about $22.00 vs. >$30.00 ea for a 40/40/20/450v can cap @ AES.

    BTW you've got the "V" on the tube upside down. The "V" goes on the bottom.
     
  16. TheLostBrain

    TheLostBrain Active Member

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    Thanks again for the input Larry.

    I'm thinking i'm probably just going to leave the filter caps in place for the aesthetic but take them completely out of circuit and then go w/ some standard electros for each of the values. I like the idea of the terminal strip to keep things nice and neat though.

    Thinking will fill everything but the bulbs and Nichicons from the local tube shop...need to ask him about the quality of the caps though...though i'd imagine he wouldn't sell junk.

    Updated List:

    Bulb Replacements
    2 x GE47

    Multi-Section Replacements
    4x 47uf / 450V Electro
    2x 22uf / 450V Electro

    Waxy Replacements
    2x .01uf 630v Polypropylene
    2x .022uf 630v Polypropylene / Polyester if Polyprop not avail
    1x .0047uf 630v Polypropylene
    1x .047uf 630v Polypropylene

    Dry Electro Replacements
    1x 47uf 35v Electro Nichicon UKL
    1x 10uf 50v Electro Nichicon UKL

    Bumblebee Replacement
    1x .01uf 630V Polypropylene

    Too funny on the upside-down 6e5 shows how wet behind the ears on this stuff I am. ;)

    Thanks again
     

     

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  17. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    If that bumblebee is coming off one side of the powercord to a ground (which I'm 99% sure it is) replace it with a X-Y rated .01uf 300VAC (note the AC Voltage type), the bumblebee is rated for DC VOLTAGE. This is a Safety cap and will fail OPEN, rather than most likely SHORT like a Normal cap would. You don't want to touch the chassis with a shorted cap and get 120volts of AC hitting you. Definitely a BAD HAIR DAY!

    This will fill the bill. Mouser..........https://www.mouser.com/ProductDetail/Vishay-Cera-Mite/30LVS10-R?qs=sGAEpiMZZMt1mVBmZSXTPLncI3oTmR2BKjb6luHm5CQ=

    The little white 1000pf cap on the pot? Leave it. It's fine. I've never found one of those bad.

    I would suggest getting the caps from mouser. They have a heavy turnaround on most series of caps and you'll get fresh ones. I don't know how fresh Stan's are and he probably doesn't use Nichicon or Panasonic E-Lytics. If he does, there should be a date code on the side. If it's less than a year old, go for it, if over no deal. I'd get the tubes from him, and tube sockets if you need one or three, but watch it on the E-lytics. Films probably ok but the fresher they are the better.
     
    Last edited: Feb 16, 2018
  18. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    I forgot to address the FM reception item. You need an EXTERNAL FM ANTENNA. Originally the R20 came with a "T" dipole attahed to the back fo the console. A "T" dipole can be bought for a few bucks plus shipping from PArts express. I buy them 10 at a time it's a little cheaper. Plus each unit I either unload on a relative or sell goes with an antenna. Just for testing take a 6ft piece of speaker wire and attach to the antenna terminals and hang it off a ceiling rafter away from power cables in the basement or florescent lights. You should be able to get the local stations at that point.

    There are better EL84/7189 type tubes out there than the JJ's. Sovtek EL84M or Russian 6P14P-EV's are probably the best for FISHER's. Most FISHERs run at close to or over 400v on the plates, so a 7189 type or a EL84 that is rated for 400v will last longer than a EL 84 rated for 300v on the plates. You can use the JJ's but just be aware that they won't last as long. Suggestion is to get your power tubes from Jim McShane as he tests tubes not on a tube tester but on a FULL VOLTAGE TEST RIG that tests all parameters of the tube, and then is matched to another tube that has the same tube draw on the cathode. Matching for gm is not matching the tube for performance.
     
  19. Catmanboo

    Catmanboo AK Subscriber Subscriber

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    The 6e5 tuning eye, not a very long-lasting item , in my experience. My 1936 zenith floor radio uses one, I've had it since the early "70's. (I was a pup then). I think I've repl aced it twice, at least since, & this radio doesn't see regular use. If you can, grab a spare. They're getting scarcer as time passes. Dontt know If our russki friends are re'popping these yet.
     
  20. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    I don't know if the Commissar's have an equivalent. I know they aren't re-popping them yet. I've got a few from the 40's and 50's that have held up quite well. They came off a Sub or Tender during a strip ship in Philadelphia Naval Shipyard in the early 2000's. And they all came out of gear in the Radio rooms or the store's lockers.
     

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