New to me...Fisher 500B

Discussion in 'Fisher' started by juddboz80, Jun 29, 2018.

  1. juddboz80

    juddboz80 AK Subscriber Subscriber

    Messages:
    416
    Location:
    Illinois
    35E27AEF-D6E5-4FF0-8A4C-36588FCA0E5E.jpeg Hello all, I bought this beauty about a year or so ago off eBay knowing I would be working on it sometime....the time has come to dig back into her!
    To start, not long after I got this I went in and did a partial recap and checked several resistors for tolerance. I put it on a variac and at about 100 volts one of the cans started leaking, so I stopped, put her on the shelf and never messed with the can caps, well now they are on the way as well as some tubes. This is my first fisher piece I’ve messed with, I own a scott 299a, LK-30, LK-72, 340B, and several tuners and absolutely love all my scott pieces, so this is going to be my test on Fisher. I’m excited!

    Anyone have any pointers on what to do/not to do? I plan on starting to read the hell out of several threads in the next upcoming days.

    What is an ibam??

    Any and all help is greatly appreciated!
     

    Attached Files:

     

    Please register to disable this ad.

  2. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,222
    Location:
    NYNY
    "Individual Bias Adjustment Modification." It is an exquisite mod developed by a member here, drewbolce. It permits the user to adjust the bias to match otherwise mis-matched power tubes, individually, in a previously fixed-bias instrument. It also gives the user the ability to drive the tubes as sound and funds dictate.

    A little research in this forum will bring up tons of stuff on its function and build.

    I always say get the can caps done, then attack in small increments testing for sound along the way. Once you got music, then it's a matter of swapping out components, adjusting for deficiencies/defects, and inserting discretionary add-ons. During the course of restoration, a DBT and variac are your friends.

    Good luck.
     
  3. Catmanboo

    Catmanboo AK Subscriber Subscriber

    Messages:
    475
    Location:
    Atwater, ohio
    I concur with the above. 150w bulb for the DBT. All the yellow caps are new (er). The can with the ridged top may be a new one, too, so good on that front. Was it missing tubes, or are you just replacing the output tubes?
     
  4. juddboz80

    juddboz80 AK Subscriber Subscriber

    Messages:
    416
    Location:
    Illinois
    I had it on a variac back when I first got it, I had replaced many caps and the yellow caps are all new that I installed, when I brought it up on a variac at about 100 volts one of the can caps started leaking so I stopped. After new cans I’ll start up the variac again.
    When I got it it had a rough looking set of tubes in it, I don’t think any were original. I plan to replace all them
     
  5. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,765
    Location:
    Glen Burnie Md.
    You'd be surprised at tubes that look rough and sound great, while some pristine looking tubes sound like shit. Get them TESTED and if they are bad, Then a discretionary tube replacement is in order. Check for a DIAMOND in the bottom surrounded by the pins on the smaller ones. These are Telefunken tubes (Fisher's tube of Chooice for the 500b). They very well may be good. You can clean them with a Q-Tip and Water. Be careful around the lettering. A USED Dryer sheet also works but be careful. A lot of times the lettering just rubs off or disintegrates.

    Seriously, Get the tubes tested before you spend more $$$.
     
  6. Dave451

    Dave451 AK Subscriber Subscriber

    Messages:
    1,096
    Location:
    Philly area

     

    Please register to disable this ad.

  7. juddboz80

    juddboz80 AK Subscriber Subscriber

    Messages:
    416
    Location:
    Illinois
    Thanks everyone for the tips, as an update I got all the can caps installed, found a few broken comp resistors and replaced those, installed new bridge rectifier, and gave her a good cleaning. I installed some preamp tubes I just bought but was able to salvage the 3 fisher branded 7591 power tubes that came with and I had 1 scott branded 7591....
    I brought her up slowly on the variac and noticed the magic eye tube slowly getting brighter and brighter as I turned the voltage up, at about 70 volts she started playing music, at first it sounded not too great but once I hit 117 vac it slowly started sounding better and better.....after a half hour it sounded phenomenal and that was on a set of jbl 2500 bookshelf speakers!
    I need to clean the controls as I noticed a lil bit of scratchyness when messing around but all the tone controls work, the tuner pulls in stations great, the magic eye works great and looks really nice, it has plenty of volume, I’m very impressed so far and I’m not finished yet
    Seems like the 500c is more desirable? Why is that? I would think with the magic eye that would make the B very desirable.
     
  8. juddboz80

    juddboz80 AK Subscriber Subscriber

    Messages:
    416
    Location:
    Illinois
    It didn’t come with any preamp tubes, it had 3 Westinghouse tubes branded the fisher and they tested good but I had to buy some telefunken s just for it....it had some Japanese labeled Millard’s for 6au6 tubes but I found quad of HH Scott labeled Mullards in my stash.....this thing sounds great so far, planning on hooking up my turntable to it tonight and a lot better speakers

    Any mods other than being stock need to be done? Or what mods can make it sound even better? I love playing around with this stuff!
    It just may give my rebuilt Scott 340B a run for its money!
     
  9. thornev

    thornev Active Member

    Messages:
    473
    Location:
    Mid Hudson Valley, NY
    Judd - Yes, the magic eye is a toy that we technicians tend to like. In my case I got the 500-C because it was inexpensive, available and has a very desirable headphone jack (I like listening with headphones - I can crank it without bothering anyone). I rarely see any B series Fishers on eBay where I usually shop. Thorne

    PS - Replacing stock 7591 tubes with new Tung-Sols 7591A improved the sound as well as trying different 12AX7's in the preamp positions. Removing the "noose" seemed to improve the sound. And I'm going to try the Unity Gain mod which I expect not too much of a sound improvement.
     
  10. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,765
    Location:
    Glen Burnie Md.
    The tuner tubes don't affect the sound quality other than making the radio signal palateable. You can run basically anything there. I run a lot of sylvania tubes in my 800c's and 400's. FISHER switched to these sometime in 1966 or 67 from TEZLE's and Mullards. A lot cheaper than Mullards and Tele's and sound pretty equal to them in the 12ax7's AFAIC. Try some. Get them fairly cheap @ ABCVACUUMTUBES.com. Specify Sylvania's.
     
  11. Rockyhill

    Rockyhill No marigolds in the promised land Subscriber

    Messages:
    3,155
    Location:
    Maine
    I put EH 7591A's in my 500B after installing Jim McShane's kit. Sounded great until one died (the EH tubes were not purchased from Jim). Installed IBAM and was then able to bias the original GE's that came with it. Sounds great, arguably better.

    Larry, Dave, Bruce, et al. were a huge help with my rebuild.
     

     

    Please register to disable this ad.

  12. juddboz80

    juddboz80 AK Subscriber Subscriber

    Messages:
    416
    Location:
    Illinois
    39AC983D-EA7A-4AC7-BA51-E404C0E225EF.jpeg Thanks guys!!! So I’ve got all the can caps replaced, went thru all the resistors and caps changing out several, got all the tubes in and fired her up....she sounds great! A lot Different tho from any of my scott amps, my scott amps sound darker and different. My ears need a day or so to get adjusted but I’m happy with the results! I think I’ll do more mods but I wanna research and listen to it for a week or so first.
     

    Attached Files:

  13. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,765
    Location:
    Glen Burnie Md.
    My neck has a crick in it so I fixed your pic.
    Clipboard01.jpg
     
    thornev likes this.
  14. thornev

    thornev Active Member

    Messages:
    473
    Location:
    Mid Hudson Valley, NY
    Always good, Larry, to have a photographic guardian angel !
     
  15. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,765
    Location:
    Glen Burnie Md.
    I had to lay down to look at it. My neck doesn't bend that way any more. LOL!
     
  16. fred soop

    fred soop Super Member

    Messages:
    1,965
    You can always turn the monitor on its side.
     

     

    Please register to disable this ad.

  17. juddboz80

    juddboz80 AK Subscriber Subscriber

    Messages:
    416
    Location:
    Illinois
    I couldn’t help myself!


    932B4289-9E31-471C-A594-D712E9C21115.jpeg
     

Share This Page