X100B 'Honey Do' List?

Discussion in 'Fisher' started by jertub, Jul 28, 2017.

  1. jertub

    jertub Member

    Messages:
    81
    I was going to sell my X100b in stock form, it needs some refreshing. The problem is I have been listening to it and I cant bring myself to sell it!

    However, I am not sure exactly what I need to do to get this running daily without worry.

    FWIW, I don't want to completely upgrade it, rather just replace critical components. My electronic knowledge is limited but I can certainly replace components and take simple measurements... I am looking for an easy solution.


    What would be your "honey do" list for a X100b in this case?


    PS- This is the service manual for the unit:
    http://www.fisherconsoles.com/non%20console%20manuals/fisher%20x100b%2020001%2029999%20sm.pdf
     
  2. Dadbar

    Dadbar Super Member

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    I would at least do the coupling caps and the cathode bias cap. These units are very easy to work on since they have a lot of room under the chassis.

    If you are up for a bigger challenge, change out the can caps in the power supply. Just be careful of the cardboard voltage doubler cap....for safety's sake, replace that with something well insulated since the outer casing carries ~200 volts or so.
     
  3. jertub

    jertub Member

    Messages:
    81
    I assume those are all the electrolytic caps C1, C2, C3, C4 in schematics.

    I also assume the coupling cap and cathode bias caps are the single value ones accessible from the bottom......where the others you mention are the cans on top that have multiple values inside them.
     
  4. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

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    C1-C2-C3 are the Main Filter Caps on top. C4 should be located near the output's and is a 100uf 100v axial electrolytic. The output couplers are C25-c26-c27-c28. Also replace C-33 at the diodes on the P.S. As there are only 4 more couplers (in the phono section), replace them also. These are C-5,C-6,C-7,C-8. You would be well advised to pull ALL the tubes and test each and every resistor in the unit. Replace any that are more than 5% out of spec.(Gold Band), unless it has a 10% band(Silver Band).

    As Porky Pig would say......That's all Folks!
     
  5. jertub

    jertub Member

    Messages:
    81
    Thanks alot, that's great i will try to get a list of material together. Looks like this might be expensive.

    When you say pull the tubes and the check the resistors.... I think you mean checking ohm with power off and the tubes are removed so their isn't a load on the circuit?
     
    Last edited: Jul 30, 2017
  6. mibag6

    mibag6 AK Subscriber Subscriber

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    The reason for pulling the tubes is to minimize the chance of a parallel load on the resistors which would give you an inaccurate measurement. If you find resistors that are out of spec, the first step is to further isolate the resistor by disconnecting one end then re-measure.
     
  7. jertub

    jertub Member

    Messages:
    81
    Excellent that is along the lines I was thinking, just like you would remove a lightbulb from a circuit if you were checking resistance to avoid phantom measurements.


    A couple of other questions

    1. Is there an immediate need to change the bias scheme from only be able to check and change bias for all 4 tubes at once to individual pot adjustment? I want to keep this task simple and realize if I keep it as is I have to get a matched quad... but of course I am worried that if one goes bad all 4 have to be replaced. Is this something I need to modify.

    2. I think I read about selium rectifiers need to be replaced. I am not certain if this pertains to this amp.

    3. The filter caps that have multiple values inside them on top. I will likely damage the cans if I try to stuff them myself, hopefully I can buy prestuffed cans like this?

    Depending on what you suggest about these questions I think I plan to make a list of what I need from Larry's suggestion of the caps that need replacing and also buy the resistors to have on hand if they need to be replaced.
     
    Last edited: Jul 30, 2017
  8. gadget73

    gadget73 junk junkie Subscriber

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    1) need to no, want to, maybe yes. its personal opinion and all, I just happen to prefer adjustments.
    2) don't know this amp
    3) Hayseed Hamfest can make you custom caps that are a drop-in. Elsewise you probably have to restuff yourself.
     
  9. mibag6

    mibag6 AK Subscriber Subscriber

    Messages:
    1,047
    Location:
    Duluth, Mn
    1) Since I rebuilt one a few years back folks here have come up with an individual balance and bias setup for each channel. I would have incorporated that into mine if it had been available at the time and would recommend it for yours but it does require more work than you may want to do. It does eliminate the need for close matched tubes.
    2) As I recall, there are no selenium rectifiers in there, just silicon.
    3)What gadget73 said.
     
  10. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

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    1.) Going by the Schematic and Service Manual, the X-100B is Cathode Biased. Changing to Fixed bias is fairly involved and is not just building and installing an IBAM OR IBBA BOARD. You'd need a separate filament (heater) transformer, and other items just to change it over. FISHER's Cathode bias system is practically bullet-proof and doesn't need changing. ONLY UNITS WITH FIXED BIAS GET THE INDIVIDUAL BOARD.

    2.) Manual says Silicon. BUT FISHER screwed up manuals just like all the other manufacturers, just not as often. Double check!

    3.) If you want exact replacements, Hayseed Hamfest is the place to go. Otherwise stuff them.
     
  11. gadget73

    gadget73 junk junkie Subscriber

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    There are ways to give individual bias adjustment with cathode bias. Looks like this uses tube heaters as the resistor, and it tickles some of the cathode voltage back into the grid to make up for it. Its already got a single bias adustment, so its possible to split it to 4. Basic idea would be what Dave came up with for the TA-600, with resistors as appropriate for the application.

    If this does operate like the 600, it will want fairly well matched tubes in order to not get stupid. Honestly matched tubes are a good thing anyway, individual bias adjustments or not.
     
  12. jertub

    jertub Member

    Messages:
    81
    Im trying to put together a bill of material. Its harder than I thought.

    Im covered for the stuffed filter caps (C1, C2, C3), its the rest of them that I am having trouble figuring out what I need:

    C4 - 100 uf 100V
    C5, C6- .01 UF 20% 500V ceramic
    C7, C8- .022 UF 400V mylar
    C25, C26, C27, C28 - .047 UF 400V mylar
    C33- .01uf 20% 600v molded

    I was looking on Mouser and there is a quite of selection of different stuff for each value, including both AC and DC. Im guessing a lot of these components and values are in many of the fisher amps so I hope someone here can help my figure out what type I need.

    PS- Thanks for the great information so far from all of you. (not just in this post either, you all share lots of valuable information on this forum that I enjoy reading.)
     
  13. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

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    C-4: Nichicon TVX series. http://www.mouser.com/ProductDetail/Nichicon/TVX2A101MCD/?qs=sGAEpiMZZMtZ1n0r9vR22SmzhV1iNnMtKBMXDwrWEZM=
    C5-C6: .01uf 630V http://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/715P10356KD3/?qs=sGAEpiMZZMv1cc3ydrPrF/QMTT/qsvz6uoNY%2bMc/kKY=
    C7, C8 C13, C14 http://www.mouser.com/ProductDetail/Cornell-Dubilier/DME4S22K-F/?qs=%2fha2pyFaduiVS0B2Fm0Rtqe36v4nu6k50Nk8qHP1EU4%3d
    C25,26,27,28 http://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/150473J400DB/?qs=sGAEpiMZZMv1cc3ydrPrF9O2k7r3G2yZSugBrusfgqo%3d
    C33 http://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/DME6S1K-F/?qs=sGAEpiMZZMukHu%252bjC5l7YX%2fSQfmjYl5Xan0wOJsgyw0%3d

    You missed C13 and C14 so added them. About $16.00 total plus shipping. They have 4.99 shipping via ups to usps.
    You'll note that all of the types are different. You don't want to get all the same caps as using all the same can impart a caps house sound(although I've never heard one yet). But I do change them up according to size, location, and how close it is inside. Across a tube would get a DME (radial film) rather than a 150 (yellow 150). You can always change the above list, and there will be guys who use different stuff that is "keep up with the Jones'es" (boutique) stuff that all it does is make his fat wallet thinner. Some guys use all the same caps, but most mix them up. A lot of guys like WIMA's and I do too, but the problem with them is you have to look thru 10K caps just to find a Wima with long leads. 99% comes with short leads for PC BOARDS.

    For the CAN CAPS I'd recommend HAYSEED HAMFEST for Custom Made CANS. Values as required, voltages are uprated a little, and Temp rating is 105*C. E-mail Tom, and send him a copy of the X-100b manual, and tell him you need the C1, C2 & C3 Can's. If C1 is cardboard covered and sits on a TAN phenolic insulator ask him for a new one. Invariably the old one will get damaged when removing the old cap. Just drill out the rivets and install the new one with 4-40x3/8 machine screw and nuts.
     
    Last edited: Aug 4, 2017
  14. jertub

    jertub Member

    Messages:
    81
    Thanks Larry, I appreciate it.

    As far as resistors are concerned.

    Do you think I should purchase one of each kind in the manual to have on hand while I check resistance?
    They are all carbon resistors. I am assuming I use metal film as replacements?
     
  15. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

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    No. Just check them and note which ones and get those, if you don't plan on making it a regular hobby. If you do then order two or 3 of everything needed, and keep the extras. Metal film is ok. Ordering the whole list gets prohibitably expensive after a while.
     
  16. jertub

    jertub Member

    Messages:
    81
    Well I got my parts on order and a copy of the service manual. Now I have to figure out where all these components are and hopefully the values and polarity are clearly marked.

    A couple of questions at this point:

    1. What the best method for drilling out the rivets and mounting the new cans?

    2. In which order should I start replacing the components?

    3. Am I going to have to add/extend any wire to get the new components in?

    Thanks I hope its cool to ask some questions.... Ive put together a few kits that had clear instructions but this will be the first project I am doing going on the schematics alone.
     
  17. Thumper

    Thumper Active Member

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    Location:
    Laurel, MD
    1 - never been inside an X100B but I'm working on a late model 400 and didn't have to drill any rivets to install Hayseeds - are those what you got?

    2 - I would start with the bias supply caps followed by the B+ caps and do the coupling caps last. Pull power tubes after each tweak and check voltages before reinstalling power tubes and testing. If it works now, testing after each change helps to test your work rather than "shotgunning" the whole thing and then it blows up and you have no idea where you screwed up (we all do it!).

    3 - if you're just changing OEM components and have ordered the right parts, you shouldn't have to.
     
  18. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

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    There is or should be a CARDBOARD COVERED can cap that is ISOLATED from the chassis by a phenolic insulator. I would say at least 50% of the time this phenolic insulator becomes cracked or broken while attempting to remove a can cap, especially by a rookie, although I have broken a few lately. The phenolic insulator is a somewhat square football shape and is riveted to the chassis. This is what needs to have the rivets removed and a new one reinstalled with 4x40x3/8" machine screws and nuts(H-D or Lowes) . Do NOT Re-USE a cracked or broken insulator. You risk having a massive short from the transformer to the chassis. Then you could be screwed.

    There is a saying out there that has been around since before my father was in short pants (I'm 62). "There are no DUMB Questions, except the one you DON'T ASK". Weall BTDT with regard to what we all thought were maybe dumb, stupid or just plain obvious that you couldn't wrap your head around. A different perspective in some cases is all you might need. Asking questions is, besides pictures is the best way to learn how to work on these. ALL of us asked questions back when we were all rookies, nubs, etc.

    Agreed with all Thumper said.
     
  19. gadget73

    gadget73 junk junkie Subscriber

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    as a second followup warning about that cardboard cap, make sure that the replacement is insulated as well. It freaking hurts if you get in contact with the case of one of those without insulation. You can use heat shrink tubing or whatever you like, it just has to not be exposed metal.
     
  20. jertub

    jertub Member

    Messages:
    81
    Thanks I really appreciate it and hopefully you don't think I am to far into the deep end on this one.

    I do have a new insulating wafer on the way for the insulated C1 can. Don't know much but from what I read it would give me a shocking surprise without it.

    Well heres two for you!!

    I don't have a clue of the function of the components I have chosen to replace... besides knowing some of them are electrolytic and have expired all I am going on what was suggested above.


    Can you generally explain what these components are , there function and why I am replacing?:

    - C1, C2, C3, C4
    - C5, C6
    - C7, C8, C13, C14
    - C25, C26, C27, C28
    - C33

    So there is a number of caps I am leaving in place. Like I said I just wanted to replace critical one so I can play it daily without worry I am going to smoke it. But I am curious, why are the other ones less critical.

    .

    That's what I have been concerned about most since I have not a clue what I need to check after each group of replacement! So after replacing each grouping above, what should I be checking? (edit: I see all the voltages in the circuit diagram now, so I slowly honing my schematics reading skills , just have to put it all together lol!)
     
    Last edited: Aug 4, 2017

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