X100B 'Honey Do' List?

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

  1. larryderouin

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

    Messages:
    19,960
    Location:
    Glen Burnie Md.
    C1 & C2 are a voltage Doubler. This doubles the B+ voltage to a higher voltage so the tubes can use it efficiently.
    C3 & 4 are the MAIN FILTER CAPS. They are your HI VOLTAGE FILTERS from AC to DC after the rectifier.
    - C5, C6 Phono section coupling caps
    - C7, C8, Coupling caps from output of Phono section
    -C13, C14 Coupling caps between sections of the tone section
    - C25, C26, Output coupling caps
    -C27, C28 Output coupling caps
    - C33 snubber cap in the rectifier/voltage doubler

    These are all either POWER SUPPLY CAPS, OR SIGNAL PATH COUPLING CAPS. These are the most important of any caps in the X-100-B. And probably the majority. One of the signal path caps goes BLEUWY and you lose a channel. Or if one of the Main Filter caps or one of it's sections goes out, you either lose the amp totally or most of it. They can also short and kill it. Plus the new caps have a higher heat tolerance than those in the early 60's. The one's in there have been cooked for going on 55-57 years so they could be pretty well ready for replacement. Electrolytics (filter can's) should be replaced every 20-30 years or when you notice them heating up more than the surrounding components.

    Larry
     
  2. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    32,777
    Location:
    Southern NJ
    also, they smell really bad when they blow their guts out.
     
  3. jertub

    jertub New Member

    Messages:
    43
    Ok i have purpose now!

    Tommorow im going to going to try to find all these components in the amp and hopefully figure out polarity. I know polarity matters with the can caps... the rest too?

    If i havent worn out my welcome i will certainly be back with some more questions and photos.

    Thanks again gentlemen.
     
  4. larryderouin

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

    Messages:
    19,960
    Location:
    Glen Burnie Md.
    Film caps have no polarity! <1uf caps are non polar except for some electrolytics. The only electrolytics in this group are C1 thru C4. All others are film caps.

    Use the manual for the X-100-b it has a tube location drawing on it. This drawing is based on looking down from the top. Reverse the drawing when you look underneath. Find the phono tubes, then using a magnifier, find the pin #'s on the sockets and locate the pin that C5-6 are on the tubes. Do the same for the tone control tubes, and finally the output's . The output couplers will probably be somewhere near the front right corner tubes V5 and V6
    (looking down on the bottom) as in the X-101-B. That's not unusual.

    Keep the plug out of the wall while you are locating all the parts.

    We'll go over how to ID what section on a Filter cap is what in the next installment (unless someone else wants to do it).
     
  5. Thumper

    Thumper Active Member

    Messages:
    210
    Location:
    Laurel, MD
    What Larry said... we're here to help, but l must ask - how are your soldering skills? This can be daunting for a beginner, and there are LETHAL voltages you're dealing with here. As in, toss your ass across the room dead. Always use a meter to make sure whatever you're working on is less than a couple millivolts first! Even so, always observe the "one hand in the back pocket" rule.

    Most I've ever eaten is 350VDC (and DC is gnarlier than AC) in one arm out the other - it sucked! I've got a couple bass amp with 760V on the plates - scary!
     
  6. jertub

    jertub New Member

    Messages:
    43
    Thumper. Thax for the warning, it might be good to address this before diving in this afternoon. (WARNING More dumb questions to follow)....


    My soldering skills are good enuf, i have recapped speakers and i built a dynaco ST70 which i did with 0 theoretical knowledge of tubes but as you know the instructions for those are beginner friendly.

    The only concern i have with soldering is that i see from photos i might have to desolder and resolder some of the resistors.... concern being i dont want to damage old components.


    As for electrical safety i am concerened too. I know the caps hold voltage, i planned to check before touching of course with my iron..... to clarify :

    To check voltage, For caps with two leads i would measure between the component? What about the cans with 4 tabs? Do you measure between the prongs or each prong to chassis ground?

    And for discharging them before desolder i was going to leave the unit off for awhile and then check or figure out how to use 2W 220k resistor i have here.

    So yes i am wet behind the ears but my intent was just to swap stuff... im not modifing anything. Not getting zapped or smoking the amp is important to me.
     
    Last edited: Aug 5, 2017
  7. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,214
    Location:
    NYNY
    If you leave the unit off for 30 minutes or so, it will have discharged enough to work on. You can actually watch a cap discharge by simply clipping your meter to it. And yes, meter to the 2 poles of an axial, for example. The cans with multiple tabs house a number of caps represented by the number of tabs. Usually the can itself is the other pole. So yes, probe to tab, other probe to chassis (assuming its still connected to chassis.) The act of connecting a meter to it is actually helping it discharge due to the meter's internal resistance.

    Just don't do this:

     
    Last edited: Aug 5, 2017
  8. jertub

    jertub New Member

    Messages:
    43
    Hi again,

    This moring I think I located all the components correctly. I like to verify what I found and I have a few concerns I hope you guys are willing to help me with.

    Location:
    C1, C2, C3 and C4 were easy to locate of course.
    C5 and C6 phono section coupling- yellow disc caps connected across pins 1 and 7 on V1 and V2.
    C7 and C8 phono output coupling- black caps connected to V1 and V2 pin 9 and a terminal strip.
    C13 and C14 between tone control coupling - black caps connected to V3 and V4 pin 1 and a terminal strip.
    C25-C26-C27-C28 output coupling are orange cylinder style connected to V5 and V6.
    C33 is easy to find by the diodes.

    My concerns:

    1. I found one burned resistor. on V4 (A-tone control) connected to pin#8. SEE PHOTO. I think its R25 2.2K and measured as such when still connected to circuit. The resistor connected to pin 3 also looks like maybe it overheated. It measured 2.2K when measured still connected but I am not sure if that's the correct value in the diagram.

    To confirm I read the diagram right, what is the value of the resistor connected to pin 8 and also the resistor conneted to pin 3?

    2. The diodes (SD1+SD2) have darkened leads. Almost looks burned, but perhaps the leads were insulated. SEE PHOTO. Is this evidence of a bigger issue? Im thinking these should be changed too, since I have to desolder the terminal strip anyway for C33 snubber. What is the correct diode replacement?

    3. Output coupling caps are rated the same for all 4 in schmatic (.047/400) However, two are larger size than the other two. So on each side I have one (.047/400) and the other is (.047 630V).


    4. Can capacitors.

    A. removal looks very hard, the twist tabs are soldered into place, things are soldered to ground, hopefully I don't short something. Whats the best method for removal and replacing?

    B. We mentioned polarity on these, only I believe the original C2 is marked with half moon/triangle etc markings. How do I figure out the polarity for my new cans I got from Hayseed?


    I hope this isn't too much to ask in one sitting. Regardless I sure appreciate all of your time so far in reading my long winded posts.
     

    Attached Files:

    Last edited: Aug 5, 2017
  9. fred soop

    fred soop Super Member

    Messages:
    1,766
    Was working on a TV once that had an intermittent problem and was reaching in the back to wiggle the most likely tube. Unknown was the fact that the picture tube had a metal envelope. A blue flash jumped to the back of my hand and the tube I was wiggling ended up on the floor against the wall behind me on the far side of the room. The "customer", a little old lady, was much more frightened than I was.
     
  10. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    32,777
    Location:
    Southern NJ
    Picture tubes also make for pretty effective capacitors. I've been nailed by CRTs that were not even in a set before. Not fun. At least it ends quickly. I've been bitten by ignition systems too, same deal, hurts, but stops fast.

    About the most painful was getting the middle of the voltage doubler on my Bogen amp when I discovered that the capacitor - was connected to the case. +350vdc right through the finger and out the palm of the same hand. Not a lethal path by any means but my hand didn't think it was very funny. If that had been hand to hand its likely my heart wouldn't have appreciated the joke very much either.
     
  11. Thumper

    Thumper Active Member

    Messages:
    210
    Location:
    Laurel, MD
    Yeah, DC is no joke. It's a totally different feeling type of shock than AC. When I got nailed thru the heart I kind of blacked out for a minute and then felt this weird buzz (not in a good way) for another 20. I could feel my heart skipping and carrying on like it didn't know WTF was up. Volts and amps are not to be taken lightly!

    OP - I can't answer most of your questions as I've never been inside one, but for can cap removal you need a soldering gun, or a huge iron. Like 140 watts or more. The chassis soaks up all the heat.
     
  12. jertub

    jertub New Member

    Messages:
    43
    Yes maybe i laid to much on the table for one sitting.

    I was hoping someone could take a quick look at the schmatics and tell me the proper value of the resistors i need.

    Unfortently i cant figure out the resistor for V4 pin 8 and pin 3.

    And is 1n4007 the proper replacemnt diode?

    Too bad radio shack has skipped town and i have to place an order for just 4 things!

    Manual:
    http://www.fisherconsoles.com/non console manuals/fisher x100b 20001 29999 sm.pdf
     
    Last edited: Aug 6, 2017
  13. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,214
    Location:
    NYNY
    Looks like 2.2k for both pin 3 and pin 8, R-25 and R-35 respectively.

    Those glass resistors used by Fisher are excellent remaining true to this day. Unlike carbon comps, they rarely drift over time. However if they experience overheating, then who knows. Might be good, might not be notwithstanding they measure fine without juice. Whenever I come across something like that I change them out. Really pennies in cost, plus time.
     
  14. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,214
    Location:
    NYNY
    Unless you have a HEAVY iron, those tabs are very hard to unsolder since the chassis is one big heat sink. Before I got a mugumbo iron. I'd dremel away a lot of material until I could free the tab. Since you're replacing the can, breaking the tab to loosen the hold is really the only thing you can do. Once you remove the can, clean up the slots and insert the new can.

    If you look at your schematic, clipped below, the positive side of the cap goes to circuit, the negative to chassis ground. In the original can, the outer tab, or the can itself, is soldered to chassis. That is your negative connection. I believe Hayseed simply provides a grounding wire which links all the internal caps' negative leads. Same difference. As far as the other connections are concerned, Hayseed marks the replacement can pretty well indicating uF. If you put up a picture of the replacement, it should be simple to identify what's what from there.

    100b.JPG
     
  15. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,214
    Location:
    NYNY
    Yeah, sometimes there's a difference between the schematic and what's actually in the unit. In your case, there really isn't a practical difference. There's been a lot of conversation over WHY the factory had two different voltages on those caps and the combination you have is typical of Fisher units across the spectrum of Fisher instruments. If you're intent on replacing them, then go to 600 and be done with it. Mind you, there has also been a lot of debate over changing those original Ero caps. There is a not so insignificant following that maintain that they are a major contributor to the "Fisher" sound. On the other side of the issue, there are those who maintain caps don't matter. Unless you have a cap tester and could verify the integrity of the cap, then it would be best to change them and not worry about it. Whenever I remove those Ero's, I try not to damage them in the event I could eventually have them tested and put back into service if good. Really your choice.
     
  16. larryderouin

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

    Messages:
    19,960
    Location:
    Glen Burnie Md.
    Hayseed uses the original diagrammatic symbols. Grounding on the can caps is the same as the originals, ie: out thru the tabs. No ground wire required. Match the symbol with the section on the schematic.

    C1 is the big single that is isolated from the chassis by the insulator. It is the top of the Voltage Doubler. You'll see a wire going from one of the outer tabs to the positive terminal of C2A (200uf). C2A is the other end of the Voltage Doubler. With them connected pos to neg you get voltage doubled. Pos to neg is called in series (like a 2 D cell battery flashlight). Just make sure nothing from that isolated cap goes directly to chassis. BIG SHORT and lots of smoke & Fireworks.

    According to the 20001-29999 manual for the X-100-B Both R25 & R35 (Pin 3 & 8 V4) is a 2.2K 1/3W resistor. In this case a 1/4W is too small, so a 1/2w resistor 5% tolerance is needed. Metal film cap is fine here.
     
  17. jertub

    jertub New Member

    Messages:
    43
    Thanks NotDigital and Larry!

    Last question for now:

    I have C1 (with wafer) and C2 mounted and wired.

    C3 is the one with 3 values, with the increase in capitance from hayseed.

    The old can does not have the symbols indented in the bottom unless they are hidden by the chassis. I think the cutouts for the terminals though may be in the shapes, is that correct? .

    3 poles:
    1--1 resistor and 1 wire
    2-- 2 resistors and 1 wire
    1-- 1 wire
    (and the ground tab of course).


    Which ones correspond to the new can?:
    half circle- 45/550
    square- 45/450
    triangle- 20/350

    Thanks again,
    Jerry
     

    Attached Files:

    Last edited: Aug 6, 2017
  18. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,214
    Location:
    NYNY
    If you look at the schematic, the original values were;

    3A 40uf
    3B 40uf
    3C 20uf

    So, the half circle and the square would be the new 45uf.

    The last one....well.......just sing, "which one of these things is not like the others.." :D

    Yes, the cut-outs on the wafer give the designations. If in doubt, trace the components following the schematic; it's a good exercise.
     
  19. jertub

    jertub New Member

    Messages:
    43
    Thanks, yes my circuit diagram reading skills are bad. I know all my answers are at my fingertips but instead I am like the monkey trying to put a square peg in a round hole.

    I THINK the triangle (20) has the 1 resistor/1 wire combo, the half circle (45) has a single brown wire and the square has the (45) 2 resistor/1 wire combo.

    That jives with the symbols that are cut into the insulated bottom around the poles.

    (ps-don't scold me, I am respectful of electricity in general and I know learning this stuff on the fly is probably not the best way.)
     
    Last edited: Aug 6, 2017
  20. jertub

    jertub New Member

    Messages:
    43
    So I have the 3 cans installed. Going to do C4 tomorrow.

    Is it bad giving it full line voltage on first fire up? The amp was working prior to this.
     

Share This Page