Fisher X-1000 restore hold my hand

Discussion in 'Fisher' started by Kingbleu, Oct 27, 2015.

  1. Kingbleu

    Kingbleu Active Member

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    The static/popping sound has gone away. Perhaps it was a loose tube socket or dirty pin/socket. Maybe in the process of switching all the tubes it corrected itself.
    However channel B is still not working. That is when I plug the RCA into channel B I get no sound. I tried switching the main output tubes but the problem remains.
     
  2. Kingbleu

    Kingbleu Active Member

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    As far as the Restoration all the caps mentioned above were replaced.
     
  3. Kingbleu

    Kingbleu Active Member

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    I'm heading out to the local electronic shop. The guy there said I could use the tube tester for $15 an hour but since Ive never used a tube tester and only watched videos on it I asked him if he could test the tubes. He said he would test them for $5 a tube or $50 to test all of them.
     
  4. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    Checking the cleanliness of the tube sockets is always one of the first troubleshooting steps anytime a unit malfunctions.

    OK. Next then, if the tubes are all good, short the two jumpers together in the dummy plug installed in the Remote Control Socket. Does channel B now produce sound?

    Dave
     
  5. Kingbleu

    Kingbleu Active Member

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    One of the output tubes was dead and one output tube was below 50 it measured a 47 which I was told on his tester is considered bad. Anyhow I replaced the bad tubes which had no effect. Also shorting the two jumpers on the dummy plug has no effect.
     
  6. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    OK, now the trouble shooting effort will become more involved, and will require great care, since it will require operation of the unit with it turned upside down, and the bottom cover removed -- so BE CAREFUL!

    Before you start that process however, make sure that the contacts of the "Speakers/Phone" switch (part of S-8) are good and clean, and that the connections to it are tight. Also check the connections at the Channel B speaker terminal board. If that doesn't resolve the issue then proceed as described above doing the following:

    With the Balance Control centered, short the two center terminals of this control together. Does Channel B now produce sound?

    Dave
     
  7. Kingbleu

    Kingbleu Active Member

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    133
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  8. Kingbleu

    Kingbleu Active Member

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    Location:
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    Yes when I short the two terminals of the balance control channel B does produce sound.
     
  9. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    OK, so:

    1. Shorting the two jumpers together in the dummy plug did NOT produce sound in channel B, but

    2. Shorting the two center terminals of the Balance Control together DID produce sound in channel B. So:

    That means that the problem MUST lie in circuits associated with pins 1, 2, and 3 of V4. Besides the components connected to these pins of this tube, this would also include:

    1. The wiring from the Remote Control connector up to the volume control,

    2. The volume control wiring,

    3. The tone control wiring,

    4. And the wiring to the Balance Control.

    If the tube in V4 is good, then next:

    Short the two center terminals of the VOLUME Control together. Does Channel B produce sound then?

    Dave
     
  10. Kingbleu

    Kingbleu Active Member

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    :bowdown: C36 was the cause of all my pain and grief. I cant believe one little cap can do so much damage. I guess everything has its place in electronics. Thank you so much Dave. Following your expert advise I started testing all the components that are connected to V4 specifically pins 1, 2. and 4. I took out C36 which is a cap rated at 50uf 3v and it measured 20uf. After replacing C36 I have sound in both channels and my amp is singing beautifully again.

    I remember when I was doing the restoration that I couldn't find any caps rated 50uf 3v. The closest thing I found was some russian caps from russia rated 47uf 3v. There are a total of six caps in the Fisher X-1000 that are rated 50uf 3v they are C11, C12, C21, C22, C35, C36.

    Now that C36 has gone which one will go next. I would like to replace the rest of these russian caps with something more trustworthy but am not sure where to get them. Normal sites like Digi Key, Mouser, ect.. have values that are close but what do you think. Is it ok to have a 50uf 300V in place of 50uf 3v I'm thinking not and there is something closer out there that I'm just not finding.

    Thanks again Dave you:rockon:
     
  11. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    KIng -- Glad you've got tunes again! If I may however, there is no way that C36 could cause the symptoms you cited. If the cap went open, shorted, or grew to 1,000,000 uF, you would still get sound out of the right channel.

    What is much more likely, is that the connections associated with C36 -- which has R76 connected in parallel with it -- went open or was an otherwise cold solder joint. Point being, if R76 became effectively open -- either literally, or due to a cold solder joint -- then the right channel would effectively go dead, or become extremely weak. Since the solder joints that affect C36 also affect R76, I would bet dollars to donuts that in the process of checking/testing/removing/replacing C36, you also restored the connections for R76 and presto, you then have tunes. For at least the right channel, this could also very possibly have been the source of the static noted earlier as well.

    Congrats on getting it going!

    Dave
     
  12. Kingbleu

    Kingbleu Active Member

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    Thanks again Dave

    If I may pick your brain some more. I'm trying to bias to 0.86v per the fisher manual and Channel B is there but Channel A is high.

    The lowest I can get Channel A is 1.05v

    I remember that after the restoration I had this same problem but since it sounded good I just let it be. Now I'm thinking maybe the cause of 2 of my tubes going out (remember I had them tested yesterday) may be related to the high bias voltage.

    What do you think?
     
  13. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    If coupling caps C47 and C48 are good and/or have been replaced, then likely you have a one or both of the output tubes in Channel A that simply require more grid bias voltage than the unit can supply. Verify if this is the case by swapping the output tubes between the two channels. If the bias problem moves to the opposite channel, then it is the tubes. If it stays in channel A, then something is up.

    Dave
     
  14. Kingbleu

    Kingbleu Active Member

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    Location:
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    I swapped the tubes from channel A to channel B and the bias problem moved. I haven't checked C47 and C48 but I will if need be. The way I understand it is if the bias problem follows the tubes than it is the tubes.

    After the restoration I replaced the tubes with matched electro harmonix EH 6CA7 from Jim Mcshane. This was almost two years ago. Is that a normal life span for a tube. I listen to about 2-3 hours daily.

    What tube and brand would you suggest and if you have any personals for sale please private message. Thank you.
     
  15. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    If the tubes have never had any events in their live of red plating or otherwise, they will normally remain fairly closely matched throughout their lifetimes. But that's not to say that within the matched set, they won't all individually drift somewhat over time, either. So much of that depends on the tubes themselves and the quality of their manufacturing.

    In days gone by, folks like Jim didn't exist. The matched quad or pair came that way straight from the manufacturer who had such an advantage in matching tubes, because they could pull from the same manufacturing run to account for things like formulation batches, metallurgy, equipment calibration, and even attendants overseeing production (making a good vacuum tube is part engineering, and literally part art). Jim has no such advantage and can only match from what he gets: Matching from a lot of 100 is well disadvantaged from matching from runs in the tens of thousands. Therefore, I'm sure that the tubes were in fact well matched when they left Jim. I'm also rather sure that unless your tubes have suffered any damaging events, they are likely still quite good.

    But a well known issue with vintage equipment when using modern manufactured tubes is that it has to be able to account for a wider tolerance of the basic tube and the matching capabilities available to us today. Against that fact, many pieces of equipment provided no ability to make these adjustments, counting only on the tight tolerances and match afforded the tubes that were available at the time -- and they could do it because the match and tolerance adherence was so good. Today, one of THE most important modifications is to install the very controls the X-1000 already employs so that the bias can be adjusted. In your case however, the controls are there, but as a second verse to the same old song, they don't have enough range for today's tubes, so in the end, the bias cannot be properly adjusted.

    I think the EH 6CA7 is an excellent tube as modern manufactured tubes go. I have two quads of these tubes from Jim myself. But be that as it may, you only have two options in addressing this: Get new tubes that are cooler running, as in pulling less current for a given amount of available negative grid bias voltage (tubes today are well established as typically running hotter than their original production counterparts), or modify the Fisher to provide greater range to the bias controls to account for today's looser tolerance tubes. A quick peek at the schematic shows that the design does not afford the availability of much extra negative grid bias, so to do that job right will likely involve more than just changing a resistor value here or there, as can so often be done in Fisher's receivers and smaller integrated designs. To resolve the issue then, you've got some decisions to make as to how you might want to proceed.

    Dave
     
  16. Kingbleu

    Kingbleu Active Member

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    133
    Location:
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    Here we go again.

    I plugged in my headphones to adjust the dc balance and noticed I was only getting one channel. I wiggled the jack back and forth and got one channel then the other but never both.

    Now only one channel is working again on all the inputs ( aux 1, aux2, tape ect.) and the headphone jack doesn't work at all.

    Please help I need tunes.
     
  17. Kingbleu

    Kingbleu Active Member

    Messages:
    133
    Location:
    Southern California
  18. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    Go back and follow the same troubleshooting steps earlier. This is not totally surprising as the component you thought was the issue really could not have been. If the troubleshooting process lands you back in the same area (likely), then closer examination of the area is needed to find out what's going on......

    Dave
     
  19. Kingbleu

    Kingbleu Active Member

    Messages:
    133
    Location:
    Southern California
    Going back and following the same trouble shooting steps.

    Shorting the dummy plug did not produce sound in the right channel

    Shorting the balance control did not produce sound in the right channel

    Im going to closely inspect everything connected to V4 I think I will pull out every resistor and cap connected to V4 and test them starting with R76
     
  20. larryderouin

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

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    BEFORE PULLING PARTS, INSPECT under a HIGH magnification loupe or glass, all of the joints, and poke at them lightly with a chopstick. Like Dave alluded to earlier with regard to C36/R76 in post 91, look for a cold solder joint or one that has come apart but looks complete. You've got an intermittent and it will have you chasing your tail.

    Go back to the LAST ITEM YOU WORKED ON BEFORE IT took a dump, then work back.
     

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