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Thread: Old 63 Bandmaster seems alittle ill

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    Old 63 Bandmaster seems alittle ill

    My amp was sounding OK on Wed But,today I turn it on and it didn't sound right Harsh not the normal sweet tone..I turned the bright switch on and off and it was making a loud pop, not the normal pop.I changed out all the tubes and it helped a little but I still get Loud Pop on both the Normal and the Vibro chanel Is there a easy check I can do brfore going all through grid plate test..

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    Visual inspection of caps in doghouse, B+ dropping resistors and screen/grid resistors. How old are the caps?

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    Quote Originally Posted by xtian View Post
    Visual inspection of caps in doghouse, B+ dropping resistors and screen/grid resistors. How old are the caps?
    Did a full recap 7 yrs ago It was fine when I played the other day Is it normal to have a loud Pop when I turn on the Bright switch,also there is a small amount scratchiness on the normal channel volume from 6 to 10 could that coupling cap be starting to go Would both the normal and Vibrato volumes be scratchy..I need to strart at my guitar check cables too..Trying to get some ideas before I open up the hood

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    Master Destroyer nosaj's Avatar
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    Quote Originally Posted by dumbassbob View Post
    Did a full recap 7 yrs ago It was fine when I played the other day Is it normal to have a loud Pop when I turn on the Bright switch,also there is a small amount scratchiness on the normal channel volume from 6 to 10 could that coupling cap be starting to go Would both the normal and Vibrato volumes be scratchy..I need to strart at my guitar check cables too..Trying to get some ideas before I open up the hood
    Scratchiness can also be a dirty pot. Try working the pot back and forth . Use your multimeter on the normal vol channel to see if there is DC there then I might suspect cap.
    nosaj

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    Quote Originally Posted by nosaj View Post
    Scratchiness can also be a dirty pot. Try working the pot back and forth . Use your multimeter on the normal vol channel to see if there is DC there then I might suspect cap.
    nosaj
    I am not real good at tech stuff I play guitar I don't fix them lol But do I put the test leads across the 1 and 3 lugs or the 1-2 lugs with the volume off what am I looking for with volume off there should be No DC voltage on the pot I do have a VTVM but I have never really used it,If I undo the coupling cap to grid it should have zero volts?

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    Supporting Member Randall's Avatar
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    Would you like to buy some punctuation?

    Black lead to chassis, red lead to pot lugs.

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    It's weird, because it WAS working fine.....

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    Master Destroyer nosaj's Avatar
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    Quote Originally Posted by Randall View Post
    Would you like to buy some punctuation?

    Black lead to chassis, red lead to pot lugs.
    Yes, Vanna I would like a .

    nosaj

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    Bent Member Chuck H's Avatar
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    And don't check for DC on the wiper with the pot at zero. Turn the pot all the way up and check at either un grounded lug.

    You should be able to check for a leaky capacitor in circuit. If there's DC such that it's affecting circuit operation you should be able to see it with a meter. If the circuit is such that the downstream end of the coupling cap is also the grid of the following tube then you should check with that tube out of the circuit.

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    Quote Originally Posted by Chuck H View Post
    And don't check for DC on the wiper with the pot at zero. Turn the pot all the way up and check at either un grounded lug.

    You should be able to check for a leaky capacitor in circuit. If there's DC such that it's affecting circuit operation you should be able to see it with a meter. If the circuit is such that the downstream end of the coupling cap is also the grid of the following tube then you should check with that tube out of the circuit.
    Thanks Chuck I overreacedt to soon,I put 3 worn out RCA 12ax7 in I didn't look close. They still work in the Vibrato curcuit,Also most of my cables jacks are showing bare copper on the tips,and a few 6100 frets are flating out,I need to recrown(I play a lot) and I messed with the dark circuit on my old Telecaster,and the setscrews are worn and they slide down a touch the control plate,,The 63 BM seems ok no voltage on pot

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