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Thread: Fender PA135

  1. #1
    Supporting Member bsco's Avatar
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    Fender PA135

    Happy New Year.....I think!! anyway, I have a question.......this amp has a three prong plug...it also has a ground select switch and the famous death capacitor as well.....I was going to just cut that cap out and leave everything the same....or do I need to re-arrange the wiring?? and why did they put the cap there in the first place.....I will have to replace all the elect. caps...and I have a few tubes that need to go, along with cleaning, etc........but I was curious about that death cap as usually when I see that cap the unit has a non-polarized 2 prong plug....
    Cheers

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  2. #2
    Supporting Member Jazz P Bass's Avatar
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    The capacitor from Line to Ground is supposed to filter out mains 'noise'.
    Whatever that is.
    If it is a Y2 capacitor, then it is safe to leave it in.
    There really is no need to change any of the wiring.
    The switch will simply not do anything.
    Then again, it could be used as a placebo switch.

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  3. #3
    Supporting Member bsco's Avatar
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    Quote Originally Posted by Jazz P Bass View Post
    The capacitor from Line to Ground is supposed to filter out mains 'noise'.
    Whatever that is.
    If it is a Y2 capacitor, then it is safe to leave it in.
    There really is no need to change any of the wiring.
    The switch will simply not do anything.
    Then again, it could be used as a placebo switch.
    Thanks Jazz for the quick reply......it is a regular cap....047/600VDC......it is not a Y2 type cap......
    Cheers

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  4. #4
    Supporting Member Jazz P Bass's Avatar
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    Yup.
    Clip it out for sure.

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    Supporting Member bsco's Avatar
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    Quote Originally Posted by Jazz P Bass View Post
    Yup.
    Clip it out for sure.
    Hello Jazz. I had to put this to one side for awhile,,,just trying to get it fixed up now.....replaced all the power supply caps......cleaned up some noisy pots...etc....basic housekeeping stuff and will cut that cap out like you suggested....outside of that it powers up ok......and had it on a light bulb dimmer......voltages seem to be good ...no hum when powered up.........I think I might replace the grid resistors on the output tubes......... the inner middle two measure 1.6K...the outside two measure 1.5K.....checked all the 100K plate load resistors and these are pretty much dead on....(the dual showman I have here had ALL the 100K's out of wack)......anyway, I will finish this up tomorrow and give it a good test before I start replacing some pre-amp tubes...I want to see if any resistors start producing any noise as this has not been powered up by the owner for a pretty long time...I'll keep you posted... I do find it strange that there is a ground select switch even though it has a proper 3 prong plug......oh and yes....I will aslo check that accessory socket with this one as well........
    Cheers

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  6. #6
    Supporting Member bsco's Avatar
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    Quick question...Is there a capacitor in this amp rated for 750uF@3V ?? I can't tell by the printing on the case as some of the lettering is missing....just checking to see if the schematic is correct of it is a typo.......
    Cheers

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  7. #7
    "Thermionic Apocalypse" -JT nickb's Avatar
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    Yes. It goes to cathodes of V1 & V2 large value for low hum on input stage.

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    Supporting Member bsco's Avatar
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    Quote Originally Posted by nickb View Post
    Yes. It goes to cathodes of V1 & V2 large value for low hum on input stage.
    Thank you very much sir......Just checked it all out...no hum.....at all......which is strange for an amp this old but I am after replacing all the main filter caps......I still have the bulb limiter hooked up in place of the fuse for now....reverb sounds horrible...the tank works but is very rusty.....will check out the tube first...I did clean up the reverb tank and amp jacks...no change.....will post back later.....
    Cheers

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  9. #9
    Supporting Member bsco's Avatar
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    Ok. Checked this reverb issue out....It is the tank...the tank works but is badly distorted during the trailing reverb sound....I swapped the tank out of another amp......sounded nice and clean......the reverb sounded kind of weak but that is probably because it was a different tank.....so the tank is the issue....outside of that everything else seems to be ok........
    Cheers

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  10. #10
    Lifetime Member Enzo's Avatar
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    Get off the bulb. None of your voltage readings are valid while on the bulb. The amp is running on reduced voltage while on the bulb.


    Please don't go looking for a 3v cap. Back in the days of that Fender, such low voltage caps were common enough, but today you won't have as much luck as you would looking for a 16v or 25v cap. And 750uf would be a non-standard value really. If I had 1000uf/35v in my drawer, I'd consider it close enough.

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  11. #11
    Supporting Member bsco's Avatar
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    Quote Originally Posted by Enzo View Post
    Get off the bulb. None of your voltage readings are valid while on the bulb. The amp is running on reduced voltage while on the bulb.


    Please don't go looking for a 3v cap. Back in the days of that Fender, such low voltage caps were common enough, but today you won't have as much luck as you would looking for a 16v or 25v cap. And 750uf would be a non-standard value really. If I had 1000uf/35v in my drawer, I'd consider it close enough.
    Hey Enzo. Thanks for the reply....I figured that a 3V cap would be impossible to find.....I have some 1000uf/35V ones here......I can pop one in easy enough....
    I had it on the bulb for awhile just to make sure that nothing screwed up...I have to clean up the sockets and such but just wanted to see if anything was going to draw excessive current and everything appears to be fine....I'll install the 4A/SB fuse back later the weekend and see if there is any issues.....
    Cheers

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  12. #12
    Supporting Member bsco's Avatar
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    Ok Enzo.....Couldn't sleep and have been up since 4 AM....I installed some 1 ohm, 1W/1% cathode resistors on the output tube sockets...the customer supplied a couple of 6l6's that he had and wanted me to try and match up two more to go with them so he could keep his repair cost down.....(you know the old saying...I don't want to spend a lot of money, and the original tubes were not very good....pretty weak) anyway I found a couple that should work....there is no hum at all when turned on and idling......two tubes on the left side measure about 22mV..... the two on the right side measure 19mV...so that should work out perfect....I still need to actually run this for abit though just to be on the safe side which I can't do yet as I will wake up the wife.....and I don't want to do that either.....anyway, I'll let you know how it all works out....iif you have any other suggestions please fire away......
    Cheers

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  13. #13
    Supporting Member bsco's Avatar
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    Alright then... Got this finished up......works good.....Gave it back to the owner and told him to run it for a few days and let me know if everything is ok before I do up his invoice....I normally don't do that but I know this guy and I can trust him......thanks to everybody who gave me advice.....
    Cheers

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