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Thread: Need Schematic for Univox U202R

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    Question Need Schematic for Univox U202R

    I need schems if anyone out there can share them with me. I am in process of restoring a cool old Univox 202r, w/6973 power tubes. Replaced most of caps & tubes but still having issues with the reverb & trem features. When I turn up the reverb it begins to squeal. Trem not working. It seems like the preamp is not quite right since the first 12ax7 carries a lot of vibration making it seem microphonic. I have tried several other tubes in this socket but get same results on all, even with a 12at7.
    When I got it someone had replaced a few caps so I am wondering if they did something wrong, used wrong values, reversed polarity? need schem to figure it out.

    I have read this amp may be a copy of a 60's Magnatone but can't confirm that & have not seen any Magnatone schem that looks like this or even uses same tube lineup here
    3 ea-12AX7, 1 ea-6AN8,1 ea-6AV6, 2 ea-6973 ,1 ea-6CA4 rectifier

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    I replaced some of the 12ax7, & got a new set of EH6973 tubes. This greatly improved overall stability, reduced a lot of the microphonics. Prior to this I could tap about anywhere on the chassis or any tubes which telegraphed thru the amp. While the squealing is somewhat minimized there is still a lot of hiss type noise when I turn up the reverb past 1 or 2. I checked the resistance on the reverb pan & it looks like it is within operating range, cleaned the RCA jacks.
    Still scrounging the net for the schematic. Univox.org has nothing like this although they feature pics of this amp.
    I can tell this is going to be worth the effort since it already starting to sound really rich, thick & creamy. I would love to get the reverb & tremolo working without hissing & squealing. I probably need to replace the old carbon comp resistors since they are over 50 yrs old & known noisy culprits.

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    I don't know if this is close.
    Same output tubes. Reverb & Tremelo.
    Univox 255R.
    Give it a look.
    Attached Files Attached Files

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    Thanks for sharing this. I will look over it once I get back home to see how it compares. The tube lineup is slightly different for what I assume is the reverb & trem but hopefully some of this will apply.

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    I know this a very old thread...

    I've got a mostly gutted U202R and looking to put it back to stcok, (or as close is possible). I have the 305R schematic and the 255R, but THIS 202R has a 12AX7 for the reverb driver, transformer less. the tank is an a short single spring in a Z pattern. it's one of the ones that has the line "Made by beautiful girls in....". near as i can tell the input impedance is about 800 and the output is 2575. Does anyone have a gutshot of one of these? i know it's pretty far fetched, and I CAN redesign the reverb driver if needed, but the preamps are different than the 305R and the 255R as well. and they are missing most of the resistors so i don't know if they were grid leak or cathode biased.

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