NAD- Bandit 112 - Dumpster Dive

Discussion in 'Amp Central Station' started by Pasta Player, Aug 25, 2019.

  1. Pasta Player

    Pasta Player TDPRI Member Ad Free Member

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    Added a speaker & grille cover after teardown, solder re-flow / check and general clean out of this Bandit 112 - Solo Series (Teal ’91).

    LOUD, crisp & clear clean channel… Lead channel seems good until activating gain switch. Hiss (“white noise”) increases proportionately from 0 - 10, both with and without anything input. Never having had any Peavey before… wondering if maybe this is normal or if I should begin checking resistors, transistors etcetera? And IF a common problem, maybe someone could point out the “Usual Suspects”?

    Hiss ONLY present with gain engaged.

    Mind you… rare that I might ever even use the lead channel - but the power of OCD compels me. Seems that there should be a filter (or somethin’) in that lead channel gain circuit to easily correct / replace?

    And yup, sprayed cleaner into that gain switch from above, below and into the front. No change. So either it’s normal… or something relatively simple is amiss?

    Otherwise, completely impressed with this old amp.

    Bandito.png
     
  2. rangercaster

    rangercaster Friend of Leo's

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    Don't use the gain ... You'll be fine ... Enjoy !!!
     
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  3. 2 Headed Goat

    2 Headed Goat Tele-Afflicted

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    Sweet find - Congrats! Try inserting a short patch cord (the type used for f/x pedals) into the send and return jacks on the the back of the amp then give it a go...
     
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  4. Pasta Player

    Pasta Player TDPRI Member Ad Free Member

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    Thanks 2HG... tried & it makes no difference. But I also used the "patch" after installing the speaker - just to see if it would be worth proceeding with the amp... when it didn't respond at first to the new speaker. Then after I cleaned it all out & went through it more closely, it no longer needed that "patch". It's now a "keeper". Hiss or no hiss. (Nods @rangercaster.)
     
  5. 2 Headed Goat

    2 Headed Goat Tele-Afflicted

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    Cheers... Cool, the "patch" rocks for sussing things out. Since the hiss is there regardless of any input, it could be a faulty cap and/or resistor, op amp in the drive section.
    I hear ya, and no really big loss as the clean channel will serve to be a great pedal platform..
     
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  6. Pasta Player

    Pasta Player TDPRI Member Ad Free Member

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    Did notice one little (slightly swollen) cap but thought I’d ask everyone before I started removing and replacing caps. Funny too, but if that patch hadn’t worked... I probably would’ve gutted the board and thrown the rest right back into that dumpster.:lol:
     
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  7. 2 Headed Goat

    2 Headed Goat Tele-Afflicted

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    Choice! Re the dodgy looking cap, yeah, see what others chime in with. You probably know you can get the schematic from Peavey... online I believe.
     
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  8. Pasta Player

    Pasta Player TDPRI Member Ad Free Member

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    Thanks, found that schematic last week. Fabricated a new grille and built a footswitch for it yesterday.
    All good now except for that lead channel gain hiss. Perhaps this too shall pass?

    Bandit.png

    FSLove.png
     
  9. gridlock

    gridlock Friend of Leo's

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    Nice job. Congrats!
     
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  10. Crobbins

    Crobbins Friend of Leo's Ad Free Member

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    Cool score, congrats.
     
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  11. codamedia

    codamedia Friend of Leo's

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    IME... that is normal operation of these amps. Stay away from the added gain switches. The lead channel itself should provide more than enough overdrive without engaging the "gain" switch.

    The magic of these amps is in the clean channel... extremely good platforms for pedal boards.

    The send/returns on these amps use shorting jacks that can lose contact without a good cleaning. When they do, no sound is produced... or sound becomes intermittent. The "patch" is the quickest and easiest method to remedy this... and is a very reliable fix.

    Whenever I see an older Peavey in the classifieds that "has issues" I know this is most likely the problem. Most people give up on them, sell them cheap, or give their amps away (or drop them in a dumpster) not knowing how simple the fix is.
     
    Last edited: Aug 26, 2019
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  12. Telecastoff1

    Telecastoff1 Tele-Holic Silver Supporter

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    Great find on that amp! I paid $20 for a Studio Pro 40 that suffered from "No Output". Took it home, inserted a patch shorty into the FX jacks and it instantly came to life. Took the amp apart and cleaned all of the jacks and pots and no need to use the patch cable afterwards.
     
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  13. Jakedog

    Jakedog Doctor of Teleocity Ad Free Member

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    The hiss is the nature of this particular beast. It is what it is.
     
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  14. Paul in Colorado

    Paul in Colorado Telefied Ad Free Member

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    I got my Backstage Plus for $20 plus shipping off ebay. I bought it as a living room amp and it's turned out to be a regular gigging amp with pedals. It's small and light and doesn't take up much space.
     
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  15. hrstrat57

    hrstrat57 Tele-Afflicted

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    Score! Nice cleanup job too looks fantastic!
     
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  16. Luthier Vandros

    Luthier Vandros Tele-Holic Silver Supporter

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    Looks GREAT! You can find some quieter opamps, but as said, it is what it is.
     
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  17. idjster

    idjster VERY grateful member Silver Supporter

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    Looks terrific! If you can live with the hiss or without the lead channel go with it. Besides, if you play loud enough you only hear the his in the empty spots. :D
     
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  18. LGOberean

    LGOberean Doctor of Teleocity

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    Mr. Harper beat me to it. I've haven't owned that particular Bandit, but I have owned teal stripe Peavey amps (Envoy 110 and Studio Pro 110), as well as the next iteration/TransTube badged Envoy 110 and Studio Pro 112, and they all had some hiss on the Gain channel. But I play mostly clean, and when I do go for gain, it's just a bit of grit. So I'd set both the "Supersat" and "Post" controls on the Lead channel down low, and made it work for me.
     
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  19. Pasta Player

    Pasta Player TDPRI Member Ad Free Member

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    Thanks LG (and Mr. Harper) I’ll probably do the same with the Supersat and Post controls. Yet my head is very hard… and I will likely replace some caps “just to see / hear” if there’s any difference. And I might even get into the opamps - changing them to OPA2134A chips (as suggested by Bill Moore & Luthier Vandros) …as time goes by.

    I do appreciate the input.

    *And as a fun side note… there are times when I might appear very much like your recent power failure pic. (i.e. “Haute Codger Couture Club”) I haven’t purchased a razor in years.:cool:
     
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