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Alternative npn for Bass Pedal Repairs

Discussion in 'd.i.y.' started by claire.fox, Apr 16, 2019.

  1. claire.fox

    claire.fox punk pony princess in a pretty party dress

  2. Marchbanks

    Marchbanks Golly, do I ever have a lot of soul!

  3. claire.fox

    claire.fox punk pony princess in a pretty party dress

    Yes, thanks for the heads up. I googled that too, as do sellers on eBay, but i would rather not pay £2.95 for postage on a individual item when I can add one to my next rswww cart order.
  4. claire.fox

    claire.fox punk pony princess in a pretty party dress

    I went with littlediode on eBay in the end £3, free P&P. But I am interested in how to select alternative npns for future reference.

    EDIT: Found a useful walk through for selecting alternatives.


    Before this thread dies I shall leave you with some gore — I think a bodge and gore thread is necessary...

    Roland PK5 Bass pedals, bought for a song, non functioning. No battery pack, burn marks on battery leads. No PSU. someone obviously tried plugging in the wrong one via the wrong input... Roland and Boss historically were a bit weird on their power delivery methods back in the day but the former owner even weirder.

    Proper 9V PSU obtained, new battery pack fitted, some minor track cleaning and repair, D1 diode replacement, fried (cracked) npn (Q3) to replace, hopefully nothing else downstream, caps all ok. can’t get a service manual (http://servicerepairmanuals.net look like they are not functioning) so I am flying cautiously. And yes, the inductor tests ok. The (D3) 5v6 zener Is untroubled, I even read 9v up to the npn so I am cautiously hopeful the custom chip is ok.


    Got my Moog Taurus VST all set... its prog nonsense from here on in

    Last edited: Apr 16, 2019
    RichardH and orangeart like this.
  5. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    BD139. with different pin out ZTX650.... many alternatives in fact.
  6. claire.fox

    claire.fox punk pony princess in a pretty party dress

    And a happy ending... it’s a wrap.

    [​IMG] Parts arrived. Cleaned the board, bodged me a broken trace with clippings from the diode. Fitted a battery pack as well.



    worked first time

    Discovered to my great joy I can have multiple synths running, so a few classic old synth VSTs have all been chained to MIDI channel 2, (Taurus Plug-in seems to be fixed on 2) so tap into poly mode and *MASSIVE* sounds ensue... mellotron VST next...

    Subwoofer with Bass Pedals, the pedalboard is slowly growing but it’s mostly a computer running VSTs a few sidechained bass-to-metal guitar sim pedals (not worked out how to do it well in VSTs without turning into a mush of ugh-harmonics) and expression pedals for volume and so on... Unsure if still punk.

    Last edited: Apr 19, 2019 at 7:45 PM
    orangeart likes this.
  7. Andrew L Weekes

    Andrew L Weekes Senior Reverse Engineer

    Good work, nice to see stuff being restored and repaired. The guide you linked to should stand you in good stead for picking alternative devices in the future, the advice is sound. Matching pinouts can sometimes be the most frustrating part, although legs can always be formed to fit, just takes a bit of mental juggling.

    Nice setup, with a couple of nice looking basses, what's the hollow body one in the pic above, is it a Schecter?

    Picked up this nice Yamaha TRBX504 last week via Gumtree, it's a nice upgrade on my entry level RBX170. I love the necks on the Yamahas and their QC always seems excellent.

    claire.fox likes this.
  8. claire.fox

    claire.fox punk pony princess in a pretty party dress

    Niiiiice. Yamaha make some of the most comfortable contemporary basses there, but that is a lot of knobs you have got there, I draw the line at 3. These days I am everything on full and sort it out on the cab, though.

    The semi hollow with f hole is a G&L ASAT Bass. That’s the angry one. Good guess, It’s like the Schechter Baron H4 but the G&L chrome hardtail gives it away, like the old Musicman (cutlass?) ashtray bridges. I only really play Leo Fender designed Basses so its kinda weird I never got a Musicman.


    On the subject of Fender, I just took in these two jazzy bad girls a couple of days ago, I was going to choose one but decided on keeping both - one for flats one for rounds... you just never know...

    Last edited: Apr 20, 2019 at 8:56 PM
  9. Marchbanks

    Marchbanks Golly, do I ever have a lot of soul!

    I’ve always thought mellotrons must have tapes... but to hell with purity, enjoy yourself!


    ...as long as it can do male, female and Russian choirs!
  10. claire.fox

    claire.fox punk pony princess in a pretty party dress

    VSTs are great these days. I don’t have many pedals but a VST clone of a vintage Boss Chorus CE1 (or a Mellotron or Moog Taurus or Wem Copycat) is better than none at all.
  11. Andrew L Weekes

    Andrew L Weekes Senior Reverse Engineer

    Lovely pair of Jazz basses, it's always good to have choice!

    If you leave the Yamaha in passive mode only three of the knobs do anything, so it's almost compliant with your 3 knob max :). I mainly use it for DI recording, the only amp I have is a little Roland Cube 20XL which is a fantastically versatile bit of kit for practicing at home and seems well made and reliable.

    Do you use the pedals / VST's in a live setting? Quite tempted to seek out one of those Roland pedals, if they go so cheaply, just for triggering stuff on the PC. I'd need to get a MIDI interface, the Focusrite 2i2 doesn't have one and all my old M-Audio sound cards with MIDI are PCI, not PCIe, so I can't put them in the PC.

    P.S. What software do you use on the PC for triggering VST's via midi (or are you on a Mac)?.
  12. claire.fox

    claire.fox punk pony princess in a pretty party dress

    Only just started on Bass pedals. Think less of a Geddy Lee and more a Killing Joke sound — rough sawtooth WASP synth arpeggios with a bit of delay using WASP or OSCar or Pro One or Rogue VSTs. Those old monosynth chips and 2 oscillator synths are easy to emulate now.

    VST Host: right. I chanced on the vPED. VST host hardware pedal. The screen thingy? Something I would make as it’s just a ruggedised mini-ITX in a box with a screen and input hardware.You can get them pretty cheaply from time to time on eBay — bear in mind this saves me a lot of foo-foo boutique hardware aggro and no boutique pedal theft worries). A physical Boss CE1 alone these days fetches £400-(£600 for a minter) a CE1 VST specifically designed to emulate or optimise for Bass is free, donationware or really inexpensive.
  13. Andrew L Weekes

    Andrew L Weekes Senior Reverse Engineer

    That vPED is interesting. Is it running Windows / Windows Embedded with a dedicated front end for hosting / controlling the VST's? It's given me an idea though, as I have this mil-spec ruggedised tablet gathering dust and needing an application, it's too heavy for any household use, it was in the bin at work, turns out there wasn't anything wrong with it. It's virtually indestructible, with some suitable interfaces it could be useful. Googling around people suggest Cantabile (https://www.cantabilesoftware.com/) as a host, or even Ableton Live (I have a Lite version that came with the Focusrite). Need something light on RAM so Ableton is out I reckon.

    It's not the fastest thing in the world (Core2Duo U9300 with 2GB), but if I minimise all the background stuff it might work, not sure how processor heavy the VST's are, I guess that will depend on their complexity, I'll have to try it! The processor in the vPed is about three times as fast, so might be a non-starter, I'm going to guess that slow CPU = latency. Worth try though, can't think of anything else to do with this brick :)

    claire.fox likes this.
  14. FireMoon

    FireMoon pfm Member

    If you're into pedals you need to watch this... The guy talking is the guy from JHS pedals he knows his stuff.

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