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Blackstar series One 200, OD1, OD2 & Crunch NOT passing Signal

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  • #16
    Just for starters I preset 100 mil diameter round pads as general purpose, 125x125 mil square pads for anything involving a wire, 40 mil tracks for original layout, thickening them to 50 or 60 mil afterwards if space allows it, in this particular case used some 30 mil tracks only because TO220-5 footprint demanded it, add fillers wherever possible, etc.

    I still use *VERY* dated Protel Autotrax for DOS since 1989 simply because I have hundreds of old PCB designs still in use, which people ask now and then, it does not pay to redo all of them in full from scratch, yet sometimes I have to slightly edit them to accomodate, say, different jack footprints, replace a TO92 Fet by a SOT23 one (only case available today), etc. , so I still keep an XP machine and a parallel port Laser printer exclusively for that use.

    As an example, this is a 2xTDA2030 power amp and supply which sometimes saves my bacon when repairing old cheap "un repairable" stuff.

    Click image for larger version

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    Many times stuff reaches me after being butchered by some "tech" , NO original boards are available whatsoever, but as Enzo says: "the amplifier is just that thingie between the power supply and the speaker" so often original board is junked , I hate repairing lifted tracks with poorly held wire "hairs" and similar unreliable kludges and I simply install a new board/supply/transformer, whateverīs needed to make it work, pulled from my inventory of similar parts used in my own amps which are in similar power class.

    Circuit is obviously NOT the original one, nor I even try to mimic it, just treat it as a black box with signal in, speaker out, supply and ground connections, period.
    User does not know or care, all he needs is that his already condemned amplifier is working again making sounds, and basically functioning "like before"and heīs happy with that.

    Last week I repaired a cheesy generic "800W rack amplifier", think those usually sold under the Pyramid/Numark/Digisound/etc. brands, actually +/-45V rails so some 120W RMS per channel into 4 ohm by mounting 2 of my general purpose 100W boards inside, am currently repairing a Yamaha 7 channel "600W" powered box mixer , some variant of the ubiquitous EM600/660/680 by mounting 2 of my 300W boards to its humongous heatsink, and so on.

    NO schematics, NO factory parts, let alone boards, thereīs a cap on price and time allowable because it IS cheap stuff (although typically 2X the USA price and NOT replaceable by something found at Craigslist or a pawnshop) so just tearing them down and replacing a fresh and guaranteed working functional block is the shortest and cheapest path.

    My PCBs look old and ugly, Autotrax does not draw polygons, but not different to classic Laney boards which probably use similar software, but "do the job" and thatīs what counts.
    Juan Manuel Fahey

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