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Thread: Is it over? 21NYC Sansamp Bass DI

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    Member Jimijames31's Avatar
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    Is it over? 21NYC Sansamp Bass DI

    The bass player in my band fried his Sansamp pedal here. I have dis-assembled it to check it out and cleaned out the fried parts. I contacted Tech21 to get the replacment resistors and diodes, the engineer gave me a slightly cryptic response but I think I can sort it out.

    After a little more work on cleaning up the board today I am thinking that it is too burned up to repair.

    Opinions?

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    If you can trace where those components connect to and can solder to a non-burned area that might work better than trying to reuse this location. I don't like how narrow Tech 21 goes with their PCB routes, they are fragile. It's not like they are saving money on copper or anything. Dealing with Tech21 for repair support is interesting. I talked with the engineer for like an hour when I was fixing a Trademark 60 last year (about the amp and then just shooting the breeze). If he could have send me a schematic, or even a screen shot of the section of the schematic or board layout it would have been much easier, but I got the fix done and everyone was happy.

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    Bent Member Chuck H's Avatar
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    Second that on either moving the location or at least elevating off the board and flying leads to good contacts. I'd even suggest cutting through any traces going into the burned area. With that much carbon on and in the board the possibility of some conductivity between traces could foul circuit operation.

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    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

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    Member Jimijames31's Avatar
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    I'll try to track down some other areas to solder in to. That was my first experience with tech 21. I agree would be great to either see a snapshot of the area on the board or a schematic. I guess I'll do my best and see if I can get her running again. On the plus side my bass player bought a newer version of the pedal so this is just for fun. Thanks for the advice.

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    Member Jimijames31's Avatar
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    Thanks Chuck, I appreciate the advice. I am pretty green with this stuff.

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    Old Timer Tom Phillips's Avatar
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    Quote Originally Posted by Jimijames31 View Post
    ...I am pretty green with this stuff.
    Hi James,
    A word of caution...In a situation like you have, in addition to replacing burnt up parts, you will need to troubleshoot the circuit and determine what fault caused those parts to burn up. Otherwise, you could complete a really nice cosmetic repair and then have the same parts burn up again.
    Cheers,
    Tom

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    Master Destroyer nosaj's Avatar
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    Quote Originally Posted by Tom Phillips View Post
    Hi James,
    A word of caution...In a situation like you have, in addition to replacing burnt up parts, you will need to troubleshoot the circuit and determine what fault caused those parts to burn up. Otherwise, you could complete a really nice cosmetic repair and then have the same parts burn up again.
    Cheers,
    Tom
    A larger pic of the circuit board being that those were diodes(maybe protection diodes) maybe blown from wrong power adapter or polarity?
    Just speculating cause you don't typically get the power source as the offender realizes what they did and just can't admit it.

    Give us some larger better pics of the PCB Thanks,
    nosaj

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    Bent Member Chuck H's Avatar
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    I was thinking the same thing. Isn't the Sansamp a preamp device? I can't imagine that sort of incineration occurred due to currents present in the Sansamp then. User must have done something odd. Like plug a power amp into it? Even then I would expect any reasonably high input impedance to avoid this sort of thing. A mystery to be sure, but my guess is that someone did that device some dirt somehow.

    EDIT: BTW... You can buy a new one of those for under $150 almost anywhere! By the time the board/circuit is reasoned out, the parts identified and ordered and the retrofit repair accomplished this doesn't even seem like a pleasant DIY repair and CERTAINLY not financially beneficial. I'd throw that thing off a bridge and buy a new one with a warranty.

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    Last edited by Chuck H; 01-07-2018 at 06:17 PM.
    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

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    Member Jimijames31's Avatar
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    You all bring up some great points. Our band actually already bought the bass player a new one. He had this one for 12 years. I told him we need to sort out what caused the problem though. I have never seen anything burned up this bad. I haven't had a chance to sort out his power supplies yet. The thing was intermitently screeching for weeks before it went out completely.

    I am attempting to repair it more for my own education and because I like doing this kind of stuff. I figure if I can get it back together we can use it as a backup.

    here's the parts list the engineer at 21tech gave me. Parts are:
    D1 and D12 = 4148
    D15 = 10V Zener Diode
    R109 and R54 = 68 Ohms

    My biggest challenge is working with no schematic and I can only find glimpses of the area in online pictures. I went as far as to contact someone who worked on one in another forum back in 2008 but he doesn't have any other pictures.

    I'll take some more pics and post them later so you guys can see the whole board.

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    Bent Member Chuck H's Avatar
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    If the unit the bass player has now is the same you have a reference right there. And I can get behind doing something like this to "stay out of trouble" as it were. I have a dozen of those around. And I get your frustration with trying to glean information from on line pics (HRMPH!)

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    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

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    Member Jimijames31's Avatar
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    His is a new model and as it happens, getting to that side of the board is a freakin nightmare. I had to use a solder wick and remove the input jack just to get the board out. I really should have removed the input and both output jacks but I managed to the pcb out with only removing one.

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    Member Jimijames31's Avatar
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    A couple more pics of the board. Plus one before I took out the fried parts.

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    Old Timer J M Fahey's Avatar
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    Even without actually tracing the schematic, follow the tracks from burnt areas towards some "external access" point.
    Nothing inside the pedal has enough voltage/current/power , Death must have come from outside.

    Either from improper or failing external Power Supply / wall wart, or some Bass Head speaker out which was conneced to input or output.

    Supply inputs often have protective diodes to avoid backwards voltage or AC ; jacks often have a couple diodes connected to +9V or ground, and some resistor in series to limit current; we have both in the casualty list.

    So please check where tracks lead to, they won´t go "anywhere" at random but basically to one of these 2 points.

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    Juan Manuel Fahey

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    Member Jimijames31's Avatar
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    Good advice, I'll check trace those and see where they lead. I suspect faulty external power supply. However, I wasn't actually there the night it happened and not all my band mates are very savvy when it comes to their gear. In this particular situation my buddy is using a power supply with little leap frog splitters between pedals. I told him we are getting him a pedal power source asap. I would hate for him to burn up the new pedal he just bought.

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    please someone help me remove the circuit board from the sansamp paradriver

    Quote Originally Posted by Jimijames31 View Post
    The bass player in my band fried his Sansamp pedal here. I have dis-assembled it to check it out and cleaned out the fried parts. I contacted Tech21 to get the replacment resistors and diodes, the engineer gave me a slightly cryptic response but I think I can sort it out.

    After a little more work on cleaning up the board today I am thinking that it is too burned up to repair.

    Opinions?

    Click image for larger version. 

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    i have been trying to remove the circuit board but can't figure it out, i took off all of the screws and bolts, i got the bottom off of the circuit board which was very easy, but can't get it off of the top of the pedal box. i'm also wondering how to assemble it, will it be easy or a nightmare?

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    Quote Originally Posted by Jimijames31 View Post
    The bass player in my band fried his Sansamp pedal here. I have dis-assembled it to check it out and cleaned out the fried parts. I contacted Tech21 to get the replacment resistors and diodes, the engineer gave me a slightly cryptic response but I think I can sort it out.

    After a little more work on cleaning up the board today I am thinking that it is too burned up to repair.

    Opinions?

    Click image for larger version. 

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ID:	46411
    FIRST TO ALL I DON'T KNOW HOW PUT A SMALL PICTURES SORRI !

    Man i have exactly the SAME problem !!!!
    how you fixed??

    I replaced all component, two diodes, one zener, and the resistor:
    D1 and D12 = 4148
    D15 = 10V Zener Diode
    R109 and R54 = 68 Ohms

    but when i plug de current, the resistor burns...again
    The tracks was erase for cause the burned, but i try to figure out seem some pictures, included yours, so...maybe i made some mistake on the tracks, but i can't figure out because....is burned !!! ajjaja
    here is some pictures:






    would you help on this?

    * Sorri for my english, am from Chile.

    thanks for advance !!!

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    Last edited by animal; 08-26-2019 at 05:00 PM. Reason: to big pictures

  17. #17
    Old Timer J M Fahey's Avatar
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    Q´hiacéi güebón culiau!!!! ... ya tomaste once? .... je je je

    I congratulate you on having traced the schematic and built it on a *separate* piece of board.

    Los gringos compran otro y ya está, nosotros *tenemos* que arreglarlo

    1) First you have to fully remove all traces of burnt PCB material, use a small Dremel drill head:



    , I add a dental hook to scrape carbon away.

    Otherwise conductive carbon is still shorting your supply.

    2) put a limiting resistor in series with +9V supply, say 10 or 22 ohm, 1/4 W

    Buy a dozen of them, you will use them as "fusistors", for the dual purpose of limiting current and burning themselves out in case of full short, the idea being that they will somewhat protect the damaged PCB and let you measure something.

    PCB straight to supply will keep burning and a fuse will blow in 1/10th of a second before you can react.

    Resistor will last a short time and let you measure something.

    First measurement is how much voltage reaches the preamp board:
    * zero V showing full short?
    * a couple V meaning something is drawing too much current?
    Not the same.

    As a side note: search the Net, I am quite sure "somebody" , specially the "pedal guys", has traced and published a schematic.

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    Juan Manuel Fahey

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