Vintage Simmons Drums (UK) Users Group

I bought the SDS2000 that was recently on ebay UK.  Cost me around £58 and classed as not working (but may be just a loose wire :-)) - good price I thought. It arrived, very nice physical condition.  Checked the fuse - blown so replaced it.  Hopefully that was all and it will work I thought, so took the lid off and powered it up.  Nothing at all for about 10 seconds then a sharp crack and smoke :-( - quickly turned the power off again. The smoke came from a tantalum cap across one of the op-amp +/- supply, put there for decoupling, so I guess it was just its time to die, and nothing too serious. Looking at the schematics, the SDS2000 uses 5V regulated for the logic, then +/- regulated for the analogue sections, display, etc. and unregulated +/- for headphones etc. Disconnected the regulated outputs from the 3 regulators, powered the unit up again and measured the output voltages.  5V was spot on, but the +/- regulated outputs were giving 1.7V and -2V.  Not right. Stuck in replacement LM317 & 337 regulators, plus replaced a few electrolytics that had seen better days.  Also replaced the blown tantalum cap. Powered back up and sprung into life :-) I now have a near-immaculate SDS2000 (with reverb).  Everything tested out fine and it sounds lovely.  I know it's a later bit of Simmons kit and there's probably not much love for it, but it is actually a very good unit.  And it was good fun and cost less than £2 to repair.

My hero!

Von meinem iPhone gesendet

Am 01.09.2013 um 19:27 schrieb <philmurr@...>:

> I bought the SDS2000 that was recently on ebay UK.  Cost me around £58 and classed as not working (but may be just a loose wire :-)) - good price I thought. It arrived, very nice physical condition.  Checked the fuse - blown so replaced it.  Hopefully that was all and it will work I thought, so took the lid off and powered it up.  Nothing at all for about 10 seconds then a sharp crack and smoke :-( - quickly turned the power off again. The smoke came from a tantalum cap across one of the op-amp +/- supply, put there for decoupling, so I guess it was just its time to die, and nothing too serious. Looking at the schematics, the SDS2000 uses 5V regulated for the logic, then +/- regulated for the analogue sections, display, etc. and unregulated +/- for headphones etc. Disconnected the regulated outputs from the 3 regulators, powered the unit up again and measured the output voltages.  5V was spot on, but the +/- regulated outputs were giving 1.7V and -2V.  Not right. Stuck in replacement LM317 & 337 regulators, plus replaced a few electrolytics that had seen better days.  Also replaced the blown tantalum cap. Powered back up and sprung into life :-) I now have a near-immaculate SDS2000 (with reverb).  Everything tested out fine and it sounds lovely.  I know it's a later bit of Simmons kit and there's probably not much love for it, but it is actually a very good unit.  And it was good fun and cost less than £2 to repair.
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Always good to here stories with a happy end. Tip to budding electronics guys...check ex gov auctions for test equipment!! Gov. generally buy top shelf gear for it's various depts (military, research etc) and quite often when it stops working they put it in a back room and forget about it, then sell it off many years later during cleanups. I have countless bits of gear that were $15,000+ when new. Most of the time it's simple fixes like the one described that get it back working again.....great stuff. 
 

--- In simmons_drums@yahoogroups.com, <buchnerelectronics@...> wrote:

 My hero!



Von meinem iPhone gesendet



Am 01.09.2013 um 19:27 schrieb < philmurr@... >:



 > I bought the SDS2000 that was recently on ebay UK.  Cost me around £58 and classed as not working (but may be just a loose wire :-)) - good price I thought. It arrived, very nice physical condition.  Checked the fuse - blown so replaced it.  Hopefully that was all and it will work I thought, so took the lid off and powered it up.  Nothing at all for about 10 seconds then a sharp crack and smoke :-( - quickly turned the power off again. The smoke came from a tantalum cap across one of the op-amp +/- supply, put there for decoupling, so I guess it was just its time to die, and nothing too serious. Looking at the schematics, the SDS2000 uses 5V regulated for the logic, then +/- regulated for the analogue sections, display, etc. and unregulated +/- for headphones etc. Disconnected the regulated outputs from the 3 regulators, powered the unit up again and measured the output voltages.  5V was spot on, but the +/- regulated outputs were giving 1.7V and -2V.  Not right. Stuck in replacement LM317 & 337 regulators, plus replaced a few electrolytics that had seen better days.  Also replaced the blown tantalum cap. Powered back up and sprung into life :-) I now have a near-immaculate SDS2000 (with reverb).  Everything tested out fine and it sounds lovely.  I know it's a later bit of Simmons kit and there's probably not much love for it, but it is actually a very good unit.  And it was good fun and cost less than £2 to repair.

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