Vintage Synth Repair

Scary sentence indeed...

Thanks!


From: Philip 
Sent: Thursday, March 11, 2010 6:52 PM
To: vintagesynthrepair@yahoogroups.com 
Subject: Re: [vintagesynthrepair] Roland SH 101 power adaptor problem


  



Introducing DC voltage of the wrong polarity to electronics can cause a lot of damage.







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From: Miguel Mendoza <miguel@...>
To: vintagesynthrepair@yahoogroups.com
Sent: Thu, 11 March, 2010 17:18:45
Subject: Re: [vintagesynthrepair] Roland SH 101 power adaptor problem

  

I just checked the psu and it's a regulated psu. I think that I never connected it in the wrong way into the SH, it hapened with other machines. Anyway, I though that swaping the polarity couldn't produce damages, is this common in other instruments?

Thank.

Miguel.


From: Philip 
Sent: Thursday, March 11, 2010 4:38 PM
To: vintagesynthrepair@ yahoogroups. com 
Subject: Re: [vintagesynthrepair ] Roland SH 101 power adaptor problem


  

There's your problem right there, if you've plugged it in the wrong way round it will almost certainly damage internal components.


The 101 is pretty sensitive to wrong psu's. It also needs a regulated supply and so It specifies a Roland PSA adaptor. Most cheap adaptors are un-regulated.


Phil.


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From: Miguel Mendoza <miguel@filminteract ive.es>
To: vintagesynthrepair@ yahoogroups. com
Sent: Thu, 11 March, 2010 15:20:38
Subject: Re: [vintagesynthrepair ] Roland SH 101 power adaptor problem

  

Hi Scott, thanks a lot for your answer. The polarity of the external power supply can be swaped changing the position of the tip. Sometimes I have plugged it in the wrong way and the result is that the unit doesn't work. Anyway, I'll check that.

Thanks!

Kind regards.

Miguel.



From: Scott S. 
Sent: Thursday, March 11, 2010 4:13 PM
To: vintagesynthrepair@ yahoogroups. com 
Subject: Re: [vintagesynthrepair ] Roland SH 101 power adaptor problem


  
Miguel, what type of power supplies are you using? I think the SH-101 is positive ground, unlike most other external power supplies. That probably is not your problem, but thought I would mention it here for reference. Roland could have put in diodes to protect it, or possibly a zener to correct the polarity?

Out of tune could just mean that it needs calibrating.

thx-shs



On Wed, Mar 3, 2010 at 2:17 PM, Miguel Mendoza <miguel@filminteract ive.es> wrote:

    

  Hello group, I'm having a problem with my Roland SH 101:

  When I turn it on, it takes some time to start working. After this, the synth is completly out of tune.
  After some time, the external power supply is getting very hot and I turn it off.

  I tried with several external power adaptors with the same result.

  I think that it could be a problem with the internal voltage regulator or a conderser but I would like to know if any of you know anything about this problem or have any idea of what it could be.

  Thanks a lot in advance.

  Regards.

  Miguel.