Vintage Synth Repair

Well, maybe oxydation. There were brown traces on the solder, but they 
went off by using rubbing alcohol. Also, it went under the varnish and 
made some oxydation on the cooper. I finally found the -real- problem, 
it's that next to the solder points, there is no more cooper under the 
varnish on one thin trace that is passing next to them. The traces going 
to the solder points are OK, strange... I scraped the varnish at two 
places and will put a jumper wire to fix the problem.

Brian Davies a \ufffdcrit :
>
> I\ufffdm a bit puzzled and no one else seems to have picked up on this, 
> solder cannot rust it has no iron in it! So just what do you mean by 
> the solder has rust on it? Note also that the PCB tracks are made of 
> copper and they are either tin plated of solder plated or varnished so 
> again they do not contain iron ergo they also cannot rust.
>
> Regards
>
> Brian Davies G3OYU
>
> www.g3oyu.co.uk <http://www.g3oyu.co.uk>
>
> ------------------------------------------------------------------------
>
> *From:* vintagesynthrepair@yahoogroups.com 
> [mailto:vintagesynthrepair@yahoogroups.com] *On Behalf Of *Antoine 
> Desch\ufffdnes
> *Sent:* Thursday, 26 January 2006 19:51
> *To:* vintagesynthrepair@yahoogroups.com
> *Subject:* Re: [vintagesynthrepair] Roland RD-300S trouble
>
> Well I'm sure that the problem is on the PCB because there is some rust
> on the diode solder points that connect to the 7 notes with
> problems.(They are all one next to the other)
>
> Does it matter if I use an other kind of diodes?
>
> grantbt@... a \ufffdcrit :
> > I don't know this unit, but I think they are probably
> > just common signal diodes like 1n4148 or 1n914.
> > If it's not the wiring/solder/diodes, it could be the
> > chip that is either driving the keyboard scan lines
> > or the chip that is reading them. You'll have to
> > follow the traces to find the offender...
> >
> > -----Original Message-----
> > >From: Antoine Desch\ufffdnes <antdes45@...>
> > >Sent: Jan 26, 2006 7:20 AM
> > >To: vintagesynthrepair@yahoogroups.com
> > >Subject: [vintagesynthrepair] Roland RD-300S trouble
> > >
> > >Hi,
> > >
> > >Someone asked me to fix a Roland RD-300S(7 notes not working). I managed
> > >to open it and remove the keys. Now, the only problem is that there is
> > >some rust on the solders, but the contact looks OK(After cleanup). I'll
> > >re-work the solder points tomorrow, but I'd like to know the diode type
> > >in case that one of them is dead.
> > >
> > >--
> > >Antoine
>