[sdiy] Solved: Crumar Performer - keyboard mystery

Florian Anwander fanwander at mnet-online.de
Sat Aug 4 17:24:02 CEST 2018


I solved the funny behaviour of the Crumar:

The problem was caused by a too high voltage on the keyboard bus, which 
again was caused from the "Crescendo"-circuit, which has a trimmer for 
offset. This trimmer is soldered on the soldering side of the pcb and 
should get its ground from a line on the component side of the pcb. 
Appearently the connection on the not easily accesible parts side was 
missing, so I connected the visible side of the solderpoint with a wire 
to ground and now everything is fine!


Am 31.07.18 um 21:04 schrieb Florian Anwander:
> Hello,
> I have here a Crumar Performer for restauration which shows a strange 
> behaviour over the keyboard:
> In string mode some keys have an rectangle suboctave playing and some 
> don't.
> It does not matter whether I am in 8" or in 16" mode or have both 
> activated.
> In brass mode this suboctave is gone.
> There is no octave relation, which might have made the TDA1008 
> suspicious. Interchanging the TDA1008s also does not move the 
> behaviour to other notes.
> The service-manual is here:
> http://www.florian-anwander.de/crumar_performer/CrumarPerformerServicemanual.pdf
> The datasheet for TDA1008 is here:
> http://www.florian-anwander.de/crumar_performer/TDA1008_PhilipsSemiconductors.pdf
> The list which note has suboctave and which not:
> http://www.florian-anwander.de/crumar_performer/CrumarPerformerSuboctave.txt
> I have no idea where this suboctave might come from. Any suggestions?
> Florian
> -- 
> http://www.florian-anwander.de/
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