The Kawai & Teisco Analog Synths Group

Thanks, I'll look into the heating opamp,
However, I noticed something that maky be confusding. The 7805 
regulator back is directly connected with its middle leg, put with no 
seperator into the heatsink... not shure it that is OK or the middle 
led is in short with the ground that way... the other regulator has a 
plastic back.

In case I don't find any heating opamp, how would you trace that ?

The 5v / -5v rails seem fine so far.

Also, afaik, when all leds lite up, does it mean the synth doesn't 
actually pass the reset phase ? 

Thanks.


--- In kawai_sx210@yahoogroups.com, "Travis Shire" <boardjunkie@t...> 
wrote:
> The +15v rail drops *when* you plug in a connector? You're not 
doing this
> with pwr on are you? NEVER do that.....ever. There's a ton of CMOS 
ic's
> in there that will be ruined from the voltage spikes created when
> plugging/unplugging a connector with pwr on. You've already found
> incorrect voltages....you seem to know what they should be. There 
may be
> 3 terminal regulators for the +/- 15v (this powers the audio op-
amps)
> such as 7815 (+15v) and 7915 (-15v). If that's the case, one pin is 
v in,
> one pin is v out (15v regulated) and one pin is gnd.
> 
> Make sure the +5v digital rail is at 5v (or very close, within a 
10th of
> a volt) with no ripple. All logic functions will need it to be 
stable for
> the CPU to do *anything*.
> 
> Best track down a schematic for the power supply pcb and trouble 
shoot
> each rail.
> 
> There is also the possibility that something is dragging a v-rail 
low due
> to a short. Op amps can do this....look for one that gets 
abnormally hot
> in a few seconds after power up.
> 
> Do some detective work and let us know what you come up with.
> 
> 
> 
>   ----- Original Message -----
>   From: gil_we
>   To: kawai_sx210@yahoogroups.com
>   Subject: [kawai_sx210] OT: Juno 106 doesn't start
>   Date: Fri, 01 Jul 2005 07:21:00 -0000
> 
>   When turning it on, all leds lite up, no sound.
> 
>   I checked the voltages and instead of 15v there are only 3.7v
>   measured
>   at the PS. I found that the 15v voltage drops as you connect the 
main
>   module board to the PS. If disconnected from the PS the system 
runs
>   on
>   the required 15v.
> 
>   Any suggestiopn where to begin checking the module board?
> 
> 
> 
> 
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