The Kawai & Teisco Analog Synths Group

Found one 80017A that's hot as hell !!

It's the first one from the right. I wonder if the short is in the
chip itself or is caused by another component that interacts with
it...

I can see that TR18 transistor, which interacts directly with leg #2 
of that IC has a solder joint on one of its legs - as there was a 
wire connected to it in the past. The entire machine looks like it 
has some mod appiled to it (a jack was added to it). The tranny 
itself is not shorted.






--- 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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