Synth-DIY Yahoo! Groups Archives

IC 4051 on TSB

2013-10-22 by <martinjboisvert@...>

Greetings,

I am in the process of changing out the IC 4051's on the TSB boards and during the de soldering process a trace got sucked up! It is the trace that connects Pin 12 on IC4. Is it possible that Pin12 is not used as it does not seem to be connected to anything on either side of the board!?!

Thanks

Martin

Re: [yamahacs80] IC 4051 on TSB

2013-10-22 by David Rogoff

I am in the process of changing out the IC 4051's on the TSB boards and during the de soldering process a trace got sucked up! It is the trace that connects Pin 12 on IC4. Is it possible that Pin12 is not used as it does not seem to be connected to anything on either side of the board!?!

Thanks

Martin

From the circuit board layout ( http://therogoffs.com/cs80/manuals/CS80_Service_Manual/12%20-%20TSB%201%20Circuit%20Board%20&%20Wiring.jpg ) and the schematic ( http://therogoffs.com/cs80/manuals/CS80_Service_Manual/11%20-%20TSB%201%20Circuit%20Diagram.jpg ) you can see that there’s nothing connected to that pin.

Also, looking at the pinout for the 4051 ( http://www.ti.com/lit/ds/schs047g/schs047g.pdf ), pin 12 is input #3. This, and input #7 (pin 4), are not used on any of the muxes because of the way the notes and octaves are encoded.

Good luck on the re-work, but I’d suggest that if you’re not comfortable with looking at the schematics and PCB layouts, at least to a simple level like this, it’s probably not a good idea to be in there with a soldering iron! I don’t know your particular electronics background - this is just a general warning to all.

David