Rhodes Chroma Polaris

One of the voices just stopped working on my Polaris.
I hope it's not gonna be too expensive :(
What are the first things to check?

On 24.01.17 16:06 , dmxkrew@... [chromapolaris] wrote:

 

One of the voices just stopped working on my Polaris.
I hope it's not gonna be too expensive :(
What are the first things to check?

Do you have an oscilloscope?

If no:
 Take the Polaris to a tech.
If yes:
 Set the VCO to full resonance and enable noise. Do you hear this on this voice?
if yes:
  Continue at the oscillator check.
If no:
 Check the signal at pin 14 of the 3372.
If signal exists:
 Check the signal at pin 12 and/or 13 of IC8 (CD4053).
   If no signal: -> CD4053 dead
If no signal at pin 14 of the 3372.
 Check then CVs at pin 15 and 13 of the 3372 while playing notes. They should be similar like at the other voices
If voltages are ok: -> 3372 dead
   if not ok -> ask here again.

If noise works, but no oscillator:
Set both oscillators to a not modulated saw wave, no sync, no x-mod and check the 3374 whether pin 2 and 17 provide a saw wave, and whether this changes with new notes.
If no: check the pitch voltages at pin 7 and 12, if these look similar like at the other VCOs, then the 3374 might be dead
If the voltages are not ok, -> ask here again.
If yes: check the signal at pin 3 and 4 of IC 7 (CD4053).
 If there is no signal at pin 4, then this CD4053 is dead.

My main suspicion is one of the CD4053.

Florian

On 24.01.17 16:26 , Florian Anwander fanwander@... [chromapolaris] wrote:

 

Set the VCO to full resonance and enable noise. Do you hear this on this voice?

Sorry, this is a typo, it should read: set the VCF to full resonance.

Thanks! I just took it to my tech but will pass on these notes, I don't think  he's very familiar with the synth.

I believe that the ICs are socketed in all Polarises. Unless they're not, a useful technique is to try swapping ICs between the bad voice and another voice, to see if the problem moves. The most likely are the 4051s in the sample-and-hold circuits, and the 4053s used for signal routing.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...