after fixing a broken pin socket and swapping all the others into golden ones on the upper middle board (that with the preset PCBs) all notes in exactly two octaves above the split point are 80% low leveled and when holding chords sound is distorting. Above and below these two malfunction octaves sound is o.k. Resonators as themselves are obviously functioning properly. All this going out with Output Mix and Res Out.
VCF and Direct out everything’s o.k. MOD out doesn’t work as well and is completely silent.
What makes my tech stuck is that we havn’t any audio signal on pin 1, connector S85 and pin 1, S86. The same on pin 4, connector S82
We can’t go on as we have no signal on this points and don’t know why.
Two resistors had been swapped as well as they looked slightly burned in their surrounding: R 46, 47 Ohm and R49, 330 Ohm
The one pin connector in the front of this middle board had also been broken for a while and measuring tension had shown 4,91 Volt.
My tech said it should have 4,55 ??
After building an extra amp setup for examination of the middle board to avoid sending the entire instrument 600 km apart to him he’s found out first that one of the three OP amps for the keyboard split was louder than the other two. So first he couldn’t understand why as everything else was o.k. Then he touched accidently one of the 3 resistor fences that are sticking in white sockets. After taking that row out and cleaning carefully everything was o.k. No he’ll throw out all the sockets of all thee and will solder all the resistor fences into the board.
What a GREAT SHAME ON ME
I’ve cleaned before all the connectors and their sockets for several times but not the resistor fences, what a shame
Now I’ve to do a three days work of cleaning all the other hundred billions of resistor fences…
It’s always the contacts, …always the contacts, …always the contacts…
Well, happiness and joy again, the Poly is now working “fully” after installing some real chip holders for the OP ICs, soldering firmly the resistor arrays into the board, replacing a broken pin, and changing one resonator Gain slider.
But one more little question:
When using the single outputs, Res., VCF., Mod., and Direct, and making the output-gain sliders fully open there is a background sound like when all keys are pressed simultanously. Not loud but significantly to notice. Pulling the slider back this effect diminishes.
On MIX output this is not the case. Also the general MIX-sound in lower leveled with the slider fully open than the others.
In the schematics it is said that the MIX output is lower for 1/3 than all other 4.
So what about this background-ringing. Seems to be normal ???
In general I’m feeling about the maximum output loudness of the Poly “not overwhelming”…
Thank you, MC, we have been in fear of this, but I’ve talked today to my tech and he is assuming anywhere a bad or loose ground-connection. I should carefully check out again every ground connectors.
Everything else, he said, would be an extensive searching, but when you’re telling this is normal…then…there’s nothing to improve. ???
Any others with some ideas ? To shield, or s.th. like that ? Or swap some parts ?
Unfortunately it is a consequence of the technology. What you are hearing is accumulative EMI of all 142 simultaneous pitches (71 keys, two pitches per key). A bad ground could cause the problem but fixing it won’t totally eliminate it. Shielding or quieter opamps will not help.
Thank you, as I didn’t yet removed the extreme dirt, the glibbery and very sticky foam rot between the slider board and the front panel on the left side, inclusive the patch button section, I’ve discovered yesterday a slack joint in the patch button section, as it didn’t work for a while and not being able to step between the patches. But after banging slightly against some buttons it works again solid as a rock.
But sometimes this backgrond noise became a bit louder and then lower again. So I’m hoping so much it will diminish or mostly be off after cleaning. But now it isn’t at all dramatic. One can live with very fine as when drawing the sliders down, the level one the PA can be enhanced. But the active cabs are pretty noisy on their own.
Next step is now the refurbishing of the Polypedal as it also shows up some fools. Cleaning the Plugs didn’t help. there must be taken a look inside and probably resolder some points as this unit had been formerly on the road by another previous owner. Strange, as it worked properly some years ago.
