Hi my Poly 61 is almost fully functional now. I am still having an issue where I can’t get the EG ADSR to work. Can anyone point me to where on the board and which board I should check. Can I check with my multimeter and find what part needs to be repaired etc?
I think I have narrowed it down but I would love some feedback. Even a photo attached showing me where I should check etc.
Thanks in advance.
Mike.
If none of the 6 EG’s are responding then the trouble is likely on the digital board (KLM-509A).
There are 3 chips that handle the decoding and buffering to trigger the EG chips(SSM 2056)
The decoder chips are IC9 and IC10 - (HD14175). The buffer chip is IC12 (HD14503). The 12 pin connector (CN12) is where all 6 digital signals leave the main board and go to the voice board (KLM-508A).
Almost forgot ask. Did you have a battery leak on the board?
Yes I bought it as is for a cheap price because it had the battery leak. Thanks for your input.
I will check all the connections when I get the chance and then see if any of those chips are bad.
Cheers,
MK
If it had a battery leak and all 6 voices are affected i would check for continuity between pin 4 of IC28 (8255) and pin 1 of IC12 (14053). That signal is the enable/disable line for all 6 EG’s.
Cheers
Pat
I checked the continuity and it all seems good.
On ic12 the voltages I am getting are as follows:
On pin 9 it is 4.98v and it doesn’t fluctuate when I press a key.
On pin 1 .084v no change…
Everything else is about .07v and when i press a key or a few keys sometimes it jumps to 4.87v then drops back down to about .07v when I release the key{s}
ok it is working now somewhat or i narrowed down the problem. There is a bunch of wires labelled c12 and another bunch of wire connector beside it they seem to be going to and from the joystick board. Seems like when I unplug c12 then i get my functionality of the adsr. I also have one voice chip that is always all over the place so I think I need to order a new one.
Thanks for your input