Missing voices after warm-up

[Gul Dukat]

Hi.
I face the issue that my EII+ is missing voices after the warm-up phase. It differs from time to time how many voices are missing (sometimes 2, sometimes 4). I couldn't find a recalibration prodecure in the manual. Any ideas?
Furthermore I have noticed that the output level is really low. I don't know if this is coherent with the voice issue.
Thanks!

[dr.c]

Along thejuntion of the analog and digital board, on the right side of the analog board, there are four circuits referenced 4051.
Take the off and put them back. DO NOT SWAP THEM AROUND

See if it helps

[dr.c]

refer as well to : http://eiiiforum.com/index.php?topic=2530.0

Power supply distribution bad soldering

[Gul Dukat]

Hey Doc.
You are my hero - that worked !! All voices are back and also after almost 2 hrs of working no failures.
BUT .... a new issue came up. It seem that one voice can't use of the filter (?) seems that the filter is always opened for that one voice ? I attached a video to demonstrate...

https://www.youtube.com/embed/65DiwHwXB68

I don't know if the sample input has something to do with the IC4051 ?  I ask because the the input is very low I always have to push it in the Gain Set to +20db also for a normal line input to get an acceptable level.
I read in some other posts that it might be a good idea to replace the crappy 4051 ICs ?
They are labelled differently - From top to bottom: CD4051BE RCA H 549 - CD4051BE RCA 245 - CD4051BE RCA H 549 .... and the last one is without a label ? Do I need to order exactly the ICs according their labels?
Any other recommendations to replace unreliable ICs - the EII casing is still open ;-)  
Thanks for your help!

[Gul Dukat]

Hi Doc.
Can you help ? ;-)
Thanks!
 

[dr.c]

Hi,

There are three or four circuits, aligned verticaly, on top of each others, labelle 4051. It can be CD14051, MCI4051, HFE4051, etc... They are analog multiplexers, used as sample&hold.
One is for the eight channel volumes, another for the filters, a third for the Q, etc...
I believe that one of them is overheating.
Just put your fingers on them, you will feel them. DO NOT INTERVERT THEM.
First, find a a floppy from another machine and see if it does the same. This nebause the adjustments are in the boot software, wich means when you try another diskette, you have to start the machine with it.
Okay;.. now, change the circuits ONLY IF YOU HAVE TO. If you change one of them, you have to recalibrate tha whole machine again ! I have NEVER done any f... calibration on these machines, its a hell, and it has to be fully calibrated before its too hot ! That's a track to follow, uh ?
If you machine works with the news diskette, then go to Special 14 and rewrite the software on EVERY diskette you have, yes, every ones. But be absolutely sure the machine works with this diskette first !
lemt me know, send me an email dr.c@noos.fr

[dr.c]

What is that messy shit on Youtube ?
YOU know what you are doing, not us. Whats wrong with this ? A distorded channel, missing ?
Play slowly, with a sufficient volume level so we can hear clearly.
You can as well go to special, disable channels, and enable only the faulty one and a "clear" one, so we can compare.

[dr.c]

About the 4051s : buy at least 24 of them, they are everywhere in machines !

The 4051 locations at : http://mapage.noos.fr/dr.c/4051.jpg