Specific stereo voice issue

[brian_ronn]

Hi Wizards

For the last 2 years I've had problems with voice 3 and 13.  5 minutes after powering up the EIII I experience voice 3 losing the right channel and voice 13 reduce the left output level.

Is this due to faulty Curtis CEM3387 voices or might this be because of poor connection between the voice board and the mother board?

Best regards

Brian
Denmark

 

[esynthesist]

Hi,

Since 2 weeks I have the same problem on voice 7. The right channel output level of this voice becomes zero a few minutes after booting...
Sometimes this channel "comes back" after one hour. Strange.
I guess it's a weak connection somewhere so I'm going to check all (ribbon) wires...
Since my voice 5 is already disabled because of distortion problems, I'm afraid my EIII will end up with 8 voice polyphony like my EII :-)

[karlscott]

I'm going to take my EIII Rack to my tech today, my stereo outs come on at first then shut down after 5 mins or so (I will let you all know the outcome and what he says as he has vast experience).

I am going to use solution 2 supplied by "DVDBORN & DR C" which is to run a new yellow wire from +5v power cable onto pin 8 of IC3 chip..

Funny thing is when i got a reply back from "DR C" this is what he said:

"Have the guy solder a yellow wire to pin 8 of IC3, the other side of the
wire going to one of the yellow wires coming from the power supply (its
the +5V) This will solve all this crappy clicks and stereo dissapear."

Firstly i must say that i'm most certainly not a tech but these are just some observations that i think i need to bring up..

So i'm thinking obviously everyones knows that those bloody ribbon cables are old and i think they need replacing, and if pin 8 powers the output board then what Dr C says about "crappy clicks and stereo disappear" makes sense.

Which ever ribbon cables are giving you problems then i think it means it's not supplying the right voltage to the output board adding the extra yellow wire should solve all of this as the board has a consistant supply of +5v...

Where can you buy that ribbon cable that connects to the output board??

What is that cable called??? i'm sure it"s not another form of IDE (i'm not to hot on computer cables!!!)

I don't see a problem getting the IDE cables, these also short out as sometimes when my EIII goes funny i just have to move the IDE cables connected to my zip & scsi drives, and everything is fine and dandy after that...

Personally i think if we can find somewhere to get all the internal cables it would solve alot of peoples problems...

I have an old mac in the loft with has shit loads of IDE cables for scsi drives in it and it runs flawlessly no problem..

It's most probably because someone has not had to go inside it every minute to fix some fault or another, all that moving around of cables over 20 years has to have caused some damage to them.

Anyway these are just my observations, if anyone knows where to get all cabling or the right names for them, lengths, 2 way splits or whatever then let me know...

I hope we can get all our output problems sorted once and for all, this machine's sound is to beautiful to let it just fade away, i'm gradually going to upgrade every part i possibly can to keep this machine in tip top shape.

My tech is a very good friend he does alot of work for, Sir Paul MCcartney, Phil Collins and the some of the guys from Tangerine Dream, to name a few i will keep everyone updated with photo's (if possible) and any useful information that he gives me...

Karl...

[karlscott]

UPDATE:

Saw my Tech today all that was needed was a total recalibration of the power supply got all voltages back up to scratch he said the power supply is like a house in that it will sink lower & lower into the foundations over the years it just needs proping up.

For all the people with chips popping out of their sockets he said the best solution is to get all the sockets unmounted and solder the actual chips to the board, would have to check out chips in question from the service manual to look at heat resistance, if their is a problem then some form of heat resistant back bracket could be implemented, (really all to technical fo me LOL).

He has done this many times from his days working at BBC, he uses eprom readers to copys the chips in case of anything, i think some old ARP synths had this same problem can't remember exactly which synth he was taling about.

He also popped cards out of sockets sprayed with some form of oxide spray, my +5v yellow wire was running at 3.7v he said he was suprised i could anything i should of been hearing distortion he said same thing happens with SP1200...

My +12v was running at 11v which is borderline on crashing so he boosted that back up to +12v

So for now everything is running sweet, fingers crossed i don't have to see his face again, actually i wouldn't mind as he did not charge me a penny...

hope this helps some of you guys, Karl....

 

[dvdborn]

For those who are brave enough. The procedure for the power supply calibration can be found here:

http://eiiiforum.com/index.php?topic=8.0

David

[karlscott]

you most certainly have to be brave!!!!!