Finally joined the EII Club (Sampling and Voice Problems).

[rtech]

No, but I can get one from work. Is there any specific model/type that I need? Is there a specific frequency it has to support?

[esynthesist]

At first it would be for audio signal measurements (very simple - even analog - scopes can do this) to locate where it goes wrong, but of course finding the cause of that problem may require digital signal capturing, so having a certain amount of memory in a digital scope could help.
I'm using a Rigol DS1052E which is 2 channels at 50Mhz and 1MB of memory. The best buy I have ever done, and so cheap ! This DSO has been sufficient for me for servicing and reverse engineering all of my pre-1990 synths and samplers. 
Note that I don't know yet what is causing the problem in your EII - that's why signal measurements are important now, e.g. the output of the voice chips at channel 5 and comparing them with the other ones. Then let's see if we have to trace back OR forward from the SSM chip  I hope forward...

[rtech]

The one at work is an older model, I check it today and it is only a 20MHz analog. I work at a computer store that used to repair computers back in late 80s early 90s. I dont think the scope has been turned on for about 10+ years. I hope it still works.  Will this do for just finding where the problem is? I have the schematics for the the eii, where will I need to probe?
Thanks for the help man, its greatly appreciated.

rtech

[esynthesist]

Sorry for late response - I forgot to check this thread... 
The analog scope will probably be OK for finding out the location of the problem.
But I have to check my EII and the service manual now; unfortunately I will have less time to spend now because my holiday is over...
Anyway, maybe we'll have to go offline in order not to blow up this thread ? And come back with (hopefully) conclusions...

[rtech]

sounds good. When ever you have spare time, just tell me where to check/probe with the oscilloscope. I'll take it from there.

thanks

[esynthesist]

I'm checking the schematics...
But to be sure: you said that there's a distorted sound coming from voice 5 even if it is disabled.
Does this mean that you really ALWAYS have this hum coming from the mix out/channel 5 out, even without playing the EII but just having it powered on ? Or is the hum only there if you touch the keys ?

Probing would definitely start with measuring the signal on the IN and OUTs of the SSM2044 and the switched capacitor filter S3528. Both on voice 5 and another (good) voice, to compare signals.

(there may be a small practical problem though; I haven't opened my EII recently, but as far as I remember part of the output board on which we have to measure is beneath the PSU, so either the boards or the PSU will have to be moved a bit in order to get access to the ICs...)

[rtech]

I just tested it again and prior to playing anything on the keyboard there is no noise. After playing some notes I get the noise in both the mix out and channel/voice 5 regardless whether the voice is disabled. It sounds like residual noise after the notes are played back, I know is not the samples because the banks I am loading are original EMU sound disks.
You are correct about the power supply being above the voice 5 chips. It will get a little tricky testing them. I will open it and see what I can do. If it looks like too much for me to deal with I will take it to Forat or another repair shop.

[esynthesist]

After playing some notes I get the noise in both the mix out and channel/voice 5 regardless whether the voice is disabled.

And when you stop playing the keys this noise is remaining, so it's not disappearing anymore ? 

[rtech]

Thats correct it remains, even after I stop playing.

[seamonkey]

Although I don't own an Ell, I have a question and a comment.
Have you tried creating some samples of your own, and if so, do you still get the residual noise?
I recently picked up an Ensoniq EPS Classic with a library of 3.5 disks. Upon playing most of the samples on the disks I experienced the same thing you describe...a residual crackling type sound after releasing a note or chord.
If I turned the unit off and restarted it would be quiet in the outputs. I had purchased a new box of floppies to have on hand to save any samples I created.
When sampling my own sounds, and saving them to disk, I experienced no noise.

Thinking I might have to have it repaired, I went to the Ensoniq forum and described the problem. The overwhelming answer was corrupted disks, which most likely had deteriorated over time.

So I'm just wondering if this could be your problem as well. It would seem even if these are original EMU samples, if the media they were stored on is corrupted, then the source material wouldn't matter.

I hope it's something as simple as that, but as we know, it never seems to be.

[rtech]

I cant sample with it because the sampling function is not working properly. There is a alot of noise on the sampling feature. I don't think it is because of corrupted data as the noise is there regardless whether I load sounds from a floppy, hard drive or transfer them from a Mac using SD for EII.

[esynthesist]

Another question (also interesting for me to know...): are the ICs such as the SSM voices plugged into a socket or are they soldered directly to the board ?
On mine, they are soldered directly, unfortunately...

Because one of the steps in tracing the problem would be to swap ICs between two channels. Desoldering will not be fun and can damage the ICs !

I would start with measuring the IN and OUT on the SSM2045 of channel 5:
- once before playing the a key for the first time
- once after playing the key (when noise has come up)
This is IC91, the IN is pin 2 and the OUT is pin 8; pin 9 can be used as ground for the probe (or another GND somewhere on the output board).
Is one of the signals changing into "noise" after hitting a key ?

If so, and it is the OUT but not the IN, the problem is quite clear.
If not, we have to go further (either back in the chain, or up to IC81)

[rtech]

I finally decided to go back and try to fix my sampling and voice issues with my EII+HD. Thanks to sfbaytech I was able to remove the HD option so I can have access to the voice 1 chips to try to fix the noisy sampling issue. I also used an analog oscilloscope to trace a sine wave input to see where it becomes noisy. The noise that i get sounds like "white noise" i tested with the scope and see the white noise going from Capacitor C95 on the service manual the label on that signal is +INPUT.V. it also comes out of IC86 pins 9,8 and 7. Does any one here know whether this is a blown capacitor issue? I already tried replacing the ICs that are listed on the schematics involved in the sampling circuit but the issues still persists.  

PS. Initially when i tried to fix this around a year ago, when I was in the sampling module the screen would show a very strong noise signal (almost the entire length of the display), but after i remove the HD components the noice is very small. When I first turn on the EII the noise is quiet high but after a few minutes of it being ON the noise decreases. It is still there but it is quiet low. I can sample but it sounds distorted like if its sampled at a very low sampling rate. I thought that I needed to do the sampling Trim procedure, but when I follow the instructions I am getting not Millivolts on the test point on IC 75 pin 1. What i get is a high voltage starting at a few volts and then rising to about 12+volts. If anyone has any suggestion I would appreciate it.

Thanks,

rtech