Emulator II+ / suddenly not playing anymore

[operasix]

Hello together and first of all thumbs up for this amazing forum and knowledge base !

Please excuse my english skills - I hope you'll understand me

I have an Emulator II+ for two years now - it worked without any problems but since yesterday it's not working anymore.
When I turn it on it loads from every disk I insert but after loading there is no sound anymore - I made a little video to show you:

https://www.youtube.com/watch?v=lEXPegb8xMU#action=share


What I noticed: In the working days of my Emulator II+ after turning it on I always had a tone like a sinus coming from very low to very high - then the disk started loading and this tone was gone.... Now when I turn on the Emulator I get this "resonant tick sounds" as you can hear on the video... they are in sync with the floppy loading sound .

I read all topics in the Emulator II tech tips  and hoped someone else had the same problem in the past - but I didn t find something like that.

I also checked all voltages of my power supply and they are all okay ! Also I found a topic where a guy with this startup sweep sound replaced IC86 - I also tried that but it didnt work for me.

Just a last information - when I turn around the main volume knob I can hear a little bit corrosion noise in my speakers - so this circuit should work.

Hope everybody could understand me Thank you for your help everybody (y)

all the best
Steve

[dr.c]

"ng it on I always had a tone like a sinus coming from very low to very high - "
You mean in frequency ?

Okay, stop messing by echanging chips "out of the blue", just loke that...

What was that IC86 ?

Did you change the startup diskette ? Shut the machine down, start up and put a new diskette.

Do this BEFORE, and then, tell me what is going on.

Cheers

[operasix]

Hey Dr.C,

thank you very much for your reply !

I tried more the 10 different startup diskettes right now - still the same... no sound after loading.

when I turn on the machine the display says "Emulator II Boot in progress" - then I insert a disc and get the message "Software Rev 3.1" and "this will take a while" - then it loads the disc - when it is ready I can choose the presets I've loaded the usual way but there is no sound coming out of the Emulator.

The sinus tone I meant could be heard on every start of the Emulator in the past before it quit working - it sounded like a filter sweep starting at a very low frequency and coming up with a little bit of resonance. This has gone since the emulator isn't working anymore - now there are only this "click-sounds" as you can hear on the video I posted.

the IC86 thing:

there was a thread here in this forum where a guy also had this startup filter sweep sound and tried to find a reason for it and fix it - the solution was to change IC86 - so I also tried to replace it with another IC (same type) - but that didn't solve my problem !
This was the thread: http://eiiiforum.com/index.php?topic=2775.0

any ideas what I could do next ?

all the best
steve

[dr.c]

Wonderfull....

What type is EXACTLY this f... IC86 ?   Banana78, 74LS447, Gizmo 475 ?

[operasix]

IC86 is CD74HCT138E (RCA H 632)

after replacing and trying the new one I replaced the old one again - so everything is like it was again.

[dr.c]

Hi,
I tried to fnd the page of the schematics involving this circuit. I have a good idea of what it can be, but I'd like to check, to be sure. Would you have it ?

Please, don not imagine that I would think you are an idiot, but did you try to :

a) - Check the separate outputs and not only the main,
b) - Chek by Master/Special/??? if the outputs are not disabled

Please do, even if it seems stupid, but you will be sure about 100000 % that the machine is bad.

[operasix]

Hey Dr. C,

I checked that - but also the solo outs are not working ! I also checked in the menu that they are not disabled !

so I also checked now if its possible to sample... connected a synth to the sample input of the Emulator and played along but the Emulatur VU doesnt react (also changed the input gain of the Emulator to max) .... the machine doesnt get an input signal.

all the best
steve

[dr.c]

Well done, for the checking.

I think I know what it is, but I need the diagram sheets. I have to dig in my archives. I'll let you know ASAP

[dr.c]

Still looking for this damn service manual. Do you have it ? If yes, can you post it somewhere ?

[Elmbeatz]

Still looking for this damn service manual. Do you have it ? If yes, can you post it somewhere ?

You mean the EII service manual?

[gertie]

is it not here? schematics & service manual

http://www.theemus.com/documentation.html

[dr.c]

I found it, it was in one of my disks... Gimme a minute to look...

[dr.c]

Okay,

As far as I can see, IC86 is a S3528 circuit, located page 7-42, Input analog, and not a :

IC86 is CD74HCT138E (RCA H 632)

I have to look further....

[dr.c]

Look at page 7-39. There is a DAC AD7524, IC63.

This circuit distributes a signal to three 4051 wich are analog multiplexers.
Each of them are controling the filters.
One is controling the volume output of the VCA's, so if its dead, = no sound !
Look at the inputs (COM Pin 3) if there is a signal coming. If not, look at the output of IC44 (TL084, Pin 7) if there is a signal. If not; I would say thet the AD7524 is dead.Still, look at the adress inputs of the AD7524 IC63, if you get someting.
Look as well at the adress inputs of the 4051's
I bert your problem is there.

You said you have checked the PSU, uh ? 

[operasix]

wow, lots of good information for me ! thank you sooo much man !

so what can I do ? replace them with new ICs ? I dont have this types... wondering where to buy them but I will check ...
how can I check if a signal is coming to com pin3 or ic44 pin7 ? what signal should be there ? can I check that with a multimeter ?

yeah I checked the psu... all voltages are correct - I will check again tomorrow and post the exact voltages here.