e-licktronic Forum

So I'm still working my way though - I have 4v pulses at base of Q44 but with a -4v offset. On the other side of R258, which connects to the base of Q44 I have the trigger pulses

...and at pin 6 of IC 40 (Which is the inverted input) I have the noise hits, pin 5 (input) goes to ground as it should, and pin 7 which is the output I have nothing, but it is connected to pins 1 and 2 of the snare level pot...

So I think I have two issues going on - one with the final output stage M5218L and associated bits, and also the fact that none of the oscillators are triggering...

At IC35 I have pulses/envelopes coming from Pin 1 (Output A) of IC35 but nothing from pin 7 (Output B).. Pulses/envelopes are coming into pin 6, and pin 5 is connected to ground as it should be.. Might swap out this M5218L at IC35 and see what happens, as I have a spare..

Dry solder joint on pin 7, re-soldered it and now:

Pin 6 input on IC35:



Pin 7 Output:



Is this right?

Man. I wish I knew. I got in to mine with a scope and realized that I'm SUPER close to understanding all of this, but just not quite there. I have a local synth tech that I trust very much that is taking a look at my Kick, Mid Tom and Hi tom. I lucked out and got everything else working first try. If I get mine back soon, I'll measure those points on my scope and see if it looks the same... That's about the best I could personally do. LOL

stairre wrote:Man. I wish I knew. I got in to mine with a scope and realized that I'm SUPER close to understanding all of this, but just not quite there. I have a local synth tech that I trust very much that is taking a look at my Kick, Mid Tom and Hi tom. I lucked out and got everything else working first try. If I get mine back soon, I'll measure those points on my scope and see if it looks the same... That's about the best I could personally do. LOL

Yeah, I recall having this feeling whilst doing the Yocto - staring at the schematics etc thinking 'I don't get it', and then thinking 'No, come on, let's try to get it' and then eventually getting to the stage of following the diagram round, figuring out what pins on the ICs are what, etc...

So yeah, now I'm at the stage where I can trace it round, and know that something goes into something else, and then comes out the other side in some for or other, but I have no idea what that form is supposed to be....

Oh well, I look at it like playing some sort of puzzle solving game, and if I figure it out by myself if will be very rewarding

Bumpity bump...

Buuuuuuuuuuuummmmmmp ?

Now working, thanks to Vincent! If anyone else is having similar issues, I'll post up the troubleshooting steps he gave me.

Dear 4teenth,

first could you send me the scope of the following point when SD is trigged:
-trig
-Accent
-VCO1, VCO2
-ENV1 to 4
-Noise

Waiting for your scope picture.

Best regards,
Vincent




to e-licktronic
Hi there,

scope outputs are in the attached zips, thanks!

Let me know if you;d rather I upload to the forum and you can answer my question there - might be helpful to someone else at some point.

Thanks,

Mark


to me
Mark,

Everything seems to working fine execpt the accent value. You should find more or less 10V.
Check continuity between IC34 pin5 and IC114 pin14
Measure SD accent to IC114 Pin14, post the result

best regards,




to e-licktronic
No continuity between IC34 pin 5 (5th from left, yes?) and IC114 pin 14 (3rd from left on bottom row)...



to e-licktronic
3rd from right, sorry


to me
I don't know what you mean by: left, bottom, top... because it depend which side your are looking
IC34 pin5 is IC34 Pin5 same thing for IC114 pin14
If you do not get continuity solder a wire between this points.



to e-licktronic
My mistake - there is continuity between pin 14 of IC114 and pin 5 of IC34.

Scope of pin 14 is attached:

Inline images 1

Does not seem to matter what steps are in the pattern..


e-licktronic <e.licktronic@gmail.com>
14/12/2016

to me
Mark,

Accent seems to work fine too so the problem should come from the output circuit.
Check continuity between IC40 pin 5 and J1 pin2




to e-licktronic
No continuity between IC40 pin 5 and J1 pin 2, but there is between IC40 pin 7 and J1 pin 2, but looking at the schematic that is as it should be, right? Output 2?

http://www.musikding.de/bilder/produkte/gross/M5218.jpg


e-licktronic <e.licktronic@gmail.com>
6 Jan

to me
Mark,

Yes you are right it's IC40 pin 7 and J1 pin 2.
Now trace the signal with a scope at this point sequencong the SD.
IC40 pin 6, IC39 pin7



to e-licktronic
Hmm - seems to be a steady 10v at IC40 pin 6, and at IC39 pin 7 I have the pattern I've played but just the noise part of the snare sound..

I've probed the board at the osc points but I'm getting nothing, so I think I have an issue both with the generation of the snare sound and the final output..

Thanks


e-licktronic <e.licktronic@gmail.com>
9 Jan

to me
Mark,

Scope Ic36 pin10 and Pin6 you should find a perfect square waveform
Measure IC36 pin14 by adjusting VR6, what is the result ?


to e-licktronic
Squares at 10 and 6, and a square at 14 that I can change the pitch of with VR6


e-licktronic <e.licktronic@gmail.com>
10 Jan

to me
Mark,

Probe now the same square waveform at IC38 pin 7 and IC37 pin 7




to e-licktronic
I get out of range or if I switch my probe to 10x I'm getting a solid 10v . . .




to e-licktronic
Weird... I'm now not getting squares at IC36...



to e-licktronic
Oops, I had the 12v supply from the TTSH arp clone I'm building connected instead of the correct 15V one...

So yes, squares at IC36 pins 6 and 10 again, but not at pin 14...

Pins 7 of IC37 and IC38 I have triangle waves..


e-licktronic <e.licktronic@gmail.com>
11 Jan

to me
Mark,

Good
Now probe the same triangle waveform when trig the snare. You should see frequency variation
Then track trig pulse signal with your probe on R266, R281, R292. You should find a 2ms pulse signal.




to e-licktronic
Okay, so yeah all good, and I have triggers at those three points.. What next?

Thanks for your continued help

3 Attachments


e-licktronic <e.licktronic@gmail.com>
13 Jan

to me
Mark,

You told me that the noise part is working ?
Check continuity between D64, D68 and D67 cathode and probe one of this point to ?
Post the result




to e-licktronic
looking at the schematic, I think you mean the anode, no? Anyway, anode there is continuity between those three, and here's what I have on the scope:

Attachments area


to e-licktronic
Noise I could hear if I probed the test point marked 'noise' yes, but it does not come through the main or individual output.


e-licktronic <e.licktronic@gmail.com>
16 Jan

to me
Mark,

Yes i mean Anode
It looks like everything working fine until here so i think the summing M5218 IC40 is dead



to e-licktronic
Ah brilliant! I have a spare M5218 from fixing a TR-707, so I should be able to swap that out when I get home after work. I'll let you know how it goes..




to e-licktronic
YES! We have a snare!