[pcb+panel] ssm2044 filter for eurorack

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TimoRozendal
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Re: Need help troubleshooting (fake IC?)

Post by TimoRozendal » Mon May 09, 2016 1:44 pm

jhosef wrote:I have a pretty good track record with my circuits - either from scratch or a bare PCB, but this has been a bit of trouble for me and I will admit defeat.

I guess that I should start by admitting that I started out on the wrong foot by plugging the boards together backwards, which promptly caused the bottom amp IC (nearest to the plug) to POP.

Also of note is that I had 2 SSM2044's that I got off of ebay awhile ago, not realizing the scourge of counterfeits. With no luck from these, I ordered one from UtSource.

After the initial snafu, I assembled the boards the correct way, confirmed that the voltages were correct at the IC sockets, changed out all the IC's to be safe and got nothing out of the filter. I did find that the bottom amp IC got really HOT with either of the SSM2044's that I had.

Suspecting a fake, I ordered from UTSource and now the bottom amp IC is cold, the SSM2044 gets warm in the center, but still nothing.

When I check the signal path with an oscilloscope, it gets through the top amp IC and promptly stops at the SSM2044.

Attached are images of both sides of the SSM2044 (UTSource one on the bottom) and the bottom PCB. My only deviation is that the 820pf is ceramic. I understand that this is no issue to it functioning, but I just got a poly one that I intend to swap at this evening

The two board layout confuses me for troubleshooting, but what else might I have damaged connecting the boards wrong? Are there other points that I can check? I strongly suspect a fake SSM2044, but am looking for validation.

Thanks.
Hi jhosef, sorry to hear about your troubles
I hoped the images in this thread where explanatory enough, but I might need to add extra info on how to combine the 2 boards.
The ssm chips are really sensitive to reversed polarity, I also fried one that way. The top ssm looks really suspect in your image, the bottom one looks really familiar. Please double check the polarity of the ssm before placing.
If you want we can take this to PM and puzzle further.
Cheers

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jhosef
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Post by jhosef » Tue May 10, 2016 6:40 pm

The connection of the boards is clear enough if you bolt them together. I didn't have a bolt available at the time, so I connected the front PCB a socket higher than the back board so it must have shorted something.

Do you have a list of the expected voltages at the ssm2044 pins? Can you explain what the test points are for? They appear to be for the cutoff?

I've probed at it enough to confirm that all the chips are an issue. I'm going to look for a better chip source but before I install that one I want be sure that u don't have fault that is killing them.

Thanks.

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jhosef
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SSM2044 for sale?

Post by jhosef » Thu May 12, 2016 11:15 am

does anyone have a verified SSM2044 chip that they could sell me?

I've had it with these obsolete IC's.

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Post by TimoRozendal » Fri May 13, 2016 1:49 pm

jhosef wrote:The connection of the boards is clear enough if you bolt them together. I didn't have a bolt available at the time, so I connected the front PCB a socket higher than the back board so it must have shorted something.
so, you shifted it one up or down? but the orientation of the boards was ok?
jhosef wrote: Do you have a list of the expected voltages at the ssm2044 pins? Can you explain what the test points are for? They appear to be for the cutoff?
tp1 and tp2 can be used to connect a tempco in thermal contact with the ssm chip (as explained in the build doc), these are not test points per se.
No, I don't have a complete list, but I can measure something hopefully in the coming days, for now the datasheet is already a starting point:
http://www.maxmidi.com/diy/ssm/ssm2044.pdf

Exptected voltages:
cutoff input pin 13 should be from about -90 to +90mV (did you do the extended range mod btw?), pin 8 : GND, pin 16 +12v, pin 9 -12V. The rest of the pins do not have a given voltage (q input range for example is defined as current depending on cutoff voltage)

see also the datasheet: http://www.maxmidi.com/diy/ssm/ssm2044.pdf

can you pm me a couple of high res photos of your builds?

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jhosef
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Post by jhosef » Fri May 13, 2016 2:23 pm

The orientation was correct and if I would have bolted them before I tested, it would not have been an issue. The post above has been edited.

Thanks for the voltages and the cutsheet. It gets the expected voltages at the -V/+V/GND, but I'll check pin 13 later. I did not do the mod.

I'll send photos of both sides of the panels when I get home later.

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gwpt
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Post by gwpt » Fri May 13, 2016 8:05 pm

Hi, is it too late to get hold of a PCB + Panel?
I don't need the chip as I have them already...

Thanks :)

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Post by TimoRozendal » Fri May 13, 2016 11:48 pm

gwpt wrote:Hi, is it too late to get hold of a PCB + Panel?
I don't need the chip as I have them already...

Thanks :)
I still have a few left, I'll PM you

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mnml
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Post by mnml » Thu Jun 09, 2016 10:15 pm

Who's a good source for the jacks and the 10-pin header? I see synthcube has the jacks and synthrotek has the header, but I'm trying to minimize the vendors I'm buying from....

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Post by TimoRozendal » Fri Jun 10, 2016 2:36 am

mnml wrote:Who's a good source for the jacks and the 10-pin header? I see synthcube has the jacks and synthrotek has the header, but I'm trying to minimize the vendors I'm buying from....
I would suggest you buy the headers along with most stuff at tayda
Simply buy these and cut them to size
(or buy a bunch of shrouded headers, e.g. here: )

Things you cannot buy at tayda: jacks, beads (can be replaced by 10R resistors), spacers, and the 820 pf (<-- I can send you that one if you want)

Since you are US based you can buy the jacks and headers and spacers/screws at Synthrotek

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mnml
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Post by mnml » Fri Jun 10, 2016 8:24 am

TimoRozendal wrote:
mnml wrote:Who's a good source for the jacks and the 10-pin header? I see synthcube has the jacks and synthrotek has the header, but I'm trying to minimize the vendors I'm buying from....
I would suggest you buy the headers along with most stuff at tayda
Simply buy these and cut them to size
(or buy a bunch of shrouded headers, e.g. here: )

Things you cannot buy at tayda: jacks, beads (can be replaced by 10R resistors), spacers, and the 820 pf (<-- I can send you that one if you want)

Since you are US based you can buy the jacks and headers and spacers/screws at Synthrotek
Thanks!

After reading this thread I spent some time looking up parts at tayda. I'm guessing from your reply that their ceramic 820pf is not suitable, due to microphonics or some other reason?

http://www.taydaelectronics.com/catalog ... /?q=A-1446

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Post by TimoRozendal » Fri Jun 10, 2016 2:16 pm

mnml wrote:Who's a good source for the jacks and I'm guessing from your reply that their ceramic 820pf is not suitable, due to microphonics or some other reason?
http://www.taydaelectronics.com/catalog ... /?q=A-1446
I recommend you use a different one, but you can socket it, try a ceramic and ask me for a (free) cap anytime.
This is always recommended for filters. I think it will improve the response of the filter, but I am not the expert on this.

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flab
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Post by flab » Mon Aug 29, 2016 3:24 pm

hey,

any of you holds a mouser project?

i am looking for this one as well

would be great

thanks

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batank
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Post by batank » Thu Nov 03, 2016 12:03 pm

Hi Timo, are you still holding any sets with chip for sale? If not, can anyone recommend a place to pick up the SSM2044 for a reasonable price?

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Post by TimoRozendal » Fri Nov 04, 2016 3:46 pm

batank wrote:Hi Timo, are you still holding any sets with chip for sale? If not, can anyone recommend a place to pick up the SSM2044 for a reasonable price?
alas no, I am out of chips and pcbs/panels. Modularaddict still has the pcb/panels.
For the chips I would pick a trusted Aliexpress seller for not too crazy prices (low or high), or get it from Electric Druid

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flab
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Post by flab » Fri Nov 04, 2016 4:54 pm

i made this one some time ago - sorry is a bit dirty also didnt paint the engraved parts, i wanted to get it done so tohear it, really nice, if someone likes the dual filter panel , i have a .cad file let me know


Image
Image

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cranleigh
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Post by cranleigh » Mon May 01, 2017 2:10 pm

Hi guys,

Would this do the job for the 820p cap?

http://www.mouser.com/ProductDetail/Cor ... bqy3Nx0%3d

thanks!

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babysealclub
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Post by babysealclub » Tue May 02, 2017 8:34 am

It looks kina large (in size). You could mount a 680nf box on top and a 150nf on the bottom of the pcb.
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Post by cranleigh » Tue May 02, 2017 12:18 pm

Thanks! Apparently, Modular Addict actually ship a 820p with the PCB and panel; I hadn't realized that (still waiting on it to arrive).

:guinness:

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Post by NiteEagle » Wed Aug 09, 2017 10:13 am

cranleigh wrote:Thanks! Apparently, Modular Addict actually ship a 820p with the PCB and panel; I hadn't realized that (still waiting on it to arrive).

:guinness:
Timo, Is that C5, because the device I received from MA has 820pH on it? I would be expecting it to say 820pF
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Post by TimoRozendal » Fri Aug 25, 2017 7:08 am

NiteEagle wrote:
cranleigh wrote:Thanks! Apparently, Modular Addict actually ship a 820p with the PCB and panel; I hadn't realized that (still waiting on it to arrive).

:guinness:
Timo, Is that C5, because the device I received from MA has 820pH on it? I would be expecting it to say 820pF
(sorry, missed a notification for this message)
yes it is correct, it should be 820p and then I think the last letter is just batch nr or something

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Post by TimoRozendal » Fri Aug 25, 2017 7:10 am

pcb/panels are back in stock

and they come with a free converter pcb for the SSI244 (re-release of the ssm2044 in a small smt package).
Syntherjack designed this conversion pcb and kindly made it available.

I just tested this and it works fine, though the resonance curve seems to be a bit different, less gradual.


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ersatzplanet
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Post by ersatzplanet » Fri Aug 25, 2017 11:41 am

I have a handful of original SSM2044 chips if somebody wants to buy them from me. They have been sitting in static foam since I got them new. I used to work for Symetrix and we made a unit called the Phase Filter using a couple of them. I have no idea if they still work or not though.
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Synthwerks is a proud member of the Mostly Modular Trade Association (http://www.mostlymodular.com).
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Post by NiteEagle » Fri Aug 25, 2017 7:45 pm

I've built two of these using the SSI2144 and JMLS conversion board. I have no control over the resonance. It does not go into oscillation at all with T3 full CW. As soon as I move T3 a small amount CCW the filter oscillates all the time with no control at all with the resonance pot. Both builds behave the same way. What should I check?

Cutoff does function normally.
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Post by TimoRozendal » Sat Aug 26, 2017 12:57 am

NiteEagle wrote:I've built two of these using the SSI2144 and JMLS conversion board. I have no control over the resonance. It does not go into oscillation at all with T3 full CW. As soon as I move T3 a small amount CCW the filter oscillates all the time with no control at all with the resonance pot. Both builds behave the same way. What should I check?

Cutoff does function normally.
I also puzzled with this yesterday when I tried the SSI2144 in a build i already had that used the SSM2044 before. I managed to get a normal resonance range by applying a negative voltage offset to the resonance cv input. Can you try if that works for you as well? If that is the case than i can provide an easy fix with an extra resistor.

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Post by NiteEagle » Sun Aug 27, 2017 11:24 am

TimoRozendal wrote:
NiteEagle wrote:I've built two of these using the SSI2144 and JMLS conversion board. I have no control over the resonance. It does not go into oscillation at all with T3 full CW. As soon as I move T3 a small amount CCW the filter oscillates all the time with no control at all with the resonance pot. Both builds behave the same way. What should I check?

Cutoff does function normally.
I also puzzled with this yesterday when I tried the SSI2144 in a build i already had that used the SSM2044 before. I managed to get a normal resonance range by applying a negative voltage offset to the resonance cv input. Can you try if that works for you as well? If that is the case than i can provide an easy fix with an extra resistor.
Yes, Timo, I can control the resonance by applying a negative voltage to the resonance cv input. Had to be between -5V and -10V to control with the trimmer. Less than -5 and it was out of control.
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