EQP-1S5 500 series PULTEC ---- HELP/BUILD thread

[mitsos]

Hi Udo,

well, firstly, yes, the faceplate (and other metalwork) fits the old kits. I'm guessing you asked because I wrote that they are laser cut.  Well, I have to correct myself, because when I wrote that I had forgotten that we changed processes a short time before the fabrication.  Basically we wanted to get rid of the marks left from stamping that the older version had, but laser ended up being prohibitively expensive at the quantities we were ordering. We ended up working on a machining/sanding process that gets rid of these marks, but it is not techincally laser cut. Sorry for any confusion.

The anodization/slik process was also improved slightly and we had blind holes drilled on the back side, so it's no longer necessary to cut the tabs off the potentiometers.  I will say that I just got a shipment of kits from Niels (first ones I've actually held in my hands from this batch) and they absolutely look fantastic.

As for the MEQ, I'm visiting at my mother house and don't have an interface atm so my testing is a bit...well... limited.  I'll definitely update the feeler thread as things move along, I hope to have something concrete in may.

cheers!

 

[kante1603]

Great to hear Dimitri,thanks a lot!

Cheers,

Udo

 

[okgb]

Interested in both the meq and stereo / dual 2 ru versions

 

[sharpeleven]

There are some problems with the two kits just received:

Both kits are missing C47 (150uf). Is this optional? You guys don't want me to install it? It's listed in both in the build docs & BOM. I can also see it installed in some pictures i found online. Please advise.  :-\

The caps provided for C35, C41, C15, C17 are too short. Some very creative lead bending is necessary to try to stretch them so they barely reach the holes.

The kits currently also seem to be missing one PRW (plastic retaining washer). Just 4 included in each.

Note: The nylon stand-off seems too long as the inductor is still loose even when fully tightened.

 

[mitsos]

Hi,

Sorry about this. We looked into it, seems our supplier sent us the wrong cap and it slipped by us.  We have some 33nF caps from the previous order (correct lead spacing) and will send some out to you ASAP, along with an extra PRW.  As for the C47 electrolytics, they are not optional, but they were missing from your kits.  Niels noticed they hadn't gone out and sent them out the next day. If all goes well, those should be arriving today. 

The nylon standoffs are the same ones we used last time, are both yours loose? (mfg variance might account for one being longer, but you'd have to be pretty unlucky to get two).  FWIW, they are not meant to be super tight so as not to damage the winding, but they should not be wobbly either.  If yours are very loose, gently filing the end might get them just right. Or a bit of tape under the large washer or inductor? Let me know if that helps, and I'll look into the ones I'm building here. 

thanks

 

[sharpeleven]

Hi,

Sorry about this. We looked into it, seems our supplier sent us the wrong cap and it slipped by us.  We have some 33nF caps from the previous order (correct lead spacing) and will send some out to you ASAP, along with an extra PRW.  As for the C47 electrolytics, they are not optional, but they were missing from your kits.  Niels noticed they hadn't gone out and sent them out the next day. If all goes well, those should be arriving today. 

The nylon standoffs are the same ones we used last time, are both yours loose? (mfg variance might account for one being longer, but you'd have to be pretty unlucky to get two).  FWIW, they are not meant to be super tight so as not to damage the winding, but they should not be wobbly either.  If yours are very loose, gently filing the end might get them just right. Or a bit of tape under the large washer or inductor? Let me know if that helps, and I'll look into the ones I'm building here. 

thanks

Thanks! So are you saying the 33nf caps provided are identical to the correct ones, except wrong size? I managed to install them all. It's not pretty but the unit still closes up. Are we safe to fire up the unit once I install C47?

I happen to have a couple 16V 150uf cap here. Is it cool to use those? What are the exact specs for C47?

 

[mitsos]

Hi, yes the 33nF caps are supposed to be 10mm lead spacing but we were sent 7.5. It slipped right by us... It will work just fine as long as the leads' internal connection was not damaged by the bending.  Never seen it happen, but it's possible.  I have broken some externally though.

The 150uF cap can be 16V no problem.  We use either 16 or 25 depending on availability.

good luck with the rest of the build!

 

[sharpeleven]

ok, managed to put it all together with some caps I had. Sounds really, really good!

However..... the output when EQ engaged is really low compared to unprocessed signal. There is about 1V drop measured at the output compared to bypassed signal.

Now, when I adjust the trimmer absolutely nothing happens! I've tried like at least 50 turns in either direction and there is zero change. Calibration sure would seem easy enough. Maybe I'm doing something wrong? Is there a more comprehensive guide available somewhere regarding calibration?

Both units show this identical behavior.

Btw, I've noticed that the R10 trimmer orientation is different on the PCB from pictures of other finished units. Did that just change recently or am I supposed to ignore PCB markings and follow the example of other builds?

Also, what should be the expected trim pot behavior? What direction should I turn to bring the output level up (CW/CCW)?

I have GAR2520 op amps installed. Same behavior in 51X rack as well as api lunchbox®

 

[mitsos]

Hi,

Calibration is normally really simple.  Your description suggests a problem in the gain control part of the circuit (R7, R10, C34).

C34 is an optional cap and should be jumpered in your case. We added this cap for anyone choosing to use a JLM99V or other opamp with high DC offset.  If there is no jumper in that position your gain circuit has no path to ground. 

Good catch on the trimmer orientation. It was flipped 180 degrees to accomodate the DC cap, so it should be installed like the silkscreen shows, the pictures you've seen are all of the older version.  so the gain increases when turning clockwise.  It won't break your circuit if you put it in the other way, you'll just have a backwards gain knob.

Let me know if that helps. Good luck!

 

[sharpeleven]

Hi,

Calibration is normally really simple.  Your description suggests a problem in the gain control part of the circuit (R7, R10, C34).

C34 is an optional cap and should be jumpered in your case. We added this cap for anyone choosing to use a JLM99V or other opamp with high DC offset.  If there is no jumper in that position your gain circuit has no path to ground. 

Good catch on the trimmer orientation. It was flipped 180 degrees to accomodate the DC cap, so it should be installed like the silkscreen shows, the pictures you've seen are all of the older version.  so the gain increases when turning clockwise.  It won't break your circuit if you put it in the other way, you'll just have a backwards gain knob.

Let me know if that helps. Good luck!

Ok, i've jumpered C34. That's C34 on the amp board. Not the C34 on the filter board, correct? There was no part provided for C34 on the filter board so I left that blank per build instructions.

The unit fires up and sounds really nice... but just for like the first 3 minutes. Then there is a gradual reduction in dynamic range setting in and finally it sounds more and more like a fuzz box with some heavy distortion (after 5-10 minutes). After being powered off for an hour or so it'll go back to sounding great, for 3 minutes. Something somewhere must be off. Both units are affected.

I think I'm gonna wait until I receive the missing parts from you in the mail, like the 'official' output cap and the missing 10mm 33nF caps. I'll replace those and see if I have better luck. [I'm working with Rev.2 boards btw.]

thanks!

 

[kante1603]

Hello,

@sharpeleven,

Just curious,you wrote you use gar2520s.Have you built them yourself or have they been assembled already?
It's because you wrote your issues travel either with mounting in a 51x or in an API rack,
so it will be module related.When you say both modules are affected then you'll have a series built error somewhere.
So to narrow things down are you sure the DOAs are o.k.?

Just a thought.....

Udo.

Edit:I remember mine came with a small pcb to build an ic based opamp.Maybe a good idea to build one ( would only take some minutes) and test it just to shoot out things......you'll know if your issue is DOA related then......

 

[sharpeleven]

Hello,

@sharpeleven,

Just curious,you wrote you use gar2520s.Have you built them yourself or have they been assembled already?
It's because you wrote your issues travel either with mounting in a 51x or in an API rack,
so it will be module related.When you say both modules are affected then you'll have a series built error somewhere.
So to narrow things down are you sure the DOAs are o.k.?

Just a thought.....

Udo.

Edit:I remember mine came with a small pcb to build an ic based opamp.Maybe a good idea to build one ( would only take some minutes) and test it just to shoot out things......you'll know if your issue is DOA related then......

Hi Udo,
thanks for your help! Great idea about getting a 'utility' op-amp around for testing. My unit didn't come with any. Is there an opamp-kit you can recommend?
Yes, I did build the GAR2520s. They have been used in other units for a quite a while now with no issues though (VP28, LC53a). Both units show almost exactly the same behavior when using ML2520 (also DIY) instead of GARs. With the ML's the progression of symptoms is just slower & more pronounced (distortion).
But I don't wanna use up too much bandwidth with this here until I get the correct components into my unit. There were several parts missing and they're coming in the mail. I've had to bend some of the leads quite a lot and used a lesser quality output capacitor cause I was just eager to get it working. I'll just give it another try once everything's here and if there's no change, lunch a more thorough investigation...
Thanks!
Chris

 

[kante1603]

Hello Chris,

you're right,wait until you get the missing parts.
Having had the DOAs in other units states they're working of course.
So this seems to be no biggie to find out.

The extra ic based Doa-pcb came with my kits,but I have the former versions.
But for now you have yours working,so no need to build them.

Good luck,keep us posted please,

Udo

 

[mitsos]

Been trying to post since last night but my computer keeps randomly shutting down, so I'll be very brief.  First thing to check anytime things don't work is for proper DC at the right sockets. Also check the PSU filter caps (small electrolytics between the opamp and edge connector) for proper orientation.  I guess you don't have smoke or you would have said something, but feel different components for abnormal amount of heat (opamp output transistors/resistors and R8 for starters).  D3 facing the right way (down)? 

Next, since you're going to take it apart to install the replacement components, I'd check the amplifier PCB itself by installing jumpers as described in the build doc.  You should get clean audio with about 17dB minimum gain.  If the problem persists, then we know to concentrate on this PCB, otherwise we move to the filter. 

By the way, do you have other modules in other places at the same time? Are they affected when this happens?

good luck, keep us posted!

 

[sharpeleven]

I'm glad to report that the problems with both my units have been solved!  8)

There is an easy fix/addition to the PCB and Dimitri will add some details here soon. Its a required fix I believe for all v2 kits currently shipping. The fix brought some useable headroom and got rid of the distortion problems I've experienced.

Thanks Dimitri!

 

[sharpeleven]

Here's a snap of what I've added. Does that look right, Dimitri? Certainly helps the sound big time!

Thought this picture might be helpful to others currently in the process of building it. Definitely left me scratching my head for a while as I was stuck with a half-functional device. Without this fix there seems to be no path to ground on the new boards.

 

[sharpeleven]

Also just noticing that there is a *LOT* less heat build-up now being generated in both of my EQPs now that the fix has been applied. Before it was tough to handle the devices immediately after let's say 10 - 15 minutes of operation.

That would also explain the gradual signal degradation I was experiencing as my opamps were probably being cooked...  :-\

Just thinking there might be a potential safety hazard there? Specially considering the new enclosure has zero vent holes and the polished metal surface does a great job at additionally reflecting/retaining heat. Some urgency in getting the word out to current builders would seem appropriate!

 

[mitsos]

Hi everyone,  we are very sorry, as Christian has posted, there was a problem during mfg of the I/O PCBs (not the filter but the amp board), and most of them are missing two (important) traces and thus have no connection to PSU ground.  We've spent the better part of yesterday and this morning sending emails out to everyone who purchased kits so far, explaining the possible problem and how to check for it. 

Christian, your picture looks good,  I took the liberty of sending it to the last few people since it looks better than mine...

We started sending out what was left of "good" PCBs in the order that kits were ordered, but most the new stock has the problem, so we are already out.  What we'll end up doing is just sending new FULLY POPULATED i/o PCBs to everyone who's ordered so far because it will be easier than trying to figure out who got good ones and who got bad ones.  This way, everyone can use the EQs with the jumpers until the new PCB comes and then just swap out the i/o PCBs. 

It will be a few weeks before the new batch arrives, but as soon as they arrive we will get them out to everyone. 

Sincere apologies for any issues/headaches and extra work this may cause you guys and hope this solution is OK for everyone.

thanks

 

[sharpeleven]

I need to replace the LED. What specs do I need? Is that just a standard one? Diffused or not? It just gave up in one of my EQPs after repeatedly dismantling the device. Would be nice if it somewhat matches the LED in the 2nd unit.

Are there even different "strenghs"/sizes existing in LEDs? Sorry for my newbie questions!  :-[

 

[mitsos]

They are just standard 3mm LEDs.  They tend to vary somewhat, if you can hold out until we get our replacement PCBs, we can send you a couple extra LEDs with those.  Of course, I can understand you wanting this 100% now, ub that case, I'd say buy two LEDs from the same mfg, to up your chances of getting them from the same batch and being close in V drop and measure the 3K9 resistors to see how close they are.  LED brightness depends on the current through them, which is determined by those resistors.

Does that help?  Good luck!