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

[Vernois]

Hi, I'm having some issues with my units.  I'm certain they worked fine initially, but now the engaged signal is very low and thin.  ie no low end. I'm using 2520 opamps of which I know work and both units are having the same problem. When I measure the V going to the op amp I get 15.4VDC, well above the voltage necessary to engage the relays (plus there is some audio coming through) and within the parameters of the opamp. It's strange that they worked and now are both not working.
I believe they are both the first gen.
Any ideas anyone?

 

[jandoste]

Any good news?
I wait it!
Thanks

Any news on this bad boy?

Cheers,

Udo.

 

[kante1603]

+1,would be a nice christmas present (for me),no? ;D

Best,

Udo.

 

[mitsos]

Hi, I'm having some issues with my units.  I'm certain they worked fine initially, but now the engaged signal is very low and thin.  ie no low end. I'm using 2520 opamps of which I know work and both units are having the same problem. When I measure the V going to the op amp I get 15.4VDC, well above the voltage necessary to engage the relays (plus there is some audio coming through) and within the parameters of the opamp. It's strange that they worked and now are both not working.
I believe they are both the first gen.
Any ideas anyone?

Hard to say... Especially if both units are exhibiting the same behavior.  Do you have an extender cable or other way of hooking up the units outside of the rack? 

If the opamps are both known working (ie, they work in other opamp circuits, preamp, etc), I would recheck the DC at the opamp pins with respect to ground. You should have +/-16V or so, depending on your power supply. If that is OK, then I would check the signal as it goes through the circuit. A great way to do this is using a probe.  If you don't have one, you can make one very easily that you can use with any guitar amp.  Here is a link with a drawing, I made the same type and use it all the time.

http://www.diystompboxes.com/pedals/debug.html

With this guy you can then probe around the PCB to see where the signal gets lost.  Start at the top 3 pin header, that's the output of the input trafo and output of the filter.  If signal is OK coming out of the trafo but "thin" coming from the filter, then the problem is in the filter and we need to break that down a bit more. But start there and let us know what happens. 

 

[mitsos]

Any good news?
I wait it!
Thanks

Any news on this bad boy?

Cheers,

Udo.

Great christmas present for me too.  Been in the middle of repairs and studio builds, and my head is going to explode. But that's what pays the bills for now... I've got a massive repair session starting tomorrow, going to throw this in the pile with the rest of the stuff and get back to you guys!

 

[kante1603]

Hi,

good things need their time.
Personally I bought lots of pcbs a long time ago (typical beginners "panic" buy),finished an 8-channel Neumann W492 after 2,5 years.Now I finally started with my sontecs-after 3 years or so,hahaha!
But hey,together with your eqs and some others I did it will form a fantastic eq-rack in the end.
So I  try to be patient,promised (.....and save my money for the meqs....).

Cheers,

Udo.

 

[jandoste]

I can't wait it please please please!
Thanks

Great christmas present for me too.  Been in the middle of repairs and studio builds, and my head is going to explode. But that's what pays the bills for now... I've got a massive repair session starting tomorrow, going to throw this in the pile with the rest of the stuff and get back to you guys!

 

[mitsos]

Hi,

good things need their time.
Personally I bought lots of pcbs a long time ago (typical beginners "panic" buy),finished an 8-channel Neumann W492 after 2,5 years.Now I finally started with my sontecs-after 3 years or so,hahaha!
But hey,together with your eqs and some others I did it will form a fantastic eq-rack in the end.
So I  try to be patient,promised (.....and save my money for the meqs....).

Cheers,

Udo.

beginner's panic buy...I like that. that's exactly what it is. I'm still sitting on PCBs from years ago.. my PM660 is half way done for about 4 years now!

 

[Vernois]

Thanks Mitsos, I think I'll order an extender right away, I've needed one for other units anyhow.
Till later.

 

[mitsos]

After a couple of emails with a recent builder, it's come to my attention that the current build doc is not "current."  I'll get it updated soon, but until then I want to re-iterate here for anyone building an EQP-1S5, that the DC blocking cap on the IO board, (marked C_DC on the latest version and C34 on the earlier one) should normally be a jumper.  It is there to block DC in the gain setting circuitry, but is only really needed with high DC-offset opamps.  So, for most people, using 2520s, melcors, most PPAs, Hardy 990s,  etc, you don't need it.  We really only added it for the JLM99V, which has close to 1V offset on its output.  I have yet to use one (pretty far from Australia) but it's fairly popular among DIY'ers so we thought it wise to keep options open.

So, until the manual gets updated, please jumper that cap!

cheers, happy building, and happy EQing!

 

[mitsos]

Hi Mitsos, I finally got around to probing one of my eq's, it seems like the signal stops right at the input transformer. I'm assuming the signal should be passing through. Any ideas?
Thanks for your help, I hate to be a pain but I want these working!
G

Hi,
yes, you should have the same signal at the output side of the input transformer. 
First, check to make sure you have the transformers plugged into the right connector (small molex with brown/red wires). It's opposite what would think intuitively. The input goes to the bottom and output goes to the top connector. I've switched them a few times...

Then there are the relays. Are they working? If they are, you should have connectivity between input and output when the EQ is bypassed (switch open, relays in resting position and LED off). When the EQ is in circuit, you should not have connectivity between input and output, but should have connectivity between input and the input trafo molex pins (same for the output trafo molex pins).

If everything seems OK, it could be a problem with the transformer itself, like a broken wire at the molex connector (visually inspect all connectors), miswired at the factory (check resistance and/or inductance with a meter, you should have about 50-60 Ohms between brown-red and orange-blue).  Could also be a cold solder joint at the transformer headers, there is not much more between the input and the transformer.

Good luck!

 

[Fellini]

Hey guys,
I noticed that there aren't any pics of the latest version available, so I decided to upload one of my build in case it can be of help.

It was a really easy build (once the C34/C_DC name change was clarified) and Dimitri's costumer service is second to none!

 

[kante1603]

Congrats Fellini,

.....but I guess it doesn't work ;D

Best,

Udo.


And welcome to the forum of course!

 

[mitsos]

Nice pic, thanks for posting!

 

[Fellini]

Thanks Udo

And thank you for the sorting sheets, they're real time savers!

 

[mitsos]

Anyone used these live?  Had an eye-opening experience with (DI'd) nylon string guitar the other day.  I normally cut the mids to get rid of the "plasticky" sound of the DI.  Did the same thing this time, except I ran the signal to the EQP-1S5 and brought the mids back with the high boost. Best guitar sound ever! (of course the bass boost/cut helped too!).  No mid plastic twang, just smooth and silky!

 

[j_fraser]

Hi All - It been a while since I last posted...

I have a pair of these wonderful EQP1S5s in the rack that have been delivering flawlessly for over a year or so, but unfortunately the second channel seems to have failed whilst in use last weekend.  Having them inserted over the mix bus for the duration of the day, whilst tweaking the right channel just stopped passing audio.  The other unit is fine. 

The failed unit passes audio in bypass, but fails to pass any audio when switched in.  I've swapped op amps (GAR2520s) to no avail, and the voltage at the op amp pins is as expected on both units.  So I am presuming this may be a relay failure?  With the units on an extender out of the rack I can hear two defined clicks from the working unit's relays on power down, however the failed unit seems to only exhibit one click.  Any pointers on how to proceed would be most welcome, as I am sorely missing the use of these babies...

Many thanks in advance.

Justin

 

[mitsos]

hmmm... I think you could test the relays while on the extender card.  You may have one getting stuck for whatever reason. 
See attached image.

The coil (power) pins are the ones towards the front of the module, if you measure between the points marked "P" you should get 24V.  If you measure between the top of R8 and the anode of D3, you should have the full 32V.

The other six contacts are the DPDT switching contacts.  The poles are the middle ones in each set of three. With the relay de-energized (off) the pole connects to the front contact (second from the front, not the coil obviously).  While in the energized position it connects to the rearmost contact. 

I would put them on an extender cable and, with the relays energized, see if the proper pads are connected. Let us know.

Good luck!

 

[j_fraser]

Thank you Mitsos, especially for the very swift reply.  That makes complete sense, so when I get a spare moment I'll pull the unit and test, then report back.  Fingers crossed it is just a simple relay failure...

Many Thanks

Justin

 

[mitsos]

no prob. hope you get it worked out.  Post back when you have a chance to test.
cheers!