PM-1000 racking - cutting down to size

[Siegfried Meier]

Ok, reread some posts and tried some new things and I think I've got it! I was using those extra posts on the mic XLR ins to ground the inputs to the main ground, and that was wrong - I should have been using Pin 1 only (what the heck are those stupid extra points on XLR's anyway, if they're not ground??)

So, phantom works, ground hum seems to be gone, although I'm still "seeing" noise on the meters from my halogen lights that are connected to dimmers - when I turn them off, that goes away. Hopefully that'll also go away when I have the unit closed up.

Thanks so much for all the help,
Siegfried

 

[Siegfried Meier]

Alright, I've still got some hum, although everything works as it should now. My halogen lights in the room still affect the unit as well - can hear it and see it on meters. Any ideas what else I can do to make these sound better?

Thanks,
Sig

 

[digitaldrummer]

that could be coming through your power mains. In that case, a simple "surge protector" (i.e. Furman <$200) isn't going to do it.

as for your other ground issue, the thing I usually do (and have forgotten a couple times, is run one of the black wires (there should be 2 left on the board) from the board to the (-) of the power supply, but tie the other to the "shield" of the mic input cables (I usually tie it in where I splice them around the phase toggle switch). see it here:

http://www.digitaldrummer.net/pm1000/recappedmodule.jpg

Similarly, you will need a ground wire from the (-) of your power supply (or chassis ground) to the shield of the output cables between the output transformers and the XLR outs (if you don't have OP trans, then this doesn't apply).

Mike

 

[Siegfried Meier]

Thank you so much for your help. The only thing I didn't connect to the main P/S ground was the output XLR grounds, simply for fear of getting some kind of a ground loop. Everything is super quiet now and works fantastic.

Thanks again to everyone for helping me with these.

 

[digitaldrummer]

Looks nice :guinness: but thats got more toggle switches than mine... :?: +48V, phase/polarity--and what's the 3rd one for?

Mike

 

[Siegfried Meier]

48V phantom, Phase, and Pad - they're the JLM Go-Betweens.

Thanks!
Sig

 

[Zetajazz44]

Has anyone replaced the stock Hi-Pass and Mid-Range selection switches with DPDT? If so, do you have pictures or a brief explanation of your wiring for using these switches?

Thanks in advance,

Zetajazz44

 

[JohnSuitcase]

I've asked this question once before on another thread, but didn't get a very thorough answer...

Is there a good reason not to use the echo send signal(s)? I'm in the process of racking 4 of these, and it seems a lot simpler. But if the sound quality is compromised, of course I'll follow the lead of everyone who's used the c37 cap to connect to the output...

I just finally put my new drill press together, can't wait to get this working!

 

[Jed]

I'm not sure about the why of not using the echo sends (haven't tried), but I can say that it couldn't really be easier to go off of c37.

You don't need to attach a wire to the leg of the capacitor, you just solder your output wire to the "BO" as shown on the previous page of this thread. That either goes to your output transformer or straight out if you're running unbalanced.

 

[JohnSuitcase]

Yeah, I guess that's true. Still have to replace the fader with one of the echo send pots, though, correct?

I think using the fader output like that gets you about 60db of gain, while the echo sends are only 55db, at least that's what I gather from the schematic and block diagram.

I'm hopeing to finish this project for a session on Sunday, so trying to move along quickly...

Thanks!

 

[Jed]

Still have to replace the fader with one of the echo send pots, though, correct?

Not really. I used the old fader pot. The only downside to doing that is that the shaft on the fader pot is bigger than the shafts on the other pots, so the knobs won't fit it.

You still have to remove one of the echo pots to mount the fader pot though. And because it's bigger I think I had to drill the hole out a little, but I didn't think it was too big of a deal. Certainly easier than the rest of the metal work.

Good luck!

 

[timmygrimm]

I'm having some issues with my PM1Ks... don't know if anyone can help.

I have no output from the BO terminal on the board. I do get output from the blue wires on the EQ pots, as well as the small yellow wire coming off the low cut / mid freq selector pcb.

Also, the input gain switch is basically acting like an on/off switch. If I crank it all the way up, I get signal (at the spots mentioned above) and otherwise nothing.

Seeing identical behavior on two separate modules, which leads me to believe that it isn't a failed component. I cut all the wires going out to the edge connectors... should I have left some?

Tim

 

[JohnSuitcase]

Not certain, but if you cut the wires the way I did, it's possible that they are shorting, which can cause some weird behaviors. Make sure none of the wires are shorted where you cut them.

Can you post some pics of your PM1000s? Maybe I or one of the others can spot something amiss.

Since both units are behaving the same, it's likely that you wired something incorrectly, pics would help!

 

[timmygrimm]

Okay, here is a pic of my test rig. Click on the link for a very large version.

http://www.bravadousa.com/testing/tim/images/pm1k.jpg

Again, my issues are:

- No output at BO terminal (i do have output at small yellow wire from mid freq / low cut pcb , as well as blue wires on eq pots)

- No output unless gain switch is maxed (i realize there is a large gain jump at the end. there is really no output in other positions, not just low output)

If anyone has thoughts about this, I'd greatly appreciate it. I have two modules exhibiting this behaviour.


Tim

 

[jrfred453]

I'm curious why you've opted to not use an output pot. Connecting the yellow wire to the echo pot worked great for me. In order to get output at BO you have to move the wire connected to the wiper of the echo pot. This kinda threw me for a loop for a couple minutes because it wasn't mentioned but was very clear from the many pictures floating around here.
Correct me if I'm wrong but the problem you are having may be that the yellow wire you are connecting to your output transformer has no ground connected you just connected it to the PSU ground instead. Seems like you've skipped over part of the circuit by not using an output pot.

 

[timmygrimm]

Cool, gotcha.

I was just taking a "first things first" approach, trying to make sure I had signal before I starting moving stuff around. I had assumed the BO was a pre-fader out, but I guess not! Will rewire and check.

Where is an ideal place to connect the output transformer ground? (and the PSU ground for that matter?). I actually couldn't find a clear description (or pic) of how the output transformer should be wired. There were color codes for the original Tamuras, but as you can see I am using Edcors.

Thanks for your help!

Tim

 

[robin]

Hey,
could anyone describe the influence of the output transformer on the sound?
Cause i've got 2 output transformers and 6 modules of PM1000.
I don't know if i put theses output transformers on only 2 modules or on the 6th?

Thanks a lot.

 

[abeLovesDIY]

Hello,

Forgive my ignorance, this is my first time working with output transformers that aren't in a kit. I'm racking some PM-1000 pres, and so far so good.
The only thing that has me confused is the output transformers.

I'm using the 1st Echo send as the Fader, so I've got the white wire coming out which is unbalanced. I'll be using an Edcor WSM 600/600 transformer.
If I look at the Service manual:



and I look at the WSM Schematic:


That would indicate (too me) that the output wire signal should connect to Pin 1 of the Edcor, and the output wire ground should connect to Pin 4 of the Edcor and Pin 1 of the output XLR. Is that correct?
If so, then Pin 5 of the Edcor should connect to pin 2 of the Output XLR, and Pin 8 of the Edcor to pin 3 of the XLR. Is that correct?