[BUILD] 1176 Rev A - Back to the beginning...

[atticmike]

@biasrocks

have you checked the documents I've talked about?

Output wiring instructions by mnats with the 1.25's schematic.

 

[ChrioN]

Look at the drawing at the far right. Its a view of the back of the connector. You can clearly see "GR" "RI" "TIP".

Verified with a CONTINUITY BEEPER on a METER.

Those are 1/4" connectors, not XLR. They are wired in a different way. http://www.neutrik.com/zoolu-website/media/document/2802/Drawing+NJ3FP6C

Uhhhggggg... 

Really??

http://www.neutrik.com/zoolu-website/media/document/2802/Drawing+NJ3FP6C

Look closely at the front view of the connector, the GROUND is on the LEFT, RING is on the RIGHT, TIP is CENTER.

I'm assuming that unless the laws of PHYSICS have changed significantly, the reverse is true when you are looking from the BACK of the connector.

You can verify all this crazy science stuff and my theory with a CONTINUITY BEEPER on a METER.

Regards,
Mark

 

[Volume11]

Since this post will probably be the third in a row to be ignored... Is there anyone out there willing to fix this thing for me for a small fee? If you are somewhere near Houston I can drop it off, otherwise I can ship it.

Can someone tell me if this is the correct or incorrect orientation for the trim resistors?


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I am still having trouble with the q bias stage. I have tried new 2k and 5k trim resistors, in both ways. Checked the hfe on q6, which was at about 130. removed q12 and 13, and replaced them with a matched set of 2n5088 with an hfe of 450. I cant get the meter to move at all. Any ideas? I have checked all of my resistors to be sure that they are the correct value, and I checked each of them before i stuffed the board. This is my 3rd attempt to get some help on this issue, no one responded to my last two posts. I'd really appreciate it if anyone has any input. Please don't suggest that I read back a few pages etc. unless you think that it will really help with this issue, as I have read this whole topic twice now. Thanks

 

[mnats]

Can someone tell me if this is the correct or incorrect orientation for the trim resistors?


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I am still having trouble with the q bias stage. I have tried new 2k and 5k trim resistors, in both ways. Checked the hfe on q6, which was at about 130. removed q12 and 13, and replaced them with a matched set of 2n5088 with an hfe of 450. I cant get the meter to move at all. Any ideas? I have checked all of my resistors to be sure that they are the correct value, and I checked each of them before i stuffed the board. This is my 3rd attempt to get some help on this issue, no one responded to my last two posts. I'd really appreciate it if anyone has any input. Please don't suggest that I read back a few pages etc. unless you think that it will really help with this issue, as I have read this whole topic twice now. Thanks

Did you compare the orientation of the trimmers with the photo on the Hairball Audio site?

Do all the voltages agree with the schematic posted on my site?

 

[Volume11]

They don't match the photo on your site. They matched the photo on my first attempt, and the q bias didn't work. I noticed a few other builds with them reversed, so I tried that, with the same results. Now that I know that I definitely have them backwards, I'll switch them back. Thanks for the tip on the voltages, I'll check those now. I appreciate it.

 

[Biasrocks]

Okay, fair enough. I'm wrong. You're still stuck.

Please verify the following connections, from the schematic

PRIMARY CONNECTIONS

BROWN -> R33 + C11/R29
BLACK -> R17 + R35
WHITE/BLK -> Q6 Emitter
WHITE/RED -> R32 + C13

SECONDARY CONNECTIONS

BLUE -> OUTPUT (+) + Meter X
RED -> OUTPUT (-) + Meter Y
YELLOW + ORANGE -> TIED TOGETHER
GREY -> R34 + C16
VIOLET -> R32 + R83

I would also verify that your getting AC voltages out of both sides of the OUTPUT transformer.

If all these check out, perhaps there's a problem with the transformer or there's a problem somewhere else on the board, most likely the LINE DRIVER stage. If that's the case, check the voltages through out the circuit and compare with the REV A voltage chart, you could also verify all the values of each component
against the schematic.

Regards,
Mark

 

[lordnielson]

Can someone tell me if this is the correct or incorrect orientation for the trim resistors?


Uploaded with ImageShack.us

I am still having trouble with the q bias stage. I have tried new 2k and 5k trim resistors, in both ways. Checked the hfe on q6, which was at about 130. removed q12 and 13, and replaced them with a matched set of 2n5088 with an hfe of 450. I cant get the meter to move at all. Any ideas? I have checked all of my resistors to be sure that they are the correct value, and I checked each of them before i stuffed the board. This is my 3rd attempt to get some help on this issue, no one responded to my last two posts. I'd really appreciate it if anyone has any input. Please don't suggest that I read back a few pages etc. unless you think that it will really help with this issue, as I have read this whole topic twice now. Thanks

If you're not getting gain reduction maybe you should look at the ratio board. Are all the resistors there and working etc.

 

[Volume11]

Thanks for the tip Nielson, I'll check them now. As far as the voltages go, I get 122v from the wall, 29.4 and 29.6vac from the secondaries, 29.8vdc on one side of R59 and 13.8vdc at TP10 (0 at TP11). Are the secondary readings close enough to 30v to be considered ok? Also, should i check voltages at any other points? Sorry for the noob questions, still learning here.

 

[atticmike]

you are not spotting the issue I've called your attention to about mnat's mismatching output x &y wiring are you?

I'm not pointing my finger at anybody but it'd be quite helpful to know whether the papers or the official wiring is correct because he said something about archaic documents?

 

[Biasrocks]

you are not spotting the issue I've called your attention to about mnat's mismatching output x &y wiring are you?

The build document from MNat's site and the Urei schematic are the same for meter wiring

BLUE -> X, RED -> Y.

I'm not pointing my finger at anybody but it'd be quite helpful to know whether the papers or the official wiring is correct because he said something about archaic documents?

The official document is the Urei 1176 schematic.

Available from the JBL website.

http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/UREI-1176LNmanual.pdf

Schematics are located near the end of the document.

There is also a schematic on MNats site.

Regards,
Mark

 

[Echo North]

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I am still having trouble with the q bias stage. I have tried new 2k and 5k trim resistors, in both ways. Checked the hfe on q6, which was at about 130. removed q12 and 13, and replaced them with a matched set of 2n5088 with an hfe of 450.

Are those the 5088's?  It looks like you are using the wrong pads for the 5088's.  They need to be mounted different than the 2N3707's.

 

[mnats]

Also, should i check voltages at any other points? Sorry for the noob questions, still learning here.

Read my earlier reply again.

They don't match the photo on your site. They matched the photo on my first attempt, and the q bias didn't work. I noticed a few other builds with them reversed, so I tried that, with the same results. Now that I know that I definitely have them backwards, I'll switch them back.

It doesn't matter whether your trimpots are 180 degrees reversed or not, only that they aren't oriented 90 degrees to the way you have them which would electrically connect all the pins together.

 

[Volume11]

Uploaded with ImageShack.us

I am still having trouble with the q bias stage. I have tried new 2k and 5k trim resistors, in both ways. Checked the hfe on q6, which was at about 130. removed q12 and 13, and replaced them with a matched set of 2n5088 with an hfe of 450.

Are those the 5088's?  It looks like you are using the wrong pads for the 5088's.  They need to be mounted different than the 2N3707's.

This picture was taken the day before I inserted the 2n5088s. I'm just about positive that I used the correct pads, I triple checked the data sheet. Thanks for the suggestion though.

 

[Volume11]

Also, should i check voltages at any other points? Sorry for the noob questions, still learning here.

Read my earlier reply again.

They don't match the photo on your site. They matched the photo on my first attempt, and the q bias didn't work. I noticed a few other builds with them reversed, so I tried that, with the same results. Now that I know that I definitely have them backwards, I'll switch them back.

It doesn't matter whether your trimpots are 180 degrees reversed or not, only that they aren't oriented 90 degrees to the way you have them which would electrically connect all the pins together.

Mnats, thanks for your replys. I'll pull up the schematic as soon as I get back to my bench. I wasn't sure if there was a specific area to check for this particular situation. Thanks again.

 

[ilfungo]

someone can tell me how to connect UTC 0-12?
thanks

 

[Biasrocks]

someone can tell me how to connect UTC 0-12?
thanks

Easy.

Pins 1&5,6&8

Check the schematic.

Regards,
Mark

 

[atticmike]

Since everybody is missing my point, here is a picture

 

[MicDaddy]

atticmike why are you trying to correlate 1/Red 2/Blue with these other pictures of X/Y?  Where are you finding these schematics with designation X/Y and Mnats pictures with X/Y noted on them? 

If you simply follow Mnats wiring guide it's very clear.  Don't think too deep into it.  If the wiring guide was wrong it would have been mentioned earlier in the thread.  If you go back and look at pictures throughout this thread of working units you will find the wiring does correlate with Mnats guide.

EDIT:

After speaking with atticmike in the chat, we've come to find that the Hairball Ratio PCB silk screening does not correlate with the Hairball http://hairballaudio.com/docs/FET_Compressor_PCB_Board_Info_V2.pdf

In the document, The ratio board is noted as Y X 28 29 VU VU, but from atticmike's picture (I haven't checked my own ratio boards) his ratio boards are silk'd X Y 28 29 VU VU.

 

[atticmike]

and here comes the picture:

 

[Echo North]

I'll have a look, but X and Y are interchangeable on the meter PCB.  Meaning if you cross them, there is no difference.  This is only true of the meter PCB not the XLR.  Crossing the XLR X and Y will throw you out of phase.