jefepeters

Re: [BUILD] 1176LN Rev D DIY
« Reply #5440 on: March 20, 2018, 01:10:30 PM »
This is with GR OFF? 

When you have GR OFF. Is pad 22 shorted to ground?

Mike

Yes, GR is off. When switched to off, pad 22 does short to ground.


Hairball Audio

Re: [BUILD] 1176LN Rev D DIY
« Reply #5441 on: March 21, 2018, 12:45:06 PM »
Yes, GR is off. When switched to off, pad 22 does short to ground.

Have you checked your TP21 DC V voltages?
With 0.775 AC V between pin 2 and 3 of the input, how high to you need to turn up the input to get 2.25 VAC at pad 15?  GR OFF.

Mike
Hairball Audio, LLC
DIY Parts and Kits
https://hairballaudio.com

Top secret stuff and upcoming releases:
http://instagram.com/Hairballaudio
http://facebook.com/hairballaudio

jefepeters

Re: [BUILD] 1176LN Rev D DIY
« Reply #5442 on: March 21, 2018, 01:22:47 PM »
Have you checked your TP21 DC V voltages?
With 0.775 AC V between pin 2 and 3 of the input, how high to you need to turn up the input to get 2.25 VAC at pad 15?  GR OFF.

Mike

DC voltages at TP21 are:

20:1   -6.66
12:1   -3.61
 8:1   -2.44
 4:1   -1.51


Starting with 0.775 VAC on input, set at 24 (12 o'clock), I need to turn it to about 19 to get 2.25 VAC at pad TP15

Hairball Audio

Re: [BUILD] 1176LN Rev D DIY
« Reply #5443 on: March 21, 2018, 05:20:01 PM »
DC voltages at TP21 are:

20:1   -6.66
12:1   -3.61
 8:1   -2.44
 4:1   -1.51


Starting with 0.775 VAC on input, set at 24 (12 o'clock), I need to turn it to about 19 to get 2.25 VAC at pad TP15

Ah so only one dot? That's good.  What is your output pin 2 and 3 reading in VAC at that point?

Mike
Hairball Audio, LLC
DIY Parts and Kits
https://hairballaudio.com

Top secret stuff and upcoming releases:
http://instagram.com/Hairballaudio
http://facebook.com/hairballaudio

jefepeters

Re: [BUILD] 1176LN Rev D DIY
« Reply #5444 on: March 21, 2018, 06:42:04 PM »
Ah so only one dot? That's good.  What is your output pin 2 and 3 reading in VAC at that point?

Mike

So after powering down and doing the measurement again, 2.25 VAC now happens at almost 3 o'clock (dot inbetween 18 and 12). At this point the output is 4.87 VAC

Hairball Audio

Re: [BUILD] 1176LN Rev D DIY
« Reply #5445 on: March 22, 2018, 08:32:32 PM »
So after powering down and doing the measurement again, 2.25 VAC now happens at almost 3 o'clock (dot inbetween 18 and 12). At this point the output is 4.87 VAC

How clean is the board? Are you confident in your soldering?  I ask because usually things like that don't change.

I'm pretty stumped. Your output seems really now.

Did we try carefully removing Q1 and seeing if that increased your output?

We also do flat rate repair if that interest you.

Mike
Hairball Audio, LLC
DIY Parts and Kits
https://hairballaudio.com

Top secret stuff and upcoming releases:
http://instagram.com/Hairballaudio
http://facebook.com/hairballaudio

jefepeters

Re: [BUILD] 1176LN Rev D DIY
« Reply #5446 on: March 23, 2018, 03:31:57 PM »
How clean is the board? Are you confident in your soldering?  I ask because usually things like that don't change.

I'm pretty stumped. Your output seems really now.

Did we try carefully removing Q1 and seeing if that increased your output?

We also do flat rate repair if that interest you.

Mike

I've retested the power supply and am now getting -8.9 VDC at CR6 instead of the the -9.9 VDC I measured both when I originally completed the power supply and also when I began troubleshooting a week or so ago. The meter in GR mode, previously aligned for 0dB, is now resting at -2dB.  Are there any likely culprits for this change in the power supply?

My soldering skills certainly aren't perfect, but in all the kits and repairs I've done over the years I haven't had problems. The board has been cleaned up with isopropyl alcohol.

-Justin
« Last Edit: March 25, 2018, 08:43:27 PM by jefepeters »

jefepeters

Re: [BUILD] 1176LN Rev D DIY
« Reply #5447 on: March 26, 2018, 02:21:26 AM »

Did we try carefully removing Q1 and seeing if that increased your output?


I just tried this and it made no difference; still measuring 0.07 VDC at TP1.

But... R4 is measuring 12.5Ω instead of 270Ω. The color coding is the same as R41, so I don't think I swapped resistors with another one somewhere in the circuit. Guess I missed it when originally checking the resistor values.
« Last Edit: March 26, 2018, 03:12:27 AM by jefepeters »

Hairball Audio

Re: [BUILD] 1176LN Rev D DIY
« Reply #5448 on: March 26, 2018, 02:39:27 PM »
I just tried this and it made no difference; still measuring 0.07 VDC at TP1.

But... R4 is measuring 12.5Ω instead of 270Ω. The color coding is the same as R41, so I don't think I swapped resistors with another one somewhere in the circuit. Guess I missed it when originally checking the resistor values.

You should be measuring for AC at TP1. 0.07 V AC at TP 1 wouldn't be that odd, usually it's closer to 0.1 but you probably have the older blue tpad so 0.07 AC would be ok.

You can't measure resistors in circuit unless you're willing to figure out the parallel resistance math. You'd have to left a leg off the PCB to measure it.

Mike
Hairball Audio, LLC
DIY Parts and Kits
https://hairballaudio.com

Top secret stuff and upcoming releases:
http://instagram.com/Hairballaudio
http://facebook.com/hairballaudio

jefepeters

Re: [BUILD] 1176LN Rev D DIY
« Reply #5449 on: March 27, 2018, 01:33:21 PM »
You should be measuring for AC at TP1. 0.07 V AC at TP 1 wouldn't be that odd, usually it's closer to 0.1 but you probably have the older blue tpad so 0.07 AC would be ok.

You can't measure resistors in circuit unless you're willing to figure out the parallel resistance math. You'd have to left a leg off the PCB to measure it.

Mike

Thanks for the corrections, Mike. I guess I shouldn't be troubleshooting at 11pm on a Sunday night.

Although I wrote DC, I was actually measuring AC volts. So, just to clarify, as you saying the AC voltages for the amplification stage (which remained the same when Q1 was removed from the circuit) are ok?


TP1  : 0.67 VAC
TP15 : 1.40 VAC
TP17 : 0.16 VAC
BRN  : 2.98 VAC
XLR  : 2.97 VAC


Hairball Audio

Re: [BUILD] 1176LN Rev D DIY
« Reply #5450 on: March 27, 2018, 01:50:37 PM »
Hard to say because you have an older unit and the pots have a different sweep.

What are those measurements if you rotate the input and the output up to the next dot on the scale?  One dot higher.

Mike
Hairball Audio, LLC
DIY Parts and Kits
https://hairballaudio.com

Top secret stuff and upcoming releases:
http://instagram.com/Hairballaudio
http://facebook.com/hairballaudio

jefepeters

Re: [BUILD] 1176LN Rev D DIY
« Reply #5451 on: March 30, 2018, 10:01:25 AM »
Hard to say because you have an older unit and the pots have a different sweep.

What are those measurements if you rotate the input and the output up to the next dot on the scale?  One dot higher.

Mike

With both the input and output one dot higher I get:

TP1  : 0.088 VAC
TP15 : 1.732 VAC
TP17 : 0.233 VAC
BRN  : 4.289 VAC
XLR  : 4.276 VAC



Hairball Audio

Re: [BUILD] 1176LN Rev D DIY
« Reply #5452 on: April 01, 2018, 12:51:04 PM »
With both the input and output one dot higher I get:

TP1  : 0.088 VAC
TP15 : 1.732 VAC
TP17 : 0.233 VAC
BRN  : 4.289 VAC
XLR  : 4.276 VAC


All that seems ok to me.  If it was one of our current units, I'd say it was a little low, but these older units have different pots and this all seems within reason.

So let's reset.

1. Based on this, you should be passing decent clean signal with GR off correct?
2. What is your current issue/problem with the unit?

Mike
Hairball Audio, LLC
DIY Parts and Kits
https://hairballaudio.com

Top secret stuff and upcoming releases:
http://instagram.com/Hairballaudio
http://facebook.com/hairballaudio

dcjams

Re: [BUILD] 1176LN Rev D DIY
« Reply #5453 on: April 02, 2018, 04:36:18 PM »
Hello

Apologies in advance if I'm polluting this thread with something OT.

Is this the correct build thread for the "Mnats" 1176 clone PCB marked "revision H"?

I realise it says "rev d" up at the top there but I'm not sure if this refers to original Urei revisions or Mnats revisions.

If it os then I'll go to page 1 and start reading ... all 273 pages ...  :-\

Thanks
Jim

Hairball Audio

Re: [BUILD] 1176LN Rev D DIY
« Reply #5454 on: April 03, 2018, 12:38:28 PM »
Hello

Apologies in advance if I'm polluting this thread with something OT.

Is this the correct build thread for the "Mnats" 1176 clone PCB marked "revision H"?

I realise it says "rev d" up at the top there but I'm not sure if this refers to original Urei revisions or Mnats revisions.

If it os then I'll go to page 1 and start reading ... all 273 pages ...  :-\

Thanks
Jim

Sounds like a really old MNATS PCB.

The best place to post would be the All Things G1176 thread:

https://groupdiy.com/index.php?topic=646.0

Mike
Hairball Audio, LLC
DIY Parts and Kits
https://hairballaudio.com

Top secret stuff and upcoming releases:
http://instagram.com/Hairballaudio
http://facebook.com/hairballaudio

dcjams

Re: [BUILD] 1176LN Rev D DIY
« Reply #5455 on: April 03, 2018, 04:31:15 PM »
Sounds like a really old MNATS PCB.


Very! :)

Thanks Mike

jefepeters

Re: [BUILD] 1176LN Rev D DIY
« Reply #5456 on: April 04, 2018, 06:09:55 PM »
All that seems ok to me.  If it was one of our current units, I'd say it was a little low, but these older units have different pots and this all seems within reason.

So let's reset.

1. Based on this, you should be passing decent clean signal with GR off correct?
2. What is your current issue/problem with the unit?

Mike

1. Yes
2. When I removed Q1 I damaged one of the legs. After installing a new matched pair of FETs and doing the alignment, the compressor is behaving much more as expected -- I don't have to turn the input past 1 o'clock or so to begin compressing.  The output pot is still scratchy, but that's more annoying than causing problems.

So, I guess I'm good to go. I'm going to run it a bit, and then try aligning again. I couldn't get the meter to accurately measure both 0dB and -10dB of compression. But I won't worry about it for now.

Thanks for all your help, Mike.

-Justin

EUC

Re: [BUILD] 1176LN Rev D DIY
« Reply #5457 on: April 17, 2018, 07:24:48 PM »
I have a Rev D that I built back in 2013 and sadly haven't used all that often. I'm in the process of trying to use it some more and have some issues. First off I can calibrate it just fine through all three steps. All dc voltages are where they should be according to the schematic. Here's the thing that is bizarre. I turn on the unit and let it warm up. Sometimes the meter when in GR pings the +3 db and stays there. If I  push on the the GR button in and out or wiggle it around it resolves back to 0db and all the readings work great. However, if I move it back to +4 then push GR button again often times it goes to +3 and stays or sometimes it goes to  0db. If it's pinged to +3 the gr metering still works it's just obviously off.  This also can happen sometimes if I turn the attack off or if I tap on the unit casing.  I thought maybe it was an issue with the GR Meter board but all seems good on the solders there. Any thoughts?

weiss

Re: [BUILD] 1176LN Rev D DIY
« Reply #5458 on: April 18, 2018, 06:03:45 AM »
I have a Rev D that I built back in 2013 and sadly haven't used all that often. I'm in the process of trying to use it some more and have some issues. First off I can calibrate it just fine through all three steps. All dc voltages are where they should be according to the schematic. Here's the thing that is bizarre. I turn on the unit and let it warm up. Sometimes the meter when in GR pings the +3 db and stays there. If I  push on the the GR button in and out or wiggle it around it resolves back to 0db and all the readings work great. However, if I move it back to +4 then push GR button again often times it goes to +3 and stays or sometimes it goes to  0db. If it's pinged to +3 the gr metering still works it's just obviously off.  This also can happen sometimes if I turn the attack off or if I tap on the unit casing.  I thought maybe it was an issue with the GR Meter board but all seems good on the solders there. Any thoughts?

did you check your grounds?

weiss

Re: [BUILD] 1176LN Rev D DIY
« Reply #5459 on: April 18, 2018, 06:05:02 AM »
does anybody know how i have to wire this older H Pad?
i can't see +/- on the markings..


 

Related Topics

  Subject / Started by Replies Last post
2 Replies
2287 Views
Last post November 07, 2004, 11:29:49 AM
by fuzzbox
5 Replies
2048 Views
Last post May 03, 2009, 08:50:12 AM
by luis
3 Replies
1618 Views
Last post January 06, 2010, 11:04:08 PM
by listen202
39 Replies
12643 Views
Last post January 15, 2014, 10:01:32 AM
by poctop