[BUILD] 1176LN Rev D DIY

When calibrating the needle moves to the right but I run out of room on the 0 adjust.  When passing audio, there is no visible deflections on the meters on +4 or +8.

Also, if you question is whether the meter is functional, it is.  I get movement of the needle during the first 2 calibrations and the needle will show gain reduction in GR mode but tends to "stick" when the release is long requiring a reset of the compression to release it.

Check wiring, especially if you used connectors.

I now have better meter performance after re-flowing the wire connector joints but still am having difficulty getting full deflection of the meter with the zero adjust during the reduction meter tracking adjustment.  I believe this may be due to mismatched transistors.  What is the best way to handle this at this point.  Trying to find better matched transistors?  I don't have a good way to check HFE (which is why I had to skip this step while building).  Thanks for all the help.
Dave

dgold said:

I now have better meter performance after re-flowing the wire connector joints but still am having difficulty getting full deflection of the meter with the zero adjust during the reduction meter tracking adjustment.  I believe this may be due to mismatched transistors.  What is the best way to handle this at this point.  Trying to find better matched transistors?  I don't have a good way to check HFE (which is why I had to skip this step while building).  Thanks for all the help.
Dave

Click to expand...

You could try a larger tracking pot.  Like 5K.

Mike

I'm assuming that would be a Bournes 5K pot at R44

dgold said:

I'm assuming that would be a Bournes 5K pot at R44

Click to expand...

yes

I have some meters I got on Ebay a while back that have their own external set screw on the outside that I'd like to use for this project. Should I just go with a trimpot for the 2K adjustment on the 1176's PCB? Or is putting the 2K external better than what I'd get out of the meters' own adjustment?

(They're GC Electronics 2Q-1030s, but I can't find a datasheet anywhere. I do know that the lamps run on 12V.)

Also, what's the third pole on the meter rotary for?

I could misunderstand you, but i'll try
External meter screw is only to set first position on the scale to get proper tracking tolerance range.
Potentiometer inside the circuit is much more for tuning correct reading in a full scale - truly i don't know how better to explain that in english
Those are different adjustements. Check mnats (or others) adjustment procedure videos and UREI manual.

ln76d said:

I could misunderstand you, but i'll try
External meter screw is only to set first position on the scale to get proper tracking tolerance range.
Potentiometer inside the circuit is much more for tuning correct reading in a full scale - truly i don't know how better to explain that in english
Those are different adjustements. Check mnats (or others) adjustment procedure videos and UREI manual.

Click to expand...

That makes sense. I just needed to know whether I needed to drill the extra hole for the external pot. It's a little less tidy but I can live with that.

Don't mean to be a pest, but I'm still looking for an answer on my question about the third pole on the meter rotary. It doesn't seem to correspond with anything on mnat's schematic that I can see.

I would give you the answer if i will know what is "third pole on the meter rotary" 
More precisely please, is it marked somehow anywhere? I'm too lazy to search.

ln76d said:

I would give you the answer if i will know what is "third pole on the meter rotary" 
More precisely please, is it marked somehow anywhere? I'm too lazy to search.

Click to expand...

There's nothing I can point to that would explain it better. If there was, I wouldn't have to ask Hairball/Mnats!   There's a PCB for the rotary switch that controls the meter behavior (GR, +4, +8). It comes with the PCB from Hairball (on the bottom right here).

It's set up for a 4-pole switch (probably the Grayhills they sell on their site), and three of the poles have traces to pads on the PCB. There's no schematic for the rotary and there's no schematic for the Hairball/mnats PCB that includes the rotaries (for the meter or ratio) and the numbered pads on the PCB.

The switch for the 1176 itself is, of course, only two poles (on each pushbutton): One to connect the meter and (eventually) the FET and the other to switch in the 8.2K (+8) or 3.6K (+4) resistors.

I'm not even sure what else one would want to do with the switch and my current plan is to use a single DPDT to switch between GR and +4, but I want to make sure I'm not missing a connection that needs to be made otherwise. I vaguely suspected that it might shut off the meter, but I don't know.

I don't know where are my boards - i didn't use it, so i can't compare to these:
http://mnats.net/1176-wiring-rotary.html
As you can see one position is connecting only the air.
Standard for rotary was +4, GR and GR off. If you are using 4 position switch, you can add +8.
I didn't use pcb for switch at all, only wired everything direct to the switch pins.

ln76d said:

I don't know where are my boards - i didn't use it, so i can't compare to these:
http://mnats.net/1176-wiring-rotary.html
As you can see one position is connecting only the air.
Standard for rotary was +4, GR and GR off. If you are using 4 position switch, you can add +8.
I didn't use pcb for switch at all, only wired everything direct to the switch pins.

Click to expand...

So two of the poles connect to the meter. The third connects to 22, and I think the only switch position it connects to is ... pad 28? (Hard to tell, there's writing over it).

oh, I see, it's Waaaaaaaay down on that page that one of the meter switch positions actually disconnects the sidechain circuit. I thought the "GR Off" position was simply disconnecting the METER, not disconnecting the entire GR circuit. Makes sense now.

I actually couldn't see the traces on the black boards very well, and I didn't realize there was a separate page on mnat's page. That was helpful.

Yeah GR OFF is "bypass" mode - of course everything flows thru the line amp so it's much more colorfull bypass
Pretty usefull.

When I'm in this step of the last calibration part :

When the attack control is "on" (full CW) and you see 0dBu at the output, use R44 to set the meter to -10.

Click to expand...

when I put attack ON (I disconnect 22 point from the bridge)
I don't see 0dB at output it stays on +10dB.
Does that mean my FET is ko ?

please help...i built a hairball 1176 rev d a few months ago and its been working perfectly and sounds amazing. however, something has happened and now when i turn it on it seems to work just fine but after about 10 minutes of warming up a loud hum starts and the input signal is very low...as in barely audible and sounds distorted. I'm new to diy and have no idea where to start...any help would be greatly appreciated

I think it was April or May I bought a pair of the 1176 rev D boards. Went to go look at the Hairball Audio site for a BOM and what do you know, it's gone. Doh. Any links to the old BOM that used to be up would be appreciated, thanks.

1176ln clone kingdom:

http://mnats.net/1176_revision_d.html