[BUILD] 1176LN Rev D DIY

[Rob Flinn]

Just hoping someone can point me to where it tells me how to sort a meter/calibration issue out

Problem as follows

I set Q bias ... all good so far

I then go for null adjust which I can get to 0.00xx volts but I can't get the meter to zero because I get to one of the end stops on the meter zero preset.  It's at minus 1 or 2 (building 2 units)

If I then bridge the link it then drops another 4-5 dB

I actually remember having this problem with another rev D I built but it's so long ago I can't remember how I solved it, & I've been scratching my head on this for some time now.

I'm using the hairball meter.

I'm sure this has probably come up before but I'm having a job finding it in this thread now it's 150 pages long.

 

[Echo North]

Just hoping someone can point me to where it tells me how to sort a meter/calibration issue out

Problem as follows

I set Q bias ... all good so far

I then go for null adjust which I can get to 0.00xx volts but I can't get the meter to zero because I get to one of the end stops on the meter zero preset.  It's at minus 1 or 2 (building 2 units)

If I then bridge the link it then drops another 4-5 dB

I actually remember having this problem with another rev D I built but it's so long ago I can't remember how I solved it, & I've been scratching my head on this for some time now.

I'm using the hairball meter.

I'm sure this has probably come up before but I'm having a job finding it in this thread now it's 150 pages long.

It should drop when you bridge the move the shorting pin back.  But if you're all the way right already with your zero pot, I see your issue.

Have you made sure all of the R values in the meter circuit are correct?

Mike

 

[Rob Flinn]

Hello Mike,

Thanks for the response.

I've actually checked the resistors several times now.....

 

[Echo North]

Hello Mike,

Thanks for the response.

I've actually checked the resistors several times now.....

Have you tried "centering" the trimmers then calibrating?  Sometimes in these two pot calibrations, if one is set too far towards one pole at the start it can make calibration difficult.

You could also increase the value of the null trimmer and see if that helps.

 

[Rob Flinn]

hello Mike

I 've tried a 2k & 5k for the Null pots.  I cant get the meter higher than -5.5dB however the pots are set with the jumper in position.  The meter zero pot is at it's end stop in the direction that makes the meter move positively.

Frustrating.  Something must be wrong somewhere, & it's not like I haven't built a few 1176 before ...

 

[dmp]

Maybe this means the transistors are really unbalanced, if everything else is correct...
Try matching / swapping the transistors and see if the trimmer will null correctly

 

[Rob Flinn]

It's possible, but I did Hfe match them prior to installation & also on one unit I tried swapping them.

If I can't nail this over the weekend I will probably sub in the Op amp circuit which is much better, always works & easy to calibrate.

 

[Trench Recordings]

andydiy.. I believe your problem must be in the ratio board.

I am no expert but check all your resistor values and check continuity between your ratio board molex header and your ratio switches.  If you can follow the schematic and trace it down.

 

[mnats]

Just hoping someone can point me to where it tells me how to sort a meter/calibration issue out

Problem as follows

I set Q bias ... all good so far

I then go for null adjust which I can get to 0.00xx volts but I can't get the meter to zero because I get to one of the end stops on the meter zero preset.  It's at minus 1 or 2 (building 2 units)

If I then bridge the link it then drops another 4-5 dB

I actually remember having this problem with another rev D I built but it's so long ago I can't remember how I solved it, & I've been scratching my head on this for some time now.

I'm using the hairball meter.

I'm sure this has probably come up before but I'm having a job finding it in this thread now it's 150 pages long.

Are any of the voltages in the meter circuit seriously out from the ones on my schematic? Did you measure the resistors or just do a visual check?

 

[AMaziad]

Hi!

I've used your method to test, and really do not have a compressor in 8:1 and 4:1.

I Zhang test video youtube please take you look at.

http://www.youtube.com/watch?v=Su7XBMKs_M0&feature=plcp


In addition, I have three pictures, help me to see there is an error?

have Opportunity R71 / R44 / R59 / R86, error?

Very grateful for the help!

is your unit calibrated with mnats videos ? when the meter is in GR mode do u see gain reduction in all ratios. Remember the threshold knee is dependent on the input / ouput volumes. Crank up the input and see if you can get compression in 8:1 and 4:1.

If not, maybe check your ratio board connections and solder points...

After a quick glance at your pics, it appears that you are missing the yellow wire on the attack pot that connect to pad 19 on the main PCB.  What do you have connected to pad 19?

I borrowed a pic from MNats wiring guide (hope that's ok).  I put the yellow wire in color so you know exactly where you should attach it.  That will go to the right most pad in the control amp section of the board.

See if that works for you.

 

[Pliplo]

wow, i was hoping i didnt have to do this, but here i am... I dont know what i was thinking but i didnt test my power supply first... i know, stupid... Anyway, unit doesnt seem to power up, it shows 230v in the power connector but the unit itself doesnt seem to be doing anything, no smoke and no funny smells... I dont know if im putting my testers thingies in the right place but im not seeing -10v or +30 in the power supply region... Gonna get back to The art of electronics, see if i find something in there, but if someone has time to look at it id appretiate it...

cheers


 





   

 

[AMaziad]

wow, i was hoping i didnt have to do this, but here i am... I dont know what i was thinking but i didnt test my power supply first... i know, stupid... Anyway, unit doesnt seem to power up, it shows 230v in the power connector but the unit itself doesnt seem to be doing anything, no smoke and no funny smells... I dont know if im putting my testers thingies in the right place but im not seeing -10v or +30 in the power supply region... Gonna get back to The art of electronics, see if i find something in there, but if someone has time to look at it id appretiate it...

cheers

Make sure you are measuring DC and not AC in those parts.  I know this from experience...  :-\

 

[Pliplo]

wow, i was hoping i didnt have to do this, but here i am... I dont know what i was thinking but i didnt test my power supply first... i know, stupid... Anyway, unit doesnt seem to power up, it shows 230v in the power connector but the unit itself doesnt seem to be doing anything, no smoke and no funny smells... I dont know if im putting my testers thingies in the right place but im not seeing -10v or +30 in the power supply region... Gonna get back to The art of electronics, see if i find something in there, but if someone has time to look at it id appretiate it...

cheers

Make sure you are measuring DC and not AC in those parts.  I know this from experience...  :-\

haha i did both cause i wasnt sure ... What im sure is that it isnt a bad solder joint... either i wired it wrong or i made an incredibly noob mistake regarding electrical rules in the assembly process, or a part is not working...

Its weird, when i turned it on i was expecting something to blow up... nothing happening is actually worse

 

[Rob Flinn]

Got my problem sorted.  As I suspected stupid mistake wiring zero pot incorrectly to small pcb to hold the preset. 

BLUSH

 

[Pliplo]

After doing some testing (guided by Zayance) i think my problem is i got a deffective switch for the meter buttons (the power one)... cause i took it out of the circuit, connected the toroidal straight to the wall outlet, and bang... lamp's on, voltages seem reasonable... Not seeing any movement on the lamp needle, even when i touch every button and knob, but maybe it needs audio coming in for that...  Gonna keep checking, more later...

 

[mitsos]

hey guys,

finishing up a dualie that's been a long time in the works.  Appears to be working OK, at least it calibrated fine. I'm curious about the "all-buttons-in" mode (rotary switch version).  I got the ratio switch Mnat's lists on his site and I think I wired it correctly, but when in the last position, the GR meter pegs hard right.  This happens on both channels.  Normal? not normal?

thanks!

 

[mrcase]

hey mitsos!
normal, slam those meters hard

 

[mitsos]

ok thanks! will do!  8)

 

[mitsos]

Hi all,

Is there any way to make the release time quicker on these things?  Maybe by increasing the resistor in parallel with the release pot?  Am I right in thinking it won't make it quicker over all since the release pot decreases in value to a short at its quickest setting(?), but this would make the range a bit smaller?

thanks!

 

[andydiy]

Hi!

Thank you give me advice!

I know the problem!

Really ratio board, I did not link R5/R6, So in 4:1 and 8:1 no compressor.

I link R5/R6, Now I feel the 4:1 and 8:1 compressors up!

I gave a photos you see everyone to see it.

Thank you!

andydiy.. I believe your problem must be in the ratio board.

I am no expert but check all your resistor values and check continuity between your ratio board molex header and your ratio switches.  If you can follow the schematic and trace it down.