[BUILD] 1176LN Rev D DIY

[StudioJakubka]

Hi there, I have problem with my Hairball 1176 rev D. After all calibration steps, more or less successful I have GR on 0 when in 20:1 mode. When I switch it to 12:1 the needle goes to -10, same with 8:1 or 4:1. There is no signal in, Attack is fully CCW (off). I have measured 21/20 and 19 and here are the results.
      20:1         12:1         8:1       4:1
PAD 22 0.49         0.211 0.123 0.055
PAD21 6.28         3.44         2.39         1.46
PAD19 1.045 0.98         0.965 0.951
Any suggestions?
Thanks

 

[dbonin]

Start at the point where the input transformer enters the PCB - apply your .775V / 1khz test signal and measure the voltage as you increase the input pot (t-pad) from full ccw  to full cw  - (if you used terminals for the wiring, disconnect them)
- you should be seeing somewhere around .340 AC coming OUT of the input transformer, with t-pad turned full cw with the leads disconnected from the pcb - this should fall to ZERO volts as you turn the input knob fully off.
-  let us know what you find.

also, make sure there is good ground continuity from the input xformer metal case to the chassis.

Okay So i checked the whole GR control amp section, the ratio section, the wiring, everything was okay, so i re-did the calibration and
suddenly I have a -17 drop with the calibration, but the r44 trimmer does nothing to get it on -10db drop. 

Note; I think there is something wrong with the T input attenuator. its very sensitive, when i move for example from -48  to -36db my VU meter jumps into full red (in VU mode) all the time while  i only moved it for 12db. but when i give a little knock to it its back normal. I think this might be the problem, when the t attenuator is in error mode there is no jumping, when i knock it it jumps again to -17 db with the 3th calibration step.
So i think it was in error mode when i did the calibration and i lowered the output till it was on 0db on the vu meter, thats why it didn't move (I think).

So forget the previous problems.

New problems:

unstable t attenuator, and r44 is doing nothing.

Thx guys for helping me out!!

 

[MountCyanide]

Greetings.
Say I'm sending .775 VAC of tone in. What voltage of signal should I be expecting to come out after the input transformer en route to the PCB?
When my t-pad input is cranked all the way I'm getting .65 on the way in to the tranny and .1 or so out.
I'm checking this out because I'm on the q-bias calibration step and can't get enough output.

 

[dbonin]

The input transformer in the hairball kit is a "step down", so you will see less vac on the transformer "out" side - however, .1 seems low when fully cranked...
Back when I checked it I was getting .3 something.  check it again when you get a chance.

Greetings.
Say I'm sending .775 VAC of tone in. What voltage of signal should I be expecting to come out after the input transformer en route to the PCB?
When my t-pad input is cranked all the way I'm getting .65 on the way in to the tranny and .1 or so out.
I'm checking this out because I'm on the q-bias calibration step and can't get enough output.

 

[Echo North]

Greetings.
Say I'm sending .775 VAC of tone in. What voltage of signal should I be expecting to come out after the input transformer en route to the PCB?
When my t-pad input is cranked all the way I'm getting .65 on the way in to the tranny and .1 or so out.
I'm checking this out because I'm on the q-bias calibration step and can't get enough output.

It's a pretty significant step down.  Make sure you are RECEIVING 0.77VAC, not just sending it (impedance an all the stuff).  It also depends on if you're calibrated properly.  Signal get's dumped right by the input.

 

[Echo North]

Hi there, I have problem with my Hairball 1176 rev D. After all calibration steps, more or less successful I have GR on 0 when in 20:1 mode. When I switch it to 12:1 the needle goes to -10, same with 8:1 or 4:1. There is no signal in, Attack is fully CCW (off). I have measured 21/20 and 19 and here are the results.
      20:1         12:1         8:1       4:1
PAD 22 0.49         0.211 0.123 0.055
PAD21 6.28         3.44         2.39         1.46
PAD19 1.045 0.98         0.965 0.951
Any suggestions?
Thanks

Your pad 22 AC voltages look ok.
Your pad 21 DC voltages should be negative.  Are they not?  Or were you measuring AC?

 

[deveng]

For those of you who have 2 of these and play slide guitar try them in series.  The popular SlideRig stomp box is based on these and the Lowell George setup.  I've only got one of mine running at the moment (hopefully get the second wired up today) and I've got it on the effects loop of my custom guitar tube preamp.  20dB of GR, fast attack and slow release.  Sounds really good.  I expect 2 in series with the settings right could sound real nice for slide work.

Regards,
Jeff

 

[StudioJakubka]

Hi there, I have problem with my Hairball 1176 rev D. After all calibration steps, more or less successful I have GR on 0 when in 20:1 mode. When I switch it to 12:1 the needle goes to -10, same with 8:1 or 4:1. There is no signal in, Attack is fully CCW (off). I have measured 21/20 and 19 and here are the results.
      20:1         12:1         8:1       4:1
PAD 22 0.49         0.211 0.123 0.055
PAD21 6.28         3.44         2.39         1.46
PAD19 1.045 0.98         0.965 0.951
Any suggestions?
Thanks

Your pad 22 AC voltages look ok.
Your pad 21 DC voltages should be negative.  Are they not?  Or were you measuring AC?

My mistake, of course they are negative DC.

 

[StudioJakubka]

Hi there, I have problem with my Hairball 1176 rev D. After all calibration steps, more or less successful I have GR on 0 when in 20:1 mode. When I switch it to 12:1 the needle goes to -10, same with 8:1 or 4:1. There is no signal in, Attack is fully CCW (off). I have measured 21/20 and 19 and here are the results.
      20:1         12:1         8:1       4:1
PAD 22 0.49         0.211 0.123 0.055
PAD21 6.28         3.44         2.39         1.46
PAD19 1.045 0.98         0.965 0.951
Any suggestions?
Thanks

Your pad 22 AC voltages look ok.
Your pad 21 DC voltages should be negative.  Are they not?  Or were you measuring AC?

My mistake, of course they are negative DC.

And I can not get 12.58V after R14. I am reading 11.51V and only 10.91V coming out from Q14. After R17 I have 25.4V and it feeds to Q2 1.79V instead of 1.75V, which sound OK, however after R14 (which is marked 22k) it is only 11.51V. Is this too low?

 

[zylvia]

I'm building the Rev D and working on the ceramic capacitors

I need the 27pF and 270pF caps and I found one marked "273"  and the other one marked "2713"

just want to make sure  if "273" = 27pF  and "2713"  = 270pF?

thanks

 

[hymentoptera]

I'm building the Rev D and working on the ceramic capacitors

I need the 27pF and 270pF caps and I found one marked "273"  and the other one marked "2713"

just want to make sure  if "273" = 27pF  and "2713"  = 270pF?

thanks

273 is probably 27,000pF (27nF, 0.027uF)

Not sure about 2713. Most multimeters worth keeping around have capacitance meter than goes down to 2nF or so, which isn't enough to measure picofarads, but I did find a cheap capacitance meter for $20 online somewhere which gets me down to 2pF.

I found all of my small value capacitors from various ebay vendors in the form of silver micas, which is what was in all the early 1176 units.

Can you borrow a capacitance meter from someone?

 

[StudioJakubka]

OK, my build now works and ratio board is fixed. I can switch between all and needle stay nicely where it should be (it was wrong resistor, 10k instead o 10M). However, I am getting audible distortion when I am with input above 36. I have try to send the same signal via the same routing to another compressor I have (VLA) and there is nothing unexpected happening. So it looks like it is input stage which distorts.
Also my meter when on +8 goes crazy, when on +4 it does not move but this is probably some wiring issue on meter PCB and I will try to fix it later today.

 

[StudioJakubka]

Another question here: I am all calibrated, all 3 steps, still have some issues described above. How long it takes till needle gets to 0dB GR? My build takes like forever, and is still sits bellow 0. Should I retouch it via front panel trimmer or is it another sign of some problem inside?

 

[MountCyanide]

The input transformer in the hairball kit is a "step down", so you will see less vac on the transformer "out" side - however, .1 seems low when fully cranked...
Back when I checked it I was getting .3 something.  check it again when you get a chance.

Greetings.
Say I'm sending .775 VAC of tone in. What voltage of signal should I be expecting to come out after the input transformer en route to the PCB?
When my t-pad input is cranked all the way I'm getting .65 on the way in to the tranny and .1 or so out.
I'm checking this out because I'm on the q-bias calibration step and can't get enough output.

Pardon, got swamped with work. So here's the follow up.
I removed the terminal blocks on the input tranny and got really retentive with grounding- so far that I added an additional wire connecting the mu-shell to the case at a stripped point/screw.
BAM: .36 vac going to the pcb.

Double checked all wiring. All continuity. Then looked over the wiring guide on the hairball site and pads 7, ground, 28, 29 caught my eye.
The pairs were mixed up. Whoops.
Just completed calibration. Success.
Back to work, and with a new weapon, YES!

 

[Echo North]

Another question here: I am all calibrated, all 3 steps, still have some issues described above. How long it takes till needle gets to 0dB GR? My build takes like forever, and is still sits bellow 0. Should I retouch it via front panel trimmer or is it another sign of some problem inside?

Takes forever.  That's the original discrete meter circuit.

 

[galloni21]

I bought a Rev D in December 2013. It took me awhile to build, and I haven't had much time to calibrate it the last couple months, but I finally got thru the Q-bias adjustment step last night. After completely that step successfully, I found that when I try to "Zero the compressors “GR” meter with the R71 zero adjust pot on the front panel" for step 2 of the calibration, moving R71 doesn't change anything with the meter set to "GR". The needle stays at the far left position (left of -20). I double checked many things and spent hours reading through posts on the DIY forum. Finally, I found the following errata on the mnats.net web page...

Revision D Version 2 10.03.08 errata:

R15 Value on overlay should be 6.8k rather than 7.5k
R64 Value on overlay should be 1.5k rather than 2.2k
Revision D Version 2.2 26.01.09:

R12 Value should be 1.8k rather than 920


For when I bought it (Dec 2013), do I need to switch these resistor values out? It's not clear to me exactly which rev d version I bought. The only other thing I see people positng about is unmatched transistors on Q12 and Q13.

Any help is greatly appreciated! Thank you

 

[hymentoptera]

I have a quick question concerning the 4 x rectifier diodes in the PSU.

Is there anything I should know about swapping one rectifier for another? The 1176 builds use 1N4003, 1N4004, etc. What can I expect if I use a fast recovery type, such as 1N4937, UF4006 or UF4007. I would think there should be no effect at all, or perhaps less noise in the PSU (or more??). I know they should be fine, funtionally, but just being nit-picky, what exactly is the difference? There must be some tiny measurable effect, but I don't know what to look for, and I admit I don't know much about diodes.

 

[Chryst]

Hey! I've build several HB 1176's without any problems, but I can't seem to be able to solve this one. Everything seems to work fine, however when I come to the last calibration step I can only get about 5 db of compression. The other calibration steps went without any problems.

To be sure I rematched a new set of FETS with higher HFE's, but the response seems to be the same. What I did notice however that it was extremely hard to get the right output voltage as the output pot seemed extremely sensitive. I've tried to measured its resistance and I only get 125 ohm instead of 250. However it was already connected, so it's possible that the lower resistance is caused by that. Output voltage can be as high as 20V though with everything cranked up.

I also remeasured all voltages and they seem to be fine.

It looks a bit like I'm lacking some throw on the input pot. However all the voltages on that side (entering the board) seem fine.

Does anybody have any suggestions how to tackle this one? Thanks for your help! It's greatly appreciated!

 

[Echo North]

Hey! I've build several HB 1176's without any problems, but I can't seem to be able to solve this one. Everything seems to work fine, however when I come to the last calibration step I can only get about 5 db of compression. The other calibration steps went without any problems.

To be sure I rematched a new set of FETS with higher HFE's, but the response seems to be the same. What I did notice however that it was extremely hard to get the right output voltage as the output pot seemed extremely sensitive. I've tried to measured its resistance and I only get 125 ohm instead of 250. However it was already connected, so it's possible that the lower resistance is caused by that. Output voltage can be as high as 20V though with everything cranked up.

I also remeasured all voltages and they seem to be fine.

It looks a bit like I'm lacking some throw on the input pot. However all the voltages on that side (entering the board) seem fine.

Does anybody have any suggestions how to tackle this one? Thanks for your help! It's greatly appreciated!

Lots going on here.

Measuring resistance in circuit rarely gives the correct reading as there is usually some parallel resistance.

Checking against the schematic w/ voltages works out?  Nothing weird?

The output pot could be slightly sensitive coma red to the original.  It's no really sensitivity but rather a steeper log curve.

In by pass is the signal clean and sound ok?

You could try a 5K rather than 2K pot in the GR section.  HFE measurements on a DMM can be hit or miss.

 

[StudioJakubka]

So I am all business now, +4, +8 and GR shows OK, compression switch works just fine and I am getting visible (on scope at least) compression. However with 0.775VAC on input I am getting audible distortion on every compression rate when GR meter shows -1 to -2dB compression. When off (attack fully CCW) the audio out is good and without distortion, when attack on it doesn't matter if I am fully CW or 12 o'clock, distortion is there. Any idea what is wrong?