[BUILD] New FET/RACK Official Help Thread - Please read first post!

[Echo North]

Ok....  With the Ratio at 20:1 and the meter at +4 and the input at around 11 o'clock and the out put at 9 o'clock attack off/on I get a drop of -10dB from 0db on the meter. After re-calibrating steps 1 & 2 on both units, when I turn the attack on and the meter from +4 to GR, I am now getting a drop of almost -10db. In the pic below the inputs and outputs ended up on both units and they were exactly the same, except the meter is a little out ....?

In +4?  Keep it in GR mode always.

http://www.hairballaudio.com/blog/resources/build-guides/fetrack-v2-buildbrstep-4-calibration

not sure what your calibration procedure is...nothing I've used.

 

[dencul]

Ya your signal is dying in your GR AMP.

This is the old rev D voltage sheet but it should still apply:
http://mnats.net/files/1176REVD_VOLTS.pdf

Check your DC voltages in your GR AMP section.  Looks for misplaced resistors, bad joints, all that good stuff.

Mike

I measured and took notes for all on the Rev D voltages sheet.
Measurements of transistors were pretty close until Q8 , when emitter read 225 mV instead of 14.7v.
I've double checked resistors and touched up many solder joints
I wanted to remove the transistors and put in sockets, but I destroyed a 2N3787 trying to remove it from Q8 so now I'll have to source a replacement and wait for it's arrival. Not sure if there's much I can do until then.  doh!

 

[ratty_7]

In +4?  Keep it in GR mode always.

http://www.hairballaudio.com/blog/resources/build-guides/fetrack-v2-buildbrstep-4-calibration

not sure what your calibration procedure is...nothing I've used.

yes your right Mike. Sorry 

I have followed Hairball 3rd calibration to point 4

Set controls as follows:
Input = "24" mid rotation
Output = "24" mid rotation
Attack = full CW
Release = full CW
Compression ratio = 20:1
Meter mode = "GR"

1. Apply a 1 KHz, 0dBu signal, confirmed with your DMM at IN + and IN - at the input XLR (0.775 VAC).
2. Moved myDMM to OUT + and OUT - at the output XLR.
3. Set output control for 0dBu (0.775 VAC) at the output.
4. Set attack full CCW (off position). Set input control for +10dBu (2.44 VAC) at your output XLR.

Now this is where things go wrong. The next step says....

5. Turn the attack control ON (Fully CW) and readjust the output level control for "0dBu" if necessary. 

Problem is my output control does not move the needle to 0db. In fact from CCW to CW the needle stays put and slightly quivers

 

[petereugenefoley]

So a friend sent me his Hairball 1176 Rev A for me to put in new Lundahl transformers, the LL5402 and LL1540. Is it possible to replace the EA trafos that were in there with these Lundahls?

 

[jdier]

Apologies... created a new thread before finding this.  If a mod could kill my other post (HERE:  https://groupdiy.com/index.php?topic=65149 ) it would be appreciated.

-------------------------------
Hairball 1176 - Discrete Meter Circuit/Null Adjust **GR Meter problem**
-------------------------------

Very much a newbie to electronics, but completed my Hairball 1176.  Power Supply test perfect, completed build and Q Bias went great.

When I get to Discrete Meter Circuit/Null Adjust, I am unable to make the meter move at all.  It sits < 0/-20 

It does not appear that I have blown the meter as I can put test tone to the input, choose +4 or +8, and my input and output controls appear effect the meter the way I would expect.

Once I switch back to GR, the meter remains all the way left, just under 0/-20.

I pulled the FET Meter board and there does not appear to be any shorts.  (however, I did notice that there are three points unused marked "22" "GRN" and "BLK"

Any help would be greatly appreciated.

Jim

 

[NickB Zar]

New Hairball 1176 rev. A
I can't complete calibration # 3 the Gain Reduction Meter Tracking Adjustment.
on step # 4  Set attack full CCW (off position). Set input control for +10dBu (2.44 VAC) at your output XLR. i only get 1.4 vac and i set input control all the way , and miter  dose not move in GR mode.
i ran some drums thru the comp and it sounds great,  miter works in +8 and +4 mode BUT NOT MOVING IN GR mode.

 

[Echo North]

yes your right Mike. Sorry 

I have followed Hairball 3rd calibration to point 4

Set controls as follows:
Input = "24" mid rotation
Output = "24" mid rotation
Attack = full CW
Release = full CW
Compression ratio = 20:1
Meter mode = "GR"

1. Apply a 1 KHz, 0dBu signal, confirmed with your DMM at IN + and IN - at the input XLR (0.775 VAC).
2. Moved myDMM to OUT + and OUT - at the output XLR.
3. Set output control for 0dBu (0.775 VAC) at the output.
4. Set attack full CCW (off position). Set input control for +10dBu (2.44 VAC) at your output XLR.

Now this is where things go wrong. The next step says....

5. Turn the attack control ON (Fully CW) and readjust the output level control for "0dBu" if necessary. 

Problem is my output control does not move the needle to 0db. In fact from CCW to CW the needle stays put and slightly quivers

So you're getting the 10dB drop at the output but can't get the meter to move at all or calibrate in GR mode?

Does the needle just sit at 0 or site far left in GR mode?

 

[Echo North]

Apologies... created a new thread before finding this.  If a mod could kill my other post (HERE:  https://groupdiy.com/index.php?topic=65149 ) it would be appreciated.

-------------------------------
Hairball 1176 - Discrete Meter Circuit/Null Adjust **GR Meter problem**
-------------------------------

Very much a newbie to electronics, but completed my Hairball 1176.  Power Supply test perfect, completed build and Q Bias went great.

When I get to Discrete Meter Circuit/Null Adjust, I am unable to make the meter move at all.  It sits < 0/-20 

It does not appear that I have blown the meter as I can put test tone to the input, choose +4 or +8, and my input and output controls appear effect the meter the way I would expect.

Once I switch back to GR, the meter remains all the way left, just under 0/-20.

I pulled the FET Meter board and there does not appear to be any shorts.  (however, I did notice that there are three points unused marked "22" "GRN" and "BLK"

Any help would be greatly appreciated.

Jim

Sounds like you have the older boards, but it's ok to keep the post here.  Leave those pads unused.

Are you able to get the 10dB drop on the output?

Mike

 

[Echo North]

New Hairball 1176 rev. A
I can't complete calibration # 3 the Gain Reduction Meter Tracking Adjustment.
on step # 4  Set attack full CCW (off position). Set input control for +10dBu (2.44 VAC) at your output XLR. i only get 1.4 vac and i set input control all the way , and miter  dose not move in GR mode.
i ran some drums thru the comp and it sounds great,  miter works in +8 and +4 mode BUT NOT MOVING IN GR mode.

If you can't get the 10dB drop at the output, or the GR meter working, you may have a few different issues.  Start by going through your whole build and checking values and resistors.  If that looks ok you may want to try new FETs.  You can email us for those.

Mike

 

[jdier]

Sounds like you have the older boards, but it's ok to keep the post here.  Leave those pads unused.

Are you able to get the 10dB drop on the output?

Mike

I have not gotten to that step.  I did Q (which was successful) then when I went to this step, I cannot get the GR meter to move to the right when GR is engaged. 

(So I stopped there)

 

[Echo North]

I have not gotten to that step.  I did Q (which was successful) then when I went to this step, I cannot get the GR meter to move to the right when GR is engaged. 

(So I stopped there)

Ah so you can't even get to the null.

Here are a few things:

1. Start with your meter trimmers dead center. If you have the 20 turn trimmers turn one direction till you hear a little "clicking" that's the end....rotate back 10 turns the other way".

2. Check your meter section components and joints.

3. Check the dc voltages in the meter section...your unit is un-calibrated so it won't really match this, but it can provide info.
http://mnats.net/files/1176REVD_VOLTS.pdf

4. Check your wiring. If you used terminals make sure wires are fully seated.

Mike

 

[jdier]

Ah so you can't even get to the null.

Here are a few things:

1. Start with your meter trimmers dead center. If you have the 20 turn trimmers turn one direction till you hear a little "clicking" that's the end....rotate back 10 turns the other way".

2. Check your meter section components and joints.

3. Check the dc voltages in the meter section...your unit is un-calibrated so it won't really match this, but it can provide info.
http://mnats.net/files/1176REVD_VOLTS.pdf

4. Check your wiring. If you used terminals make sure wires are fully seated.

Mike

Centered all trimmers (except Q Bias which set correctly)

Checked and reflowed meter joints

CD Voltages:

Q11  14

Q12  -1.2    13.1    -1.8

Q13    -2      -1.9      -1.3

 

[ratty_7]

So you're getting the 10dB drop at the output but can't get the meter to move at all or calibrate in GR mode?

Does the needle just sit at 0 or site far left in GR mode?

Hi Mike
No I am not getting a 10db drop and yes the meter just sits there -1 to -2 in GR mode....

 

[riddor74]

Just finished out build and completed calibration on our 2 x Rev D blackface hairballs.

They sound great and the quality of the kit is super,

We have once issue following calibration, the VU meters we perfectly sitting at 0 however after about 5/6 hours they have dropped to -1 on both units,

Is it just a case of using the zero adjust pot accessible via the front panel, if I do this does it effect any internal calibration?

Also are they specific settings you need to enagage before using the zero adjuster (if this is the way to over come this)?

Tristan

 

[Echo North]

Centered all trimmers (except Q Bias which set correctly)

Checked and reflowed meter joints

CD Voltages:

Q11  14

Q12  -1.2    13.1    -1.8

Q13    -2      -1.9      -1.3

Q13 is crazy off.  You may want to replace it.

 

[Echo North]

Hi Mike
No I am not getting a 10db drop and yes the meter just sits there -1 to -2 in GR mode....

If you were able to set your Qbias but can't get a drop, you have issues in your GR amp. Look back a few posts and post the TP22 and 21 voltages as described:

https://groupdiy.com/index.php?topic=63600.msg825178#msg825178

Mike

 

[Echo North]

Is it just a case of using the zero adjust pot accessible via the front panel, if I do this does it effect any internal calibration?

Hi,

Hes the discrete meter fluctuates. That's why UREI put an adjustment on the front.  You can turn that pot all you like, it won't harm the other adjustments. Just where the needle sits.

Mike

 

[ratty_7]

If you were able to set your Qbias but can't get a drop, you have issues in your GR amp. Look back a few posts and post the TP22 and 21 voltages as described:

https://groupdiy.com/index.php?topic=63600.msg825178#msg825178

Mike

Set up both my units with a 0dB 1K signal on the input, in/out at 12 o'clock, attack release full CW.
     
      Unit A                      Unit B
VAC @ TP22        VAC @ TP22
20 =  381.8            20 = 0.55.6
12 = 188.2              12 = 032.6
  8 = 126.3                8 = 023.1
  4 = 65.9                    4 = 12.7

VDC @ TP21        VDC @ TP21
20 = -05.91            20 = -05.91
12 = -3.395            12 = -3.388
  8 = -2.601                8 = -2.592
  4 = -1.809                4 = -1.793

Both VDC are about the same, but the VAC on both my units and are very different...!!!

 

[Echo North]

Set up both my units with a 0dB 1K signal on the input, in/out at 12 o'clock, attack release full CW.
     
      Unit A                      Unit B
VAC @ TP22        VAC @ TP22
20 =  381.8            20 = 0.55.6
12 = 188.2              12 = 032.6
  8 = 126.3                8 = 023.1
  4 = 65.9                    4 = 12.7

VDC @ TP21        VDC @ TP21
20 = -05.91            20 = -05.91
12 = -3.395            12 = -3.388
  8 = -2.601                8 = -2.592
  4 = -1.809                4 = -1.793

Both VDC are about the same, but the VAC on both my units and are very different...!!!

Does it work fine in GR off mode? More specifically does it pass signal and sound good?

If so, those TP22 readings on unit B would indicate bad solder joints at either your output pot, attack switch, or a bad joint, incorrect resistor on your ratio board or ratio connectors.  Have a close look.  If you can't find it we'll trace through it.

Mike

 

[ratty_7]

Does it work fine in GR off mode? More specifically does it pass signal and sound good?

If so, those TP22 readings on unit B would indicate bad solder joints at either your output pot, attack switch, or a bad joint, incorrect resistor on your ratio board or ratio connectors.  Have a close look.  If you can't find it we'll trace through it.

Mike

Seems like bad solder joints on input pot on Unit B the readings are now....

20 = 381.9
12 = 189.1
  8 = 128.3
  4 =    66.8