Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #640 on: May 04, 2017, 06:41:05 PM »
Sorry I meant I'm still getting these readings below with the replacement pcb and switch...


with the switch in 115V...

blk/wht resistance: not getting a reading
blu/red resistance: not getting a reading

with the switch in 230V...

blk/wht resistance: 97.6 ohms
blu/red resistance: 116.2 ohms

is the voltage selector switch bad in 115V (my region)?


Hairball Audio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #641 on: May 04, 2017, 07:29:01 PM »
If you're in the USA it might be best for you to send in the Voltage SW, Power Tx, and Meter Switch.

I could try sending you a new TX but it seems fine in 230V mode and I hate to just keep sending you stuff when nothing really adds up.

Email me.

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

Top secret stuff and upcoming releases:
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Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #642 on: May 19, 2017, 05:05:13 PM »
Hi,

I have strange issues regarding my REV A build (the new one).

First I have unfortunately missplaced CR 10. Repaired it and everything was pretty nice working. When compared to my other unit they were sonically as twin brothers.

After some time though the unit sounds quite unpleasantly distorted pretty soon and seems not compressing as it should.
Also the unit starts to distort pretty soon when adjusting input gain. under 36 marking already. And to get any compression I need to drive it quite hot (around 18). Funny though as soon as I turn off compression (with attack knob) sound is nice and clear as it should.

I have followed DC voltages and found out these problematic values:



Q3:  B:      7.04 VDC (should be 6.73 VDC)
          C:   16.02 VDC (13.74 VDC)
´         E:       6.44 VDC (6.13)

Q7  B:  4.6VDC (5.22)
         C: 
         E:  4.05VDC (4.71)

Q8  B: 15.28VDC (16.93)
         C:  30,5VDC
         E:  14.6 VDC (16.31)

Q9: B: 3.5 VDC (3.6)
         C: 17.3 VDC (14.96)
         E:  2.97 VDC (3.09)

Q10  B: 17.3 VDC (14.96)
            C: 30,5 VDC
            E:16.7 VDC (14.39)

Everything else seems more or less on the place (cca 0.1- 0.2 VDC variations)
My PSU gives 30.5VDC/-9,7VDC

I have checked visually all resistors in GR CONTROL AMP circuit, such as all of them around problematic transistors and did not find any false piece.

Unfortunately I do not have access to oscilloscope at the moment to see where and when is something wrong going on.

Calibration can be made correctly, but  audibly generates  unit when fed with  +10dBU  for step 3. quite lots of harmonics content.

Thanks for any suggestion where should i look at

Jan

Hairball Audio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #643 on: May 22, 2017, 01:51:36 PM »
Hi,

I have strange issues regarding my REV A build (the new one).

First I have unfortunately missplaced CR 10. Repaired it and everything was pretty nice working. When compared to my other unit they were sonically as twin brothers.

After some time though the unit sounds quite unpleasantly distorted pretty soon and seems not compressing as it should.
Also the unit starts to distort pretty soon when adjusting input gain. under 36 marking already. And to get any compression I need to drive it quite hot (around 18). Funny though as soon as I turn off compression (with attack knob) sound is nice and clear as it should.

I have followed DC voltages and found out these problematic values:



Q3:  B:      7.04 VDC (should be 6.73 VDC)
          C:   16.02 VDC (13.74 VDC)
´         E:       6.44 VDC (6.13)

Q7  B:  4.6VDC (5.22)
         C: 
         E:  4.05VDC (4.71)

Q8  B: 15.28VDC (16.93)
         C:  30,5VDC
         E:  14.6 VDC (16.31)

Q9: B: 3.5 VDC (3.6)
         C: 17.3 VDC (14.96)
         E:  2.97 VDC (3.09)

Q10  B: 17.3 VDC (14.96)
            C: 30,5 VDC
            E:16.7 VDC (14.39)

Everything else seems more or less on the place (cca 0.1- 0.2 VDC variations)
My PSU gives 30.5VDC/-9,7VDC

I have checked visually all resistors in GR CONTROL AMP circuit, such as all of them around problematic transistors and did not find any false piece.

Unfortunately I do not have access to oscilloscope at the moment to see where and when is something wrong going on.

Calibration can be made correctly, but  audibly generates  unit when fed with  +10dBU  for step 3. quite lots of harmonics content.

Thanks for any suggestion where should i look at

Jan

Start by reading that. There are a few nuggets in there.

http://www.hairballaudio.com/blog/resources/post/fetrack-operational-faq

Also if you're input signal is +10dBu, that is way too high.

Mike

Hairball Audio, LLC
DIY Parts and Kits
http://hairballaudio.com/shop

Top secret stuff and upcoming releases:
http://facebook.com/hairballaudio
http://twitter.com/HairballAudio/

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #644 on: May 22, 2017, 07:07:06 PM »

Start by reading that. There are a few nuggets in there.

http://www.hairballaudio.com/blog/resources/post/fetrack-operational-faq

Also if you're input signal is +10dBu, that is way too high.

Mike

Hi Mike,
Thanks for response.
I have read that already, such as whole forum. I have misled you by saying I fed the unit with 10 dB. What I meant was when I pushed input to gain 10dB for step 3 in calibration procedure I had these distorted harmonics audible at the output. I fed the unit with 0dBU from my Neutrik signal generator. Also my unit does not compress until I am with inout at way beyond "noon". First I thought I had the problem at preamp stage, but as I have said, when I bypass compression by using attack knob, signal is clear. So I think there is probably something in GR circuit. But I have found out these weird voltages around transistors as stated in my first post. Unfortunately I am not so expert in electronic to see where else should I look at. I think to swap Q1 and Q11 to see if it helps. I thought to ask you first about any other ideas or if these voltages is somewhat ok. Or I should look at transistors.

Thanks for suggestions
Jan

Hairball Audio

Re: [BUILD] New FET/RACK Official Help Thread - Please read first post!
« Reply #645 on: May 22, 2017, 07:17:32 PM »
Hi Mike,
Thanks for response.
I have read that already, such as whole forum. I have misled you by saying I fed the unit with 10 dB. What I meant was when I pushed input to gain 10dB for step 3 in calibration procedure I had these distorted harmonics audible at the output. I fed the unit with 0dBU from my Neutrik signal generator. Also my unit does not compress until I am with inout at way beyond "noon". First I thought I had the problem at preamp stage, but as I have said, when I bypass compression by using attack knob, signal is clear. So I think there is probably something in GR circuit. But I have found out these weird voltages around transistors as stated in my first post. Unfortunately I am not so expert in electronic to see where else should I look at. I think to swap Q1 and Q11 to see if it helps. I thought to ask you first about any other ideas or if these voltages is somewhat ok. Or I should look at transistors.

Thanks for suggestions
Jan

Set your unit to:
Input: 12 O’Clock
Output: 12 O’Clock
Attack: GR ON (Full CW)
Release: Full CW
Ratio: 20:1
Meter: GR
Signal: Sine 1kHz @ 0dBu

1. Using chassis as your ground reference, what is your AC V at TP22 for all 4 ratio settings.
2. Using chassis as your ground reference, what is your DC V at TP21 for all 4 ratio settings.

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

Top secret stuff and upcoming releases:
http://facebook.com/hairballaudio
http://twitter.com/HairballAudio/

Question.. so how much would replacing R70 with a 5% tolerance resistor instead of 1% effect the meter and the accuracy. Will it even work? Thanks!