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

[Echo North]

Yes un-linked.

I'm really not sure which one is working correctly they both calibrate the way they should and compress.

The one you built is focusing on the top end on the signal.

The one I built has hotter output and is focusing on the low end on the signal.

The one we built should be working correctly.  Compression is definitely going to have an EQ like effect on your program material. My guess is the newer one has an error somewhere in the build.

Go through the troubleshooting test with both units and see what you get:
https://www.hairballaudio.com/blog/resources/post/fetrack-troubleshooting-guide

You can do a simple freq response check by doing step to with say a 200hz, 1K, and 10K signal. Should be flat.

Mike

 

[Ricardus]

OK. I think I'm psychologically ready to tackle these beasts. 

 

[Echo North]

OK. I think I'm psychologically ready to tackle these beasts.

Do it!

 

[Ricardus]

Do it!

It's on my bench and in my vise!

 

[Matgre]

Hi all,

might have overlooked it..
On Rev A, is it a problem if the input transformer (T1) touches the big orange drop (C10) on its coating sitting just beside it?

Thanks for help!
Mat

 

[Matgre]

Low voltage between OUT + OUT -.

Hi everyone,

please keep ignoring my post above, no components are touching... exept Q12 and Q13 of course.

Just finished assembly of an 1176 RevA v1.15 and could need some advise now and hope someone is willing to give. 
In the calibration process i cant calibrate QBias because of not getting proper voltage between OUT + OUT -.

All solders look good and tripple checked for misplaced components.

Did the troubleshooting procedure on the Hairball site.

PSU reads as it should, GND 0,3Ohm, CR8 cathode 30,73VDC , CR9 anode -9,69VDC

1. QBias Voltage:  as supposed to, highest reading (fullCW) 1,775VDC and lowest (fullCCW) 1,019VDC

2. Amp Stages:  low voltage at all testpoints: TP1 (0,074VAC), TP15 (0,005VAC), TP17(0,0008VAC), Transformer BRN(0,002VAC) and of course between OUT+ - (0,005VAC).

For TP1 issue:
TPad and T1: With 0,775VAC at input, i get VAC readings of (386,3 mVAC) on  Inputtransformer lead1  and the Tpad input. 255mVAC on Tpad out and inputtransformer lead4. Looks like nothing gets past the transformer exept the 74mVAC.
Is there a way to test Q1 exept swapping with Q11?

For TP15 issue:
All VDC are  around the ones in the RevA DC Voltage Chart in the signal amp section.

For TP17 issue:
Sorry but not sure if i test R23 right, pot goes from 0,6Ohm at infinite to around 100K at 24, then back to 34k at 0.  Shouldtn it go from 0Ohm to 250k or is it just a range?
17,15 VDC at C7 + side coming from Q3 and around the ones in the RevA DC Voltage Chart.

Outputtransformer BRN issue: all VDC are around the RevA DC Voltage Chart in the line amp section.
Checked continuity for the wiring, all seems good.

Thank you for any suggestions.
Mat

 

[Echo North]

Your issue is that your signal dies in the Signal Preamp section.  75 mV is normal after the transformer (TP1). I would look closely in that section.

On the output pot, there are some parallel resistance things that are going to throw off your readings in circuit.  If you want to test it, you can remove it and test it.

Mike

Low voltage between OUT + OUT -.

Hi everyone,

please keep ignoring my post above, no components are touching... exept Q12 and Q13 of course.

Just finished assembly of an 1176 RevA v1.15 and could need some advise now and hope someone is willing to give. 
In the calibration process i cant calibrate QBias because of not getting proper voltage between OUT + OUT -.

All solders look good and tripple checked for misplaced components.

Did the troubleshooting procedure on the Hairball site.

PSU reads as it should, GND 0,3Ohm, CR8 cathode 30,73VDC , CR9 anode -9,69VDC

1. QBias Voltage:  as supposed to, highest reading (fullCW) 1,775VDC and lowest (fullCCW) 1,019VDC

2. Amp Stages:  low voltage at all testpoints: TP1 (0,074VAC), TP15 (0,005VAC), TP17(0,0008VAC), Transformer BRN(0,002VAC) and of course between OUT+ - (0,005VAC).

For TP1 issue:
TPad and T1: With 0,775VAC at input, i get VAC readings of (386,3 mVAC) on  Inputtransformer lead1  and the Tpad input. 255mVAC on Tpad out and inputtransformer lead4. Looks like nothing gets past the transformer exept the 74mVAC.
Is there a way to test Q1 exept swapping with Q11?

For TP15 issue:
All VDC are  around the ones in the RevA DC Voltage Chart in the signal amp section.

For TP17 issue:
Sorry but not sure if i test R23 right, pot goes from 0,6Ohm at infinite to around 100K at 24, then back to 34k at 0.  Shouldtn it go from 0Ohm to 250k or is it just a range?
17,15 VDC at C7 + side coming from Q3 and around the ones in the RevA DC Voltage Chart.

Outputtransformer BRN issue: all VDC are around the RevA DC Voltage Chart in the line amp section.
Checked continuity for the wiring, all seems good.

Thank you for any suggestions.
Mat

 

[Matgre]

Your issue is that your signal dies in the Signal Preamp section.  75 mV is normal after the transformer (TP1). I would look closely in that section.

On the output pot, there are some parallel resistance things that are going to throw off your readings in circuit.  If you want to test it, you can remove it and test it.

Mike

Hi Mike,

thanks for the reply, was out of town the last days and returned to my build today.

It looks like a broken FET.  No signal after Q2.

The stupid thing is, after reading more about the same problems, i firts thought its Q1 and pulled it.. When putting it back in it fell under my chair and i rolled over it.. smashed.  :

Think i need to order a matched pair of 2N5457´s now as well..

 

[Echo North]

Hi Mike,

thanks for the reply, was out of town the last days and returned to my build today.

It looks like a broken FET.  No signal after Q2.

The stupid thing is, after reading more about the same problems, i firts thought its Q1 and pulled it.. When putting it back in it fell under my chair and i rolled over it.. smashed.  :

Think i need to order a matched pair of 2N5457´s now as well..

Shoot us an email.

 

[YoDudeRock]

Hey Mike,
    I am building a Rev A (one of two) and CR8 is coming up at a little over 32v.  That IS over the recommended 30V +/- 5% . 
Is this a problem or no big deal?    FYI, CR9 is -10.04, which perfectly in range.


Thanks,
Chris Trentham
Ready To Rock Audio LLC

 

[Echo North]

Hey Mike,
    I am building a Rev A (one of two) and CR8 is coming up at a little over 32v.  That IS over the recommended 30V +/- 5% . 
Is this a problem or no big deal?    FYI, CR9 is -10.04, which perfectly in range.


Thanks,
Chris Trentham
Ready To Rock Audio LLC

The zener diode has a 5% tolerance so that's a little weird. However, if you haven't stuffed the rest of the board yet, nothing is really under load and that can change things. 

It's not really a big deal, maybe stuff the PCB then see what you get.  Nothing is going to blow up at 32V DC.

Mike

 

[frenkonio]

Well with that you have no HF. See how everything is lower under the 10K label?

Either way they should all be the same.  Could be something wrong with the input transformer, but honestly in thousands of transformers I've only seen freq response issues in like 2 units.  So it absolutely could be the tx, but I'm hesitant because your measurements are opposite to what you are hearing.

I would re-measure. If you get the same results, something is up with your measurement set-up.  If they are indeed the opposite way, confirm that R4 is 270Ω and not 270K or something.  Also confirm the value of R5, C22, C1.

If that is fine let me know. You might have a bad tx.

Mike

R4 is ok. R5, C22 and C1 are all ok. Measurements too. I have noticed that the input TX just wiggle when I touch it. I desoldered it easily and noticed that his small feet move when touched. It doesn't happen on other input TX I got in some kits I still didn't assembled.
Let me know, I'm going nuts

 

[Echo North]

R4 is ok. R5, C22 and C1 are all ok. Measurements too. I have noticed that the input TX just wiggle when I touch it. I desoldered it easily and noticed that his small feet move when touched. It doesn't happen on other input TX I got in some kits I still didn't assembled.
Let me know, I'm going nuts

The can have a little wiggle yes.

Mike

 

[frenkonio]

The can have a little wiggle yes.

Mike

So how could I measure if it is not good? I mean the TX (all other input TX I have mounted till now didn't wiggled, anyway...)

 

[Echo North]

So how could I measure if it is not good? I mean the TX (all other input TX I have mounted till now didn't wiggled, anyway...)

Measure the DC R on each side be measuring the resistance between to 2 outer pins on each side.  One side is like 16Ω and the other side is maybe 32Ω.

Mike

 

[Diamondj421]

Hey guys,
I had a bunch of issues with a Rev D. I had burnt the hell out of the main PCB/traces during the build so it turned into a P2P project. It’s fixed but now when I turn it on, the needle stays pinned to the left. I’ve found that by giving a firm tap to the front panel the needle returns to the right and operates perfectly until I turn it off again. I almost feel like the Fonz. Any idea what could cause this? I thought it could be a loose connection but I feel like it would turn on and off occasionally if that were the case.

 

[Echo North]

Hey guys,
I had a bunch of issues with a Rev D. I had burnt the hell out of the main PCB/traces during the build so it turned into a P2P project. It’s fixed but now when I turn it on, the needle stays pinned to the left. I’ve found that by giving a firm tap to the front panel the needle returns to the right and operates perfectly until I turn it off again. I almost feel like the Fonz. Any idea what could cause this? I thought it could be a loose connection but I feel like it would turn on and off occasionally if that were the case.

Might have the meter fastened too tight.  That can warp the VU scale card and cause the needle to stick.

Mike

 

[Diamondj421]

Might have the meter fastened too tight.  That can warp the VU scale card and cause the needle to stick.

Mike

Good to hear! Thanks Mike!

 

[frenkonio]

Measure the DC R on each side be measuring the resistance between to 2 outer pins on each side.  One side is like 16Ω and the other side is maybe 32Ω.

Mike

In or outside circuit? I got it desoldered now

 

[Echo North]

In or outside circuit? I got it desoldered now

outside if it's disconnected.