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

[Echo North]

Can I purchase the bourns and will it work with this board? Which model?  Thanks

Shoot us an email.

 

[alex_dempsey]

Hello,

I am having some trouble with the power supply on my kit. I just finished building it and the ground test is reading correctly but I'm only reading like 200 mVDC when I do the next test. I've tried looking around for issues but can't seem to find any. Ideas on why I'm not getting any voltage?

Thanks.

 

[Echo North]

Hello,

I am having some trouble with the power supply on my kit. I just finished building it and the ground test is reading correctly but I'm only reading like 200 mVDC when I do the next test. I've tried looking around for issues but can't seem to find any. Ideas on why I'm not getting any voltage?

Thanks.

There is a -10VDC and a +30VDC rail.

Which one is having the issue?

Mike

 

[seanweaverguitar]

So I'm using the Hairball Rev. A daily now and it's ridiculously good (I've only used it on bass and electric guitars in the middle of my guitar blues-rock project for some instructional work so granted I haven't run acoustic guitar or vocals through it yet but for what I'm doing I can't imagine anything better; I drove the input stage yesterday (GR off) coming out of Lola on a 1x12" open back turned up to 8 and got the most vicious Page kind of dirty guitar-rock rhythm sound) & dreaming about building several more.....

I'm torn between a Rev D and the new Rev F although in time I'm sure I'll wind up with all of them. Stupid question but I'm thinking ahead....

For the Stereo Link on the Rev A, I'm assuming it wouldn't really be right to link that to a different revision? I'm micing cabinets now in stereo so often it's probably another Lola & Rev A to keep things even but just wanted to check in here for suggestions before I officially decide which way to go on the next order. I'm finally getting good guitar sounds!!! Thanks Mike

Sean

 

[Echo North]

So I'm using the Hairball Rev. A daily now and it's ridiculously good (I've only used it on bass and electric guitars in the middle of my guitar blues-rock project for some instructional work so granted I haven't run acoustic guitar or vocals through it yet but for what I'm doing I can't imagine anything better; I drove the input stage yesterday (GR off) coming out of Lola on a 1x12" open back turned up to 8 and got the most vicious Page kind of dirty guitar-rock rhythm sound) & dreaming about building several more.....

I'm torn between a Rev D and the new Rev F although in time I'm sure I'll wind up with all of them. Stupid question but I'm thinking ahead....

For the Stereo Link on the Rev A, I'm assuming it wouldn't really be right to link that to a different revision? I'm micing cabinets now in stereo so often it's probably another Lola & Rev A to keep things even but just wanted to check in here for suggestions before I officially decide which way to go on the next order. I'm finally getting good guitar sounds!!! Thanks Mike

Sean

Nice!

Ya linking would mostly be for overheads on drums and you would want the same setup on both sides.  No need to link on a stereo guitar set up IMO.  And you could use different pres and revs.

Mike

 

[Uroarz]

Hey guys I'm calibrating my 1176 rev A for the second time. What would be a full reset for the pots? i understand CW for the q-bias but what about the others? I'm on the "Reduction Meter Tracking Adjustment" and my output isn't going above 0.293 VAC. I'm putting in 1db 0.775 VAC on the input but the output is maxing out at 0.293 VAC. I'm assuming i need to reset all the pots but let me know. Thanks! -Austin

 

[Echo North]

Hey guys I'm calibrating my 1176 rev A for the second time. What would be a full reset for the pots? i understand CW for the q-bias but what about the others? I'm on the "Reduction Meter Tracking Adjustment" and my output isn't going above 0.293 VAC. I'm putting in 1db 0.775 VAC on the input but the output is maxing out at 0.293 VAC. I'm assuming i need to reset all the pots but let me know. Thanks! -Austin

Pots or trimmers?  The rest of the trimmers should be centered.  The front pots should be set according to the calibration guide.

Sounds like you have larger issues.  Check this guide and report back:

http://www.hairballaudio.com/blog/resources/post/fetrack-troubleshooting-guide

Mike

 

[CBarx]

Hey Mike, Casey from Nashville here.  I wrapped a mass FetRack build a while ago, but had one Rev A give me a problem so it sat on the workbench for a while untouched while a wrapped up some client projects.  I'm back at it now and have narrowed some things down. 

1st - I had CR9 go bad on me.  +30v was fine, but the -10v was reading at basically nothing.  Luckily I had a spare and was able to replace it.  Power section is now good. 

I've been able to go through the entire calibration step up until setting the Gain reduction meter.  This is where I found out that my compressor will not compress. 

I've gone through the troubleshooting guide, and have found that Q Bias is fine, amplification stage is fine, GR Amplification Threshold section is fine. 

I'm having troubles in 3 areas.  1st - GR Control Amp values are incredibly low.  They are listed below:

.054v  - Ratio 20
.024v - Ratio12
.018v - Ratio 8
.015v - Ratio 4

Second, when I probe the anode side of CR2 for GR Control Amp Output testing, I get a complete audio dropout and a quickly declining voltage reading making it near impossible to get an accurate value.

3rd, I've noticed that the ratio ribbon cable must be positioned in the EXACT right spot in order for audio to pass, and for the GR meter to zero.  I've tried re-soldering these connectors, but with no improvement to how the unit acts.  I'm starting to wonder if there is a short or break in one of the conductors on the cable itself. 

Note that all FET voltages in the Signal Preamp, Signal Line Amp,  and GR Control Amp sections are readings are within a 10% tolerance of what is listed on the REV A Voltage chart. 

 

[Echo North]

Hey Casey,

I'm having troubles in 3 areas.  1st - GR Control Amp values are incredibly low.  They are listed below:

.054v  - Ratio 20
.024v - Ratio12
.018v - Ratio 8
.015v - Ratio 4

Where is this at? Pad 22? Measuring AC?

Second, when I probe the anode side of CR2 for GR Control Amp Output testing, I get a complete audio dropout and a quickly declining voltage reading making it near impossible to get an accurate value.

That's super weird.  Not sure about that one.

3rd, I've noticed that the ratio ribbon cable must be positioned in the EXACT right spot in order for audio to pass, and for the GR meter to zero.  I've tried re-soldering these connectors, but with no improvement to how the unit acts.  I'm starting to wonder if there is a short or break in one of the conductors on the cable itself. 

Could be.  You should be able to continuity test between pins on the connectors to see if there is an issue. Are any of the wires crossed on the connector?

Mike

 

[CBarx]

Where is this at? Pad 22? Measuring AC?

That's super weird.  Not sure about that one.

Could be.  You should be able to continuity test between pins on the connectors to see if there is an issue. Are any of the wires crossed on the connector?

 
Mike

Yes Pad 22 measuring AC

No wires crossed on the connector cable, and continuity is good on all wires.  Continuity is good on all pins on CN3 and CN2.  Not sure what's going on there.  I may try seeing if hitting some solder points will fix anything there.  Everything looks good, but crazier things have happened.

 

[Echo North]

Yes Pad 22 measuring AC

No wires crossed on the connector cable, and continuity is good on all wires.  Continuity is good on all pins on CN3 and CN2.  Not sure what's going on there.  I may try seeing if hitting some solder points will fix anything there.  Everything looks good, but crazier things have happened.

Check your relay soldering, R19-22, and R78 values.  Make sure you don't have like a 470K where there should be a 47K.

Also can send out a new cable.

Mike

 

[Echo North]

Any reason the power resistor wouldn’t be dropping voltage for the vu lamp? Everything appears to be grounded.

No path to ground.  Is the lamp dead?

 

[CBarx]

Check your relay soldering, R19-22, and R78 values.  Make sure you don't have like a 470K where there should be a 47K.

Also can send out a new cable.

Mike

Ruled out Ratio Switch board.  All solder points are good and all resistor values are correct.  Cable is definitely funky, but I know there's still something else going on in here.  Going to poke around a bit more.

 

[CBarx]

That's super weird.  Not sure about that one.

Going through voltages again, and in addition to getting .05v and below at TP 22,  I simply cannot perform GR Control Amp voltage  checks because CR2 goes nuts every time I hit it with a probe.  My 1k sine goes completely silent, meter slams back down to -20, and voltages will bounce all over the place.  I assume I should see if I have a replacement CR2 in my stock?  I already had a dead CR9 so perhaps I'm just having a bad batch of diodes on this build?  CN2 > CN3 cable is getting worse, I think the pins in the housings are not making proper contact unless I put horizontal pressure on the cable.

 

[Echo North]

Going through voltages again, and in addition to getting .05v and below at TP 22,  I simply cannot perform GR Control Amp voltage  checks because CR2 goes nuts every time I hit it with a probe.  My 1k sine goes completely silent, meter slams back down to -20, and voltages will bounce all over the place.  I assume I should see if I have a replacement CR2 in my stock?  I already had a dead CR9 so perhaps I'm just having a bad batch of diodes on this build?  CN2 > CN3 cable is getting worse, I think the pins in the housings are not making proper contact unless I put horizontal pressure on the cable.

Could be a bad diode. 

If you're not getting a V drop at the output in GR mode, you still need to sort out why you have no AC at PAD 22.

Trace it out on the schematic follow it from PAD 15 where it should be close to a 2VAC to pad 22 and see where it dies.  It just goes through the relay, connector, R78 if in 20:1, the ratio switch, back through the connector, through the attack switch, then to pad 22.

Mike

 

[CBarx]

Could be a bad diode. 

If you're not getting a V drop at the output in GR mode, you still need to sort out why you have no AC at PAD 22.

Trace it out on the schematic follow it from PAD 15 where it should be close to a 2VAC to pad 22 and see where it dies.  It just goes through the relay, connector, R78 if in 20:1, the ratio switch, back through the connector, through the attack switch, then to pad 22.

Mike

So at .775v on the XLR input I'm getting 3.8v at TP15 @20:1 ratio.  Which is 1.8v higher than mentioned above.  That's with input and output at 12 o'clock.

 

[Echo North]

So at .775v on the XLR input I'm getting 3.8v at TP15 @20:1 ratio.  Which is 1.8v higher than mentioned above.  That's with input and output at 12 o'clock.

I wouldn't worry about it being too high right now.  Figure out why, when you turn on GR, that AC V is not making it to pad 22. It's a short linear path on the schematic.

Does that PAD 15 voltage drop at all when you turn on GR?

Mike

 

[CBarx]

Could be a bad diode. 

If you're not getting a V drop at the output in GR mode, you still need to sort out why you have no AC at PAD 22.

Trace it out on the schematic follow it from PAD 15 where it should be close to a 2VAC to pad 22 and see where it dies.  It just goes through the relay, connector, R78 if in 20:1, the ratio switch, back through the connector, through the attack switch, then to pad 22.

Mike

I've now been able to rule out the Ratio board entirely as well.  I pulled my other working RevA and swapped out the Ratio board and cable.  It's performing exactly the same way, which tells me that for some reason continuity is a problem on CN3 (even though I've already tested this).  All that to say, when I can get CN3 manipulated to bring signal back up to normal, I'm still seeing a .08v reading at TP22

 

[Echo North]

Does that PAD 15 voltage drop at all when you turn on GR?

 

[CBarx]

Does that PAD 15 voltage drop at all when you turn on GR?

Sorry for the late reply, I was unable to access the support forum for a couple of days.  The answer to your question is "no", there is no voltage drop.