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

[Echo North]

Yes, that is correct.

Definitely something in your GR Meter Driver Amp section.  You've been through that a few times?

Mike

 

[Joarsylvan]

Those caps are right.

Some of those components have no solder flow on the top, that's not necessarily a problem, but it might mean you have a part that's not fully soldered.  You might want to reflow these joints, particularly those in the signal amp.

Mike

Okey, thanks. I will look into the soldering. It’s either that or some parts are broken I think? Maybe a bad connection with the cable to the ratio-pcb?


I started to wonder now about this black plastic-thing I put in the part where it says ”normal operation”. Is this supposed to be soldered in to place? Because I did solder it.

 

[Nao_Idea]

Working now?

A needle worth of swing on the release pot is normal.

Mike

Hello,

It is working.  Thank again for your help.

Mike

 

[Anode]

Hi all

Anyone have a procedure for REV F Tracking adjust  because there isn't PIN SHUNT on the PCB.

Thanks by advance.

Best

Anode

 

[ron_swanson]

You have something going on in the GR Control amp.  Check your DC voltages for each transistor in that section...use the D chart linked in the troubleshoot guide.

Hey Mike,

I basically pulled apart the GR Control Amp section - tested all resistors, caps, transistors, diodes and then reassembled / re-soldered.  Nothing seemed out of place and everything tested positive as expected.  The good news, it's working now and I've been able to calibrate!    Won't be in the studio for a few days, so it will be awhile before I can test in a 'real use' environment, but all seems well now at least on the bench using a low end I/O and micro desk speakers.  The bad news - unfortunately - is... I don't know what exactly the problem was?  Since all components tested correctly stuffed correctly, a bad solder point or other? 

Lastly, it would be nice if the calibration and troubleshooting pages could be updated with specific F unit instructions when someone gets a chance. 

Anyway, thanks for the assistance.    Time to get rocking!

Cheers, Greg

 

[Joarsylvan]

Hello again! I went over the soldering and found a couple of not great ones. Those are now fixed.

I now have a clean signal, no distortion. But it’s still quite low and it looses its strength somewhere early in the chain. And no compression, just clean (but low) signal.

Cables are testes, everything seems to be in it’s right place and every resistor is tested three times at the least.

Since I don’t have a clue now concerning what could be wrong I’m thinking that I am left with no alternative but to send the pcb to you. Maybe one of the caps or transformators are broken? Idk.

Oh, and I think I broke the R71 adjustment when trying to calibrate the VU meter...  :

 

[Echo North]

Hi all

Anyone have a procedure for REV F Tracking adjust  because there isn't PIN SHUNT on the PCB.

Thanks by advance.

Best

Anode

Just skip the null adjust and do the tracking...ignore the stuff about the pin.

 

[Echo North]

Hey Mike,

I basically pulled apart the GR Control Amp section - tested all resistors, caps, transistors, diodes and then reassembled / re-soldered.  Nothing seemed out of place and everything tested positive as expected.  The good news, it's working now and I've been able to calibrate!    Won't be in the studio for a few days, so it will be awhile before I can test in a 'real use' environment, but all seems well now at least on the bench using a low end I/O and micro desk speakers.  The bad news - unfortunately - is... I don't know what exactly the problem was?  Since all components tested correctly stuffed correctly, a bad solder point or other? 

Lastly, it would be nice if the calibration and troubleshooting pages could be updated with specific F unit instructions when someone gets a chance. 

Anyway, thanks for the assistance.    Time to get rocking!

Cheers, Greg

Ya probably a bad joint from what you describe.

We'll get the calibration updated.

 

[Echo North]

Hello again! I went over the soldering and found a couple of not great ones. Those are now fixed.

I now have a clean signal, no distortion. But it’s still quite low and it looses its strength somewhere early in the chain. And no compression, just clean (but low) signal.

Cables are testes, everything seems to be in it’s right place and every resistor is tested three times at the least.

Since I don’t have a clue now concerning what could be wrong I’m thinking that I am left with no alternative but to send the pcb to you. Maybe one of the caps or transformators are broken? Idk.

Oh, and I think I broke the R71 adjustment when trying to calibrate the VU meter...  :

It's hard to say.  Could be a lot of things.Have you checked the transistor DC voltages?

 

[kingofspain2]

all Qs are within volt tolerances of 10%, q2 base however is reading 0.86 volts instead of 1.06 volts, there's also a hyper sensitivity to the amplitude of the noise when touching R8 or C1, signal ground and chassis are separate, entire chassis is continuous...  thoughts?

A working rack unit had the main board swapped with the noisy unit to isolate where the noise is originating, the issue remained in the rack chassis that is noisy, the noisy board works fine in the working chassis, the noise in the working unit is persistent before and after the swap, but it's within the noise floor and isn't an issue.

further investigation in the chassis components finds that the noise disappears when any of the lugs on the attack pot are probed with an oscilloscope, and that removing the violet wire from the ratio board connector to the main board stops the noise. Also from a cold condition, the noise seems to only appear when the +20 ratio button is pressed on it's own or with any other button combination with +20 pressed. Grounding the attack pot lugs also gets rid of the noise completly, not the switch lugs, just the potentiometer lugs, as well as the release pot lugs. Current suspects are the ratio button board, attack pot, and release pot, however none of these parts appear to have anything wrong with them, any advice is appreciated.

 

[scott2000]

all Qs are within volt tolerances of 10%, q2 base however is reading 0.86 volts instead of 1.06 volts, there's also a hyper sensitivity to the amplitude of the noise when touching R8 or C1, signal ground and chassis are separate, entire chassis is continuous...  thoughts?

signal ground and chassis not connected???

Nowhere?

 

[kingofspain2]

signal ground and chassis not connected???

Nowhere?

chasis is connected to ground at cathode of c25

 

[scott2000]

chasis is connected to ground at cathode of c25

Yeah/...... but that ground should be going many places.... if I'm looking right.... I'm sure Mike will have some direction....

I've never built one of these so just trying to decipher schematic..... got stuck looking at the A version for a bit...lol


So everything worked perfect before the cap mod????


got a pic of your board??....maybe something will pop out.......

 

[Joarsylvan]

It's hard to say.  Could be a lot of things.Have you checked the transistor DC voltages?

Yeah, I really have no clue, and I’ve measured voltage to the best of my ability.. I will be sending it to you I’m afraid, haha.

Seriously, thank you for taking the time on the forum and for your support. True hero!

Should I send the PCB without the XLR?

 

[kingofspain2]

A working rack unit had the main board swapped with the noisy unit to isolate where the noise is originating, the issue remained in the rack chassis that is noisy, the noisy board works fine in the working chassis, the noise in the working unit is persistent before and after the swap, but it's within the noise floor and isn't an issue.

further investigation in the chassis components finds that the noise disappears when any of the lugs on the attack pot are probed with an oscilloscope, and that removing the violet wire from the ratio board connector to the main board stops the noise. Also from a cold condition, the noise seems to only appear when the +20 ratio button is pressed on it's own or with any other button combination with +20 pressed. Grounding the attack pot lugs also gets rid of the noise completly, not the switch lugs, just the potentiometer lugs, as well as the release pot lugs. Current suspects are the ratio button board, attack pot, and release pot, however none of these parts appear to have anything wrong with them, any advice is appreciated.

Picture of rack, board is fine, was swapped with working unit, problem didn't migrate with board, has to be chassis issue

 

[frenkonio]

Hi guys, got an issue on a Rev. A I successfully built one year ago. From today everything passes inside the compressor gets out with something like an HPF on everytime.
Any idea on where to start troubleshooting?

 

[Echo North]

Hi guys, got an issue on a Rev. A I successfully built one year ago. From today everything passes inside the compressor gets out with something like an HPF on everytime.
Any idea on where to start troubleshooting?

You've got no high end?

Do the signal test through the unit as described in the troubleshooting guide using a 500 Hz signal (note TP1, TP15, Output BRN). Then do it again with a 10KHz and see where you are dumping the signal.

Mike

 

[kingofspain2]

Picture of rack, board is fine, was swapped with working unit, problem didn't migrate with board, has to be chassis issue

Mike - any ideas? 

 

[frenkonio]

You've got no high end?

Do the signal test through the unit as described in the troubleshooting guide using a 500 Hz signal (note TP1, TP15, Output BRN). Then do it again with a 10KHz and see where you are dumping the signal.

Mike

Nope, I got no low end frequencies, looks like an hpf filter on.

 

[RobertBraz]

I believe I have isolated my issue to the input section. I am only reading 0.07VAC at TP1. I have triple-checked my solder joints on the input transformer, input pot, and Q1. Where should I look next?