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

[Echo North]

Well working through this some more (by myself apparently LOL) i found that the signal was only getting to TP1. I found out that if I play with C1 by wiggling it I could get the signal to TP15 and 17 and the output which is good. So I tried various times re-soldering C1 but still have that problem. I'm wondering if my 1uF cap has a intermittent problem within itself. i got the Orange drop upgraded caps. i may just put the 1uF electrolytic in to see if I have any problems with that. i may need to have a new 1uF cap sent to me but I will see.

Now either way when I can the cap to work i can actually calibrate it now which is good but still the C1 is an issue that needs to be resolved.

Hi,

Sorry, big weekend, family was in town.

Did you ever get a new cap? We can send you new one.  Maybe a loose lead.

Mike

 

[nickcion]

TP1 low resistance is normal.  What is it?  Something like 16Ω (I can't remember exactly).

Which pins on T1 are shorted to the can of T1 (using your Ω meter)?

Mike

13 ohms from t1 to chassis.

both sides of the secondary are shorted to can.. (and the pin for the can, on that same side) 5,6,8

 

[Echo North]

13 ohms from t1 to chassis.

both sides of the secondary are shorted to can.. (and the pin for the can, on that same side) 5,6,8

That's not good.  Might be happening down the line.  Can you pull the transformer and test it off the PCB?

 

[Echo North]

6 in the can.  8 get's shorted in the circuit.

5 should not be shorted.

 

[nickcion]

t1 pulled

55ohm primary
14.6 ohm secondary

secondary is isolated from the can

 

[Echo North]

t1 pulled

55ohm primary
14.6 ohm secondary

secondary is isolated from the can

Seems right.  I'll double check tomorrow.  However, in the PCB BOTH secondary pins were shorted to the can?

What rev do you have? Is Q 1 installed?

 

[nickcion]

i believe the newest revision..  just got back to school.

I did install a new Q1 over the weekend.

 

[Echo North]

i believe the newest revision..  just got back to school.

I did install a new Q1 over the weekend.

I mean Rev A or Rev D?

Those ohm readings are good.

 

[nickcion]

Rev A

 

[Echo North]

Rev A

Is the input transformer still removed from the PCB? If so, what is the DC R (Ω) between TP1 and chassis ground?

Mike

 

[nickcion]

Is the input transformer still removed from the PCB? If so, what is the DC R (Ω) between TP1 and chassis ground?

Mike

T1 is out. Q1 is in..

chassis to TP1 is 267 ohms.. (but I'm unsure of DCR as a term)

 

[Echo North]

T1 is out. Q1 is in..

chassis to TP1 is 267 ohms.. (but I'm unsure of DCR as a term)

That seems good.

Maybe try putting T1 back in.

Make sure your QBias is set as described in the troubleshooting guide and try again. If your Qbias is messed up you'll never get output.

Mike

 

[Silmica]

Hi,

Sorry, big weekend, family was in town.

Did you ever get a new cap? We can send you new one.  Maybe a loose lead.

Mike

I found out it was not the cap. I think because these leads on the orange drop caps are fairy thick that pushing it through the holes maybe damaging the trace around the holes possibly? I put the cap in holes that were more inward (was fun doing that with short leads) and managed to get it to work well. I am able to calibrate it and it works great now.

It's funny that I was putting up messages hoping someone could chime in with some help but after working through it all and looking at the schematic and thinking about it logically I was able to get it to work. Strange though that the CR9 zener diode went bad on me. I tested the power supply before continue stuffing the board. I got one from a local electronics store but the leads on it are very thick and I kind of just have it tacked in there and it is working. Not sure if you have ever had that problem before. When I took the zener out and tested it with a meter I got .2ohm either way that I put the leads on it.

 

[Echo North]

I found out it was not the cap. I think because these leads on the orange drop caps are fairy thick that pushing it through the holes maybe damaging the trace around the holes possibly? I put the cap in holes that were more inward (was fun doing that with short leads) and managed to get it to work well. I am able to calibrate it and it works great now.

It's funny that I was putting up messages hoping someone could chime in with some help but after working through it all and looking at the schematic and thinking about it logically I was able to get it to work. Strange though that the CR9 zener diode went bad on me. I tested the power supply before continue stuffing the board. I got one from a local electronics store but the leads on it are very thick and I kind of just have it tacked in there and it is working. Not sure if you have ever had that problem before. When I took the zener out and tested it with a meter I got .2ohm either way that I put the leads on it.

Glad you got it sorted!

 

[ElSmurf]

Started building my REV D partial kit yesterday and was a bit puzzled by the Zener heat sink. I got the Aavid heatsink from the Mouser BOM which doesn't seem to fit the diode. Did I miss something?

Also, my input transformer got a bit roughed up during shipping and all the pins seem to be bent. Is there any way to test it before soldering it in?

Cheers!

*edit* I just figured out that the Aavid heat sink is supposed to go on the 2N3053, is this correct? And was the Zener heat sink supposed to be in my kit?

 

[Echo North]

Started building my REV D partial kit yesterday and was a bit puzzled by the Zener heat sink. I got the Aavid heatsink from the Mouser BOM which doesn't seem to fit the diode. Did I miss something?

Also, my input transformer got a bit roughed up during shipping and all the pins seem to be bent. Is there any way to test it before soldering it in?

Cheers!

*edit* I just figured out that the Aavid heat sink is supposed to go on the 2N3053, is this correct? And was the Zener heat sink supposed to be in my kit?

Did you get a complete kit? You should have 2 heatsinks. One for the 2N3053 and one for the diode.  We have a missing parts form if you're missing it.  You can test your supply without it, it's not crucial.

Sorry about the input.  Bend the leads straight and make sure the are not touching the holes in the can. If they are secure you're fine.

Mike

 

[ElSmurf]

Did you get a complete kit? You should have 2 heatsinks. One for the 2N3053 and one for the diode.  We have a missing parts form if you're missing it.  You can test your supply without it, it's not crucial.

Sorry about the input.  Bend the leads straight and make sure the are not touching the holes in the can. If they are secure you're fine.

Mike

Mike, thanks for getting back to me. I just filled out the form. I bent the leads on the transformer back into place and everything looks fine now.

While going through my kit  to make sure nothing else was missing, I noticed my VU meter has an LED instead of a lamp, does that make any difference for the resistor on the VU lamp board?

Thanks!

 

[Echo North]

Mike, thanks for getting back to me. I just filled out the form. I bent the leads on the transformer back into place and everything looks fine now.

While going through my kit  to make sure nothing else was missing, I noticed my VU meter has an LED instead of a lamp, does that make any difference for the resistor on the VU lamp board?

Thanks!

Oh that is really weird.

The resistor would need to be different.

We can send you a lamp insert for the mere....just shoot me an email to the info@  email.

Mike

 

[Madgan]

Hello all - I apologize in advance for being the newbie with the newbie question...

Recently finished a Rev. D build v1.12. Everything seemingly went smooth throughout the entire build without a hiccup.

My problem surfaced when I was unable to successfully set the Q-Bias. With the input signal level set properly I was only able to generate approx. 1V AC at the output with the output pot fully CW.  I checked the power supply  and I'm seeing +30V DC at CR8 but I am not getting -10 V DC at CR9. The voltage is hovering somewhere around -5mV DC. The power supply passed the initial test before populating the boards however... Here's what I have done since:

Reflowed all capacitor, resistor and diode connections in power section.
Rechecked the values and placements of all resistors on all boards with my DMM and a color coding chart.
Checked for continuity and then the DC voltage readings on all transistors.
I found no issues or readings out of whack...

The capacitor voltages:
40V DC on the + of C23 and -.5mV on the -
30V DC on the + of C24 and -.5mV on the -
-.5mV DC on the + of C25 and -16.4V DC on the -
-.5mV DC on the + of C26 and -5.2mV on the -


With my limited understanding and troubleshooting knowledge I am at a wall. It appears nothing else will work properly without the power supply operating correctly.

Thanks you for any help that can be thrown my way

 

[Madgan]

Hello all - I apologize in advance for being the newbie with the newbie question...

Recently finished a Rev. D build v1.12. Everything seemingly went smooth throughout the entire build without a hiccup.

My problem surfaced when I was unable to successfully set the Q-Bias. With the input signal level set properly I was only able to generate approx. 1V AC at the output with the output pot fully CW.  I checked the power supply  and I'm seeing +30V DC at CR8 but I am not getting -10 V DC at CR9. The voltage is hovering somewhere around -5mV DC. The power supply passed the initial test before populating the boards however... Here's what I have done since:

Reflowed all capacitor, resistor and diode connections in power section.
Rechecked the values and placements of all resistors on all boards with my DMM and a color coding chart.
Checked for continuity and then the DC voltage readings on all transistors.
I found no issues or readings out of whack...

The capacitor voltages:
40V DC on the + of C23 and -.5mV on the -
30V DC on the + of C24 and -.5mV on the -
-.5mV DC on the + of C25 and -16.4V DC on the -
-.5mV DC on the + of C26 and -5.2mV on the -


With my limited understanding and troubleshooting knowledge I am at a wall. It appears nothing else will work properly without the power supply operating correctly.

Thanks you for any help that can be thrown my way

Spent a few more hours inspecting, reflowing, etc... I have -15V DC going into the R82 resistor but only -5mV DC comes out. That seems to be the start (or a byproduct?) of where things go bad. The resistor tests fine (1k) out of the circuit.