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

[Dacey]

What is your signal source?  The input of the FET/RACK is loading it, that's why you get the drop.

If it's not calibrated, ignore the meter. With this unit, the calibration is no fine tune adjustment, it's the difference between it working, and not working at all.

Mike

Signal source is RC Oscillator model 555.  I'm off to find a real one will get back to you if I encounter further issues. Thanks for your assistance Mike.

 

[Echo North]

Signal source is RC Oscillator model 555.  I'm off to find a real one will get back to you if I encounter further issues. Thanks for your assistance Mike.

If you have a sine wave generator in you DAW (protools has one). Check out the FET/500 calibration section for info on how to use it.

Mike

 

[mrbobbailey]

You're not dropping any voltage across your resistors which would mean you're not drawing current on your negative rail.  I would suspect the zener diode (CR9).  Confirm it's soldered well, the pads look good, and it's oriented correctly. If all that looks good you may want to replace it. Email me for a new one.

Mike

Mike,

I meant to reply right away this week.  I got the replacement in very quick order, installed the zener diode, and all measured up as expected!  Thank you, guy!

 

[Echo North]

Mike,

I meant to reply right away this week.  I got the replacement in very quick order, installed the zener diode, and all measured up as expected!  Thank you, guy!

Awesome!

 

[ilfungo]

hi
how many mA the 1176 need on the 2 secondaries ( power transformer)?
Thanks!

 

[Echo North]

hi
how many mA the 1176 need on the 2 secondaries ( power transformer)?
Thanks!

In general, you need about a 25VA transformer.

 

[Diamondj421]

Disaster struck while removing transistors Q9, Q10, Q12 and Q13. This has become a P2P project at this point. I wanted help as to where each leg of the 4 transistors should go. Q10 appears to be reconnected properly. E and B of Q9 are right but I'm not sure where C goes. As for Q12 and Q13, the pads are too burnt up to decipher. I need a tutorial on properly removing parts from a PCB. I'm shooting at about a 25% right now and that doesn't fly for me.

 

[Diamondj421]

Here's the picture of Q12 and Q13.

 

[Echo North]

Yikes. You may want to stop removing parts.

Use the schematic to confirm you're making the correct connections.

http://mnats.net/fetrack.html

 

[Diamondj421]

In the schematic, which of the lines going from the transistors are B. C and E?

 

[Echo North]

In the schematic, which of the lines going from the transistors are B. C and E?

http://www.physlink.com/education/askexperts/Images/ae430c.gif

 

[Diamondj421]

Pardon the mess but is this right? I checked with the schematics and I'm fairly certain I got it but wanted to check with the master. If there is no lead coming from the point, the connection is still in tact.

 

[Diamondj421]

Pardon the mess but is this right? I checked with the schematics and I'm fairly certain I got it but wanted to check with the master. If there is no lead coming from the point, the connection is still in tact.

Actually I think the emitter from Q12 should go to R68... is that right? Sorry for all the questions. At this point I'd normally just send this to you but recently found out that I have my first baby on the way so I need to save money. :/

 

[Echo North]

Actually I think the emitter from Q12 should go to R68... is that right? Sorry for all the questions. At this point I'd normally just send this to you but recently found out that I have my first baby on the way so I need to save money. :/

Yes and R44

 

[lackstudios]

OK, sad to say it wasn't the transformer :-( HELP

 

[Echo North]

OK, sad to say it wasn't the transformer :-( HELP

Go through all the tests I did with this user:

https://groupdiy.com/index.php?topic=63600.msg827887#msg827887

 

[lackstudios]

Go through all the tests I did with this user:

https://groupdiy.com/index.php?topic=63600.msg827887#msg827887

OK, so I followed the thread, but I'm getting .312 ACv and .375 ACv on the 2 orange secondary leads...the reading is the same with the unit off/unplugged :-/ I double checked the 115 switch on the rear also...

This sounds strange, but i probed WHT/BLK and BLU/RED on the new transformer and still read OLΩ 
I tried it plugged in and unplugged...

 

[Echo North]

OK, so I followed the thread, but I'm getting .312 ACv and .375 ACv on the 2 orange secondary leads...the reading is the same with the unit off/unplugged :-/ I double checked the 115 switch on the rear also...

This sounds strange, but i probed WHT/BLK and BLU/RED on the new transformer and still read OLΩ 
I tried it plugged in and unplugged...

Ya something is up there with your testing I think.  I tested both those windings before I shipped it out and the read the usual 100Ωish.

What if you measure Ω at the selector switch (unit unplugged from the wall....no power).

Let me find the terminals...one sec...

 

[Echo North]

Power off (unplugged from wall).

With the transformer plugged in to the voltage select PCB...unplug the 3 pin connector at the top of the voltage PCB and measure the DC Ω between the two outer pins.  You should get 51Ω ish.

Mike

 

[lackstudios]

Power off (unplugged from wall).

With the transformer plugged in to the voltage select PCB...unplug the 3 pin connector at the top of the voltage PCB and measure the DC Ω between the two outer pins.  You should get 51Ω ish.

Mike

OLΩ nothing...