[BUILD] FET/500 Official Support Thread

[mdmitch2]

Not all 4 points.  Just the two circled. There are 2 separate switches on the switch. They have no relation to each other.

Google DPDT. One switch is the 3 terminals on one side, one switch is the three terminals on the other side. The middle terminal on each side is the common.

Thanks -- I went ahead and just swapped the two switches, and the problem stayed with the yellow LED. I also pulled the resistor and resoldered the LED for probably the third time (having also swapped it once already). I also checked it with the diode meter, and it seems fine, and it lights up a little with the DMM.  I also pulled and tested R510....


So if it's not related to one of those three components.....?

 

[mdmitch2]

Not all 4 points.  Just the two circled. There are 2 separate switches on the switch. They have no relation to each other.

Google DPDT. One switch is the 3 terminals on one side, one switch is the three terminals on the other side. The middle terminal on each side is the common.

Are there test points that may be instructive for diagnosing this? I checked voltage at the LED, and the cathode is showing 15.75 volts, and when the switch is engaged, R510 is getting 31.5 volts.

 

[Echo North]

Are there test points that may be instructive for diagnosing this? I checked voltage at the LED, and the cathode is showing 15.75 volts, and when the switch is engaged, R510 is getting 31.5 volts.

Has to be a bad pad.

Check out "SW1G$2" on the right.

http://mnats.net/files/FET-A500.pdf

Just 3 components in series.  One of those traces is dead.

Mike

 

[mdmitch2]

Has to be a bad pad.

Check out "SW1G$2" on the right.

http://mnats.net/files/FET-A500.pdf

Just 3 components in series.  One of those traces is dead.

Mike

I connected R510 directly to the LED with a spare resistor leg, and that solved the problem.

Thanks for your help!

 

[Echo North]

I connected R510 directly to the LED with a spare resistor leg, and that solved the problem.

Thanks for your help!

Nice.  8)

 

[hiegdk]

Hi there, this is my first FET 500 build (Rev D) but I've built a bunch of Lolas. I'm having an issue with the GR meter. I have both meters in DOT mode. The 'SLAM' LED (LED220 I believe) is constantly lit regardless of the ratio setting and I can't seem to get any of the other GR LEDs to light up during the GR meter calibration steps. I've tried setting the trim pots to their center points but so far no adjustment has resulted in any change in the GR meter (SLAM LED stays lit, no other LEDs activate).

The Q-bias adjustment seemed to work as expected and the VU calibration went smoothly as well. I've cleaned the boards real good and reflowed a few solder points that looked dull.

Anyone have any advice?

 

[Echo North]

Hi there, this is my first FET 500 build (Rev D) but I've built a bunch of Lolas. I'm having an issue with the GR meter. I have both meters in DOT mode. The 'SLAM' LED (LED220 I believe) is constantly lit regardless of the ratio setting and I can't seem to get any of the other GR LEDs to light up during the GR meter calibration steps. I've tried setting the trim pots to their center points but so far no adjustment has resulted in any change in the GR meter (SLAM LED stays lit, no other LEDs activate).

The Q-bias adjustment seemed to work as expected and the VU calibration went smoothly as well. I've cleaned the boards real good and reflowed a few solder points that looked dull.

Anyone have any advice?

I don't have a lot of test point advice on those. It is important that you center all trimmers.  Go over all of you component values and soldering.  Also, check the section on the main PCB related to GR metering. It's the stuff around the IC (make sure that IC is the correct value). Also make sure all points of the 10 pin connector are soldered well.

 

[antoine00]

Hello,

I've just finished building my 1176 Rev A 500 comp and have problem when calibrate It.

I have a lot of noise coming out of the comp -18Db (less when the output is fully clockwise). I Have noise even when I send nothing to the 1176.
A very low signal compared to what I send to the comp (when bypass It).

I'll check this with a friend of mine but If you have any idea ;-) This could be a shortcut ;-)

Thanks a lot for your support and your Job at Hairball!!!
Antoine

 

[hiegdk]

I don't have a lot of test point advice on those. It is important that you center all trimmers.  Go over all of you component values and soldering.  Also, check the section on the main PCB related to GR metering. It's the stuff around the IC (make sure that IC is the correct value). Also make sure all points of the 10 pin connector are soldered well.

Thanks.  I've confirmed all the values around IC1 and double checked the soldering in that area and all seems fine. When I put the GR meter in BAR mode with the 0 adjust and Tracking adjust at their halfway points, input and output at midway, attack and release all the way up and ratio at 20:1 all of the LED in the GR meter are lit up including the SLAM LED. Not sure if that help narrow it down or not. At this point I'm at a loss as to what to try next.

 

[denov]

my qBais doesn't seem to be doing anything to the output.  i see change on my multi meter when i move the in and out pots.  the LEDs for the meter light up while during CCW but the voltage on the meter doesn't change.  where/what should i start looking at?

thanks

 

[Echo North]

my qBais doesn't seem to be doing anything to the output.  i see change on my multi meter when i move the in and out pots.  the LEDs for the meter light up while during CCW but the voltage on the meter doesn't change.  where/what should i start looking at?

thanks

What is your output level (in VAC or dB)?

If you have a Rev A  make sure you have the link wire in the ROPT1 spot.

Mike

 

[Echo North]

Thanks.  I've confirmed all the values around IC1 and double checked the soldering in that area and all seems fine. When I put the GR meter in BAR mode with the 0 adjust and Tracking adjust at their halfway points, input and output at midway, attack and release all the way up and ratio at 20:1 all of the LED in the GR meter are lit up including the SLAM LED. Not sure if that help narrow it down or not. At this point I'm at a loss as to what to try next.

With the 20 turn trimmers, it can take a bit to get it into the proper range. With the zero set midway can you get that meter to trop by turning the tracking adjust to either extreme? Same with putting the tracking center, can you get zero adjust to move it?

Mike

 

[Echo North]

Hello,

I've just finished building my 1176 Rev A 500 comp and have problem when calibrate It.

I have a lot of noise coming out of the comp -18Db (less when the output is fully clockwise). I Have noise even when I send nothing to the 1176.
A very low signal compared to what I send to the comp (when bypass It).

I'll check this with a friend of mine but If you have any idea ;-) This could be a shortcut ;-)

Thanks a lot for your support and your Job at Hairball!!!
Antoine

Are you able to calibrate it?

Does the QBias change your output?

Mike

 

[antoine00]

Are you able to calibrate it?

Does the QBias change your output?

Mike

Hello Mike,

can't calibrate It... and the Qbias doesn't seems to change my output...

Is It bad doctor?!!! ;-)

Thanks for your help Mike!!!

 

[Echo North]

Hello Mike,

can't calibrate It... and the Qbias doesn't seems to change my output...

Is It bad doctor?!!! ;-)

Thanks for your help Mike!!!

It's a Rev A?

Do you have a link wire in the ROPT1 spot?

 

[antoine00]

It's a Rev A?

Do you have a link wire in the ROPT1 spot?

Hello Mike,

It's a REV A and I put the wire in the Ropt1 yes....

 

[Echo North]

Hello Mike,

It's a REV A and I put the wire in the Ropt1 yes....

hmmmmm.

Is it possible for you to safely have the unit and your rack and probe around the top of the PCB with a DMM?

Mike

 

[hiegdk]

With the 20 turn trimmers, it can take a bit to get it into the proper range. With the zero set midway can you get that meter to trop by turning the tracking adjust to either extreme? Same with putting the tracking center, can you get zero adjust to move it?

Mike

Tried both, no movement. Could it be possible I cooked a transistor? I've certainly done that before on my Lola builds. If so, which one(s) would be involved?

 

[antoine00]

hmmmmm.

Is it possible for you to safely have the unit and your rack and probe around the top of the PCB with a DMM?

Mike

Sounds tricky!!!! ;-)
Yes!!! I can test the unit outside the rack and check the top PCB... I've got an extension connector for my lunchbox.
It's the one proposed by "soundskulptor" a french company that make preamps like you.

I can check everything going IN and OUT the FET500 Rev A.

Once again, Thanks a lot for your help!!!
Have a nice Sunday

Antoine

 

[Echo North]

Tried both, no movement. Could it be possible I cooked a transistor? I've certainly done that before on my Lola builds. If so, which one(s) would be involved?

There are no transistors. There are actually very few parts in the GR meter. Have a look at the schematic:

http://mnats.net/files/FET-A500.pdf

If you scroll down to the meter schematic, it's just the few parts around IC204. There is that LM317, a trimmer, and few resistors and a cap.

Then on the main schematic, just the few parts around IC1.

So for the GR circuit, there are actually more parts on the main PCB.

Check all those parts.

Do you have another FET/500? To swap meter PCBs?

Mike