[BUILD] FET/500 Official Support Thread

[Echo North]

Would switching the cap, resistor, etc. in the attack circuit to the values of later versions give me longer attack times on the longer end of the range?  I'm looking to keep the fast attack on the short end of the range but be able to dial in longer attack times too. 
I can't tell if doing that would affect the function of other aspects of the circuit or if the attack section of the circuit operates independently. 

Thanks!

Either the timing cap or the pot I imagine.

It's on my list of things to do (sorting out attack mods).

 

[Winetree]

Thanks,
Mnats BOM is a lot easier to read in a list form Instead of the Squares.
Mnats color LED layout is different also. I'll use yours as pictured.

 

[wnlively]

Hi
I was wondering if it is possible to purchase the  LED s and meter board for the  FET 500

Thanks
Neal

 

[barbaroja]

Would be nice to see how it stacks up do don's classics U76A. I am a happy owner. Just a little bit noisy when output is pushed but thats its nature. BTW, dons classics uses all carbon resistors for the signal path so those would add to the noise. I saw metal film resistors for the FET 500 but not sure if all of them are MF. I propose we use some vocal and drum clips and give a run to these pretty things, cant have enough of listening tests!

 

[Echo North]

Would be nice to see how it stacks up do don's classics U76A. I am a happy owner. Just a little bit noisy when output is pushed but thats its nature. BTW, dons classics uses all carbon resistors for the signal path so those would add to the noise. I saw metal film resistors for the FET 500 but not sure if all of them are MF. I propose we use some vocal and drum clips and give a run to these pretty things, cant have enough of listening tests!

Just a guess but I would assume it's the DC/DC converter that accounts for the noise in the U76A .  I believe that's part of the reason MNATs decided against using  a DC/DC converter in the signal chain and opted for the neg rail audio ground.  Much quieter.

 

[barbaroja]

Is the FET 500 rev A quiet?

 

[Echo North]

Is the FET 500 rev A quiet?

It tested within the original spec for noise.  It's as quiet as the rack version which is quiet.

 

[barbaroja]

Is the FET 500 rev A quiet?

It tested within the original spec for noise.  It's as quiet as the rack version which is quiet.

A lot of difference with rev D?

 

[Echo North]

Is the FET 500 rev A quiet?

They are all the same.  I think the A being noiser is a myth.  I've never found it to be noiser.  It has more THD which is different than pure noise (hiss).

It tested within the original spec for noise.  It's as quiet as the rack version which is quiet.

A lot of difference with rev D?

 

[barbaroja]

Thanks for the answers. Do they have any kind of eq or filter in the detector circuit, in a preset way? Such as the screw in the LA2A or the API 2500 thing. I feel the A responded different to peaks than D, (talking about the racked clones). The D being a little more present, or mid forward. Maybe just is a perception or maybe at this late I should be sleeping now...  Anyway, it's kind of nitpicking.

 

[wnlively]

I purchased a matched pair of the FET 500 REV D some time , built the first one .
Off during the holidays I started the second build and I have found that for the ceramic capacitor C11 in the second kit I have a 47uf  instead of the  10pf that was in the first kit.  After looking at the BOM on each REV I see thar the 47uf is used on the REV F.

Can I use the 47uf in the place of the 10pf on the REV D ?

Thanks
Wnlively

 

[barbaroja]

I have Led 211 half lit all the time. Flux cleaned, connections checked. Any ideas?

 

[mnats]

I have Led 211 half lit all the time. Flux cleaned, connections checked. Any ideas?

This is addressed in the LED section of my FET/500 page linked from the first post of this thread.

 

[barbaroja]

I have Led 211 half lit all the time. Flux cleaned, connections checked. Any ideas?

This is addressed in the LED section of my FET/500 page linked from the first post of this thread.

Great! Thanks.

 

[mixedbymike1]

I just built a stereo pair of FET/500s. I built them at the same time, but one of them has an issue with it's True Bypass.

When I press the bypass switch on one unit, the unit does not bypass, nor does the bypass LED come on. I've made sure the relays are oriented correctly, and the solder joints on the relays and switches are clean of any bridges. Any other suggestions on what to check?

 

[mnats]

I just built a stereo pair of FET/500s. I built them at the same time, but one of them has an issue with it's True Bypass.

When I press the bypass switch on one unit, the unit does not bypass, nor does the bypass LED come on. I've made sure the relays are oriented correctly, and the solder joints on the relays and switches are clean of any bridges. Any other suggestions on what to check?

The bypass is a series circuit formed by the two relay coils, the LED, a dropping resistor and the switch. This is done for efficiency - putting a unit in bypass doesn't cause it to draw excessive current. However it means that if any one of these circuit elements has an issue the circuit will not work. Possibilities are covered in the General Troubleshooting page linked from the first post, but in order of probability:

Resistor value is incorrect
LED is reversed
Poor solder joint on one or more component(s)
Faulty switch
Faulty relay coil

If you hadn't mentioned it then the relay orientation would have come early in the list.

Please report back with your findings.

BTW, please see http://garyes.stormloader.com/its.html.

 

[mixedbymike1]

I found the schematic so I should be all set tracking the problem down now. Thanks for your help!

'It's' was a typo, since I don't proofread everything I type on a message board, but since we're on the subject: http://www.writingclasses.com/Products/PubsDetail_Excerpt.php/ExcerptID/434

 

[JoelCoteBergevin]

I have a problem with my Rev D. After the calibration, I went to put on the faceplate but it wasnt sitting flush so I had to resolder the bypass and the GR off LEDs. However, when I was resoldering the GR off LED, one of the pad came off the PCB.

What can I do to resolder the LED in place ?

Thanks

 

[Echo North]

I have a problem with my Rev D. After the calibration, I went to put on the faceplate but it wasnt sitting flush so I had to resolder the bypass and the GR off LEDs. However, when I was resoldering the GR off LED, one of the pad came off the PCB.

What can I do to resolder the LED in place ?

Thanks

Yikes.  You may want to turn down your iron a little 650-700 degrees is a good range for lead solder.

Solutions:

1) You'll need to make a little wire jumper.  Solder one piece of wire to the lead with the pad missing then follow the trace to see what the next pad the trace connects to and solder the other end there. 

If you download the MNATS project PDF you can see the LED connections on the schematic.  Pretty simple.

http://mnats.net/fet500.html

2) find the trace that connects to the missing pad and scrape off a little solder mask exposing the trace and solder the lead to the trace.

Mike

 

[Echo North]

From the looks of it, if it's the positive/anode lead, it just connects to the pad right beside it for R510.  The cathode or negative lead has a lot further to go. If you look under C21 there should be a little via there, you could jumper over to that.  I'm looking at the D, not sure which rev you have but they all should be pretty similar for the LED circuit.

There night be some repair guys on here with better fixes, but these are generally easy fixes if you take your time.