[BUILD] FET/500 Official Support Thread

[Echo North]

Hey guys, I just built a pair of Fet500 Rev A's, and may be observing a little bit of strange behavior. On both units, when using VU trim to set the -10 LED, I don't get any change across the full range of adjustment (with the DMM reading 0.388 volts). The LED is in fact already at -10, and it just stays there. I noticed that if I lower the voltage with the output knob to 0.350 volts, then the LED drops down to -20 and I can then use the VU trim to bring it back up to -10. I'm using a Fluke 87v, and I double checked voltages with another DMM, and they match. Any thoughts?

Hmmm try setting it at +4 which would be the first orange LED. Set your output to 1.25VAC. You should see the trimmer adjust it up and down an LED around +4. It's not a huge adjustment range.

Note, I built a Fet 500 when they first came out, and I don't remember having this issue, but I do think that the PCB has since been revised, so maybe this is normal?

Maybe. I usually do it at +4...however the lower you do the adjustment on the scale, the more accurate the meter will be (per the meter chip datasheet).

Also, I noticed that the kit came with 2N3707 transistors for Q3, Q5, whereas the BOM states 2N3708. These seem to be pretty comparable, so I didn't worry about it....

Nope that is fine.

 

[leoaudio13]

Hi,
I just completed my Rev A 500 build. All are working find except i have some difficulties with the Gain reduction tracking pot. Gotta try to reset it again according to posts here.
Unfortunately, The bypass switch does not work at all. Even it is in bypass mode, the LED didnt light up. Tried to check with DMM, LED working fine. With SW3, measured continuity is fine while in Bypass and out of bypass mode. Any suggestions please ? Much appreciate.

 

[Echo North]

Hi,
I just completed my Rev A 500 build. All are working find except i have some difficulties with the Gain reduction tracking pot. Gotta try to reset it again according to posts here.
Unfortunately, The bypass switch does not work at all. Even it is in bypass mode, the LED didnt light up. Tried to check with DMM, LED working fine. With SW3, measured continuity is fine while in Bypass and out of bypass mode. Any suggestions please ? Much appreciate.

SW3 requires a functioning LED to work. Make sure the LED is soldered in the correct orientation and it is making contact with the solder pads.

Some times it looks soldered, but if you wiggle it you can see a leg is floating off the pad.

Mike

 

[leoaudio13]

SW3 requires a functioning LED to work. Make sure the LED is soldered in the correct orientation and it is making contact with the solder pads.

Some times it looks soldered, but if you wiggle it you can see a leg is floating off the pad.

Mike

Thank you Mike! It was the LED that made the SW3 to stop. All is good now. Gonna order Rev F soon !

 

[leoaudio13]

My attack and release knobs are in reverse order ( left for long time and right for shorter time ). Is that normal at all ?

 

[mdmitch2]

Hmmm try setting it at +4 which would be the first orange LED. Set your output to 1.25VAC. You should see the trimmer adjust it up and down an LED around +4. It's not a huge adjustment range.

Maybe. I usually do it at +4...however the lower you do the adjustment on the scale, the more accurate the meter will be (per the meter chip datasheet).

Nope that is fine.

Thanks, that did the trick --- no issues when setting at +4 (the LED moved between -1,0,1).

 

[Echo North]

My attack and release knobs are in reverse order ( left for long time and right for shorter time ). Is that normal at all ?

Normal for this style compressor yes.

 

[blueberryjam]

hey guys,

Not being a DIY-er myself I decided to order a pair of FET 500 model D off someone who builds them on ebay. Upon receiving them I've rapidly noticed that both unit's  VU-Meters don't behave the same way, and are not showing the same gain reduction levels when fed the same material (I'm not sure whether this is only a VU issue).

So I started (trying) to recalibrate, and noticed that on one unit, several gain reduction LEDs light up at the same time, as if the meters were set to bar mode (but they are not). The other unit meter seemed to be working properly in dot mode, but just a minute ago it switched to bar mode all of a sudden ! So I'm starting to think I ordered the units off the wrong guy

Is there something I could do by myself to try and identify the issue ? (I know how to use a DMM, and not much else) Or would I be better off sending them to be repaired ?

cheers !

 

[Echo North]

hey guys,

Not being a DIY-er myself I decided to order a pair of FET 500 model D off someone who builds them on ebay. Upon receiving them I've rapidly noticed that both unit's  VU-Meters don't behave the same way, and are not showing the same gain reduction levels when fed the same material (I'm not sure whether this is only a VU issue).

So I started (trying) to recalibrate, and noticed that on one unit, several gain reduction LEDs light up at the same time, as if the meters were set to bar mode (but they are not). The other unit meter seemed to be working properly in dot mode, but just a minute ago it switched to bar mode all of a sudden ! So I'm starting to think I ordered the units off the wrong guy

Is there something I could do by myself to try and identify the issue ? (I know how to use a DMM, and not much else) Or would I be better off sending them to be repaired ?

cheers !

Hmmmm. Hard to say. Definitely sounds like a meter issue. On the GR meter usually only one LED lights up at a time.

I remember seeing behavior like that in repairs, but I can't remember the solution. A good place to start is to make sure the PCB, especially the edge connectors are VERY clean and free of flux. You can scrub the bottom liberally with isopropyl alcohol.

Also look at the build map and confirm all of the components on the meter board are in the right place.

Make sure you're calibrating with a sine wave and not pink noise.

Mike

 

[blueberryjam]

Thanks for the help Mike ! Will try and see if I can find the issue this week-end.

 

[blueberryjam]

hey ! Me again !

As advised I started cleaning the pcb boards. They were pretty dirty indeed. The seller who built the unit had used a lot of flux, so when I used the isopropyl alcohol the flux spread out and the pcbs became very very sticky. It took me hours to clean them properly.  :'(

When I plugged them back both unit seemed to behave properly, so today I started calibrating again. It went fine at first, then at one point when calibrating the VU I noticed that the leds were moving when I touch the attack knob (Not moving it, just touching it with my hand). Right after that, the problem came back and the first 5 leds of the GR meter would light up at the same time in GR ON mode. Would that give us any clues about what the issue could be ?

Decided to do some more cleaning because the pcb was still a bit sticky where the leds are connected. Will plug it back and test again tomorrow.

 

[Echo North]

hey ! Me again !

As advised I started cleaning the pcb boards. They were pretty dirty indeed. The seller who built the unit had used a lot of flux, so when I used the isopropyl alcohol the flux spread out and the pcbs became very very sticky. It took me hours to clean them properly.  :'(

When I plugged them back both unit seemed to behave properly, so today I started calibrating again. It went fine at first, then at one point when calibrating the VU I noticed that the leds were moving when I touch the attack knob (Not moving it, just touching it with my hand). Right after that, the problem came back and the first 5 leds of the GR meter would light up at the same time in GR ON mode. Would that give us any clues about what the issue could be ?

Decided to do some more cleaning because the pcb was still a bit sticky where the leds are connected. Will plug it back and test again tomorrow.

Not really. Probably some ground buzz. That's not normal but may resolve when the unit is in the bracket with faceplate/nuts installed.

You can give it a pretty good soak.

Mike

 

[blueberryjam]

Thanks Mike.

Did some more cleaning and was finally able to calibrate both units ! They seem to be working fine now, except that one unit still had that "bug" once ; it's meters flicked then switched to bar mode when I touched the attack pot. I turned off and on the 500 series chassis and it went back to working properly.

Been thinking about switching the knobs for the FET style ones you have for sale in the parts store. I'm thinking that since the sides are plastic and non conductive, that should keep me for having that issue again. Both my ratio knobs screws are stripped anyway so i could use a replacement.

Would the FET Style Miniature Knob 1/8" Shaft fit the FET 500 series ?

 

[Echo North]

Thanks Mike.

Did some more cleaning and was finally able to calibrate both units ! They seem to be working fine now, except that one unit still had that "bug" once ; it's meters flicked then switched to bar mode when I touched the attack pot. I turned off and on the 500 series chassis and it went back to working properly.

Been thinking about switching the knobs for the FET style ones you have for sale in the parts store. I'm thinking that since the sides are plastic and non conductive, that should keep me for having that issue again. Both my ratio knobs screws are stripped anyway so i could use a replacement.

Would the FET Style Miniature Knob 1/8" Shaft fit the FET 500 series ?

Conductivity isn't your issue, at least with the knobs.  Make sure the pot nuts are tight against faceplate. You should not be getting buzz or meter flicker when you touch the knobs. That's a ground error somewhere in the system/unit.  Using plastic knobs may stop it, but it's still an issue that may pop up in other ways.

But yes those knobs would fit.

Mike

 

[Blackdawg]

Hey guys,

I just built 2 REV F FET500s. Great kits!

My issue is that both of my VU meters are fully lit when i turn them on..on both kits. None of the trim pots seem to do anything. Im using a Lindell 510 rack.

Going through the meter PCB now to double check stuff. Just seems odd that both are doing that.

Any tips??

Thanks!

Monte

 

[Echo North]

Hey guys,

I just built 2 REV F FET500s. Great kits!

My issue is that both of my VU meters are fully lit when i turn them on..on both kits. None of the trim pots seem to do anything. Im using a Lindell 510 rack.

Going through the meter PCB now to double check stuff. Just seems odd that both are doing that.

Any tips??

Thanks!

Monte

The VU part of the GR part of the meter?

 

[Blackdawg]

The VU part of the GR part of the meter?

Yeah the top half of the meter. Lights up completely. It'll slowly light up till all of the LEDS are lit. I did put the jumper in for Bar Mode. It also lights up from the bottom up..as in the yellows light up first and then goes up to green.

The other odd thing i notice is my Grayhill switch. If i line up the knob with the notch it does not point to the correct labels on the silk screen. It is way off. I set the switch up as per the instructions though. Do I just tighten down the knob so the set screw isn't on the flat part?

 

[Echo North]

Yeah the top half of the meter. Lights up completely. It'll slowly light up till all of the LEDS are lit. I did put the jumper in for Bar Mode. It also lights up from the bottom up..as in the yellows light up first and then goes up to green.

The other odd thing i notice is my Grayhill switch. If i line up the knob with the notch it does not point to the correct labels on the silk screen. It is way off. I set the switch up as per the instructions though. Do I just tighten down the knob so the set screw isn't on the flat part?

As far as the silkscreen/knob, that's just knob placement. I usually set it at SLAM with no issue. I deal you want to avoid the flat part.

For GR meter,  start by setting the trimmers associate with that adjustment dead center. Turn them until you hear a click, then rotate back 10 full turns and they will be centered.

Mike

 

[Blackdawg]

As far as the silkscreen/knob, that's just knob placement. I usually set it at SLAM with no issue. I deal you want to avoid the flat part.

For GR meter,  start by setting the trimmers associate with that adjustment dead center. Turn them until you hear a click, then rotate back 10 full turns and they will be centered.

Mike

Thanks for the response. Will give it a go. I had set all the trim pots dead center via my Ohm Meter. But sounds like something is off. So i'll give it ago!

Monte

 

[Blackdawg]

That helped! Thanks!

Also why does it work backwards? I thought the greens would have lit first from the top down.