EFG Deluxe troubleshooting

Discussion and support for users and builders of Oakley Sound musical products.

Moderators: Kent, Synthbuilder

Post Reply
User avatar
Sparrows78
Learning to Wiggle
Posts: 24
Joined: Sat Feb 03, 2018 5:37 pm
Location: Sweden

EFG Deluxe troubleshooting

Post by Sparrows78 » Thu Oct 08, 2020 9:23 am

Hi!
Testing out my newborn EFG Deluxe and ran into som trouble. First thing I see when connecting power only is that GATE led is on constantly.
The preamp seems to be working, both x1 and x10 gain works, volume works and PEAK led is working as it should. GATE out is sending signal constantly, as is SLEW out. Theese signals does not change no matter if I am turning knobs or insert audio in PRE in or FOLLOW in.

Everything LOOKS right to me on the PCB so I am lost at the moment. All help is highly appreciated!
/Johan

User avatar
Synthbuilder
Super Deluxe Wiggler
Posts: 3050
Joined: Tue Mar 24, 2009 9:12 am
Location: Cumbria, UK

Re: EFG Deluxe troubleshooting

Post by Synthbuilder » Thu Oct 08, 2020 9:59 am

Sparrows78 wrote:
Thu Oct 08, 2020 9:23 am
First thing I see when connecting power only is that GATE led is on constantly. The preamp seems to be working, both x1 and x10 gain works, volume works and PEAK led is working as it should. GATE out is sending signal constantly, as is SLEW out.
You may have two faults there. That the peak LED works suggests the envelope follower core is working. For the gate not to be working you could have a fault around the circuitry based around U3 pins 5, 6 and 7. If pin 7 is permanently high (ie. 13V or so) then there are a number of causes; for example, R20 too high, threshold pot not soldered, C6 shorted or failed.

Slew out is probably a fault with the circuitry around the V2164. Check you have no solder shorts around U4 and U5. That said, R46 and R47 could be wrong. Check that these are 22K and 100K respectively. Also check that D9 is the right way around.

Maybe also worth checking the wiring to and from the sockets.

Tony

User avatar
Sparrows78
Learning to Wiggle
Posts: 24
Joined: Sat Feb 03, 2018 5:37 pm
Location: Sweden

Re: EFG Deluxe troubleshooting

Post by Sparrows78 » Fri Oct 09, 2020 7:33 am

Thanks,
I found that I had missed to solder one of the pads on R25. After fixing this, the GATE is working, but now the FOLLOW led is on permanently. I checked all your suggested failure points but everything looks good. I also replaced U3 but still the same problem.

/Johan

User avatar
Synthbuilder
Super Deluxe Wiggler
Posts: 3050
Joined: Tue Mar 24, 2009 9:12 am
Location: Cumbria, UK

Re: EFG Deluxe troubleshooting

Post by Synthbuilder » Fri Oct 09, 2020 8:33 am

Sparrows78 wrote:
Fri Oct 09, 2020 7:33 am
I found that I had missed to solder one of the pads on R25.
Well spotted. :tu:

Interesting that the peak LED was still working without any negative supply to U3. It just shows that it's always worth checking the power supply pins of each IC when things don't work right.
... but now the FOLLOW led is on permanently.
Check the voltage on pin 14 of U3. It should be close to 0V with nothing plugged into the 'slew in' or 'pre in' inputs. If it isn't 0V, and something like +5V, then check the output of the slew filter, pin 1 of U4. That too should be 0V as both pin 14 of U4 and pin 1 of U4 should follow each other.

If not, check that 'slew out' working OK. The slew control is basically a low pass filter (based around U4 and U5) and can be used to filter audio. Make sure that bit is working by sticking something like a 110Hz sawtooth into the 'slew in' and listen to the 'slew out' as you vary the slew speed control. It should sound like a standard filter sweep but concentrated on the lower frequencies.

User avatar
Sparrows78
Learning to Wiggle
Posts: 24
Joined: Sat Feb 03, 2018 5:37 pm
Location: Sweden

Re: EFG Deluxe troubleshooting

Post by Sparrows78 » Fri Oct 09, 2020 4:59 pm

So this is the measurements,
U3 pin 14: 12V
U4 pin 1: 13,6V

I run a sawtooth in SLEW IN and there is no signal at SLEW OUT, no matter how I turn the slew speed.

There is clearly something wrong here... ;)

User avatar
Sparrows78
Learning to Wiggle
Posts: 24
Joined: Sat Feb 03, 2018 5:37 pm
Location: Sweden

Re: EFG Deluxe troubleshooting

Post by Sparrows78 » Fri Oct 09, 2020 5:29 pm

I found one more thing,
if I connect power when SLEW SPEED pot is on max the FOLLOW led gets lit, but dimmed. Now, if I turn SLEW SPEED counter clockwise the led suddenly jumps to bright light. If I turn the SLEW SPEED clockwise again, nothing changes - the led stays bright.

User avatar
Sparrows78
Learning to Wiggle
Posts: 24
Joined: Sat Feb 03, 2018 5:37 pm
Location: Sweden

Re: EFG Deluxe troubleshooting

Post by Sparrows78 » Fri Oct 09, 2020 7:48 pm

I’m embarrassed and at the same time happy to say that I found two more unsoldered pads - pin 15 and 16 on U5. The EFG is now working. Sorry for taking your time, these things happens when I rush a build :)
Thanks for the support
/Johan

Post Reply

Return to “Oakley Sound Systems”