EFG Deluxe - Possible emerging fault

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eljay
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EFG Deluxe - Possible emerging fault

Post by eljay » Fri Jan 10, 2020 7:12 am

I've notice recently that the Orange 'Follow' LED is frequently lit, albeit at a low level, when there is nothing at all (neither inputs or outputs) connected to the EFG module, this will go away for an indeterminate period of time if I actually provide an input signal for a brief period and then remove it. The Follow LED appears to correctly track an input signal when there is one. I'm wondering if I'm seeing the beginnings of a component failure and would welcome any advice on where to look (capacitor maybe?). Other than this it all seems to work correctly at the moment.

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Synthbuilder
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Re: EFG Deluxe - Possible emerging fault

Post by Synthbuilder » Fri Jan 10, 2020 10:36 am

eljay wrote:
Fri Jan 10, 2020 7:12 am
I've noticeD recently that the Orange 'Follow' LED is frequently lit, albeit at a low level, when there is nothing at all (neither inputs or outputs) connected to the EFG module...
Does it go out when turn the Slew Speed up? If so, it's the small amount of DC offset produced by the filter based around the V2164 when the filter is set to really low cut off frequencies. What's the actual voltage from the Slew Out socket when the LED is lit. If less than 100mV with the Slew Speed at its slowest then there's nothing to worry about. You may find different V2164 chips produce lower offset voltages though.

Tony

eljay
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Re: EFG Deluxe - Possible emerging fault

Post by eljay » Fri Jan 10, 2020 11:06 am

Adjusting the Slew speed has no effect, adjusting any of the other controls also has no effect. I have measured the output from the Slew Out socket, this is not stable and seems to cycle around approx 400mV. I'm assuming there is some bleed through from somewhere, is it likely to be the V2164 istself playing up?

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Synthbuilder
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Re: EFG Deluxe - Possible emerging fault

Post by Synthbuilder » Fri Jan 10, 2020 12:12 pm

What's the voltage on the ABS_OUT connection? Pin 7 of the I/O_2. This should be 0V give or take a few mV. If not the problem lies upstream of the V2164 - perhaps the circuitry around U6. If the voltage at ABS_OUT is around 0V then the problem is probably the 2164, or a dodgy solder joint or connection to the 2164.

Tony

eljay
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Re: EFG Deluxe - Possible emerging fault

Post by eljay » Sun Jan 12, 2020 8:05 am

Thank-you for the feedback Tony. As per usual for me, having taken the module out of the rack and tested it in isolation all appears to now be well. I did initially observe the raised voltage at the Slew Out socket and disconnected the 8-way I/O_2 cable from the Socket Board to the PCB to track it back further, after this it went away never to return! I can only assume disconnecting and re-connecting the cable fixed a loose crimp or ? Anyway all is well, the LED is out when it should be and the module is working A-Okay. Which reminds me I really should use it more.

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