Rockett Flexdrive dissected

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Rockett Flexdrive dissected

Postby Manfred » 12 Jul 2016, 21:24

I traced each diode in the circuit and compared the read traces with reference diode traces.
So I found out as follows.
Ge-diodes are 1N34A green band.
Big Si-diodes are 1N4005.
Small Si-diodes are 1N4148

FlexComponentsSide.jpg


FlexSolderSide.jpg


FlexDrive.JPG


DiodeGeCompare.jpg


DiodeSiBigCompare.jpg


DiodeSiSmallCompare.jpg
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Re: Rockett Flexdrive dissected

Postby 287m » 12 Jul 2016, 23:48

hello manfred :thumbsup
the switch :
fat = spst
clip = on-on or on-off-on?
treble = on-on or on-off-on?

and the 1n4001 look backward for me
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Re: Rockett Flexdrive dissected

Postby Manfred » 13 Jul 2016, 07:15

Hello 287m,

thanks for finding the fault.

and the 1n4001 look backward for me

You are right, the 1N4001 is drawn in wrong orientation, here the corrected schematic.

FlexDriveCorrected.JPG


fat = spst
clip = on-on or on-off-on?
treble = on-on or on-off-on?

Fat: off on.
Clip: on off on.
Treble on off on

I read the datas of the built-in J201:

Vgs(off)=-0,72V at Id=5,2µA
Vgs(on)=0,38V at Id=1,26mA
gfs=1,9mA/V at Id=0,8mA to 1,3mA
Idss=0,58mA at Vds=3,01V
Rds(on)=549,1O at Id=1,3mA and Vgs=0,0V
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Re: Rockett Flexdrive dissected

Postby tube-exorcist » 13 Jul 2016, 08:33

I bet the tone control is drawn wrong too and should look like one from a tube-screamer - please verify.
"I've noticed there's an inverse relationship between cost of gear and talent. If you need the most expensive gear to get decent tones, then you suck as a player."
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Re: Rockett Flexdrive dissected

Postby Manfred » 13 Jul 2016, 20:39

tube-exorcist wrote:I bet the tone control is drawn wrong too and should look like one from a tube-screamer - please verify.


Sorry, I cannot verify the pedal again, because I gave it already away.
It was very hard to trace, but I used the tube screamer circuit as pattern and it was not in accordance with the screamer tone control, that amazed me.
The Flexdrive tone control affects nut much in my opinion, it acts rather as treble lift when the knob is turned clockwise.
have a look at https://www.youtube.com/watch?v=znfmGeitCyM
Tone knob variations at the playing time from 3:38 to 3:45.
I think that explains the different tone circuity.
I'm not without fail, maybe a owner of the Flecdrive would be so kind to recheck the tone circuit.

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Re: Rockett Flexdrive dissected

Postby Manfred » 14 Jul 2016, 20:20

tube-exorcist wrote:I bet the tone control is drawn wrong too and should look like one from a tube-screamer - please verify.


hi,

I thougt about the circuit differences and made a circuit simulation.
The shown tone circuity has indeed no effect.
You are right regardíng the screamer tone circuity.
Thanks that you took a closer look at the schematic. :thumbsup

FlexDriveCorrected2.JPG
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Re: Rockett Flexdrive dissected

Postby tube-exorcist » 15 Jul 2016, 07:53

Now there is only missing a 22k resistor (maybe 2k2) between pin 6 and 7 of the second opamp (instead of the short).
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Re: Rockett Flexdrive dissected

Postby Manfred » 15 Jul 2016, 13:03

tube-exorcist wrote:Now there is only missing a 22k resistor (maybe 2k2) between pin 6 and 7 of the second opamp (instead of the short).


The short is ok, there is no resistor in between.
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