[BUILD] MFOS Echo Rockit eurorack

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Bodo1967
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Re: [BUILD] MFOS Echo Rockit eurorack

Post by Bodo1967 » Wed May 26, 2021 8:34 am

RoddSolid wrote:
Tue May 25, 2021 11:53 am
I have one of those 12 dollar DIY scopes.
That should do, as long as you can see the input, square wave oscillator and LFO signals. Just choose a frequency easy to monitor.
... why buy it for $100 when you can build it yourself for $150?

RoddSolid
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Re: [BUILD] MFOS Echo Rockit eurorack

Post by RoddSolid » Thu May 27, 2021 3:27 pm

So I got home from work yesterday and hooked up my scope to the tip and the reing of the output. I got nothing on the scope so i plugged it into my amp and got no sound coming out. I found that the wire from the 1st lug of my volume had broken off at the board. I fixed that but still got no sound.
I just wanted to know if I had the scope hooked up right.
It'll probably take me a few days to figure out what went wrong. I've definitely learned my lesson about cheap parts.
:cloud:

RoddSolid
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Re: [BUILD] MFOS Echo Rockit eurorack

Post by RoddSolid » Thu May 27, 2021 5:29 pm

I should clarify, the wire just broke. It was in place and the unit was making noise up until yesterday. Now there is no sound..
:cloud:

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Bodo1967
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Re: [BUILD] MFOS Echo Rockit eurorack

Post by Bodo1967 » Fri May 28, 2021 2:36 am

Concerning the audio input path, start at the input jack and see whether you have a credible signal there. If yes (provided you have a line signal), make sure the input selector witch is set to line, and check pin 4 of U3-A, and so on until the formerly present signal becomes awol. This is to isolate the problem location.
When checking the VCF, make sure the cutoff frequency (R13) is sufficiently high for your signal.

Concerning the LFO, check pin 1 of U5-A for a triangle and pin 7 of U5-B for a square wave, and so on. Set the R51 pot to rather high frequency (simply because they are usually easier to watch on the oscilloscope than very low frequencies). Proceed in a similar way with pin 8 of U5-C.

If that is all in order, proceed to the MPF102 (Q2) and finally to the PT2399.
... why buy it for $100 when you can build it yourself for $150?

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