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ProducerMatt
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Post by ProducerMatt » Fri Jan 12, 2018 11:01 pm

Hey Tony, does the difference between these three types matter at all? I noticed they have different Hfe values. https://www.mouser.com/Semiconductors/D ... ?P=1yxk9o5

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Synthbuilder
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Post by Synthbuilder » Sat Jan 13, 2018 7:49 am

You can use either BC549B or BC549C parts. The differences in Hfe don't matter in this application.

Tony

ProducerMatt
Learning to Wiggle
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Location: Dallas, Texas

Post by ProducerMatt » Sat Jan 20, 2018 2:01 pm

At last, replacing the transistors fixed it. I’m thinking one of the transistors must have been bad to begin with.

What a mess. But at last I finished it and it sounds GREAT. Thanks so much for your help, Tony! Onward to the oscillators. I just have to figure out this damn box header...

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Dr. Sketch-n-Etch
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Post by Dr. Sketch-n-Etch » Sat Jan 20, 2018 2:40 pm

This thread is the nightmare I have when I contemplate selling kits to people with little or no experience with electronics.
For every bullshit job, you need a bullshit education -- Brian Eno

ProducerMatt
Learning to Wiggle
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Joined: Sun Sep 03, 2017 3:19 pm
Location: Dallas, Texas

Post by ProducerMatt » Sat Jan 20, 2018 4:13 pm

Yeah, I can see that.

To be clear, I don’t think I fried the transistor. I think the SynthCube kit came with a bad one. It was displaying these symptoms before I ever pulled the “reverse power” shtick.

In the future I’ll be testing everything before doing any assembly.

ProducerMatt
Learning to Wiggle
Posts: 35
Joined: Sun Sep 03, 2017 3:19 pm
Location: Dallas, Texas

Post by ProducerMatt » Sat Jan 20, 2018 4:15 pm

Also, I shouldn’t forget to say: Tony, you’re an angel and I’ve never had customer service this good. Thank you!

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Synthbuilder
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Post by Synthbuilder » Mon Jan 22, 2018 8:42 am

ProducerMatt wrote:Also, I shouldn’t forget to say: Tony, you’re an angel and I’ve never had customer service this good. Thank you!
:tu:

MuadMusic
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Post by MuadMusic » Sat Sep 07, 2019 9:29 am

The two grounds on the MOTM power connector are NOT connected (unless you have the MOTM header attached). This causes all sorts of issues IF you are using the DOTCOM power supply. Forexample, there may be a good deal of bleed of the unfiltered signal in the output.
The simple solution is to solder the two middle MOTM power holes (GND).
See attached picture
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Synthbuilder
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Post by Synthbuilder » Sat Sep 07, 2019 1:29 pm

MuadMusic wrote:The simple solution is to solder the two middle MOTM power holes (GND).
:tu: This is the recommended way of doing this. See page 9 of the Builder's Guide. But maybe I need to make this more clear in the parts list section too.

Actually on newer boards I have started to use the normally unused pin 6 location on the dotcom connector for panel ground. Most of the current boards still do not have this feature but as boards are updated I will add this to all of them. The MU Dizzy board also connects pin 6 to 0V which allows these new boards to have separate panel and module 0V lines.

Tony

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