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Fatman help

Posted: Mon Jul 16, 2012 8:32 pm
by MrBlenderson
Things have been going great for me and my Fatman, I've been using it in nearly all my recordings! Now it has stopped working. At first it started making weird digital sounding noises in response to MIDI notes, and now it will not make any sound. The MIDI activity light blinks and then turns solid red after a while. The gate light does not respond to incoming MIDI data.

The MIDI light turns solid red even with no MIDI input plugged in.

I don't even know where to start!

Re: Fatman help

Posted: Mon Oct 29, 2012 11:59 am
by Bachmanm
Since you say "digital noises", I suspect tha the software is not running correctly. Since SW doesn't normally go bad (PROMs can go bad every once in awhile), I would suspect the connections to these chips or power.

Looking at the circuit, the MIDI red LED only needs +5 and the opto to work properly. the Micro could mess it up, but it should be an input. If it is lighting up VCC must by present. (check it with a DMM to make sure it is 5v. But maybe ground is not getting to the micro or PROM.. so next..

Check all the solder joints on the Micro, PROM and DAC

If these chips are in sockets, gently lift them out (going from both ends) and inspect the pins for corrosion. If all is well, re-insert them and try again.

Hopefully this magic fixes it. I have seen many circuits come back to life just by removing a re-inserting chips and/or connectors

Re: Fatman help

Posted: Mon Oct 29, 2012 1:41 pm
by MrBlenderson
Thanks for the tips! I actually ended up sending it in to Scott and everything is working great!

Re: Fatman help

Posted: Tue Dec 18, 2012 3:34 am
by cooky24
I think you should find someone who is expert in this.

Re: Fatman help

Posted: Tue Dec 18, 2012 8:17 pm
by toneman
So....what problem(s) did Scott find?? Might be helpfull to other Fatman owners/builders.

Re: Fatman help

Posted: Wed Jan 02, 2013 1:58 pm
by PAiA-Scott
Looking back at the service report, it was a matter of touching-up soldering and repairing some printed circuit damage.

I am noticing a quite a few kits being returned for service with the basic trouble being lead-free solder used in the assembly and the extra heat needed for it resulting in lifted and broken printed circuit pads and traces.

It is definitely easier going and with increased chances of trouble-free completion of the build when 60/40 alloy tin/lead rosin-core solder such as Kester "44" (0.031" 0.8mm is a good size) is used for building hobby kits.

Below are examples of TubeHead kits in for repair that were assembled using no-lead and tin/lead.


60/40 sn/pb (tin/lead)

Not only does the lead-free require more heat, but it is "sticky" whereas the 60/40 rosin core quickly melts and flows to the surfaces (wire or component lead and solder pad) in the joint.

The rosin in the core of the solder (such as the "44" brand) "primes" the surfaces as the solder melts, with the solder displacing it as it fills the pad and goes up the wire/component-lead in a cone shape.

ps One trouble on the second image is a solder bridge between the lower right two pins of the lower, central eight-pin IC footprint/soldering.

Re: Fatman help

Posted: Wed Jan 02, 2013 5:50 pm
by MrBlenderson
I think that was it - that and general sloppiness as it was my first DIY kit.

It's working great and I use it in nearly everything I do!

I'm looking forward to a 9700S build later this year.