MOTM

Hello @all, ( might be my first post here )

I have populated 4x Motm300 PCBs.
Two Modules were built in motm Format with onboard Pots, 
and those are running fine, no Issues.

Then i built the third one in euroformat and this one makes nothing, it's dead,
exept that it makes noises, especially when i turn the coarse pot.


all Boards were populated in parallel, there should really be no fault,
so my first assumption is that i have a bad part.
The Styroflex Cap in the core i replaced allready. It's still the same.
Power i measured on the IC sockets on all Boards together bevore i puted in the ICs as far i remember ( they were stuffed 5-6 month ago )

Hope to get some advice for debugging / measurings.
thanks

On Sat, 30 May 2009, funkyfortyatyahu wrote:

> Hope to get some advice for debugging / measurings.

Did you follow the instructions in the 'Troubleshooting'
section of the manual?

--
Monty Brandenberg

On 30 mei 2009, at 18:52, funkyfortyatyahu wrote:

> Then i built the third one in euroformat and this one makes nothing,  
> it's dead,
> exept that it makes noises, especially when i turn the coarse pot.

Are you powering the euroformat ones with +/- 12V or +/- 15V? I'm not  
sure if they will work on the lower voltage.

Ben

Hello,

Thanks for reminding that there is a troubleshooting section in the docs.
forgot about this.
Those Voltage measurements i have not done, but did now.
( i run my DIY-Euroformat with +-15V , so no problem here )


Measurements were fine, exept point f)
I have here 0,86V(CCW) to 0,62V !!(CW)which is REALLY wrong !
( In the meantime i built my Motm300 #4 which has for example 0.25V - 14,6V.)


#3 looks good when controlling by Eye, i can't see any wrong wiring, shortcuts or anything else.
Any more advice ? Paul ?


( i "replyed" two times allready but none of those posts came thru )

thanks, 
funky40

On Wed, 3 Jun 2009, funkyfortyatyahu wrote:

> #3 looks good when controlling by Eye, i can't see any wrong wiring, shortcuts or anything else.
> Any more advice ? Paul ?

There is only one way for the circuit to work but there are
infinite ways it can fail.  It may be impractical for anyone
to identify your particular problem.

But as you have three working 300's and one non-working, there
is one obvious approach to take:  compare the two.  Best with
an oscilloscope.  Or paired AC/DC readings from a voltmeter (as
appropriate) if that is all you have.  Start at the summing
amplifier.  Adjust coarse knobs to give similar voltage levels
at the input.  Then work towards the MAT-02.  Identify the
anomalous input/output sets.  You have one already:  U4B
feeding MAT-02.  But something 'in front' of these may be
at fault.  U4B appears to be working backwards in your case.

--
Monty Brandenberg