[DSP-10] DC voltages not right

[kd7ts]

Gene Hightower wrote:
> I received a new MAR-3 in the mail from Daniel Schultz, so I was able
>  to finish my DSP-10 main board today.
>  
>  Thanks Daniel!
>  
>  I put 11V into the thing and...  well, no smoke, anyhow.

11 volts may not be enough to get the 10 volt regulators to a point of regulation.

>  
>  First thing I noitice is that it's drawing only 230 mA -- so I know I
>  have issues.

Dunno, what's the correct number ? What state did it come up in ? Do you have the ADSP2181 or the KDSP ? Is it connected ?
>  
>  Checking the DC voltages I find a few problems:
>  
>  U14 pins 2&13 read 5.37  (maybe close enough to 5.5?  dunno)

Left and right audio lines, seems wierd that there is DC here, but make a note to look at it later. I doubt this is significant.


>  U1 and U2 pin 3 are both 0.013V (should be 3.5 and 4.7)

first and second receive amps... normal if you are in transmit. watch the LEDs on the board when you power up. Did you install the diode referred to as SR105 ? Is there some sort of DSP connected ?

>  R110 reads 1.75V (should be 0.23)
 
first LO drain current/V... Maybe the part(Q101) isn't oscillating ? seems likely if this is the first time on. 

>  U105 pin 3 reads 2.5V (should be 3.5)

first LO buffer.. a little lower than it should be 

>  U106 pin 3 read 4.77 (close enough to 4.6?  dunno)

second buffer of previous... OK

>  R59 reads 1.4V (should be 0.91)

second  osc drain current/V dunno again.. probably not significant at this point.  Same as  R110, worry later.

>  U8 pin 3 reads 2.5V (close enough to 2.8?  dunno)

second LO buffer amp ... OK


>  U9 pin 3 reads 3.2V (close enough to 3.6?  dunno)

second LO second buffer amp OK
>  
>  Everything else was spot on.


Looks to me like you're doing OK. I don't see anything obviously incorrect.
>  
>  I'm still new to radio and kit building, so I'm sure I've done
>  something silly.  I'm going to quit for today and take a look at
>  things with fresh eyes tomorrow.
>  
>  Any and all suggestions are welcome.  Thanks!
>  
>   -- Gene


There are a lot of builders that have done this and have gone through the trouble shooting extensively. This would be a great time to throw in your opinion or experiences with this. I only built one, and my memory of this is not that great!

73 Mike KD7TS
>  

>