What Jim said as far as finding the bad module goes. Once you find it
things to look for will be shorted caps and chips and burnt resistors.
I suspect a chip since an IC connects to both supply rails and most
caps go to one or the other. Look at the chips carefully for signs of
heat. Sometimes they will split open...but sometimes the split is only
visible on the underside of the chip. You can also clip your meter
across the supply rails on the module (on the continuity setting) and
then pull the chips one by one and see when the short goes away.
Ike
Sent from my iPhone
On 2010-01-18, at 4:46 PM, Nick Sullivan <[email protected]>
wrote:
Ike-
So we disconnected the power to the cue send modules, the echo send
modules, the 2 mix module, 2 mix to cue module, and the oscillator
module. With those modules disconnected we got the voltage on the
power supply back to +/-18v with the master module connected.
Right now looking for input as to what would driving the voltage
down in those disconnected modules?
Thanks again for all the help
-Nick
On Mon, Jan 18, 2010 at 11:07 AM, NS <[email protected]>
wrote:
Ike-
Thanks for your insight
This console was made it 78' and we are not sure if it is a series
III or a series II as there seems to be no rectifying diodes outside
of the power supplies as the power comes in from the cables and is
fed directly to the master module while the other supply feeds the
bus modules.
We have disconnected that master module from the power and
disconnected the ribbon that feeds the input modules power and logic
and am still not getting the correct voltage out of the supplies
when it is hooked up to the console.
I've tried to use one supply to hook up one side of the console and
this problem still remains. Given that both the power to the master
module and input modules are disconnected would be anything in the
bus modules that could be shorting me out?
Once, again, thanks for your time and appreciate the help
-Clark
On Jan 18, 2010, at 5:38 AM, Ike wrote:
> Two PS's are probably summed through diodes (usually 3 pins of a
bridge rectifier). Check these for shorts, they should be on the
panel where the supplies connect to the desk. You may be shorting
the two supplies' outputs together. Another thing to try is to see
if the board will run on one supply with fewer channels powered,
like 24+ the master section. This would also point to a problem with
the PS input panel.
> Ike
>
> Sent from my iPhone
>
> On 2010-01-17, at 2:36 PM, [email protected] wrote:
>
>> I have a series 3 console that was custom built for Lonnie Mack,
circa
>> 1978, 36 channels 24 bus. There are 2 power supplies, 1 supply
lost the
>> -18 due to one of the legs of the TIP145 transistor breaking. It
made
>> the other transistor in the other supply get burnt. We have
repaired
>> both supplies but when we put power to the console, there seems
to be a
>> short as the +/- 18 volts are down to 7 & 0 volts. Something has
>> definitely shorted out or something. I have disconnected the
power from
>> the master module, and the channels that were fed off of the ribbon
>> cable and re tried the power, now I had +/- 7 volts. When the
supplies
>> are not hooked up they read the correct voltage.
>>
>>
>> Looking for some help and where to start looking for the problems
>> Thanks ahead in advance,
>> Clark
>>
>>
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