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Re: OT: Vortex issue



Toby G wrote:
> Really you need a o-scope and a schematic.  You wanna look at the signal 
> at various points.  Unless you can see with your own eyes that a 
> component is burnt it's gonna be quite difficult.
> 

> 
>> Generally speaking, you cannot test most components in circuit, 
>>
(these days there *are* test devices designed to work on components
  in circuit)



The schematic is available
http://www.andybutler.com/vortex/vortex.htm#docs
(courtesy of Lexicon)

There's plenty of tests to be done before removing anything.

If there's marked Voltages on the Schematic, these
can be checked.
e.g. the power supply to the output chip, pin 8
should be at 8V
the reference voltage on pins 3, 5 should be 3.5V



I just remembered, the Vortex has it's
own tone generator
http://www.andybutler.com/vortex/tonegen.htm
If it can't produce a clean sin wave at the o/p,
then the o/p is faulty.
(watch for rare bug, sometime the generated tone 
  isn't pure).

A scope is nice of course, but not in any way essential
for tracing the onset of distortion in an audio path.

You need a test signal of course, but if you don't 
have a suitable signal generator, a music source
can work too. (one where you'd notice any additional
distortion).

It's possible to make a test probe out of a regular
guitar lead with one plug removed, and the hot wire
available as a probe.
Plug the jack end into an amp, and then you'll
be able to check the signal for  distortion 
at suitable points in the circuit.
I once did fault finding on a tape deck, and 
run the fault down to a simple transistor circuit
at the Output.
(but then it had to go to a 'real' repair guy)


I wouldn't recommend making your first attempts
at fixing on a valued piece of gear however,
it's *not* easy to replace components on a double
sided circuit board without damaging the board,
and it's a pain to then solder in tiny wires to fix
the resulting damage.
It *is* easy to short out just the wrong connection
and burn out *another* component.


andy butler







t