Saab: 1992 saab 900 not elec. power, digital voltmeter, jumper cables

Question
I purchased a 1992 saab convertable a few weeks ago and on the way to work today the motor just died, AAA got it to start with a jump start but soon as you take the cables off the engine dies, the alternator and battery look pretty new, are there any alternator relays I should check? What is a good way to check the alternator?

Answer
John:
 It sounds like a VERY dead battery... and a defective alternatorthat is NOT charging. The simplest way to get a good check on your alternator's output is with a digital voltmeter; You should have a minimum of 14.0 volts across the battery with the engine running.But since your alternator cannot even sustain the engine running,it certainly appears to be at fault.Any relay operation would not be dependent upon whether or not jumper cables were attached.
 The most common cause of alternator failure is "bad brushes" or a bad regulator. Brushes are quite easy to replace..If you are so inclined, you could do it yourself;if you need help in this regard, feel free to get back to me.
 Otherwise, you'll need to remove the alternator and bring it to a shop for repair.  Insist on "checking the brushes"first; there is a tendency for the shops to want to sell you a new alternator for lotsa$$$ instead of replacing brushes for approx $25.

  Hope this helps
    Jerry