A little but important update. Great news, both pickups are in working order, the test with the stereo headphones was a succes! And it's definitely a short scale instrument, the tape measure can't be wrong!
 
And John, your advice about the trim pots on the back proved very useful, and yes indeed, all the tweaking resulted in full - centered - centered - full for me also!
 
I'm very thankful to be part of this great group of people, the support and interest is absolutely mindblowing...

You may find you need to back off the trims for the pickups if you find you're overdriving your preamp.  Otherwise, I like keeping the signal relatively hot from the source...
 
John

This looks like it:
 
http://club.alembicguitars.net/Images/393/7261.html
 
And this thread looks useful as well:
 
http://club.alembicguitars.net/Images/449/8450.html

Looks like you're a stereo/mono adapter cable away from being ready to play for real!  Either that, or you need to locate an external power supply and the associated cable.
 
What a fabulous deal you have now that you understand that everything works!  Heck, if you decide you don't love the bass, you can easily double your money.

Well, the great deal and potential profit is one thing, but I really love this bass. It happens to be almost identical to the custom order I've had in mind for a long time. I like to believe this bass was destined for me to pick it up...

Another update: after some searching around the local music store made me a 1/4 stereo jack to 1/4 mono jack cable in about two minutes. The pickup selector switch is in the BOTH position, just as EffClef advised, and the result is fabulous! The windows rattled severely when this baby sang for the first time using both its pickups!
 
Now all that's left for me to do is patiently waiting for news from the 'A-files'. In the meantime I'll be looking around for an external power supply, and maybe, just maybe a stereo cable and a second amp to enjoy the bass in stereo...(!)

Hey, great. I was going to suggest making a cable but I figured finding an adapter would be easier.
 
Now I guess you can decide whether to leave the selector tucked inside the body (if you find a switch in the normal horn place in the way for slapping and popping).  
 
Sounds like you've figured out the hum-cancel trimpots, too, great!
 
Hopefully the factory can track down the serial number from the date codes - if nothing else, to make sure it's not a stolen bass.
 
Enjoy it!
 
EffClef

This thread has really been a crash course in 'experiencing the Series I' for me. A warm 'thank you' to everyone who contributed!
 
And EffClef, your last remark is bang on. I'm still a bit concerned about it being a stolen bass, although the store in case has a good policy of finding out if there's something wrong with the items they buy and sell. I specifically asked the saleperson about this subject before any money had changed hands. They are located one street away from the local police station actually! But still, as I said, I'll keep my fingers crossed, hoping to hear something from Mica or Val soon...

Well I hope it doesn't turn out to be stolen. It must have a very interesting history. The engraved plate - Alembic made special Epic basses for Guitar Center, apparently, with engraved plates, and that's the only time I've seen that (on Ebay).  
 
I wonder what the LED is supposed to indicate. Is it on when you plug in the 1/4 cord?
 
The extra strap button hole is a pain but maybe not - since it's already been done, you can try it in both places, I suppose.
 
Even if you have to pay for a new cable and DS-5 or DS-5R, your price from the pawn shop was good enough that you're probably still in bargain territory after that. Was there a case?
 
EffClef

I expect the LED to light when the 5-pin cable is connected and/or the DS5(-R) power supply is turned 'on', but that'll have to wait to be confirmed (still have to find both). No case, but even at more than 3 times the price I paid, it would've been an incredible deal, especially in this part of the world.
 
Mica/Val, please forgive me for asking maybe too soon, but is there any news about harness checkout number '1937' yet?

No news yet?
 
In a week or two (max) I'd like to take 'Birdy' to Edwin van Huik to treat her (and myself) to a cable, DS5 power supply and a new set of strings. I've looked, searched and asked around myself, and at this moment I'm 99,99% sure that she's not a stolen instrument, but I just hope that'll be confirmed before I invest that kind of money in her. If there's definitely no chance that the serial number will be found, I'd appreciate to hear that also...
 
Thanks & best regards,
Wilfred

Mica, I send you a personal e-mail about this 4/5 days ago. Could you or Val please confirm that '80 1562' or '82 2401' (from the list of stolen Alembics) aren't my bass?
 
- early 80's Short scale Series I
- Small standard body, crown peghead
- Birdseye maple top and back
- Purpleheart (?) neck laminates
- Mahogany body
- Schaller tuners
- Engraved 'Series 1' truss rod cover
- Pickup selector switch 'hidden' in the electronics cavity, replaced with plain brass plate
 
I have planned to go shopping next weekend for the DS5, cable and a new set of strings, and if it's not too much trouble, I'd love to hear from you soon!
 
Thanks & kind regards,
Wilfred