Finally got all my repairs (engs were out) done and fired up the engs. Starboard alternator does not appear to be working. Took the alt to a alternator repair facility but didn't take the regulator. They spun it and flashed the field. Seems to be capable of producing power. Before I blame the regulator I wanted to see if there was a fuse or a fuseable link somewhere that could have opened.

Does a 1990 29 Fever have an alternator fuse somewhere?

Does the alt output connect to the batt wire at the starter solenoid? I was standing on my head when I connected the batt wire. May have missed a wire..

Fuse at starter solenoid. White plastic square thing.

Thx! I'll take a look.
When I started the eng I had to tie both batteries together since they were both low on charge. I didn't switch back to single batt ops after it started so I probably put a serious load on the alternator.

Put a voltmeter on the power output terminal and was reading batt voltage so it looks like the wiring is OK. Started eng and the voltage didn't rise.
There are 2 wires coming off the regulator and connected to the wiring harness. I believe one is for batt sensing (it is hot) and the other goes to the ign circuit for excitation voltage I think. Guess I need to turn the ign switch on and verify it's getting power.
Can I test the regulator by apply 12v to the excitation wire and see if the brushes get power?

Here a pic of my type of alternator.
http://www.mercruiserparts.com/Show_...OR+%28MANDO%29

I checked the excitation lead and sure enough, it does get power when the ign switch is turned on.

I found, on Youtube, a procedure to test the regulator. Basically you connect a 12v bulb to the brushes and using a variable output 0-20v power supply, to ramp the voltage up on the excitation lead. Bulb should light up as you increase the P/S voltage to around 12v. When you hit around 14.5v, the bulb should go out.

I don't have a variable P/S, so I just took the alt and reg to the alternator repair facility. They said it's working fine.

Went back home and load tested the battery for that eng, It failed miserably. Indicated 12.6v but when a load was applied, the voltage dropped to zero. Replaced the batt and now the alt is working like a champ.
I thought once I had the eng started (by tying the batts together), the alt would continue to produce power after I isolated the batts, but apparently, that's not the case.
When this alt dies, I'm definitely replacing it with a single wire model. These old Mando alternators are strange animals.