alt-charging/not charging

[vongiese]

my 88 accord alt is possibly on the fritz?
Voltage with car off is about 12.5v
when I start it - voltage stays at 12.5v or so, and seems that it won't start charging until I turn on lights or fan, etc - at that point the idle comes up a bit and volt meter shows 14.5v. If I just let it idle - eventually it will start charging at 14.5v, but seems to take couple minutes....
I pulled alt and replaced brushes (they were shorter than spec). Re-installed alt and no changes - still does the same thing.
What could be the problem? This is the second set of brushes on this alt. (289,000 miles)
thanks

[POS carb]

probably the voltage regulator is bad or isn't getting the signal from the ignition II position.

[vongiese]

Thanks for the reply - I haven't worked on it yet - car is still doing the same thing so it hasn't been a problem. I'll let you know what i come up with.
Anyone else had a similar wxperience with an alt not charging until a load is put to it?
thanks