Picked up a pair of these recently with xovers in need of repair/replacement.
One capacitor on the woofer side of each board had exploded and obviously the sonics are not quite right. I'm trying to get to the underside of the board to see if my minimal soldering skills can handle replacing them, but can't separate the +/- terminals from the plastic cover in order to expose the board. They seem to be simple screw threads holding the terminal points, and I didn't want to mess them up unless I was replacing whole xover, but the metal posts won't budge. Someone please help a dumb ass.

lets hope some one answers helpfully. ive got the same dilema but different issue. i did find some one who wants them free. but he hasnt emailed back.

are the xovr assemblys removable from the rear? or do you have to go in thru a speaker opening from the front.
I had the 3500s and they are some good sounding spkrs. hope you can fix them.
Wish I didn't sell mine

Yes, is removable from the rear, as the xover board is screwed to the plastic terminal post cover that also houses the L pads controls. Thanks

I just picked up a pair of these myself and plan to replace my caps so I just pulled one out to take a look. Besides the obvious 6 screws on the back you'll need to to flip it over and remove the L-pad knobs. Underneath those are 2 12mm nuts. Last, it appears you'll need to desolder the terminal blocks from the back of the board. It appears the screws you refer to are under the board holding the terminals to the plastic cover, but it appears that the terminal leads pass through the board and are soldered on the back. I can't test that last step until my desoldering pump arrives, but that appears to be the only place it is still attached on the only method by which to detach it. Good luck.

You have to unsolder the speaker posts to get the circuit board in the 3500 crossover to pop out. I have refurbished about 5 pairs of these in the last 2 years by replacing their electrolytics with polypropylene caps. They sound fabulous. I still own and listen to 2 pairs of the 3500's daily. Great Sansui speakers if you ask me.