Monitor 5b's x-over upgrade w/pics

I decided to start a new thread in the appropriate forum as a reference for those who want to see how it's done. This upgrade was very simple if only a bit time consuming. No special tools needed and anyone with a steady hand and basic soldering knowledge can do this. There is a minimum of dis-assembly required. I do however recommend pulling the drivers and the passive radiator, especially if you want to upgrade the internal wiring. It also gives you a chance to visually inspect the drivers for damage and/or correct parts. However there is enough length of wire to pull just the x-over out for upgrading.

These pictures and the basic procedure can be used as a reference for all the Monitor series x-over upgrades. Look here for a Polk schematic: http://www.polkaudio.com/forums/showthread.php?t=38755. It's also a good idea to pull the x-over and compare it to the schematic because Polk changed things on the fly many times. If you are in doubt or have any questions call Ken Swauger at Polk customer service and he will answer any questions.

I also recommend doing one x-over at a time so if you get confused or forget where something goes you have an unmolested one for reference. Polk used Black and Green for positive (+) and white for negative (-). I also wrote the polarity on the back of each tweet so as not to get confused upon reinstallation.

Also you will need to contour the leads on the caps and resistors to get them to fit properly. Be gentle especially where the leads exit the body of the part. They can be damaged but you really have to apply some pressure to damage them. Just a note of caution.

Once the x-over has been removed from the cabinet there are 4 plastic compression clips that attach the pcb to the terminal cup. Gently compress the tabs with pliers (needle nose work best) and detach the pcb from the terminal cup. The pcb can be folded over to work on removing and reinstalling the parts.

The new caps are substantially larger than the older ones so I removed the 2 original caps by snipping the leads close to the pcb. I did however make notes on a piece of paper. It appears some of the caps originally use were polarized, this makes no difference whatsoever and the new caps are (and should be) non-polarized.

Then I un-soldered the remaining part of the leads from the pcb. I did it in this order to do a mock up of the new caps because they are substantially larger and you need to think it out a bit for best fit.. The larger cap can hang over the pcb a bit w/o having any concerns about the terminal cup fit back into the cabinet. If it protrudes a lot you will have to angle the terminal cup a bit to get it to clear the cabinet. However there are no other clearance issues.

Removing and reinstalling the resistor is simple. The new resistor is longer than the original (if you are using Mills) so you need to contour the leads a little bit to get it to fit snuggly.

Here are the pics.

1-2) Old x-over with new red and black wiring
3) New parts from Parts Express
4) I left the wiring alone from the terminal cup to the pcb. Note: the gloppy glue from the factory. This is used to seal holes etc., since the cabinet needs to be absolutely air tight.
5) Action shot
6) Setting the new caps. See how huge they are?
7) New caps installed Note: The original resistor still in place
8) You can unclip the pcb, fold it over, and work the magic
9) You can let the large cap protrude over the side of the pcb w/o any difficulty refitting the terminal cup into the cabinet.
10) Newer generation 5b original x-over w/poly switch (small blue square part). I bought a single 5b for parts if I needed them.
11) New vs. Old x-over parts.
12-13) New and New x-over parts
14) a shot thru the passive radiator cut-out of the upgraded x-over re-installed in the cabinet.

The end