Replace all nine of those capacitors - it's a hassle to figure out exactly which ones might be bad and they are very cheap to replace, so just do them all at the same time. Be sure to replace them with NEW capacitors from a quality source. Don't use parts found on ebay (these are often counterfeit) or your junk drawer from 1980 (capacitors degrade with age). Nichicon is a good brand. I bought mine from Digi-Key (http://www.digikey.com/
), a reputable source for electronic parts in the US.
Be sure to pay attention to the ratings of each capacitor you are replacing, and use the same capacitance rating and voltage rating (you can use a higher voltage part if you need to, but not a higher capacitance part). Also, pay attention to the physical sizes of the capacitors you are replacing so that when you order the new ones you won't have problems with them fitting on the board (there isn't much room for oversized parts).
THANK YOU for this very helpful and informative post. We did an extensive remodel on our house in 2008. With the studs bare, I thought it was the best time to wire the house for "whole home audio," so after looking at a number of solutions, I purchased a "b-stock" Speakercraft MZC-66 in late 2008 through an authorized reseller (who also installed it... and is now out of business) for a painfully large amount of money (for me, anyway). After five years of gentle use (once or twice a month -- only one or two zones at a time) I noticed my speakers making a loud "tick tick tick tick" sound when the power to the main unit was on, even if that zone with those speakers wasn't being used.
There seems to be no shortage of people complaining about the high cost and crappy quality of Speakercraft products -- but few resources for advice on how to get them repaired, other than to send them back and pay as much to have speakercraft repair them as a new unit costs. No thanks.
When I first discovered the problem, I was searching for a solution and stumbled upon this post of yours, as well as a listing by an independent retailer of the amplifier cards on a popular internet auction site. Without any electronics tinkering experience, the $100 brand new card sounded like the better idea. So I bought one, and when it arrived I started to troubleshoot (pulling out the speaker wires one zone at a time) to figure out which zone / card needed to be replaced. BUT -- painfully -- I discovered in the processes that I didn't have one, but FOUR amplifier cards that were fried. Although I was readily willing to part with $100 to repair this thing, the idea of spending $400 on it wasn't so appealing.
Having read your post several times now, and giving myself a crash course on soldering (and desoldering) -- I think I'm up to doing the repair myself -- and even adding a new cooling fan with a heat activated switch. The one thing that I'm having trouble figuring out is which capacitors to order. It's a foreign language to me.
So... if it isn't a big hassle, and in the spirit of helping out another guy that was suckered by Speakercraft (and perhaps others like me who might stumble on this in the future), could I trouble you to provide a little more info:
(1) You provided a link to a site where I can get capacitors. Could you please provide detailed info on which ones to select? It looks like there are two sizes to replace on those boards. No? I would love to know how to order the same ones you used for the replacement.
(2) Did you add a fan? I'm planning to do that while I have it apart. I think I have that part of the project all figured out using an external power supply that powers a fan on a thermal switch. That said -- if you did that as well (or something like it) I'd love to hear the details... and also any tips for this relative noob on tapping into the internal power supply.
(3) How's your's working after you did the repair? Any issues?
Thanks again for the great post,