After reading thru the forums and trying out some things, I am posting in the hope that I can get some help from the community.

My iFi speakers (purchased at Costco) are about 2 years old and likely out of warranty. Last week, they just did not power on. After reading this forum a bit, I opened up the sub-woofer and found the fuse was blown. Got the replacement fuse from RadioShack and put it in. I tested before connecting anything with just the circuit board and ipod dock plugged in and it seemed fine (no speakers and woofer connections made). Next I put back everything and made the speaker and woofer connections and then turned on and the fuse blew even as I turned it on. 

So I blew couple more fuses before narrowing down the problem to the sub-woofer. If I made the sub-woofer connction to the circuit board, the fuse would blow out. The RSX speakers themselves are fine. Now I have everything back and working except for the sub-woofer.

Just looking for some help on repairs. I read about replacing capacitors. It seems a bit out of my expertise level though I could read up and do something with a soldering iron if I was sure that it is the capacitors. But I cannot be sure it is the capacitors or the sub-woofer itself. Any way of narrowing this down to decide if it is the capacitors or the sub-woofer?

Also, how to remove the grill from the iFi sub-woofer and detach the sub-woofer from the frame? Can it be replaced with any 8" 8 ohm or 4 ohm sub-woofer (it says 6 ohm, but I dont see any 6 ohm replacements on the market)?

I just dont want to trash such a fine system on account of the sub-woofer not working, but without the sub, the system does not sound as good.

Any help from the experts is greatly appreciated. 

First things first.

Make sure you used a "slow blow" or "time lag" fuse.  After that I can help you on a few troubleshooting scenarios.

 Hi Andy,

  Thanks for the response. Yes I am using slow-blow fuses only. I double checked to make sure that that is what I got from Radio Shack:

 http://www.radioshack.com/product/index.jsp?productId=2102760

 harish

OK good.

Read through these instructions first, and if you are not comfortable doing any of these tests, don't do it.

It's best to have a wood bench to work on.

Do not touch any part of the amplifier while performing any of the tests or while the amplifier is plugged in.  Make sure your hands are clean and dry.

Opening the amplifier panel will expose you to lethal voltages.  Take all precuations necessary, and do not touch any part of the amplifer while the unit is plugged in.

Before removing the amplifier panel, turn off the mains power switch on the amp panel and unplug the AC power cord, and disconnect everything from the amplifier.  Wait for one minute before removing the amplifier from the subwoofer. Unplug the subwoofer wires from the amplifier circuit board.  Squeeze the tab of the connector and the connector can be easily unplugged.

Check 1:  With the AC unplugged inspect the primary AC circuit board (the one with the fuse).  Pay close attention to MOV1 (the shiny yellow coated disc located next to the fuse).  If it appears to be cracked, or shows other signs of damage this could be the cause of the blown fuse.  If it looks OK then continue.

Disconnect the tranformer primary from the primary AC circuit board (the transformer is the big donut shaped object with a bolt running through the middle).  Squeeze the latch and the connector will easily come off.  Then bend the wires out of the way so the connector is not touching anything.  These wires should be red.

Lay the amplifier on its side to facilitate the following test.  Make sure the switch is off and then plug in the AC power cord.

Put one hand in your pocket and with the other hand turn on the mains power switch.  Wait a few seconds and then turn off the switch.

Unplug the AC power cord.

Inspect the fuse.  If the fuse is blown there is a problem on the primary AC board, it is probably MOV1.  If the fuse is OK, continue.

Check 2:  Make sure the AC switch is off and the AC power cord is unplugged.  Reconnect the tranformer primary wires to the primary AC board.  Make sure the connector snaps into place and check by pulling on the connector.

Now disconnect the transformer secondary wires.  These connectors are located on the large circuit board next to the tall black cylindrical capacitors that are the power supply filter.  The wires should be brown and yellow.  Bend them out of the way so that the connectors are not touching anything.

Lay the amplifier on its side to facilitate the following test.  Make sure the switch is off and then plug in the AC power cord.

Put one hand in your pocket and with the other hand turn on the mains power switch.  Wait a few seconds and then turn off the switch.

Unplug the AC power cord.

Inspect the fuse.  If the fuse is OK, then reconnect the wires and continue with the next check.

If the fuse is blown then try a 3.15A slow-blow fuse.  Do not try anything larger than a 3.15A fuse.  NOTE: If you have a 230V iFi system, you may try a 2A fuse.

Check 3:  Make sure the AC switch is off and the AC power cord is unplugged.  Reconnect the tranformer secondary wires to the large circuit board.  Make sure the connector snaps into place and check by pulling on the connectors.

Lay the amplifier on its side to facilitate the following test.  Make sure the switch is off and then plug in the AC power cord.

Put one hand in your pocket and with the other hand turn on the mains power switch.  Wait a few seconds and then turn off the switch.

Unplug the AC power cord.

Wait for one minute before proceeding.

Inspect the fuse.  If the fuse is OK, go ahead and replace the amplifier into the subwoofer and remake all connections, and test the system.

If the fuse is blown then try a 3.15A slow-blow fuse.  Do not try anything larger than a 3.15A fuse.  NOTE: If you have a 230V iFi system, you may try a 2A fuse.

The reason for trying a 3.15A fuse (2A for 230V systems) is that not all fuses handle inrush current the same way.  The fuse rating is the continuous rating.

The iFi has a very large power transformer for what it is (to support full power output to all three channels simultaneously) and the inrush current can be substantial.

 Hi Andy,

  Thanks for the detailed debugging tips. Based on your tips I have now revived my iFi to full working condition.

  Here is the summary: I procastinated for a couple weeks  after getting your tips, just because my two satellites were working and it was only the sub-woofer that was not working and your tips looked liked I neded to spend a lot of time. (I had replaced the fuse with a new 2.5A last month as described in my original mail and I got the satellites to work but had to disconnect the subwoofer to keep the fuse from blowing again). But this week the entire system went out cold again, likely because the 2.5A fuse blew out again.

   So I read thru your tips again and got a pack of 3.15A fuses from RadioShack. I did only the check1 visual inspection without disconnecting any wires and found everything to be in order. The yellow  coated disc was not cracked nor damaged. I then went directly to replacing the 2.5A fuse with the 3.15A fuse (lazy I guess to actually disconnect each of the wires and test like you have mentioned. If this one blows then I will do all of that). Then I connected my sub-woofer and speakers and everything works fine now. Just have to wait and see for a longer time if this continues to work.

Thanks again for the help: I spent $6 on the two packs of fuses but your advice helped my regain my $200 iFi system to its full working condition without taking it to a repairman.

harish

Andy,

Thanks for this helpful post.  It looks like the OP's problem was fixed with a fuse replacement.  I have not been so lucky.

My iFi is about two years old, and was left powered on at all times.  I went away on a business trip for a week, and when I came back, it was dead.  No light on the dock, no response to any control, no sound from a line-in signal.

I searched the forums, found this post, and got myself over to the Shack for appropriate fuses.  I got a package of both 2A and 3.15A slo-blo fuses.

Took the subwoofer apart, checked the original fuse - blown.  Inspected MOV1 - appears to be OK, no obvious problem.  Disconnected the transformer primary connection and tried Check 1 with a new 2A fuse - no problem seen (fuse OK).  Moved on to Check 2 - reconnected transformer primary, disconnected transformer secondary, and tested again.  The 2A fuse blew immediately when power was switched on.  I tried again with a 3.15A fuse, and got the same result - the fuse blew immediately when powered-on.

Just for grins I tried it again with the transformer secondary (and primary) connections in place - same results (fuse blew immediately, both 2A and 3.15A.)  For whatever it's worth, the power supply filter caps physically appear to be OK - no bulging or obvious leaking.

So...what do I do now?  Any help you could offer would be appreciated.