M-Audio AV40 Dead Monitors Revival (capacitor replacement)

I was recently given a pair of dead M-Audio AV40 near field monitors.  These little speakers are great!  However, I was puzzled as to how exactly they had failed.  After some googling I found that a few of the capacitors used on these have a tendency to go bad and leak.  I decided to open up the case and sure enough: I found the capactior were bulging and had a chemical leak at the top.  I removed the capactitors and ordered them from mouser.com as follows:

EEU-HD1E221
Panasonic Aluminum Electrolytic Capacitors - Leaded
US HTS:8532220040 ECCN:EAR99 COO:JP     2     2
RoHS: Compliant1
667-EEU-HD1V472
MFG Part No:EEU-HD1V472

EEU-HD1V472
Panasonic Aluminum Electrolytic Capacitors - Leaded
US HTS:8532220040 ECCN:EAR99 COO:JP     2     2
RoHS: Compliant1
688-SKHHAK
MFG Part No:SKHHAKA010

The board shows the charges +/- so this helps when installing the replacements.

I used a solder remover and even though the capacitors were glued, I was able to just pull/tilt them off once the solder had been completely removed.

The only problem I encountered with this fix is that a small circuit board that was glued to the inside of the case detached and I wasn't able to reattach it.  Also, the amp heat sink might have been shorting with the speaker when I closed the case and tightened the screws.  The problem became worse when I noticed that even without tightening the screws, the short would happen when I would apply pressure to plug in the power cable. To fix this I applied a small amount of silicon around the case where the screws go so that It would add some space so the the speaker wouldn't short with the heat sink.

Well that was that--now go out and revive some gear by replacing capacitors!

tags: 
audio production, gear

Comments

Submitted by Bob (not verified) on
Comment: 
Hi. When you listed the part numbers for the capacitors you bought from Mouser, you did not indicate the capacitance values. I see in the picture that the voltage limit of one of the capacitors is 35 volts. Other than that we know nothing.

Submitted by admin on
Comment: 

If you google the number I provided, then you can find out all the specs for each capacitor -- P.S. sorry for the way late reply.  Totally forgot these comments were being filtered.

Submitted by Bob (not verified) on
Comment: 
Woah, hold the fort. When I opened my speaker cabinet I found the circuit board layout to be quite different. The power connector and rectifier are in the middle of the board instead of the edge and in their place is a transformer or a choke coil, and the capacitors are in a different place. Where do I go from here?

Submitted by admin on
Comment: 

Sorry again for yet another very late reply.  I believe there is a newer version of the AV40's that was released. You may have that version with slightly different internal design.  Also, that version *might* not have the "bass boost" switch.

Submitted by Bob (not verified) on
Comment: 
Woah, hold the fort. When I opened my speaker cabinet I found the circuit board layout to be quite different. The power connector and rectifier are in the middle of the board instead of the edge and in their place is a transformer or a choke coil, and the capacitors are in a different place. Where do I go from here? I do not know if my question went through or not so please forgive me if this is a repeat.

Submitted by Bob (not verified) on
Comment: 
After buying a pair of M-audio av40 speakers I found the same high-heat issue with the left speaker. The circuit board layout has been changed from the original layout indicated in this post so identifying the faulty parts would take some independent investigation. I took the back off of the left speaker and waited and waited to see which capacitors became hot but the board barely became lukewarm even after a few hours of operation. It ran cool only after I took the amplifier board out. I am going to check the board for a possible crack from a factory defect, and also use a small sheet of plastic to isolate the speaker magnet from the housing of the power transformer, in the event that it is contacting the speaker and possibly causing some sort of power drain. This is only a trial method, but since the board ran hot with it in place and ran cool with it out of the cabinet, some variable is causing the destructive heat, and this might be the cause. If it works I will write again to inform this post.

Submitted by Matt (not verified) on
Comment: 
Thanks for the tips! I can't seem to get the back of my AV40 off :( I removed all of the outside screws but it seems like maybe they glued the back panel to the speaker box? Any tips?

Submitted by admin on
Comment: 

Hey there buddy, sorry for the late reply.  I do remember having a bit of trouble removing the back but I don't remember anything in particular other than patiaence.  Hope it worked!

Submitted by ghostils (not verified) on
Comment: 
Just wanted to say thanks for the how to on capacitors just did my av40s today, easiest replacement ever.

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