Skip to main content ↑ ↓

Notice

Please note that most of the software linked on this forum is likely to be safe to use. If you are unsure, feel free to ask in the relevant topics, or send a private message to an administrator or moderator. To help curb the problems of false positives, or in the event that you do find actual malware, you can contribute through the article linked here.
Topic: Active Subwoofer Does Not Power On (Read 4734 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

Active Subwoofer Does Not Power On

I was a mobile DJ for a while a few years ago, and I used a Yamaha MSR800w as my primary subwoofer.  One night, someone got stupid and ran into a lamp running on the same breaker/fuse as my gear, and it blew the breaker/fuse.  All of my gear was fine except my subwoofer. 

It will not power up.  I've checked all fuses inside, all fine.  I don't remember smelling anything funny (I opened it up the second the dance floor cleared), and nothing looks to be out of order or burnt on the board inside.  From here, I'm lost.  I want to take it to a professional, but I'm afraid of paying a ton of money for a simple fix.  I was hoping to find one of two things here:

1.  First steps to diagnose the problem (and ultimately fix it)
or
2.  A better place for this post


The sub has been sitting unused for about 2 years at this point, and I'm ready to put it back to work.  I've done a lot of searching looking for any relevant information that can help, but I haven't had much luck.  I came to the first forum that looked like it could help, so please let me know if I'm in the wrong place- and if so, please point me in the right direction.

Thanks so much!

Active Subwoofer Does Not Power On

Reply #1 –
Quote from: Trump600 on
I was a mobile DJ for a while a few years ago, and I used a Yamaha MSR800w as my primary subwoofer.  One night, someone got stupid and ran into a lamp running on the same breaker/fuse as my gear, and it blew the breaker/fuse.  All of my gear was fine except my subwoofer. 

It will not power up.  I've checked all fuses inside, all fine.  I don't remember smelling anything funny (I opened it up the second the dance floor cleared), and nothing looks to be out of order or burnt on the board inside.  From here, I'm lost.  I want to take it to a professional, but I'm afraid of paying a ton of money for a simple fix.  I was hoping to find one of two things here:

1.  First steps to diagnose the problem (and ultimately fix it)
or
2.  A better place for this post


The sub has been sitting unused for about 2 years at this point, and I'm ready to put it back to work.  I've done a lot of searching looking for any relevant information that can help, but I haven't had much luck.  I came to the first forum that looked like it could help, so please let me know if I'm in the wrong place- and if so, please point me in the right direction.

Thanks so much!


Find the make and model of the subwoofer and obtain a service manual for it. The service manual will probably contain step-by-step diagnoistic instructions that are tailored for it.

Active Subwoofer Does Not Power On

Reply #2 –
Quote from: Arnold B. Krueger on
Find the make and model of the subwoofer and obtain a service manual for it. The service manual will probably contain step-by-step diagnoistic instructions that are tailored for it.


It's in my hands.  You can get a free version of it here.  The best I could find was a short mention under Inspections on page 15, 2-1--
Quote
"Also, check the POWER indicator lights up."


Maybe this?: 
Quote
"2-5 Protection circuit test:  Apply DC +5 V (power supply output resistance = 10k Ohms) between pins 1 and 2 of the connector CN207 and check that the relay turns off within 1 second.  Also, check that it returns automatically within 10 seconds when the DC +5 V is shut off."


Either way, no instruction on what to do next...

Active Subwoofer Does Not Power On

Reply #3 –
Quote from: Trump600 on
Quote from: Arnold B. Krueger on
Find the make and model of the subwoofer and obtain a service manual for it. The service manual will probably contain step-by-step diagnoistic instructions that are tailored for it.


It's in my hands.  You can get a free version of it here.  The best I could find was a short mention under Inspections on page 15, 2-1--
Quote
"Also, check the POWER indicator lights up."


Maybe this?: 
Quote
"2-5 Protection circuit test:  Apply DC +5 V (power supply output resistance = 10k Ohms) between pins 1 and 2 of the connector CN207 and check that the relay turns off within 1 second.  Also, check that it returns automatically within 10 seconds when the DC +5 V is shut off."


Either way, no instruction on what to do next...


I take it that you have zero experience with repair of problems like this?

This might help:

How-Diagnose-Fix-Everything-Electronic

Active Subwoofer Does Not Power On

Reply #4 –
Quote from: Arnold B. Krueger on
I take it that you have zero experience with repair of problems like this?


I've done electrical projects before and have a small working knowledge.  I've never done audio repair though.  If you're going to toss out the typical "go see a professional" line, I understand.  I'm just looking for a little support on a project that could possibly be just a simple oversight of mine...

 

Active Subwoofer Does Not Power On

Reply #5 –
Quote from: Trump600 on
Quote from: Arnold B. Krueger on
I take it that you have zero experience with repair of problems like this?


I've done electrical projects before and have a small working knowledge.  I've never done audio repair though.  If you're going to toss out the typical "go see a professional" line, I understand.  I'm just looking for a little support on a project that could possibly be just a simple oversight of mine...


I think the book might help. Given the time the woofer has sat on the shelf, it would seem like the time to acquire this book or something like it (read user reviews and investigate books with similar titles) and study it could be a big help to you for the rest of your life.

That is in fact how many of us learned what we know. Reading had a lot to do with it, and does even if you are taking a class.

To some degree guiding someone with very limited background as suggested by the questions to this point on a step by step basis is not going to be overly productive. Fixing problems like this is tough enough when the box is on my test bench which is a very high bandwidth situation as compared to an online forum.

Active Subwoofer Does Not Power On

Reply #7 –
It's strange that a blown circuit breaker would damage anything that's plugged-in, but maybe it somehow created a voltage spike.

Quote
I've done electrical projects before and have a small working knowledge.
Do you have a multimeter?

There's a lot of "stuff" between the AC input and the power transformer.  I'd check to see if you are getting AC voltage into the transformer.  (Or, check to see if you're getting AC out of the transformer first.)  Of course, be careful with power-line voltages!


If you can't repair the amp, you could replace the amp with an off the shelf plate amplifier.  (You'd need to make some cabinet modifications.) 

Or just disconnect the internal amp, convert it to a passive sub and get a separate power amp.  (Not quite as portable or as easy to connect-up at the gig.)

Active Subwoofer Does Not Power On

Reply #8 –
Quote from: DVDdoug on
It's strange that a blown circuit breaker would damage anything that's plugged-in, but maybe it somehow created a voltage spike.


Or in the confusion of the outage, we're conflating cause and effect. The subwoofer was overdriven, and it may have shorted out internally and took out the externhal breaker before it also took out an internal fuse. Next time we try to run the subwoofer, the blown internal fuse avoids repeating the blowing of the external circuit breaker.

Its possible that the subwoofer driver overheated and the rubbing voice coil caused a short that led to the rest of the conflagration. In that case only the enclosure is still any good, and economics has us looking at total replace.

From a troubleshooting view point, wiring the internal sub up to an external amp might be a first good diagnostic move.

If a DVM is at hand disconnect the subwoofer driver from the amp and then I'd look at its DC resistance and see if it is atypically low.

I'd also put my hand on the cone and gently push it through its stroke, and see if I hear any rubbing. It might even be locked in place by now.