Velodyne SPL 1200 subwoofer repair

[nhhiker]

Hey folks,

I have a Velodyne SPL 1200 subwoofer that recently fried on me, and I'm hoping that someone out there can help. I'm very much a noob when it comes to electronics, but I'm handy with a soldering iron and would love to learn.

Symptoms:
- Sub initially worked fine, but emitted a high pitch whine in addition to normal audio after running for 5-10 minutes
- Sub died when I was testing it with a tone generator on my phone. There was a loud POP and now the sub no longer powers on.

What I've done:
- I removed the plate amp from the back of the sub
- There are 6 large capacitors in a row, and the top is blown off one of them (see pic below). It clearly needs to be replaced.
- The caps are 470uF, 200V, 85C (see pic below)
- Cap dimensions are 21mm x 36mm
- I took a look on mouser and digi-key, but am a little bewildered by the number of types of capacitors and their stats

My questions (please forgive the number):
- Any idea in the pic below what "<circle with dots in it> - NEG means"?
- Should I replace all 6 caps or just the 1?
- Is mixing cap manufactures advisable or should it be avoided?
- I've read that CapXon caps are pretty notorious for failure. Are there particular manufactures that are known for high quality?
- Is the type of these caps aluminum electrolytic? Should they be replaced with the same type, or does it matter?
- Should I match the temp rating of 85C for the replacement, or could I go higher?
- I've noticed that caps have a number of hours lifetime associated with them. I'm guessing that I should pick one with a high lifetime? Maybe AEC-Q200 qualified?
- There are other stats like ripple current and ESR. Do I need to worry about these?
- And finally, there is some kind of rubbery caulking between the caps and between the caps and a metal box that they're near. I'm guess that the box is the power supply. Is there a certain type of caulking (high temp?) that I should replace this with?

Thanks in advance for any advice anyone can give. It would be great if folks could give replacement recommendations.

[David_AVD]

Be aware that those models can be very dangerous to work on. Most of the circuit is referenced to the mains.

Apart from that row of caps, the electros inside the caged area could be bad. It's a pain to get apart.

Those units can be quite hard to get working. Maybe see how much a new module is first.

[onsenwombat]

Without commenting any other items in this:
1) Replace all el caps. Capxon I reckon is one of those most notorious dogshit manufacturers of them all.
2) Going higher on the temperature rating per se has no ill effects. Be aware of any possible deltas in electrical parameters though.
3) Mixing manufacturers should be ok, at least as long as parameters match the original values "close enough." The caveat here obviously relates to item 1). If you replace only some of them and there's some funky series connections or so, things might happen. So, replacing all would be my choice.
4) Take lifetime numbers for any value only from manufacturers that actually produce anything of quality. If you're looking at these piss-poor Chinese "copycaps," this number is fabricated anyway.
5) These look like normal aluminium electrolytic caps for me at least. ESR, voltage & ripple current ratings to be taken in account when getting replacements.
6) Decent manufacturers include e.g. Panasonic, Nichicon, Rubycon, NCC/UCC, Epcos etc.

[nhhiker]

Thanks for the advice David_AVD!

I definitely don't want to risk frying myself or even worse, someone else! Thanks for alerting me to the danger. It never occurred to me that a power supply transformer also serves to isolate everything from the mains, and if that's missing, it's dangerous.

I am also going down the path of getting Velodyne to do the repair as well, and after your advice, I'm definitely leaning in that direction!

[nhhiker]

Thanks for all the info and advice onsenwombat!

[SoundTech-LG]

Having worked on these amps as their worldwide repair tech for 3 years I developed an attitude.
Most of the time the entire module got swapped out due to an inherent design flaw...  due to transients and high voltage swings, with lack of proper clearances between conductors... arcing in the inner layers of the PCBA. The Co. refused to redesign the board. So the new module was installed, and yes, we later saw them come back again for replacement. The other big problem was the large output filter/Inductor was not up to snuff. Bad cores. They did eventually came out with some better ones. Diddling with these may occupy your time for awhile, and you may even pronounce it "FIXED" if you're lucky. Don't kid yourself. These are doomed to fail, and always will. Hope you have fun while you get there. The blown caps are the very least of the problems these have. Do be careful with the 360 Volts waiting to bite you, or your test equipment.
Good thing Velodyne moved from audio to digital vehicle navigation equipment???

[nhhiker]

Wow, SoundTech-LG, and I thought that Velodyne made a quality sub at the time that I bought it. You may have fixed my amp the last time that it blew! I was shocked to see that their audio division was sold off to a company in Germany and their subs are have largely disappeared from the US. Maybe it's time to kiss this one goodbye, or buy a new OEM plate amp for it (though I doubt these are very good quality).

[SoundTech-LG]

Well, when they laid off the entire Dept. back in the 2009 DROP. That was the beginning of the demise.
I had seen the selloff information some time ago, had forgotten about it. I would not spend ANY money on that amp. The Plate Amp replacement is a much better idea. Not sure if the SPL-1200 has motional feedback, to my memory. Probably not, so you could retain the woofer if that's the case, and find a nice Plate Amp replacement. Try partsexpress.com to start with... maybe Amazon or ebay has something?

[Audiorepair]

Having worked on these amps as their worldwide repair tech for 3 years I developed an attitude.
Most of the time the entire module got swapped out due to an inherent design flaw...  due to transients and high voltage swings, with lack of proper clearances between conductors... arcing in the inner layers of the PCBA.

Many thanks for that, it just confirms that the PCB itself is a VERY overlooked point of failure, and almost impossible to diagnose.

I'm sure a few bells are ringing in a few minds now.

[David_AVD]

I think I've only ever successfully repaired two of those amp modules. The others were written off.

The "Bash" based subs (sold as various brands) are often a pain to work on as well.

[EHT]

Yeah, I had an SLP-R 1000 which I attempted to repair, and I'm usually able to fix stuff for which the parts can be obtained. I thought it must be possible, but I concurred with SoundTech-LG after wasting a lot of time. I got it working, but it was noisy/distorted at low volumes. One problem is that the components (especially the caps) are highly stressed by the combination of high-frequency, high-current and high-temperature, not to mention the vibration! It means that it sufffers from degradation of multiple components, most of which are a royal PITA to reach due to the stupid boxed-in design.
Also, the 370V is high current with all of those caps; it is *lethal* not just unpleasant.
So, easy change is wire the woofer directly to the rear terminals and use an external amp. Doesn't look as neat, but safe. BTW, I wired it up to a stereo linear amp which does 500W RMS in bridge mode. This can overdrive the woofer, so I don't know where they get "1000W" from. Still, at that level nothing stays put on your shelves!

[SoundTech-LG]

Yeah, it's laughable how they rated those amps. Maybe instantaneous P-P in your dreams RMS watts, or some other lie.
Fixed so many of those modules. Quite challenging. Management highly discouraged swapping out modules. They wanted each and every amp module troubleshot til you puked. Most PCBAs though eventually turned out to be carbon traced and arcing internally in between layers.
Some you could hold up to a strong light, or sunlight, and see the carbon trails.

[nhhiker]

Thanks EHT!

I knew that caps could zap you, but had no idea that the caps in a sub amp stored enough juice to actually kill you.

I'll look into an external amp or a plate amp and see what I can find.

[nhhiker]

This is probably another noob question, but if I end up getting a plate amp, how can I safely dispose of the old amp? I can bring it to the local recycling center, but I don't want someone there to get zarched handling it!

The only thing that I could think of is to toss it in a river to short it, though I'm sure the fish wouldn't like that solution! 

[Tom45]

The only thing that I could think of is to toss it in a river to short it, though I'm sure the fish wouldn't like that solution! 

The electric eels might not like the competition.

[nhhiker]

The only thing that I could think of is to toss it in a river to short it, though I'm sure the fish wouldn't like that solution! 

The electric eels might not like the competition.

[EHT]

This is probably another noob question, but if I end up getting a plate amp, how can I safely dispose of the old amp? I can bring it to the local recycling center, but I don't want someone there to get zarched handling it!

It's just aluminium & common e-waste, so wherever your local centre takes such stuff. However, I suggest just unbolt the amp module but keep the back plate since it fits the speaker box and seals well. Mine still looks the same from the back, I just attached the woofer to the terminal posts internally.

Regarding the danger - it has the rectifier connected directly to the AC line as well, so combination of that and the caps = high voltage & high current. If you were working on it, you'd have to check to with a DMM to see how long it takes for the caps to discharge before approaching it.

BTW, I guess by 'plate amp' you mean what this thing is, so the replacement would be another class-D amp fitted in the speaker box. You might find one with a better design if you buy a decent brand but it will still suffer from high temperatures and vibration.  I suggest keeping the amp external so that you can keep it cool and not vibrate it to bits. I just bought an old linear amp. Hi-fi quality doesn't matter, you just need high RMS power (maybe 250-500W).

[nhhiker]

Thanks EHT! I started looking at plate amps & in the description of one, it actually said that they recommended an enclosure internal to the sub for exactly the reasons you point out. Between the lousy electronics and internal amps, subs seem to be designed to fail right from the start. I'm starting to look into external amps now.

[EHT]

Good stuff! One complication is that you also need a crossover. If you just feed the full-range signal to the sub, it won't cause any damage but if you can't tune the pole of a low-pass filter to match the roll-off of your main speakers, you'll get too much amplitude around this point, i.e. typically somewhere between 40 and 100Hz. It will sound boomy.

I used a Behringer CX2310 which has a sub frequency cutoff and volume control, and an old Samson stereo linear PA amp which supported bridge mode (L & R channels driven out of phase to double the power). You may find a more elegant solution!