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What to do with non-working Velodyne sub?

post #1 of 11
7/15/10 at 1:05pm
Thread Starter 
I have a Velodyne Deco 8" sub that is no longer working. It started to crackle and pop, and after an email exchange with their tech support, I replaced the large capacitors in the amp (one had leaked.) It worked fine for about a month, then began again with the same symptoms. I'm pretty sure the exchanged caps are fine, and all the rest look OK, but bottom line, it's not working.

Last year when I asked about a repair Velodyne quoted me $175 flat repair. Now they are quoting me $235 and up. I'm thinking I want to cut my losses.

Being as how I am not an electrical or audio engineer, but just a guy who likes to listen to music and watch movies loud, I was wondering if I can just plop in a replacement amp like this one: Dayton amp

It will fit in the original opening, but I have no idea how it would work with the original driver, and I'm assuming the driver is OK due to the symptoms.

I would prefer not to spend more than $200, especially since I originally paid around $700, and the Velodyne support guy on their thread thinks that a 5 year lifespan for a subwoofer is not too bad. What do you all suggest?

TIA.

Here are the specs for the Velodyne sub I have: Velodyne Deco
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post #2 of 11
7/15/10 at 2:30pm
The documentation listed that Velodyne amp at 600w rms. You would likely need to go to one of the 500w PE amps.

In April, I used a 500w PE BASH amp as a replacement on a 9+ year old 15" subwoofer. I think the newer amp sounds at least as good as the old one.

The issue would be getting the newer amp to fit in your situation. My son glued 2"x4"s in a rectangular shape to the back of my subwoofer and then screwed the amp into the rectangular shape. It is a quick repair but not necessarily appealing.
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post #3 of 11
7/15/10 at 5:32pm
The electrolytic caps that you replaced are likely polarized.
If you install them reverse-polarity, they will work for a short time.

Also, if the replacements are under-voltage rated, they won't last long.

The circuit board is likely to give you some indication to the proper polarity for the polarized caps.

Just trying to save you some money.
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post #4 of 11
7/15/10 at 6:57pm
Thread Starter 
Quote:
Originally Posted by PassingInterest View Post

The electrolytic caps that you replaced are likely polarized. If you install them reverse-polarity, they will work for a short time. Also, if the replacements are under-voltage rated, they won't last long.

Just trying to save you some money.

They were polarized but I was careful about that. The caps were the same as the ones I replaced. If that's the problem, I can blame Velodyne engineers. BTW- I LIKE saving money.

Here's a picture of a current model that looks the same as mine:


@wwinkler- Thanks for the tip on the BASH amp. I am leaning more in that direction. The first Dayton one I mentioned (100w) is a drop in fit. Another one here (240w) I would have to adapt to the cabinet but it's workable.

What would be the effect of using a lower-rated amp? It's not like I ever cranked the Velodyne amp up past 4 or so.
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post #5 of 11
7/17/10 at 4:00am
When you get a too powerful or just right powerful amp, you have adequate reserves for explosions, etc. I run my 500w BASH amp at 1/4 because it is slightly more powerful than my previous amp. The PE 240w amp would likely work fine most of the time but might be overdriven (with audible distortion) when there are big demands to provide low Hz sound at high levels.
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post #6 of 11
7/18/10 at 2:27am
I set my sub amp at a 1/4 too, anymore than that and the cone sounds like it's gona pop out.
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post #7 of 11
7/18/10 at 4:18am
Quote:
Originally Posted by jet150 View Post

I set my sub amp at a 1/4 too, anymore than that and the cone sounds like it's gona pop out.

That is a gain control and has nothing to do with how much power is sent to the driver. The gain control is for matching the level of the sub with the speakers in your system. If the volume level set by your AVR calls for a full signal on the LFE channel then the sub amp will send full power to the subwoofer driver.
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post #8 of 11
7/18/10 at 6:21am
Quote:
Originally Posted by Brucio View Post

They were polarized but I was careful about that. The caps were the same as the ones I replaced. If that's the problem, I can blame Velodyne engineers. BTW- I LIKE saving money.

Here's a picture of a current model that looks the same as mine:


In that case, it seems very likely that your bridge rectifier is passing some AC, meaning that at least one of the four diodes in it is shorted.

Your full-wave bridge rectifier is the black square component at the end of the electrolytic cap row, not far from the transformer.

Replacing your bridge rectifier is cheap and easy, but you also need to replace the damaged electrolytic caps again.

If you want assurance that the bridge is bad before going further, but if you don't have an oscilloscope, it can be checked with an ohmmeter, but remove it from the circuit first. Each of the four diodes inside should read a low resistance in one direction and an open in the other direction. Use the diode setting on your meter.

Or, you can just make one last ditch effort to repair the amp and replace the components without testing, because they're cheap. Oh, and make sure the new bridge rectifier is oriented the same way as the original.

Replacing the bridge rectifier and caps is still cheaper than buying a new amp.
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post #9 of 11
7/18/10 at 8:40am
I have a Velodyne Microvee with the same problem. (It's less than three years old, but since I'm not the original owner the warranty won't apply and I wasn't into the $235 repair plus shipping costs.)

I removed the back plate/amp, made a new back plate with binding posts and turned it into a passive. I'm powering it with the Dayton APA150 from PE which has a low pass crossover built in. I know it's way less power than the original plate amp, but it seems to work ok for me although I haven't given it extensive listening yet.
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post #10 of 11
3/10/11 at 11:46am
Thread Starter 
Quote:
Originally Posted by PassingInterest View Post

In that case, it seems very likely that your bridge rectifier is passing some AC, meaning that at least one of the four diodes in it is shorted.

Your full-wave bridge rectifier is the black square component at the end of the electrolytic cap row, not far from the transformer.

Replacing your bridge rectifier is cheap and easy, but you also need to replace the damaged electrolytic caps again.

You are The Man! I finally got around to doing this. Thanks for the tip about the rectifier- I am a complete electronics Noob. Only Velodyne knows for how long, but for $20 worth of parts, I now have a working subwoofer!!!

I put in a rectifier with the same specs as the original, except for a higher rated amperage; hope that helps in the long run.
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post #11 of 11
3/10/11 at 12:31pm
I'm glad it worked out.
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