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Post by thespianator on Dec 19, 2015 21:00:53 GMT -5
While picking up a tuner from CL, I also got a deal I couldn't refuse (I gotta knock that off) on two Velodyne HGS10 servo controlled subwoofers, with one having an obvious problem: it makes a motorboating noise when plugged in to AC after about 3 seconds (no signal applied). Apparently no schematics are available on the net. (hopefully the second sub works ok).
It's a 45 lb sub with a 1000 watt amp and a 310 ounce magnet structure in about a 1 cubic foot box. They were quite highly rated back in '01 when it was made, so I figure it was worth a shot.
MT, any ideas where to start? (besides not dragging this stuff home?)
**HAPPY HOLIDAYS EVERYONE**
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Post by mastertech on Dec 19, 2015 21:19:34 GMT -5
HGS controller.pdf (209.88 KB) HGS module.pdf (74.97 KB) See how close these are to yours. I am taking some time off for the holidays so if you need assistance maybe someone else can chime in. 
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Post by masterdoor on Dec 20, 2015 16:15:43 GMT -5
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Post by thespianator on Dec 20, 2015 16:20:32 GMT -5
Thanks, MT! Have a great Holiday to you and yours, and of course everyone here.
Thanks, Masterdoor - I'd be happy to find obviously bad filter caps (I have an esr meter for the others), but access isn't easy.
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Post by thespianator on Dec 21, 2015 15:15:27 GMT -5
OK, got plate amp out. Nothing obviously burnt or leaking, nor shrunken shrink-wrap. Going through it with ESR meter. Hard to know what is the appropriate ESR value for small caps, but found one 10uF 50V cap with an ESR of 4.6 ohms. Seems high.
Would that be possible to cause the motorboating/buzzing sound or would that more likely be a main filter cap? Anyone know? Could be IC?
Thanks
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Post by masterdoor on Dec 22, 2015 14:30:53 GMT -5
You need to check DC voltage from psu, if you have high AC ripple.
That 10uF cap has to high ESR. But i dont think its your main problem.
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Post by thespianator on Dec 22, 2015 17:18:58 GMT -5
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Post by thespianator on Dec 22, 2015 21:05:08 GMT -5
Checked the main filter caps for ESR. All OK for ESR However, the caps are rated at 1000uF but each measured around 2800-3000. Does that mean they are wired in parallel?
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Post by thespianator on Dec 23, 2015 13:07:59 GMT -5
You need to check DC voltage from psu, if you have high AC ripple. That 10uF cap has to high ESR. But i dont think its your main problem. Reassembled, tested for DC voltage at the speaker output. It reads almost 400mv DC at the speaker output. What's next? |
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Post by masterdoor on Dec 25, 2015 15:24:26 GMT -5
I didn't mean speaker output. You have some different voltages from PSU that feeds the amplifier. Something like +-15-18V rail that feeds op-amps and main amplifier rail +-100-200V. The preamplifier has its own PSU. The amplifier PSU is probably SMPS. You can check over filter caps. Yes, they are in parallel to increase powerbank. My main language is not english, so bare with me |
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Post by thespianator on Dec 25, 2015 16:27:27 GMT -5
I didn't mean speaker output. You have some different voltages from PSU that feeds the amplifier. Something like +-15-18V rail that feeds op-amps and main amplifier rail +-100-200V. The preamplifier has its own PSU. The amplifier PSU is probably SMPS. You can check over filter caps. Yes, they are in parallel to increase powerbank. My main language is not english, so bare with me No problem with language, since I don't speak schematic very well (LOL!). Your communication is fine. What is SMPS? Also, in order to get to the PCB in that caged area where the main PS is, I have to remove one of the main caps to get at one screw and all 6 of the power transistors have to be unsoldered from the main board. This is a lot of work just to access the main PSU! |
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Post by masterdoor on Dec 25, 2015 17:06:01 GMT -5
First step: check over filtercaps outside the caged box (secondary side filter caps). If voltage is stable and no high AC ripple, then theres no need to open caged box. SMPS = Switch Mode Power Supply ![]()  |
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Post by masterdoor on Dec 25, 2015 17:21:14 GMT -5
Also check PSU on preamplifier board. Its a common transformer.
There are two voltage regulator just right side of it.
Check right pin for output voltage (pin3), if its a 78xx and 79xx regulator.
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Post by thespianator on Dec 26, 2015 18:42:44 GMT -5
First step: check over filtercaps outside the caged box (secondary side filter caps). If voltage is stable and no high AC ripple, then theres no need to open caged box. SMPS = Switch Mode Power Supply ![]() How do I determine if there is AC ripple? What would that look like with a DVM? |
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Post by masterdoor on Dec 27, 2015 15:13:51 GMT -5
First check DC if its stable.
To check AC ripple you need a oscilloscope.
Preamplifier PSU, you can check with DVM.
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