| Electronics > Repair |
| Repair help requested for Class D Subwoofer module of 18 inch 1000W amp module |
| (1/1) |
| Studi-Jo:
Hi, I am 52, mobile DJ, and studied electronics 20 years ago. After that I never practiced. I have a DB Technologies DVA S10 18 inch subwoofer, 1000 Watts. On my last gig it started to smell.... Decreased volume and had no choice to switch it off. Once at home I opened the enclosure and found a complete stuck 18 inch subwoofer, this occured the smell. Ordered a new one and installed it but when I power the active speaker, without any audio input connected, it immediately and always gives a weird sound It's not a 50 Hz hum but a higher frequency resonance sound so there is also a problem with the amplifier. I removed the amplifier module "DigiPro 1000S" and opened it. Surprisely the Power Supply Unit is 3/4 of the module and only 1/4 is the amplifier. Found online the schematics: https://drive.google.com/file/d/1LB0oHgbkXONhuaymQSkRktFjN_DAph3A/view?usp=sharing Because I need the subwoofer cabinet soon for other gigs, I ordered a complete new module but it would be nice if I was able to repair the old one and keep it as a spare. Visually I checked ELCO's and power components but nothing seems broken or smells burned. Started to check the output of the Power Supply Unit: New: +13,7 VDC (VDD) -13,7 VDC (VSS) -72,7 VDC (-HV) +72,6 VDC (+HV) -59 VDC (VDR) Old: +13,7 VDC (VDD) -13,7 VDC (VSS) -98,6 VDC (-HV) +98,5 VDC (+HV) -85 VDC (VDR) Old PSU gives more voltage to the amplifier MOSFETs but I guess this is not an issue. The PSU seems OK. How to proceed? The Amplifier has HEXFET Power Mosfets. Is it possible to check the state good/bad by unsoldering and measuring? I found datasheets from most important components. Any ideas or step by step instructions how to proceed would be highly appreciated! Thanks in advance, Johan |
| m k:
You have now four output channels, so even more comparing options. For more sophisticated stuff you need a more sophisticated picture. It's a low frequency stuff, so maybe an old scope is enough. |
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