Just fixed my PV1000 that would not power on. Verified 185vdc on bulk capacitors. Measured 11vdc on U5 (UC3842) from pin 5 (gnd) to pin 7 (vcc). Then measured 0vdc from pin 5 (gnd) to pin 8 (ref). This should be 5vdc. This means that U5 is shut down for undervoltage. Turned out to be two open resistors. R94 100k 2w and R77 33k 2w. Never would have guessed that as there was no sign of heat discoloration. They are next to each other between U5 the UC3842 PWM IC and Q3. This prevented the proper startup voltage for U5. Replaced them and I'm off and running once again. Hope this helps someone.
Funny, my PV1000 stopped working Feb. 6th, 2015. It's a 2003 model. I found your post and decided to take a peek but I didn't have such success. Just plan lack of knowledge.. I took that sub out and poked around with a volt meter, checked the Fuse first of course.Didn't appear or feel like those resistors were "plug and play" so I didn't take my investigation any further. I'll have to bring it in. However, I will print your post out and maybe it will help the guy who's going to attempt to fix my little guy. Thanks for taking the time to write up the post.
I joined this forum so that I could message Tom Ulrich and thank him for this. I had no idea how to fix my PV-1000. I didn't want to send it back to Boston Acoustic's service department because it was around $130 + shipping. A great sub, but going on 20 years old. So, I figured I'd try his solution, ordered some resistors on eBay, took apart the sub, stared at the circuit board and the service manual from hifiengine for a while, then soldered in the new resistors. Turned it on and it works.
Thanks Tom!!!
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I have a 2002 model PV1000 that I turned off, moved to another room (January 2020) and then it did not power up. ARGHHH!!! - found this post and it was helpful. Here is what I found on mine: I had 14VDC across pins #5 and #7 on U5. I had zero volts across pins #5 and #8. My R77 resistor read fine at 33K ohms. My R94 resistor read 175K ohms. The R94 resistor is supposed to be 150K 1/2 watt. I replaced only the R94 with 150K 1/2 watt and unit back up and running. Thanks for the direction on this!
SOURCE: I have a Boston Acoustics
I have the same problem. La Mars covers the factory repair for these. Their number is 712-546-1644. Have you fixed your problem yet ?
Mark
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I notice there were a hummmmmm sound coming from the subwoofer for the past two weeks. when the power is on when i shut the power off the noise stop . is that and easy fix?
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