Glotz

Thanks for the input, but in reality I don't want to put too much money into it. There is really no way of telling how long the driver will last after 20 years of use. LOTR blew the voice coil cover loose on the front of the driver a few years back but I was able to glue it back on. It's been working fine but you never know when that voice coil will start scraping... 🥴 (I hate that sound) Glotz

That's... "Keep listening... you may ear something"

My first post here was March 8th. Due to lack of the proper equipment (oscilloscope) I have not been able to properly troubleshoot the power supple so I am going to get on with life and just drive the LF-10 enclosure with an external amp. I'm not one to give up such an endeavor but can only do so much with a digital multimeter. ☹️The enclosure may last another 20 years? I guess I've gotten my money's worth! Thanks to all for posting you thoughts, tips and tricks. And as they say, "Keep listening... you may hear something". glotz

If I had an alternative I would sell. 😊 If I don't get it fixed (receiving remaining parts today) I will use an external amp to drive it. I don't need much in my music studio, just enough to be able to hear the low end during a mix down. Of course I'm going to have to buy a replacement for my surround sound entertainment system. Any suggestions for the sub for a surround sound entertainment system??? glotz

Please comment if you have any suggestions!

So this is where I'm at... I have pulled the MOSFETs and they seem to check ok in a simple test circuit, biased on and drawing current, 260 mA, not a lot. The two transformers don't seem to be open, there are 9 terminals on the inputs and 8 terminals on the outputs. There is a device, no markings, that looks like a small signal diode without a cathode stripe. I am assuming it is a Diac used in the PWM circuit. (See photo) Diode check shows an open in both directions probably because it doesn't produce a high enough voltage to turn it on... or it's open. Some of these operate in the 30 - 70 breakover voltage range so I'm going to have to come up with a supply high enough to turn it on. Maybe a bunch of 9V batteries in series.

Thanks for all replies. Yes, this LF-10 has taken a lickin' and kept on tickin' ... until now. Bought it on 12/31/01 for $575. One 10" speaker and two 10" passive radiators. I ordered the FETs and the PNP this morning. Should have them in two days. I plan on pulling the parts and testing them as the Captain suggested. I will keep you updated on the progress or lack there of in the next few days. Since no one mentioned having a schematic I assume there are none available for Klipsch gear??? Thanks, glotz

There are no burned or broken parts that can readily be seen. No swollen or leaky caps. All diodes I was able to check with a diode meter seem to be ok. The PNP transistor seems to be ok. I don't have an oscilloscope. glotz

Hi All, My LF-10 subwoofer quit working and it appears to be the switching power supply module. I do not have a schematic. The green LED comes on when the power switch it turned on or when the switch is in auto and a signal is applied. The relay on the rectifier board kicks in and is supplying 161 VDC to the "PRI DC IN" terminals on the switcher module. I assume this is the unfiltered, full wave rectified voltage. The "SEC DC OUT" terminals on the opposite side of the switcher module read 0 VDC. What limited trouble shooting I am able to do without a schematic found two resistors that were bad. A 100k ohm in the collector of a PNP transistor was open and a 110 ohm resistor in the base read 989 ohms. I am assuming these two resistor and the PNP transistor are part of the pulse width modulation circuit driving the FETs used for swithcing. Replacing both these resistors did not change anything. Can someone please provide some assistance in getting this fixed. I would hate to see it go it the trash pile. Thanks for your help, Warren