Here’s the deal, I’ve had my Klipsch Promedia THX 5.1 system since 2001. Last Friday 05/11/07 around 4:00pm the satellite speakers went dead. By 05/12/07 2:00pm I repaired them by replacing 2 faulty MOSFET switches (chips). The final cost for this repair, $13.00. Well, actually around $20, if I include the bridge toll ($3) & the gas ($3) used when traveling to the electronics parts supply store in Philadelphia. I live in South Jersey.

Anyway, this solution is for those of you with the problem of the Satellite speakers dying or cutting off and on, but the SUB is ok. This solution probably also fixes those systems which have the opposite problem: The SUB cutting out or dead, but the Satellites are ok.

 Both SATS & SUB use identical components (chips) for power switching, but are on opposite sides of the same board.

OK, here what you’ll need to do

You’ll need to know basic soldering, so you’ll need a soldering iron with a fine (small) tip, solder, and soldering flux. Also get a solder sucker to remove the old solder. Don’t use the copper braid stuff to remove it; it takes too long to heat up and that extra time can heat damage your board’s components.

PARTS NEEDED:

Quantity 2: high speed MOSFET switches, part number IRFZ44N. Part number IRFZ44 can be used as well. Equivalents from other suppliers will work too.

These part numbers are equivalent to the NTE part number NTE2395. Go to www.NTEINC.com and use the cross reference. There you can read the spec sheet if you’re into that sort of thing. There, also in the specs, you can see a drawing of the part if you need a visual clarification. Click on the parts distributors in your state link to find parts suppliers nearby. I found a store nearby who had the IRFZ44 chips. There’s also online distributors, but beware online of the minimum order; that will cut into your savings!

This NTE site is a favorite for “OLD SCHOOL” component level electronics troubleshooters like me! I’m not really “old” though, I can still dunk a basketball! (occasionally).

!!!!!!!!!!!!!!!!!!!Remember to unplug your power cord 1^st!!!!!!!!!!!!! 

The board you’ll be replacing parts on is the one containing the BASH circuitry. From here on I’ll refer to it as the crossover board. You can identify it by looking for the two little boards on it with the word “BASH” on the outside of each one. This board is the “switching” part of this switching power supply. This also is the signal crossover board; it separates the high and low frequencies. Notice the 2 big copper coil wound inductors, just like the crossovers found in car and home speaker boxes. This board also ties the low level preamp signals from your PC, to the high level amplifier circuitry of the Klipsch system. You can find this board by following the Red & Black wires that daisy chain across the top of the surround (SAT) boards back to where they start. Again it’s the board with the 2 smaller boards with the words “BASH” on their sides. To remove the crossover board, unscrew the 2 screws on the outside cover. You will also have to remove the 2 sets of Red & Black wires from each side of the crossover board. Label the wires accordingly. The words, SUB (+) & SUB (-) are on the board next to one heatsink, SAT (+) & SAT (-) are next the other. I will be referring to these wires again in the next section.

The crossover board has 2 identical circuits, one side is for the SATELLITE speakers, and the other side is for the SUBWOOFERS. You can figure out which side you need by looking at the Red & Black wires mentioned above. The daisy chained Red & Black wires from the 5 SATELLITE amplifier boards plug into the SAT+/-.  The other Red & Black wires with SUB+/- go to the SUB amplifier board. Remember, the SUB board is the only board not connected in the daisy chain. If needed, cut the cable ties holding these wires to make sure you trace them correctly. These wires plug into both sides of the crossover board. Remember to look for SAT+/- & SUB+/- written on the crossover board itself. There are 2 black heatsinks (plates) on each side of the crossover board near each Red & Black wire plug-in. The heatsink near the SAT plug-in is for SATS and the one nearest the SUB plug-in is for the SUBS. On each heatsink there are 3 black clips. These clips have holes on one side of them. These clips hold 3 chips on to the heat sink. Remove the clips. I used a small flathead screwdriver by lifting (spreading) the clip and sliding it off. Under each clip are the following:

Quantity 2:  MOSFET switches (a kind of high speed switching transistor). The number on these 2 chips is IRFZ44N.

Quantity 1:  Semiconductor Diode. The Part Number on this one is U1520. (You will NOT be removing this chip). It’s hard to find it aftermarket (not impossible) so BEWARE!!

Hint: The MOSFETS have 3 legs; The Diode has 2 legs!!!!

Remove the heat sink by unscrewing it from the board (2 screws). The 3 chips will stay in place. Take care not to damage the cards with “BASH” written on them or you’ll probably regret it!

Remove the plastic liners from the back of the 2 MOSFET chips. You’ll need these for the replacement chips so do not throw them away, put them aside. You’ll notice there’s a white paste on them, this stuff is heat sink compound, available at any Radio Shack. I just re-spread & re-used the compound already on the liners and chips.

Removing the 2 MOSFETS, Part Number IRFZ44N:

I found it easier to just bend them back and forth until the legs snapped off. That way they are out of the way to get to at the solder joints. You’re going to heat the solder joints up. Put flux on the joints before you heat them. With flux, they will heat a lot faster causing less damage to the board. Suck the points clean of solder & remove the broken off legs using the solder sucker and a small needle nose pliers or tweezers.

Installing the new MOSFET chips:

Push them through the solder holes making sure the backs of the chips (silver side) are towards the “BASH” cards, identical to the U1520 diode chip. If you put them in backwards you’ll probably regret it!!!

Make sure the height of the chip is about the same as the U1520 diode chip. It doesn’t have to be perfect, but be in the ballpark. I did this by bending the legs on the solder side (back side) of the board when the height was correct.

Solder the new chips on to the board. Solder on the back side only. Remember to dab flux on the legs and solder points first, this makes the solder flow fast and heats up the replacement chips less. Add new solder to the tip of the soldering iron only, not directly to the legs. This reduces the heat on the new chips. Touch the soldered tip of the iron to each leg of the chip. With flux on the legs, the solder will quickly flow into the solder joint. Add more solder to the iron as needed.

Remember to cut the extra bit of leg off after each soldered joint when you’re done. You don’t want the legs to bend & touch or you’ll probably regret it.

Viola! You got yourself a repaired crossover/switching board, (you repaired the switching part) and you saved some time & dough $$!!

Re-install the heatsink and liners. Reconnect the plugs and remount the board.

SHOUT OUTS:

I’d like to give the United States Air Force a big shout out for training me as a Biomedical Engineering Technician. Their electronics course is the best in the world!

Over 20 years later their training still puts food on my table, a roof over my head, and saves me money with things like this. GO AIR FORCE!!!!!! Mad Love!!!!!

I wrote this while listening to my newly repaired Klipsch Promedia THX 5.1’s in Stereo (2 channel). I’ve used them over the past 4 years as a powered 2^nd room (living room) for my 3 room DENON 5803 Audio/Video amplifier. The Denon 5803 is in my main media room (finished basement) and has a 7.1 THX Ultra 2 surround. The 3^rd room is the patio area and has 2 rock shaped weatherproof patio speakers (from LOWES). I have a Logitech Harmony 890 radio frequency remote controller to select and adjust the Denon wherever I am in the house or outside.

The Klipsch Promedia speakers sound much improved. The sound must have been degrading over time as the chips went bad, I didn’t notice. Now I notice! The system really sounds new again!!

GOOD LUCK!!!

That is a good step-by-step description.  The time taken to help others will be appreciated.

Just a few points to clarify:  1) The sat only or sub only problem can be caused by a variety of failures, including Q510 on the power supply board or the HC1011 chip itself, or even feedback circuits on the main board. I've seen over 20 different things that can cause these nice systems to fail.  I note this just so people do not get hopes up too high, nor give up if the MOSFET replacement posted above is not the solution for each owner.

2) The board is not a crossover, but a dual regulator that uses feedback from the amplifiers to determine how high a voltage to supply to the amplifiers. (You may notice that the coils are actually identical in size, which you would not expect for a crossover that has to feed through high frequencies on one side, and block those high frequencies to the sub side.) One side regulates for the satellites, and the other side regulates for the sub.  The full voltage (roughly 75 volts for the sub and 55 volts for the satellites) is only needed for brief peaks.  For 98% of the time it would be so high (at most listening levels), the system would overheat, be inefficient and/or require more expensive design elements.  The regulator board rapidly adjusts the rail voltage, from a normal of 7 to 9 volts to satellites (THX or Ultras) and 10.5 volts to the sub (both THX and Ultra) up to the full 55 or 75 volts respectively. 

3) After repairing the regulator board, it is always a good idea to check the current drain by the amps.  Sometimes an amplifier board draws a high current, straining the regulator, and triggering its failure.  Current drain for THX boards is well under 100mA each (5 in parallel for sats means less than .5 amp to the satellites. The sub is a single board). Ultra drain is often 120 mA or so per amplifier board. 

I have the Promedia 5.1s, and the sats are dead - they were doing the popping/clicking/random turning on and off. I opened the amplifier and swapped the power connections for the sats and sub amps - probably not 100% safe but it works for now. I want to actually repair the circuit, and I see your solution above is only one case as noted by the second poster. Is there any way I can do tests to determine what is at fault in my system? I do have a basic knowledge of electroncis, and I have a multimeter that does amps, ohms, volts and frequency (as well as temperature and I think tests capacitors).

 I can tell you for certain that each satellite amp works and the sub amp works, and that regulator board that you call the crossover board works only on one side (the sub side). So it has to be on that board or the end of the board prior to it - which seems to be a secondary power supply board or something, it has the big yellow transformer.

 Your solution may address the problem, and it seems cheap, and I am not afraid to try it. I am just wondering if there is a way to test that, and other things, before I do the surgery to know for sure what my problem is.

 Edit: Actually, I just tested the load on the satellite circuit, and it's at 1.5 amps. I'm going to test each amp individually to see what each is taking. I still have to repair the regulator as well, I hear rapid clicking coming from that side and not the sub side (the working side)

Rear Left+Right take about 150 mA each. Center is takign about 333 mA, Front Right is taking about 400 mA and Front Left is taking over 500 mA. According to the second poster, these are all out of bounds, especially the front 3 speakers. Is there any way to address this problem?

 This fix works great.  Just wanted you to know the SUBS take part number NTE2396 and the SATS take NTE2395.

You cannot use the NTE2395 for the subs.  I replaced all four mosfets and they sound great.  Thanks for the info.

Best Regards,

Kevin Mattocks

The 13$ solution:

Here’s the deal, I’ve had my Klipsch Promedia THX 5.1 system since 2001. Last Friday 05/11/07 around 4:00pm the satellite speakers went dead. By 05/12/07 2:00pm I repaired them by replacing 2 faulty MOSFET switches (chips). The final cost for this repair, $13.00. Well, actually around $20, if I include the bridge toll ($3) & the gas ($3) used when traveling to the electronics parts supply store in Philadelphia. I live in South Jersey.

Anyway, this solution is for those of you with the problem of the Satellite speakers dying or cutting off and on, but the SUB is ok. This solution probably also fixes those systems which have the opposite problem: The SUB cutting out or dead, but the Satellites are ok.

 Both SATS & SUB use identical components (chips) for power switching, but are on opposite sides of the same board.

 

OK, here what you’ll need to do

You’ll need to know basic soldering, so you’ll need a soldering iron with a fine (small) tip, solder, and soldering flux. Also get a solder sucker to remove the old solder. Don’t use the copper braid stuff to remove it; it takes too long to heat up and that extra time can heat damage your board’s components.

 

PARTS NEEDED:

Quantity 2: high speed MOSFET switches, part number IRFZ44N. Part number IRFZ44 can be used as well. Equivalents from other suppliers will work too.

These part numbers are equivalent to the NTE part number NTE2395. Go to www.NTEINC.com and use the cross reference. There you can read the spec sheet if you’re into that sort of thing. There, also in the specs, you can see a drawing of the part if you need a visual clarification. Click on the parts distributors in your state link to find parts suppliers nearby. I found a store nearby who had the IRFZ44 chips. There’s also online distributors, but beware online of the minimum order; that will cut into your savings!

This NTE site is a favorite for “OLD SCHOOL” component level electronics troubleshooters like me! I’m not really “old” though, I can still dunk a basketball! (occasionally).

 

 

!!!!!!!!!!!!!!!!!!!Remember to unplug your power cord 1^st!!!!!!!!!!!!! 

 

The board you’ll be replacing parts on is the one containing the BASH circuitry. From here on I’ll refer to it as the crossover board. You can identify it by looking for the two little boards on it with the word “BASH” on the outside of each one. This board is the “switching” part of this switching power supply. This also is the signal crossover board; it separates the high and low frequencies. Notice the 2 big copper coil wound inductors, just like the crossovers found in car and home speaker boxes. This board also ties the low level preamp signals from your PC, to the high level amplifier circuitry of the Klipsch system. You can find this board by following the Red & Black wires that daisy chain across the top of the surround (SAT) boards back to where they start. Again it’s the board with the 2 smaller boards with the words “BASH” on their sides. To remove the crossover board, unscrew the 2 screws on the outside cover. You will also have to remove the 2 sets of Red & Black wires from each side of the crossover board. Label the wires accordingly. The words, SUB (+) & SUB (-) are on the board next to one heatsink, SAT (+) & SAT (-) are next the other. I will be referring to these wires again in the next section.

 

The crossover board has 2 identical circuits, one side is for the SATELLITE speakers, and the other side is for the SUBWOOFERS. You can figure out which side you need by looking at the Red & Black wires mentioned above. The daisy chained Red & Black wires from the 5 SATELLITE amplifier boards plug into the SAT+/-.  The other Red & Black wires with SUB+/- go to the SUB amplifier board. Remember, the SUB board is the only board not connected in the daisy chain. If needed, cut the cable ties holding these wires to make sure you trace them correctly. These wires plug into both sides of the crossover board. Remember to look for SAT+/- & SUB+/- written on the crossover board itself. There are 2 black heatsinks (plates) on each side of the crossover board near each Red & Black wire plug-in. The heatsink near the SAT plug-in is for SATS and the one nearest the SUB plug-in is for the SUBS. On each heatsink there are 3 black clips. These clips have holes on one side of them. These clips hold 3 chips on to the heat sink. Remove the clips. I used a small flathead screwdriver by lifting (spreading) the clip and sliding it off. Under each clip are the following:

 

Quantity 2:  MOSFET switches (a kind of high speed switching transistor). The number on these 2 chips is IRFZ44N.

 

Quantity 1:  Semiconductor Diode. The Part Number on this one is U1520. (You will NOT be removing this chip). It’s hard to find it aftermarket (not impossible) so BEWARE!!

 

Hint: The MOSFETS have 3 legs; The Diode has 2 legs!!!!

 

Remove the heat sink by unscrewing it from the board (2 screws). The 3 chips will stay in place. Take care not to damage the cards with “BASH” written on them or you’ll probably regret it!

Remove the plastic liners from the back of the 2 MOSFET chips. You’ll need these for the replacement chips so do not throw them away, put them aside. You’ll notice there’s a white paste on them, this stuff is heat sink compound, available at any Radio Shack. I just re-spread & re-used the compound already on the liners and chips.

 

Removing the 2 MOSFETS, Part Number IRFZ44N:

I found it easier to just bend them back and forth until the legs snapped off. That way they are out of the way to get to at the solder joints. You’re going to heat the solder joints up. Put flux on the joints before you heat them. With flux, they will heat a lot faster causing less damage to the board. Suck the points clean of solder & remove the broken off legs using the solder sucker and a small needle nose pliers or tweezers.

 

 

 

 

 

Installing the new MOSFET chips:

Push them through the solder holes making sure the backs of the chips (silver side) are towards the “BASH” cards, identical to the U1520 diode chip. If you put them in backwards you’ll probably regret it!!!

Make sure the height of the chip is about the same as the U1520 diode chip. It doesn’t have to be perfect, but be in the ballpark. I did this by bending the legs on the solder side (back side) of the board when the height was correct.

Solder the new chips on to the board. Solder on the back side only. Remember to dab flux on the legs and solder points first, this makes the solder flow fast and heats up the replacement chips less. Add new solder to the tip of the soldering iron only, not directly to the legs. This reduces the heat on the new chips. Touch the soldered tip of the iron to each leg of the chip. With flux on the legs, the solder will quickly flow into the solder joint. Add more solder to the iron as needed.

Remember to cut the extra bit of leg off after each soldered joint when you’re done. You don’t want the legs to bend & touch or you’ll probably regret it.

 

Viola! You got yourself a repaired crossover/switching board, (you repaired the switching part) and you saved some time & dough $$!!

Re-install the heatsink and liners. Reconnect the plugs and remount the board.

 

 

SHOUT OUTS:

I’d like to give the United States Air Force a big shout out for training me as a Biomedical Engineering Technician. Their electronics course is the best in the world!

Over 20 years later their training still puts food on my table, a roof over my head, and saves me money with things like this. GO AIR FORCE!!!!!! Mad Love!!!!!

 

I wrote this while listening to my newly repaired Klipsch Promedia THX 5.1’s in Stereo (2 channel). I’ve used them over the past 4 years as a powered 2^nd room (living room) for my 3 room DENON 5803 Audio/Video amplifier. The Denon 5803 is in my main media room (finished basement) and has a 7.1 THX Ultra 2 surround. The 3^rd room is the patio area and has 2 rock shaped weatherproof patio speakers (from LOWES). I have a Logitech Harmony 890 radio frequency remote controller to select and adjust the Denon wherever I am in the house or outside.

The Klipsch Promedia speakers sound much improved. The sound must have been degrading over time as the chips went bad, I didn’t notice. Now I notice! The system really sounds new again!!

 

GOOD LUCK!!!