As per you requested this is the repost with designations!
I am repairing a Kenwood KAC X1R and it had started out with me buying a previously repaired amp! The guy tore up the traces for the power supply mosfets STP60NF06FP's Q17, Q18, Q19, Q20, Q22, Q23, Q24, Q27 and I had to repair that, most of it was traces to the gate resistors!
I repaired the traces and put in new gate resistors R34, R37, R39, R46, R47, R57, R58, R59 since the old ones had been way out of wack they are chip resistors 22 ohm 1/10th watt! He had the same issue with the error 02, which I got around! The easiest way to get around it is, connect the ground and remote that is live and insert the positive wire then immediately hit the rotary knob as a button, it will come into a menu!
I found out the impedance protection was not turned on! I hit the reset button and the power light came on, so did the fan, I tightened the positive power cable and it said it was already drawing two amps on the lcd, the amp played, but started to warm up, before a mosfet on the output shorted and it went back to error 02!
I went to remove the positive power cable and it was warm, the place where the heat sink for the output section mounts to the amp case was hot as well 158 degs and climbing what the lcd reported! I took it apart and one mosfet had shorted Q168, but I replaced the pair Q184, Q168, since they were both showing a short while soldered, they were all new as well before hand, but only two showed a short, before removal and then only one Q 168 was actually shorted, The output mosfets IRFB33N15DPBF are Q168, Q169, Q170, Q171, Q184, Q185, Q186, Q187, but I replaced them with IRF3415PBF which handle 43 amps, not the 33 amps which the 33n15's handle, both are 150 volt!
I have a service manual! My questions are! The mosfet retainer clips are not tight on the output section, could this have caused excessive draw and heat as well as draw on the power supply? And on one of the transformers it was kind of warm L2, would this have caused the warm power cable? It was drawing 8 amps on the lcd and though it said I only had 11.2 volts, the voltage meter said it was 12.22v could low voltage have been the issue with the power cable? Any help will be important!
I am repairing a Kenwood KAC X1R and it had started out with me buying a previously repaired amp! The guy tore up the traces for the power supply mosfets STP60NF06FP's Q17, Q18, Q19, Q20, Q22, Q23, Q24, Q27 and I had to repair that, most of it was traces to the gate resistors!
I repaired the traces and put in new gate resistors R34, R37, R39, R46, R47, R57, R58, R59 since the old ones had been way out of wack they are chip resistors 22 ohm 1/10th watt! He had the same issue with the error 02, which I got around! The easiest way to get around it is, connect the ground and remote that is live and insert the positive wire then immediately hit the rotary knob as a button, it will come into a menu!
I found out the impedance protection was not turned on! I hit the reset button and the power light came on, so did the fan, I tightened the positive power cable and it said it was already drawing two amps on the lcd, the amp played, but started to warm up, before a mosfet on the output shorted and it went back to error 02!
I went to remove the positive power cable and it was warm, the place where the heat sink for the output section mounts to the amp case was hot as well 158 degs and climbing what the lcd reported! I took it apart and one mosfet had shorted Q168, but I replaced the pair Q184, Q168, since they were both showing a short while soldered, they were all new as well before hand, but only two showed a short, before removal and then only one Q 168 was actually shorted, The output mosfets IRFB33N15DPBF are Q168, Q169, Q170, Q171, Q184, Q185, Q186, Q187, but I replaced them with IRF3415PBF which handle 43 amps, not the 33 amps which the 33n15's handle, both are 150 volt!
I have a service manual! My questions are! The mosfet retainer clips are not tight on the output section, could this have caused excessive draw and heat as well as draw on the power supply? And on one of the transformers it was kind of warm L2, would this have caused the warm power cable? It was drawing 8 amps on the lcd and though it said I only had 11.2 volts, the voltage meter said it was 12.22v could low voltage have been the issue with the power cable? Any help will be important!
The IRF3415 may not be a suitable replacement. Sometimes, the output stage of a class D amp is very sensitive to changes.
The output drive circuit may have been damaged when the outputs failed. That could be causing the overheating.
The clips for the FETs can sometimes be bent to tighten them up but you need to do it in a very controlled manner to reduce the risk of breakage. The best way is probably in a vise. A safer way may be to insert a piece of cardboard between the clip and the face of the transistor.
What size power cable?
When doing repair work, you need to use a power supply with both volt and amp meters. If you don't have a supply, you can use a voltmeter connected across a piece of wire with a known resistance to monitor the voltage.
Do you have an oscilloscope?
The output drive circuit may have been damaged when the outputs failed. That could be causing the overheating.
The clips for the FETs can sometimes be bent to tighten them up but you need to do it in a very controlled manner to reduce the risk of breakage. The best way is probably in a vise. A safer way may be to insert a piece of cardboard between the clip and the face of the transistor.
What size power cable?
When doing repair work, you need to use a power supply with both volt and amp meters. If you don't have a supply, you can use a voltmeter connected across a piece of wire with a known resistance to monitor the voltage.
Do you have an oscilloscope?
No don't have oscilloscope, almost bought one, there are several types to choose but choosing on a budget is the issue, the cable is 4 aug ground and power! On the drive circuit, parts and location id's are listed in the manual, should I go part by part checking for a short or failure?
I had to replace the original output mosfets because the original owner/repairer had lead to two of them being shorted in the first place! I figured upping the amperage wouldn't hurt! The manual to the amp says, Error 02 When the unit has failed and direct current voltage is generated to the speaker's output. But that error code I did get around with the service manual instructions and it worked for a few minutes!
It is still a little weird that the power cable was heating up, as if there was too much current being drawn or like there is a short, but that would be limited to the transformer right, even though the power supply mosfets were cool? I have two different types of multimeters, perhaps I should have used the one to measure amperage drawn while testing! I have checked every transistor for low readings with the diode check and shorts but cannot find anything!
Perhaps I should be checking all the resistors as well? I had a resistor issue in a polk audio class a/b 4 channel that kept leading to a failed channel that would over heat! It also caused some transistors for the output section to heat up! Once I changed it on all of the channels the issue went away, it was leading to excessive heat from the pnp and npn output transistors! But it wouldn't go into protect mode!
Could that be an issue? I know it was a class A/B but it was a drive circuit resistor and the small transistors would heat up fast as well as output ones!
I had to replace the original output mosfets because the original owner/repairer had lead to two of them being shorted in the first place! I figured upping the amperage wouldn't hurt! The manual to the amp says, Error 02 When the unit has failed and direct current voltage is generated to the speaker's output. But that error code I did get around with the service manual instructions and it worked for a few minutes!
It is still a little weird that the power cable was heating up, as if there was too much current being drawn or like there is a short, but that would be limited to the transformer right, even though the power supply mosfets were cool? I have two different types of multimeters, perhaps I should have used the one to measure amperage drawn while testing! I have checked every transistor for low readings with the diode check and shorts but cannot find anything!
Perhaps I should be checking all the resistors as well? I had a resistor issue in a polk audio class a/b 4 channel that kept leading to a failed channel that would over heat! It also caused some transistors for the output section to heat up! Once I changed it on all of the channels the issue went away, it was leading to excessive heat from the pnp and npn output transistors! But it wouldn't go into protect mode!
Could that be an issue? I know it was a class A/B but it was a drive circuit resistor and the small transistors would heat up fast as well as output ones!
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Also I just measured R810, R811, R812, R813 and they measure 3.3 ohms, but they are supposed to be 6.8 ohm 1/4 watt chip resistors, they look good and clean! They are connected to Q26 2SD2012-F transistor! The Collector of 2SD2012-F runs through them and down to C14 on the negative side/terminal trace!
If you find a used CRT based scope with a triggered sweep, it's likely to be good enough.
The power supply can run cool and the outputs hot if the output section is defective.
You cannot use the amp function of the meter directly if the amp is drawing excessive current. IT will either damage the meter or blow the internal fuse. That's why I suggested measuring across a shunt (length of wire).
I'd recommend getting the correct output transistors and checking all components in the drive circuit for the FETs that failed.
This isn't likely to be a significant problem for now as long as you have the 40v on the collectors of Q25 and Q26.
The power supply can run cool and the outputs hot if the output section is defective.
You cannot use the amp function of the meter directly if the amp is drawing excessive current. IT will either damage the meter or blow the internal fuse. That's why I suggested measuring across a shunt (length of wire).
I'd recommend getting the correct output transistors and checking all components in the drive circuit for the FETs that failed.
This isn't likely to be a significant problem for now as long as you have the 40v on the collectors of Q25 and Q26.
Ok thanks, the meter I was talking about is one that measures high amperage that I would place the clamp around the positive power cable to check the amperage draw during operation, much like BigDWiz does during dyno test's, much in the same way you would check wattage output, amperage draw times A/C voltage from amp output!
I did pull the two main caps at C13 and C14, there is a big resistance difference, I flipped the meter at 20m ohms and C14 measured .43 and C13 measured .03! They also kind of rattle so I am replacing them! I also bent the clamps to tighten the transistors mounts ahead of time!
The rds for the 33N15's that were stock is .056 ohms and the IRF3415's I used have an rds of .042 ohms! But I am still checking the drive circuit section! Thanks for the fast replies! I do hope if people have their amp stuck in Error 02 they try the method I tried to get it working!
I just couldn't believe the guy I bought it from thought he could start a business repairing amps, but I gave him some tips on saving the traces next time and checking resistors! He even used knock-off 60n06's not knowing they fail! Some sellers actually sell quality transistors on ebay, but a lot of them are knock-offs!
I did pull the two main caps at C13 and C14, there is a big resistance difference, I flipped the meter at 20m ohms and C14 measured .43 and C13 measured .03! They also kind of rattle so I am replacing them! I also bent the clamps to tighten the transistors mounts ahead of time!
The rds for the 33N15's that were stock is .056 ohms and the IRF3415's I used have an rds of .042 ohms! But I am still checking the drive circuit section! Thanks for the fast replies! I do hope if people have their amp stuck in Error 02 they try the method I tried to get it working!
I just couldn't believe the guy I bought it from thought he could start a business repairing amps, but I gave him some tips on saving the traces next time and checking resistors! He even used knock-off 60n06's not knowing they fail! Some sellers actually sell quality transistors on ebay, but a lot of them are knock-offs!
To do that you need a clampmeter that does DC amps. That's relatively rare.
If you can predict what transistors will work in a class D output stage with any great degree of success, you're a better tech than I am. It's sometimes easier with this type of amp that has the deadtime set farther back in the circuit but it's still difficult looking at the datasheet alone.
If you can predict what transistors will work in a class D output stage with any great degree of success, you're a better tech than I am. It's sometimes easier with this type of amp that has the deadtime set farther back in the circuit but it's still difficult looking at the datasheet alone.
As soon as I get the Capacitors probably mon or tues I will give it another shot, it was actually only one mosfet that heated so much that it shorted, but the one next to it tested for a short as well while installed, again they were Q184, Q168!
All the rest were fine, they were really loose on the heat sink and the insulator is kind of odd compared to others! The guy who tried to repair it did not pay attention to the output section at all, obviously two were shorted. It was also missing screws all over, but I did have extras and replaced the missing ones!
Other than the service manual there isn't much on the amp itself! But I even charged the main caps 56V 4700 uf with the diode function to compare the results via 20v dc on the multimeter and one was 2.11v and the other 2.42v, I compared that with a new pair tested the same way and they both read the same exact voltage!
The Amp seemed pretty good, I was running it on a 4 ohm svc sub, I use a pioneer DEHP-5900IB on my bench, it has 3 sets of 4v preouts, I had demo mode enabled on the amp the lcd rotates between voltage and amperage allowing me to monitor the voltage and amp draw! Once it got too hot on the output side error 3 enabled, then I heard the short, then it went to error 02.
I took it apart and found out the mosfet shorted, the caps are original and I pulled them just in case they dried up and though they hold voltage, it varies and they rattle inside, the bad one's ground was connected to the trace that runs under the board to L4 and L5 and the top of the board to R204 it looks like the traces lead up to the collector of Q26, then another trace to ic 14 and a few other locations in the drive circuit! Also I did have to replace the Diodes at D12 and D13, the numbers were so low it would have kept it from operating.
And the clamp I do have only features A/C amperage, they do have DC amperage analog gauges and lcd's with shunts for vehicles, perhaps that would be something to add to my bench! I do know when it started up, it said it was drawing 2 amps with no audio on the lcd.
I will keep working on it, I really appreciate how you help others here on diy, your well known on many sites I have searched! I will get back to you when I install the caps and put it back together!
All the rest were fine, they were really loose on the heat sink and the insulator is kind of odd compared to others! The guy who tried to repair it did not pay attention to the output section at all, obviously two were shorted. It was also missing screws all over, but I did have extras and replaced the missing ones!
Other than the service manual there isn't much on the amp itself! But I even charged the main caps 56V 4700 uf with the diode function to compare the results via 20v dc on the multimeter and one was 2.11v and the other 2.42v, I compared that with a new pair tested the same way and they both read the same exact voltage!
The Amp seemed pretty good, I was running it on a 4 ohm svc sub, I use a pioneer DEHP-5900IB on my bench, it has 3 sets of 4v preouts, I had demo mode enabled on the amp the lcd rotates between voltage and amperage allowing me to monitor the voltage and amp draw! Once it got too hot on the output side error 3 enabled, then I heard the short, then it went to error 02.
I took it apart and found out the mosfet shorted, the caps are original and I pulled them just in case they dried up and though they hold voltage, it varies and they rattle inside, the bad one's ground was connected to the trace that runs under the board to L4 and L5 and the top of the board to R204 it looks like the traces lead up to the collector of Q26, then another trace to ic 14 and a few other locations in the drive circuit! Also I did have to replace the Diodes at D12 and D13, the numbers were so low it would have kept it from operating.
And the clamp I do have only features A/C amperage, they do have DC amperage analog gauges and lcd's with shunts for vehicles, perhaps that would be something to add to my bench! I do know when it started up, it said it was drawing 2 amps with no audio on the lcd.
I will keep working on it, I really appreciate how you help others here on diy, your well known on many sites I have searched! I will get back to you when I install the caps and put it back together!
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Perry just in response to your advice on my kenwood! I did order the 33n15's and installed them along with the main capacitors and the power supply caps, reset the amp as I said it was done above or below in this article and it works great! It does have a 2 amp draw at idle or atleast that is what the lcd reads, I had to re-enable the fan in this mode as well as impedance protection and a few other things I checked, I ran it under load including a 2 minute 30hz test track just on a 4 ohm sub and it leveled out at 109 degs f after ten minutes on the lcd with volume nearly maxed from my DEH-P5900IB with 4v preouts! It works great! So thanks for the help! Just so people can be reminded, to get into the menu especially to adjust the fan control, enable impedance protection! You have to connect the ground to the amp, install the remote wire and have it live, then while pushing the rotary knob in, insert the live positive cable into the B+ input, let off the knob and use the rotary function to select the choice or function you wish to change and push in the rotary knob to select, then turn the rotary knob to select on or off! This will help with error 02 codes to get the amp to turn on and allows access to important modes you wish to enable or disable, like fan control, impedance protection and a few more! So this is basically closed and the amp is working properly!
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