Hello. I have a kenwood amp (kac 846) that does not seem to power up at all (no led light). Where do I even start to troubleshoot. I have a multimeter and can take apart the amp. What next? If there is a thread for basic amp troubleshooting will someone let me know. Also all my fuses are fine. Thanks in advance.😕
info
Hello, first take your multimeter and check the transistors of amp. First the supply fets, power audio transistor, diodes, resistors. If the supply fets are good, then to next step.
Hello, first take your multimeter and check the transistors of amp. First the supply fets, power audio transistor, diodes, resistors. If the supply fets are good, then to next step.
With the amp powered up (including remote), measure the voltage on each pin of the power supply IC. It's likely to be a TL494 or a TL594. Download the datasheet (google datasheet TL594) so you'll know how the pins are numbered.
You'll set the meter to DC volts.
The black lead will be connected to the chassis ground connection of the amp. You'll touch the red meter probe to each of the pins of the IC.
List the voltages like this:
Pin 1:
Pin 2:
Pin 3:
Don't let the meter probes slip and short between pins.
Insert a 10 amp fuse in the B+ line for added protection while testing.
You'll set the meter to DC volts.
The black lead will be connected to the chassis ground connection of the amp. You'll touch the red meter probe to each of the pins of the IC.
List the voltages like this:
Pin 1:
Pin 2:
Pin 3:
Don't let the meter probes slip and short between pins.
Insert a 10 amp fuse in the B+ line for added protection while testing.
pc494
I think i found the power supply IC but not sure. I found no IC with TL494 but did find a IC made by NEC labeled PC494C. This IC has 16 leads. Is this the same thing?
I think i found the power supply IC but not sure. I found no IC with TL494 but did find a IC made by NEC labeled PC494C. This IC has 16 leads. Is this the same thing?
The 'x94' IC is produced by many different manufacturers. You'll find various prefixes and even clones with completely different numbers.
C494 - actually UPC494 produced by NEC
TL494 and TL594 - mainly produced by Texas Instruments but also others.
KA7500 - likely produced by KEC
The TL494 and 594 are essentially the same IC (only slight differences which are generally insignificant).
C494 - actually UPC494 produced by NEC
TL494 and TL594 - mainly produced by Texas Instruments but also others.
KA7500 - likely produced by KEC
The TL494 and 594 are essentially the same IC (only slight differences which are generally insignificant).
Alright I used the multimeter (DC Volts) to measure the voltages on each of the pins on the TL494 compatible IC. I get no voltages on any of the pins so I assume the IC is not getting any power. Once again all my fuses are fine and I have power, remote power and ground all hooked up. Which direction do I head in now? I also tested some of the regulators attached to the amp chassis with same results, no voltages. Thanks again for helping me out. This is my first attempt at electronic circuit troubleshooting.
The power is likely supplied to the IC via a PNP transistor. The number on the transistor would begin with an A (i.e. A733, A1534). You'll have to follow the traces to find the transistor. Confirm the connection between the transistor and pins 8, 11 and 12 of the 494 (meter set to ohms, no power applied to the amp, ~0 ohms = a direct connection between the two points).
If this amp uses surface mount components, the part numbers will be coded.
Can you post a reasonably good quality photo of the inside of the amplifier?
If this amp uses surface mount components, the part numbers will be coded.
Can you post a reasonably good quality photo of the inside of the amplifier?
Not trying to thread jack but I too have the same model amp that just started popping both 20amp fuses about 3 seconds after power up. I am also curious about troubleshooting these amps and the outcome of this thread..
If I should start a second thread LMK.
If I should start a second thread LMK.
euspanks:
I've located a manual. I should have it tomorrow.
cancruiser:
You likely have shorted output transistors (large black devices mounted to the heatsink). None should read near zero ohms between pins 2 and 3. If that's not the problem, start a new thread.
I've located a manual. I should have it tomorrow.
cancruiser:
You likely have shorted output transistors (large black devices mounted to the heatsink). None should read near zero ohms between pins 2 and 3. If that's not the problem, start a new thread.
Thanks Perry. I checked all of them and found 1 C5100 and 1 A1908 that both checked out at 0. Can I assume that this should be and easy repair by just replacing these two? If so is there a good place online to find them?
http://www.mcminone.com/search.asp?keyword=2sa1908
Add a '2S' prefix to the part number on the transistors.
It's possible that there is no other damage. When you replace the transistors, power it up via a 7.5 amp fuse. If it plays at low volume without blowing the 7.5A fuse, it's likely OK. The transistors (all of them) need to be clamped/screwed down tightly before applying power.
Apply new heatsink compound (Radio Shack) between the new transistors and the heatsink. Clean the area before applying new compound.
Add a '2S' prefix to the part number on the transistors.
It's possible that there is no other damage. When you replace the transistors, power it up via a 7.5 amp fuse. If it plays at low volume without blowing the 7.5A fuse, it's likely OK. The transistors (all of them) need to be clamped/screwed down tightly before applying power.
Apply new heatsink compound (Radio Shack) between the new transistors and the heatsink. Clean the area before applying new compound.
euspanks:
With the amp powered up (including remote), measure the DC voltage on each pin of Q32.
Connect the black meter lead to the ground terminal of the amplifier. Touch the red lead to each pin of Q32. Don't let the lead slip and short between the pins.
With the amp powered up (including remote), measure the DC voltage on each pin of Q32.
Connect the black meter lead to the ground terminal of the amplifier. Touch the red lead to each pin of Q32. Don't let the lead slip and short between the pins.
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