Kenwood KAC-7202

Perry Babin · 2013-02-21 12:17 am

I don't have photos but it appears that that's what it is. This is the part number:
02DZ16F-Y

but it will probably be easier to buy a generic replacement. For testing, you can use a through-hole zener.

S Merlington · 2013-02-21 10:15 pm

The diode is defective ..

I was looking at a differnt diode so didnt think it was bad..

The Diode D3 is defective wondering what way it faces since the diode on the board now is burnt..

Perry Babin · 2013-02-21 10:17 pm

The striped end of the zener connects to the resistor and the base of the transistor.

S Merlington · 2013-02-22 8:59 pm

Ok now i get the Positive 15 volts..

But now i get 40 volts on all 3 legs of the transistor that controls the - 15 volts..

Any ideas what would cause this?

Perry Babin · 2013-02-22 9:25 pm

Do you mean negative 40v?

The zener either has a bad connection to the pads or is open. This may have caused damage to some of the op-amps. Most op-amps can't withstand more than a bout 32v total across their power supply terminals. This would have applied 55v across them.

S Merlington · 2013-02-22 9:34 pm

Is it the same with this also the stripped side goes to the base of the transistor ?

Perry Babin · 2013-02-22 10:26 pm

No. It's reversed for the negative regulator. If it was installed reversed, the voltage should have been limited to less than 1v out from the regulator.

S Merlington · 2013-02-23 1:31 am

Ok i have both + - regulated voltages now..

How do i check to see if the op-amps are defective ?

Amp powers up but has no output

S Merlington · 2013-02-23 1:54 am

Ok with all parts put back in the amp when i try to power it up the red light will come on for 2 secs then shut off..

Heres what i get on the 494

Pin 1:2.54
Pin 2:0.56
Pin 3:4.73
Pin 4:0.61
Pin 5:1.45
Pin 6:3.58
Pin 7:0.00
Pin 8:13.89
Pin 9:0.02
Pin 10:0.03
Pin 11:13.79
Pin 12:13.79
Pin 13:4.94
Pin 14:4.94
Pin 15:4.94
Pin 16:0.00

Any ideas??

Perry Babin · 2013-02-23 6:18 pm

The amp is in protect. I'd suspect that it's DC offset protection. Do you see excessive DC on either of the bridging speaker terminals?

S Merlington · 2013-02-23 6:50 pm

No both measure 0.02

When i first power up the amp i get a pulse of DC voltage about 5 volts from the left channel..

When the amp protects the voltage is at 0

I replaced the C4467's in th left channel 1 was defective..

Perry Babin · 2013-02-23 7:28 pm

The DC goes away because the amp goes into protection.

Before the regulator problems, was the amp going into protect mode?

S Merlington · 2013-02-23 7:29 pm

Yes

I found a A965 driver for the outputs thats defective..

Is there a good sub for that?

Perry Babin · 2013-02-23 7:39 pm

There are probably a lot of transistors that will work. If you can't find the original, I'd try a KSA1220A.

S Merlington · 2013-02-23 8:42 pm

I dont get this amp..

Replaced the A965 with the orginal..

Amp goes straight to prtection..

I pulled all outputs and drivers from the left channel amp still is stuck in protection..

Im going to pull the outputs from the right channel to see if the amp will power up

S Merlington · 2013-02-23 8:50 pm

All of the outputs are removed from the amp..

amp is cycling back and fourth betwwen powering up and protection mode..

Any ideas on where to go next?

Perry Babin · 2013-02-24 1:52 am

If you remove W308 near the 494, does that allow the amp to remain on?

Be careful, this will disable the protection circuit.

S Merlington · 2013-02-24 2:15 am

I dont see W308

Perry Babin · 2013-02-24 2:26 am

It's a wire jumper.

S Merlington · 2013-02-24 2:35 am

I see W8 and W608 dont see W308

Kenwood KAC-7202

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