Kenwood KAC-7202

S Merlington · 2013-02-16 7:47 pm

Does anyone have the board location of the positve 15 volt regulator?

Perry Babin · 2013-02-16 8:11 pm

Q1. on the heatsink.

S Merlington · 2013-02-16 9:35 pm

When i try to power this amp up the power 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 3:4.63
Pin 4:0.31
Pin 5:1.48
Pin 6:3.58
Pin 7:0.00
Pin 8:13.79
Pin 9:0.00
Pin 10:0.00
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 what might cause this?

Perry Babin · 2013-02-16 10:52 pm

DC offset in one channel?

S Merlington · 2013-02-17 12:25 am

Ok got the amp to power up..

Heres what i get on Q1

Leg 1:0.00
Leg 2:45.6
Leg 3:0.6

I replaced that regulator and still dont get 15 volts on the 3rd leg.. Any ideas ?

Perry Babin · 2013-02-17 4:18 am

Check R3, D3 and C4.

S Merlington · 2013-02-17 1:47 pm

R3 tests good.

Replaced D3

Replaced C4

Amp still doesnt produce the positive 15 volts

Perry Babin · 2013-02-17 1:58 pm

What's the DC voltage on each end of R3?

S Merlington · 2013-02-17 2:44 pm

1 side:45.6

Other side:0.1

Perry Babin · 2013-02-17 3:04 pm

What is the resistance across D3 in the circuit?

S Merlington · 2013-02-17 3:18 pm

I get 17.23K ohms

Perry Babin · 2013-02-17 3:35 pm

Remove Q1 and post the DC voltage on all 3 of its pads.

S Merlington · 2013-02-17 7:15 pm

Pad 1:0.06
Pad 2:45.7
Pad 3:-0.74

S Merlington · 2013-02-18 10:16 am

Any ideas where to check next ? see post 13

Perry Babin · 2013-02-18 12:20 pm

Did you pull one leg of R3 out of the board when you checked it?

Either something is preventing it from pulling the voltage up on the diode and capacitor or it's well out of tolerance.

S Merlington · 2013-02-18 8:11 pm

I measured it out of the board.. It measured 12.95 K ohms

Perry Babin · 2013-02-18 9:41 pm

You're going to have to find what's dragging the voltage down. The diagram only shows the Zener, the capacitor and the base of the transistor connected to the resistor.

S Merlington · 2013-02-20 11:51 pm

Do you happen to know the part numbers for the diode and the regulator?

Perry Babin · 2013-02-20 11:56 pm

There is no regulator. The transistor, the zener and the resistor work together to regulate the voltage.

The transistor is a 2SD2012-F. The diode is a 16v zener.

S Merlington · 2013-02-21 12:00 am

The diode your talking about is a SMD on the bottom side of the board??

Kenwood KAC-7202

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