AMP not Powering On (56k Warning)

[QikoCB7]

Hi Everyone!

History:

The install was done by me around 4 years ago. It was working fine for the next couple of years. At some point I gave the car to a relative.
When I got it back, the amp was no longer installed. It was disconnected. Even the fuses were gone.... hahaha. So I placed it back in the box and left it alone, and drove the car without audio.

This weekend I finally had some free time to hook it back up. Installed 3 new fuses and reattached all the wires but…

My amp doesn't work, it is dead

No LED lights on the amp but there is power. 14+ volts on the power line, 12+ volts on the remote/turn on wire, and good ground.

So I disconnected it and brought it into the house. I began reading up on some troubleshooting steps and tried the following below. This is what it looks like opened up on the solder side and front.

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It seems the IC is KIA494AP. I am not sure what the numbers 716 means.
This is the data sheet for the IC KIA494AP datasheet pdf datenblatt - KEC(Korea Electronics) - BIPOLAR LINEAR INTEGRATED CIRCUIT (VOLTAGE-MODE PWM CONTROLLER IC) ::: ALLDATASHEET :::.

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The mosfet is DFP50N06.
The data sheet DFP50N06 - N-Channel MOSFET - DnI datasheet pdf - datasheet.co.kr

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My test power supply is a Corsair 750TX.

Some kinda of wire wrapped but it appears the glue rubbed off.

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The RCA side of the AMP.

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These are the Fuses I am using. Purchased from digikey.

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My Digital multimeter is DVM850BL. I set the dial to voltages - range 20.
http://www.vellemanusa.com/products/view/?country=us&lang=enu&id=350297

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So I hooked up the AMP to the PC power supply, and getting 12 volts on the power terminal. I then loop a wire to the remote/turn on terminal with 12 volts too. The ground terminal is connected to the PC power supply’s ground. Nothing else connected. No fuses, no RCAs connected, and no speakers.

The amp is still not turning on. No LED lights.

I checked the output voltages on the speaker terminals. Left side is .10 Volts and the right side is like 1.07 Volts.

I also checked the output voltages for each socket for the fuses. All of them are producing 10 volts. When I hook up a bulb to each one, it doesn’t light up.

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I then checked the mosfets on the power side. I placed the red probe on the middle leg, and placed the black probe on the first and last leg. Each one shows 12 volts I did the same for the next 11 mosfets. All of them are 12 volts. I then checked the resistors next to them. All of them show 12 volts.

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I am not sure how to troubleshoot the IC. Or the rectifiers.

I am stump, I have no idea why it is not powering on. Anyone with any suggestions?

Thanks!

 

[Perry Babin]

For all DC voltage readings (unless otherwise instructed), place the black probe on the ground terminal of the amp.

Install the fuses.

What is the DC voltage on the three legs of the power supply FET? If they're all essentially the same, you only need to post the DC voltage on the three legs of one FET.

 

[QikoCB7]

Thanks Perry!

I set the DMM to DC voltage to 20V and placed the black probe on the chassis ground. There appears to be a wire label "CH GND" screwed to the chassis.

I measured the 12 mosfets on the powered side of the circuit board with the red probe.

Each leg displayed 0.00 volts.

Second time I set the DMM to DC voltage to 200m and measured the 12 mosfets again.

The First legs are 01.1mV
The Last Legs are 01.1mV
The Center Legs always seem to drop down to around 00.4mV

 

[ivkata]

with a fuse installed and black probe on amp ground u must have 12v on middle leg of all power supply transistors .Once u confirm u have 12v on all check for voltage on leg 1 the one on the left side u must have ~5 volts if u have less the power supply is not starting .Also confirm that on pin 12 of the kia494 u have 12 volts .

 

[Perry Babin]

The ground screw to the heatsink may be DC isolated. Use the ground terminal that is next to the B+ and remote terminals outside the amp.

 

[QikoCB7]

Thanks Guys!

I will use the ground terminal that is next to the B+ and report back
Here is an image of the incorrect ground I used too.

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[QikoCB7]

I set the DMM to DC voltage to 20V and placed the black probe on outside ground terminal.

Power Supply Mosfets:

All center legs are 12.35V
The rest of the legs are 0.00V
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IC - KIA494AP:

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1. 1.01V
2. 6.67V
3. .10V
4. .29V
5. 0.00V
6. 0.00V
7. 0.00V
8. 0.10V
9. 0.05V
10. 0.00V
11. 0.10V
12. 11.68V
13. 6.67V
14. 6.67V
15. 6.67V
16. 2.24V

Rectifiers:

(I believe they are called that). They are the same measurements on the other side too.

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D11P1

1. 8.65V
2. 8.75V
3. 8.63V

D12P1

1. 8.65V
2. 9.11V
3. 8.63V

 

[Perry Babin]

The 494 appears to have failed. There may be other problems also because you should have approximately 12v on pins 8 and 11.

 

[QikoCB7]

So I should trace PIN 11 backwards to the B+, and check the components for failure?

Thanks,

 

[Perry Babin]

It's probably a bad connection on one of the jumper wires.

 

[QikoCB7]

Thanks Perry! I will check a few things tonight.

 

[QikoCB7]

I set DMM DC voltage to 20V.
So I traced pin 11 backwards and it connects to a jumper.

So I decided to hook up 18 AWG wire from the remote/turn on terminal to pin 11.

I placed the black probe on the ground terminal on the outside. I measured 12V on pin 11, and 12V on pin 8.

Afterwards, I removed the board from the chassis and observe the circuit trace on the back starting from pin 11.

I believe I cause more damage to the board. I noticed the trace on the board is no longer glued to the PCB. Also, somehow it split into 2 parts too.

So I solder the 18 AWG on pin 11 to the jumper wire. Screwed it back in and measured it again. Same measurements but it is still not turning on.

The mosfet's 1st and 3rd legs are still 0.00V. Center legs are 12V.

Any suggestions? I'll post pics of the damage and rewiring.

 

[Perry Babin]

What's the resistance with the black probe on pin 7 of the 494 and the red probe on pin 8 of the 494?

Did you smell it burn when you connected the jumper?

 

[QikoCB7]

Here is the back side of the board:

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Earlier I placed electrical tape over the wires, and taped the loose traces with tape too. I screwed the board back in and reconnected the B+, ground, and remote terminals. I didn't smell anything burning, or see any smoke. I disconnected the connections to the terminals.

I set DMM to Ohm 20k.

I placed black probe on pin 7 and red on pin 8.

The numbers kept going up. It did not stop.

 

[Perry Babin]

If you still don't have 12v on pins 8 and 11, you need to follow it all of the way back until you get to the remote terminal of the amp.

 

[QikoCB7]

Thanks Perry!

I had 12 V on pin 8 and 11. But i blew the mosfets on the left side and it appears i burned another trace on the pcb.

Bah i need to buy parts. What kind of jump wires do i use? I am not sure what size awg.

Gonna order mosfets, them drivers, jumper wires, an ic. Anything else i should add?

 

[Perry Babin]

The wire size isn't critical as long as the wire has at least as much copper as the trace did.

Read the basic repair page and pay special attention to the information in the yellow box. IF you do as is suggested there, you won't blow any FETs.

 

[QikoCB7]

Thanks Perry!

I am searching for the parts but unable to find the IC KIA494

I did find KIA494P
Match-a-knob Electronics Wholesale Distributor

I searched TL494 but found TL494CN
TL494CN Texas Instruments Voltage Mode PWM Controllers

I am guessing TL494CN can be considered a good substitute ? They seem to match.

I having a hard time figuring out a substitute for the mosfets DFP50N06.

Any suggestions? Thanks!

 

[Perry Babin]

The TL494 is the same as the KIA 494. The TL594 is also a good substitute.

The IRFZ44 or IRFZ46 are good subs for the DFP part.

 

[QikoCB7]

I am researching a couple more parts.

I am looking to replace a1266, which I believe are drivers? It comes back as a possible PNP TRANSISTOR EPITAXIAL.
A1266 datasheet, A1266 datasheets, A1266 datenblatt, A1266 manual, A1266 data sheets, A1266 pdf - ALLDATASHEET.COM

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Closes I found is a BD139 Transistor. Is this a good substitute?

Also, I was observing another IC, IL4558S-9. It appears to be a Dual Operational Amplifiers.

Datasheet:
IL4558S-9 pdf, IL4558S-9 description, IL4558S-9 datasheets, IL4558S-9 view ::: ALLDATASHEET :::

It is a SIP-9 design. I have like 5 of these on the board but I am looking at the one near IC 494.

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I found other similar OP AMPs like KIA358S, KA1458S, or KA458S but all these appear to be obsolete. Is SIP-9 also obsolete? I found a ton of 8 DIP designs.

What would replace an IL4558S-9 SIP-9 IC?

Thanks!