hifonics hifi1000.1d - Page 3

ian33 · 12th April 2012, 01:40 AM

no i don't have a scope yet.Am looking for one

ian33 · 12th April 2012, 02:02 AM

picc

Perry Babin · 12th April 2012, 06:30 AM

The power supply driver IC is a KA7500. It's essentially the same as a TL494/594.

Without a scope, it's going to be difficult to trace the problem. You stated that the driver transistors were OK. If the gate resistors are OK, you really need to be able to look at the signal.

What is the value of the gate resistors?

What are the power supply FETs that you installed?

ian33 · 12th April 2012, 11:16 PM

gate resistor 47 ohms

Powere supply FETs irfz44n replace with the same

owener just told me he think someone try to power this amp up with 220v AC
Nothing in this amp looked badly burnt. All i found bad was two shorted outputs and leaky PS FETs.Also one rectifier had an open circuit from the middle leg to the body.i change both. Both rectifiers are out of circuit

Perry Babin · 13th April 2012, 01:01 AM

There shouldn't be a problem with those FETs and resistors.

With the rectifiers out of the circuit, are you reading something near 5v DC on the gates of the power supply FETs?

ian33 · 13th April 2012, 01:34 AM

Three of them read 3.03v and the other three read 3.08v

Perry Babin · 13th April 2012, 02:48 AM

What's the DC voltage on pins 9 and 10 of IC1 on the power supply driver board?

ian33 · 13th April 2012, 02:57 AM

#ka7500 IC

pin 9 3.05v

pin10 10.03v

Perry Babin · 13th April 2012, 03:00 AM

These should be very nearly identical, especially considering that the voltage on the gates of the FETs is nearly identical.

Are you sure that you have the pins right and there were no mistakes measuring the voltage?

If there was no mistake, post the voltage on all pins of IC1.

ian33 · 13th April 2012, 03:37 AM

sorry i check the wrong pins

pin 9 3.37v

pin 10 3.40v

IC is had to reach

I will post the voltage on all pin after i take the card out of the board and used wire to connect it back to the boad

12th April 2012, 06:30 AM	#23
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The power supply driver IC is a KA7500. It's essentially the same as a TL494/594. Without a scope, it's going to be difficult to trace the problem. You stated that the driver transistors were OK. If the gate resistors are OK, you really need to be able to look at the signal. What is the value of the gate resistors? What are the power supply FETs that you installed? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

13th April 2012, 01:01 AM	#25
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	There shouldn't be a problem with those FETs and resistors. With the rectifiers out of the circuit, are you reading something near 5v DC on the gates of the power supply FETs? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

13th April 2012, 02:48 AM	#27
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	What's the DC voltage on pins 9 and 10 of IC1 on the power supply driver board? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

13th April 2012, 03:00 AM	#29
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	These should be very nearly identical, especially considering that the voltage on the gates of the FETs is nearly identical. Are you sure that you have the pins right and there were no mistakes measuring the voltage? If there was no mistake, post the voltage on all pins of IC1. __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

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12th April 2012, 01:40 AM	#21
ian33 diyAudio Member Join Date: Jun 2010 Location: the caribbean	no i don't have a scope yet.Am looking for one

12th April 2012, 11:16 PM	#24
ian33 diyAudio Member Join Date: Jun 2010 Location: the caribbean	gate resistor 47 ohms Powere supply FETs irfz44n replace with the same owener just told me he think someone try to power this amp up with 220v AC Nothing in this amp looked badly burnt. All i found bad was two shorted outputs and leaky PS FETs.Also one rectifier had an open circuit from the middle leg to the body.i change both. Both rectifiers are out of circuit

13th April 2012, 01:34 AM	#26
ian33 diyAudio Member Join Date: Jun 2010 Location: the caribbean	Three of them read 3.03v and the other three read 3.08v

13th April 2012, 02:57 AM	#28
ian33 diyAudio Member Join Date: Jun 2010 Location: the caribbean	#ka7500 IC pin 9 3.05v pin10 10.03v

13th April 2012, 03:37 AM	#30
ian33 diyAudio Member Join Date: Jun 2010 Location: the caribbean	sorry i check the wrong pins pin 9 3.37v pin 10 3.40v IC is had to reach I will post the voltage on all pin after i take the card out of the board and used wire to connect it back to the boad

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