Hello.
I need help in repairing of M-Audio sound card. The model is Fast Track Pro. The problem is highly distorted output. Unfortunately I couldn’t find the schematic. I measured voltages of power supplies pins of opamps. Positive seems ok (4.5V), while negative is only minus 0.8V. I attached the photo. Does the chip which I marked make negative voltage? The marking on the chip is: first line – 67351 or 6735I, second line – 95T, third line – CD8Q. I didn’t find anything on the Internet about this chip. Maybe negative supply is formed somewhere else?
Thanks!
I need help in repairing of M-Audio sound card. The model is Fast Track Pro. The problem is highly distorted output. Unfortunately I couldn’t find the schematic. I measured voltages of power supplies pins of opamps. Positive seems ok (4.5V), while negative is only minus 0.8V. I attached the photo. Does the chip which I marked make negative voltage? The marking on the chip is: first line – 67351 or 6735I, second line – 95T, third line – CD8Q. I didn’t find anything on the Internet about this chip. Maybe negative supply is formed somewhere else?
Thanks!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Just based on what you show it does look like it could be a negative rail generator as there is a coil and diode also shown. Before condemning anything make sure there is no problem on the negative rail that is drawing excess current. The diode itself could be a suspect too.
If you have a bench PSU you could try and backfeed the negative rail in situ with it all working and see if the current consumption is excessive.
If you have a bench PSU you could try and backfeed the negative rail in situ with it all working and see if the current consumption is excessive.
When I connected external negative power supply the card started to work properly. So it seems that the problem is in the part of the positive to negative supply conversion. But I cannot find what is that chip. I searched similar 8 pin convertors but those I watched had different pin location… Maybe someone knows the marking of the chip or proper analogue?
Thanks.
Thanks.
The diode is a high speed type and it might not test well in circuit.
Not doubting your readings
but you need to sure. Does the chip or diode get warm in use ? Can you measure a supply voltage to the DC convertor chip ?The diode seems ok. Voltage drop 0.2V. Voltages on the pins: 1 plus 5.57V, 2 plus 1.22V, 3 plus 0.2V, 4 plus 0.8V, 5 minus 0.8V, 8 plus 5.57V. Electrolytic caps are ok. I didn’t removed smd caps for checking but they are less subjected to damage. I watched the pins with oscilloscope – all voltages are constant. The chip and diode are cold.
What do you think my next step should be?
What do you think my next step should be?
Hello friends !
I have a FAST TRACK PRO and it turns on and gets all the lights on.
The PC reconfirms it, but it does not switch. Would someone have the electric scheme for me to try and repair?
Thank´s for support ! Hugs from Brazil!
marcdebarros@hotmail.com
I have a FAST TRACK PRO and it turns on and gets all the lights on.
The PC reconfirms it, but it does not switch. Would someone have the electric scheme for me to try and repair?
Thank´s for support ! Hugs from Brazil!
marcdebarros@hotmail.com
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