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Electronics => Repair => Topic started by: CRTBeam on July 13, 2018, 04:51:35 pm

Title: Tascam US-4x4 - worth trying to fix?
Post by: CRTBeam on July 13, 2018, 04:51:35 pm

So, my trusty audio interface has released the magic smoke. I don't fully know the cause, but i suspect transient on the usb side of things. It blew a hole in the main CPU wich is LPC1820FBD144. So the question is, will replacing the CPU will make it work again? There is a little 8-pin flash(MXL25L4006E, to be precise) and there is a usb software tool for updating firmware. The only programming header on the PCB is connected to this little flash. The chip has a hardware USB support so it should be recognised by the PC(I think). Getting the chip in single quantity, proved to be difficult, also prices aren't the lowest. So should I pay $40 for a chip and try, or should i save up for a new interface?

Title: Re: Tascam US-4x4 - worth trying to fix?
Post by: helius on July 13, 2018, 05:46:11 pm

LPC1820FBD144 has no on-chip Flash or EEPROM, but you should verify it has no configuration fuses that need to be programmed.
Transient on the USB side shouldn't fry the chip. There are TVS diodes to protect it. I would check the power supply isolation.

Title: Re: Tascam US-4x4 - worth trying to fix?
Post by: CRTBeam on July 13, 2018, 06:38:19 pm

It has OTP memory. I found a pdf describing it. Sadly I don't really know what should be written to it. I'm a noob when it comes to the microcontrollers. Should BOOT_SRC be changed to SPI (little flash chip)?