Tokin 614 J component????

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I have an old device that uses a serial port for communications with a PC, and for the life of me I can not get it to work with a USB to RS232 device. Works fine if I connect it to a real serial port. Between the DB25 and the Max238 are a few chips marked "Tokin 614 J", my web searches are coming up empty. I think they are some kind of ESD protection, maybe an opto-isolator. The have 2 legs on one side, two more on the other which suggests opto and the USB/232 adapters will not have to current to push through one of these.

Before I tear them out and put jumpers in I thought I would ask and see if anyone knows what they are and what harm might come from the removal. If the only harm might be that I burn the Max238, so be it. I may also bypass that part of the Max238 and install an FTDI USB to TTL serial device and be done. Default operations are with no handshaking, so I should only need TX, RX, ground which should allow USB conversion without too much difficulty.

Thanks for any help provided.

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Highly unlikely to be optos in that location. More than likely some form of EMI/ESD protection device. Take a look at the NEC/Tokin product line offerings.

Writing code is like having sex.... make one little mistake, and you're supporting it for life.

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Did that but couldn't find a match to that number anywhere.

The more I think about it, the more I may decide to try connecting the USB device to the TTL side of the Max238 and see what happens.

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The USB device, if a commercial cable, will have a level converter in it, so that could damage your board. Honestly, it should work... I'd take a scope and look at the signal levels when everything is connected.

Writing code is like having sex.... make one little mistake, and you're supporting it for life.

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Try with 100 ohm first ;)

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Yes a 100 ohm resistor instead of a piece of wire would be a good idea.

I'm going to bring the board to work and pull those devices and see if they from a bridge in the path or just and overflow. If it's just an overflow then they must be just ESD and I can probably get by with removing them. If a bridge then they could be just about any sort of buffer and I can still probably get by with removing them.

I also need to solder some test wires down to the low level side of the Max238 to put a scope on them and see what I'm dealing with. Having the USB comm port mounted in the equipment would certainly make it easier to use. This thing uses a Siemens SAB 80C166 processor running at 5 volts, so I'm pretty sure the low level serial also runs at 5 volts.