MSP430-JTAG-ISO-MK2 target driver chip type (attempting to repair damaged unit)

[ovirt]

Hi,

I am attempting to repair an MSP430-JTAG-ISO-MK2 which was accidentally attached to a target board which had 12V on pin 2 (Vcct). It looks like four of the five driver chips which interface with the JTAG pins were damaged. I can see the marking on the physically undamaged chip and also on one of the damaged ones, but not the other three. The marking I can see is "CT2R" and these are 8-pin DIL small outline SMD chips.

With those damaged chips removed the unit powers up and otherwise seems to operate ok, but I don't know what chips I need to obtain to replace the damaged ones. Can anyone tell me what they are: U3, U4, U5 and U6? Or even what they think they might be? My first guess is a voltage translating line driver/transceiver of some kind.

We're ordering a replacement unit anyway, but I would still like to try to repair this damaged one so that we have a spare unit, if possible.

Thanks!

[LubOlimex]

Hey,

U2, U3, U4, U5, U6 are all the same ICs – SN74LVC2T45 in VSSOP 8-pin package.

However, pin 2 of the JTAG is TRSTN and it has nothing to do with U2, U3, U4, U5, U6 – the wire connected to this pin 2 goes to pin 5 of the main chip and there is only a 3.3V pull-up via resistor matrix RM4G4 (10k) on the way. This means that either the 12V was not applied only to pin 2 but to other pins also OR the main chip of the board U1 was severely damaged. If it is the second scenario then probably the damage is beyond repair (other components got damaged too not only the main chip and the SN74LVC2T45 ICs).

Best regards,
Lub/OLIMEX

[ovirt]

Hi Lub,

Thanks for your reply.

Pin 2 of the JTAG as shown here:

https://www.olimex.com/Products/MSP430/_resources/msp430-jtag-tiny-v2-iso-mk2-layout.jpg

which is TVCC, Vcc supply to target board.

Thanks for the info. I will get some of those devices and see if replacing them brings any life back to this unit! Unfortunately there is some track damage as well, so I can only hope for the best for now.

The replacement unit should arrive tomorrow so we will be careful not to repeat our mistake!


Regards,

[LubOlimex]

Oh well,

This confusion happened because in our design files the internal JTAG is named simply "JTAG" and the one that you had in mind is named "MSP_JTAG_EXT".

The board has two JTAG interfaces, the external one that the end customer uses ("MSP_JTAG_EXT") and internal one that is used to upload firmware to the unit faster via another programmer.

Anyway, my previous point stands since TVCC_IN still has no direct connection to U2, U3, U4, U5, or U6. For sure another component burned in this case - the IC1 which is MCP602 in SO8.

Best regards,
Lub/OLIMEX