Help with Problem X axis Stepper Please

[GND]

I had a quick look at this device's datasheet, and the only difference between the H and the HQ versions seems to be that the HQ is tinned with lead based solder, so it's not "lead free" as is required these days for commercial use. But for your purposes it really makes no odds - go for either and you'll be fine!

It also said that the rear of the chip is metal and connected internally, so you need to take precautions. However depending on what the heatsink is connected to, then it may have been designed to be non insulated, as that part of the chip appeared to be grounded. But just be aware of the options here!

[howser37]

Thanks GND, i have ordered the untinned one and will try that. I will look at the other other chips for guidance on how its connected to the heatsink.

[GND]

Sounds like a plan! Let us know how it goes....

Cheers
Graeme

[john swift]

either the TA8435HQ stepper driver IC needs to be electricaly isolated from the heatsink or the heatsink needs to be grounded
otherwise a faulty IC will damage other ICs mounted on the same heatsink !

take a close look at the discoloured contacts


check the socket for heat damage that may of softened the spring contact
so it will no longer grip the new IC's pins as tight as it should


John

[GND]

Good clarification, John - I assumed as much but I was in a bit of a rush and didn't explain myself very well last night! The back of the chip is internally connected to ground, so if the designer of the equipment didn't insulate it from the common heatsink, then the heatsink must be grounded as you say. I'd argue it's not ideal practice, and that insulating the chips individually is perhaps preferable. But best just reproduce what the manufacturer did, as it seems to work. Unless that was the cause of the failure of course....!

Well spotted regarding the contacts - they do look a bit iffy! Those are "turned pin" type sockets - high quality ones, which is a good start. But definitely worth following John's suggestion to check them carefully, or even replace them. That of course involves soldering :-)

Graeme

[howser37]

Thanks John and GND. I will check the pins for damage

[howser37]

Just in case anyone else is searching the forums about a similar issue, i replaced the damaged driver chip with a new one and the axis is now working fine again. There was a small silicone pad on the back of the old driver chip and thermal grease so i used this pad on the new chip and applied MX4 Thermal non electrically conductive paste to the back of the chip.

I did check that all the socket pins were working correctly and were not damaged prior to installing the new chip. The only slightly difficult thing was getting the pins into the socket without bending them as they are quite delicate. I did several hours of cutting last night with no issues