Problem with a White's TDI

[AlexP]

Hello,

My 4.5 years old (SMT) White's TDI won't start when the outside temperature is below 10deg Celsius. The battery status leds light up, but there is no sound from the speaker. After several tries to turn it on, eventually it would sometimes turn on and then work just fine. This only happens in winter. No problems whatsoever in the summer.

Could it be the crystal that causes the problem?

[Carl-NC]

No, it's probably the micro. We started with an Atmel micro which, for some reason, had a tendency to lock up on power-up, exactly as you describe. I switched over to a PIC which, miraculously, has almost the exact same pinout, and the problem went away. We can fix the TDI by swapping out the micro, and there would be no charge. But it would have to come back to the factory for this.

[AlexP]

Thanks Carl. I am in Bulgaria and sending it to the USA is not an option. I will try to fix it myself or get someone to fix it for me. Where on the PCB is the micro and what PIC can it be substituded with? Here is an actual photo of the PCB of my White's TDI - http://img272.imagevenue.com/img.php..._122_490lo.jpg

[Geo]

Thanks Carl. I am in Bulgaria and sending it to the USA is not an option. I will try to fix it myself or get someone to fix it for me. Where on the PCB is the micro and what PIC can it be substituded with? Here is an actual photo of the PCB of my White's TDI - http://img272.imagevenue.com/img.php..._122_490lo.jpg

I don't think that you can replace the mpc. You have n't the code????

[Mechanic]

Hi AlexP,

Add a little heater to the board! Seriously though if it is temperature related a low value resistor could be added above the micro with some sort of contact paste/glue and just switch the resistor on for a few seconds(how ever long is required to heat it up enough) before starting the detector up. Of course, select the resistor so it does not burn up!! The micro will be the square part with lots of legs! If your still unsure, post a photo. Also try heating up the micro a bit with a small hot air gun just to confirm that this method will work.....

Cheers Mick

Ok just saw the pic The micro is the one next to the 6 pin header, the so14 device.

[dougAEGPF]

Thanks Carl. I am in Bulgaria and sending it to the USA is not an option. I will try to fix it myself or get someone to fix it for me. Where on the PCB is the micro and what PIC can it be substituded with? Here is an actual photo of the PCB of my White's TDI - http://img272.imagevenue.com/img.php..._122_490lo.jpg

What no white paint covering the board and components!!!
dougAEGPF

[Orbit]

Indeed, where is the Atmel CPU ??

[Orbit]

it's okay I can see where above the driver !

[Orbit]

How about some better pictures 4 tdi ic circuits can not be seen ,I have the impression the VCO made ad 654 and not with 555 ic - Is not that the ?

[Carl-NC]

Thanks Carl. I am in Bulgaria and sending it to the USA is not an option. I will try to fix it myself or get someone to fix it for me. Where on the PCB is the micro and what PIC can it be substituded with? Here is an actual photo of the PCB of my White's TDI - http://img272.imagevenue.com/img.php..._122_490lo.jpg

I can't read it on that photo, but it's the chip next to X1. I could probably send you a replacement chip if you can get someone to swap them.

[AlexP]

I can't read it on that photo, but it's the chip next to X1. I could probably send you a replacement chip if you can get someone to swap them.

Yes, that would be great. I am not into electronics and will get someone to replace it for me. I guess I can't just buy the same chip from somewhere because it needs to be pre-coded by you?

[Carl-NC]

Correct.

[AlexP]

Correct.

You sending me a replacement chip is my only option then. Should I p.m. you to arrange the details?

[bklein]

Hi AlexP,

Add a little heater to the board! Seriously though if it is temperature related a low value resistor could be added above the micro with some sort of contact paste/glue and just switch the resistor on for a few seconds(how ever long is required to heat it up enough) before starting the detector up. Of course, select the resistor so it does not burn up!! The micro will be the square part with lots of legs! If your still unsure, post a photo. Also try heating up the micro a bit with a small hot air gun just to confirm that this method will work.....

Cheers Mick

Ok just saw the pic The micro is the one next to the 6 pin header, the so14 device.

Actually you already have one - the heat sink. Mount an aluminum or copper tab from it to the top of the Atmel chip.

[Qiaozhi]

Actually you already have one - the heat sink. Mount an aluminum or copper tab from it to the top of the Atmel chip.

Interesting workaround, but it probably won't work. Since the micro has failed to start, the MOSFETs won't be switching, and hence no heat.