Want to know the value at "zd801" on si-727r-ds

ZD3 is a 18v zener. Also check the surface mount resistor on the back of the board that is attached to ZD3, I think it is R9. Should be 10 ohms. This resistor sometimes opens when the diode goes short.

Hi, I'm having the same problem with one of mine M1 Active 620. Please have you found out characteristics of D5 Zener diode, voltage?

1M200Z B0 200V
part no. NDLZ001M200Z

HZK Series

Silicon Epitaxial Planar Zener Diodes for

Stabilized Power Supply

open the following link and it help you it has all the detail about the mentioned diode

You need to get a service manual, this has all servicing information, including, the schematic diagram too, this will have values, for all components.
It could be a Zener, of almost any voltage, within a range, or a shottkey diode, a signal diode, or a flywheel diode.

its stamp on the side in tiny print
standerd values are 3.3 volt 5.1 12.0 ...

if it broke and is unreadable
you need to know the part location on
the board D or Z then #

On the cathode of the zener diode look for a filter cap and check its value the voltage of the zener should be less than the working voltage of the zener. Basicly its likely being used as a shunt regulator as protection and regulation of the voltage. When the zener hits a certain threshold it will breakdown and start conducting to ground until the supply regulates and then it will recover. If the filter cap for that voltage rail was 25V I would guess that the zener would probably be regulating between 12 and 20 volts. I'd pick a 15V Zener its probably +- %10 on the original and any system should be able to take a %10 tolerance as a general design rule.

I was not able to find any service or schematic for this model. The colors means that the value is 22.6 volts zener diode with the other blue band indicating where the cathode is.
Could you tell me where or what other components this zener diode is connected to?

TomTom One uses a Linear Technologies chip LTC3455 as a USB/charger power controller. See http://cds.linear.com/docs/Datasheet/3455fc.pdf. This chip is susceptible to high transient voltages that result from resonances created by parasitic inductances and capacitances of the USB/in-car charger cable . Good designs using this chip suggest that a 1 ohm resistance be put in the path of the cable to reduce the Q of the resonance and hence transient voltages. A 6V Zener diode D5 also serves to protect the chip from these transients.
If the Zener diode is blown it is most likely the the LTC3455 chip is gone as well. You can replace the chip which costs £5.00 (located in the shielded portion of the PCB). The recommended Zener Diodes for this chip are either the EDZ5.6B or EDZ6.2B manufactured by ROHM (http://www.rohm.com/products/databook/di/pdf/edz5.6b.pdf or http://www.rohm.com/products/databook/di/pdf/edz6.2b.pdf). These can be used to replace D5. The STMicroeletronics SM2T6V8A can also be used to replace D5 (http://www.st.com/stonline/products/literature/ds/8694/sm2t.pdf). All the Zeners cost a modest £0.22. I hope this is helpful.
Emmanuel Zyambo

ordinary zener diode