The zener is connecting the G and S of N-CHANNEL 900V
Dear ALL, can anyone help me? I have a problem in seeing code written on a zener diode I am to replace on a Chinese made Sony plat screen Tv (LGPDP42V7)PSU board. The zener is connecting the G and S of N-CHANNEL 900V - 1.56- 5.8A /TO-220FP transistor (P6NK90FP)on the PSU board
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just read the model and then google it, beside, if you short them, you need to replace them with same value, and this will be determined by the circuit, if you did not change the circuit - just buy two new diodes and install them, do not bother with voltages as they have some tolerance and type will determine it.
I'm not sure what your question is. A zener diode is a voltage regulator of sorts. The zener voltage is the avalanche voltage...the voltage that the zener diode will maintain when it's connected in series with an impedance, usually a resistor, IF the voltage across the zener diode and the impedance, in series, is greater than the avalanche voltage (zener voltage), and the polarity of the voltage across the zener diode is thus: positive cathode, negative anode (i.e., reverse bias). The excess voltage (the margin) appears across the impedance. Zeners are often used as voltage reference diodes in regulated power supplies. Does this answer your question?
The zener diodes are 1N4774, I believe they are one watt. Try 3 watt metal oxide for the resistors. You might as well replace the 6800uF 63 volt main filter capacitors and the 220uF 50 volt capacitors while you're at it. Half the time the heat that cooked your other parts takes them out as well.
Yes, Zener diodes can work both on forward and reverse biasing. The primary difference between a zener diode and the ordinary junction diode is it is designed specifically to operate with a reverse bias voltage that is high enough to cause the the device to breakdown and conduct a high reverse current. Hope this answers your question and provides you with some help. If you need further assistance please let me know.
If you do not mind, would you please rate my help. I would very much appreciate it. Thanks
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.