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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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PH-17D diode ratings?
This surface mount device is about the same size as other surface mount
diodes (1N4001, 1N4007) that I have dealt with. Markings: PH-17D and cathode band It appears to be a garden variety diode. Diode test on Fluke 87: 0.587 More curious about ratings. g. beat |
#2
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PH-17D - 177 volt zener
"g. beat spam protected wrote in message
. .. This surface mount device is about the same size as other surface mount diodes (1N4001, 1N4007) that I have dealt with. Markings: PH-17D and cathode band It appears to be a garden variety diode. Diode test on Fluke 87: 0.587 More curious about ratings. g. beat Well, it appears to be a 17 volt Zener diode. I have reverse engineered enough of this circuit (and a few voltages measurements) - to convince myself this is indeed a zener - probably 1/2 watt? The circuit is Weller's original control board (circa 1980s) for the "EC" series of soldering stations. Ceramic substrate and all surface mount (not bad for a 20 year old board - date stamped). Anyway, this control line is "LOW" (~ 1 volt) when the Triac is ON (soldering iron heater ON) and goes "HIGH" (~22 volts) when Triac is OFF (soldering iron heater OFF). This allows the LED in-line with the 24 VAC .. LED is ON, when control line is LOW LED is OFF, when control line is HIGH So, this appears to be the logic they used to create LED status light for heater activation :-) g. beat |
#3
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PH-17D - 177 volt zener
On Tue, 13 Jun 2006 19:33:33 -0500, "g. beat" @spam protected put
finger to keyboard and composed: "g. beat spam protected wrote in message ... This surface mount device is about the same size as other surface mount diodes (1N4001, 1N4007) that I have dealt with. Markings: PH-17D and cathode band It appears to be a garden variety diode. Diode test on Fluke 87: 0.587 More curious about ratings. g. beat Well, it appears to be a 17 volt Zener diode. I have reverse engineered enough of this circuit (and a few voltages measurements) - to convince myself this is indeed a zener - probably 1/2 watt? The circuit is Weller's original control board (circa 1980s) for the "EC" series of soldering stations. Ceramic substrate and all surface mount (not bad for a 20 year old board - date stamped). Anyway, this control line is "LOW" (~ 1 volt) when the Triac is ON (soldering iron heater ON) and goes "HIGH" (~22 volts) when Triac is OFF (soldering iron heater OFF). This allows the LED in-line with the 24 VAC .. LED is ON, when control line is LOW LED is OFF, when control line is HIGH So, this appears to be the logic they used to create LED status light for heater activation :-) g. beat I suspect the "PH" is Philips. To calculate the wattage dissipated by the zener, determine the LED current and multiply by 17V. Assuming a current of 10mA, the wattage would be 170mW. - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |
#4
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PH-17D - 17 volt zener
"Franc Zabkar" wrote in message
... On Tue, 13 Jun 2006 19:33:33 -0500, "g. beat" @spam protected put finger to keyboard and composed: This surface mount device is about the same size as other surface mount diodes (1N4001, 1N4007) that I have dealt with. Markings: PH-17D and cathode band it appears to be a 17 volt Zener diode. I have reverse engineered enough of this circuit (and a few voltages measurements) - to convince myself this is indeed a zener - probably 1/2 watt? The circuit is Weller's original control board (circa 1980s) for the "EC" series of soldering stations. Ceramic substrate and all surface mount (not bad for a 20 year old board - date stamped). Anyway, this control line is "LOW" (~ 1 volt) when the Triac is ON (soldering iron heater ON) and goes "HIGH" (~22 volts) when Triac is OFF (soldering iron heater OFF). This allows the LED in-line with the 24 VAC .. LED is ON, when control line is LOW LED is OFF, when control line is HIGH So, this appears to be the logic they used to create LED status light for heater activation :-) g. beat I suspect the "PH" is Philips. To calculate the wattage dissipated by the zener, determine the LED current and multiply by 17V. Assuming a current of 10mA, the wattage would be 170mW. - Franc Zabkar -- Thanks. I assume 20 mA for most LEDs, but that still places a 1/2 watt variety as most likely. Thank you ! g. beat |
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