Hello All,
A friend brought me a defective motor system by which the motor was variably driven and in the circuit was a triac. It was open. Upon close inspection there is what appears to be a tvs transient voltage suppresion device in series with the gate! It's about impossible to get any identification info off the device but the pc board has a double diode symbol which looks like two diodes facing each other with a common cathode bar. The other end of the "diode" goes to a capacitor and a relay contact. There is a 3 ohm resistor that is open and a blown npn transistor also.
I've looked allot for any circuit where a tvs is in series with a componant but could not find any. Does anyone know why this type of device would be in series with a part like this?
If it is truly not a tvs, then maybe the pc board silkscreen is wrong and this is just an open diode, with its cathode connected to that gate.
What's the consensus about this?
Thanks!
Tom
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Thanks! The parts in the red are those that failed. The part named "DB" is the one that I can't identify. As I mentioned, the silkscreen shows the symbol for a TVS but I can't understand how that part could work in series when it it's normaly in parallel. So I'm thinking it is actually a diode. I can't read the number/letters off it because they are to badly rubbed away. This part has failed open. Thanks for your help!
Hi Tom, In the circuit, the 3ohm resistor is called a fusible resistor, Its not a fuse but it will blow up if anything goes wrong with the circuit. Thus fusible resistor.
The part TR is a TRIAC which is mainly used to control the AC voltage. The 150R resistor and the .1uF capacitor forms a snubber network.
The DB in the schematic called a DIAC.The name comes form DIode AC switch, its used to assist even triggering of a TRIAC.
The Transistor control the relay thus it switches the TRIAC circuit ON/OFF.
I had a question about portable internet. I'm not even sure if that's the right term but basically I'll be moving into my cousins empty apartment for a month. There's no internet because she's been gone for so long, is there anyway to create like a hotspot that I can use to do work?
Well to know the DIAC rating the TRIAC partnumber is required. What is the TRIAC partnumber?
Sourav Gupta
PermalinkProvide the schematic diagram
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