Help Identify this Part please

[EEEinator]

hears a Picture
View attachment 60535

its the black chip in the middle with a big T on it with the little heatsink on it

The circuits its used in is to dim a light bulb in a microscope, the bulb is 125v AC and 30W

i need to find a replacement

Thanks

 

[ericgibbs]

hi,
The markings on the PCB show it as Triac, what the voltage and power rating of the lamp?

EDIT:
why do you suspect the Triac?

 

[EEEinator]

the bulb is 125v AC, 30watts

 

[ericgibbs]

the bulb is 125v AC, 30watts

hi
why do you suspect the Triac?

 

[EEEinator]

I didn't, im trying to find out what it is, I only said big T to help identify it in the picture

 

[EEEinator]

Coult it be an SCR?

 

[ericgibbs]

Coult it be an SCR?

I wasn't using the 'T on the device to decide if its a Triac, look at the silkscreen print on the pins of the device G,T1,T2,

 

[EEEinator]

ok that looks correct do you happen to know an equivelent part i could use? thanks so much

 

[4pyros]

The soldering on that board looks bad.

What is not working?

why do you suspect the Triac?

TRIAC failure modes
In some cases the triac in your circuit can be dagamed typically because of overcurrent, overvoltage or too much heating. Triac failure modes can be either "blown open" or "blown short".

If the Triac blows open, all connections are opened up as the semiconductor material has failed catastrophically and the explosive force inside the device clears disperses the internal wiring.

If the Triac blows short, the shorts can be to any combination of the terminals. MT1 to MT2 (gate open), MT1 to gate (MT2 open), MT2 to gate (MT1 open) or MT1 and MT2 to gate.

There are normally no half-way houses in the failure modes. They go either fully short or fully open. The most common failure mode seems to be a short circuit.

 

[EEEinator]

There is a second one in the circuit that has broken apart and thats why i need to replace it

 

[4pyros]

There is a second one in the circuit that has broken apart and thats why i need to replace it

Can you show us a pic of the blown one. I spent some time trying to find a cross for it to no avail. I think it may be a SMD code. I will look some more later.

 

[EEEinator]

View attachment 60654

heres a pic of the broken one

 

[alec_t]

Looks like a TO-202 outline. Try a ZD405 ? (It's rated 600V, 4A, 5mA gate current). £0.80 in my 3yr-old Farnell catalogue.

 

[4pyros]

No luck finding a cross.
Whare in the world are you?
Can you order fro Digi Key?

 

[EEEinator]

yes i luv digi key

 

[4pyros]

OK from the 1st pick I see D1 as a DIAC so you need a triac without a DIAC built in.
One common one is a BT136 witch Digi Key has. Try that.

 

[EEEinator]

Thank you, im gonna try this one 568-3650-5-ND from digikey's website and ill let you know how it goes