Need Help ID'ing SMT Component

Thread Starter

lpmurphy1

Joined Jul 13, 2020
4
Hi all - I have a blown SMT component on a board from a Hoover condenser dryer. I managed to get another similar board but I believe the firmware is different so the dryer still won't run properly. The SMT component is the same on both boards but I don't want to 'swap' components as I'm unsure what other damage there may be in the original board - best case for me to ID component, get another one and put it back into old board to try.

I have done a google search for the markings, tried to ID the manufacturer but no luck. It's a three terminal component with the middle terminal not being connected at all.
Please see attached photos showing the blown component on the 'old' board and the same component on the 'similar replacement' board. I suspect the component to be a Zener diode but can find no match with the markings on the component. Also got a partial hit for Diac/Triac but I can't see that as being the case.

I don't even really know what the proper full designation is as there is a series of three characters on one line, followed by one letter on another line and three more characters on another line i.e. Z7S G F642

It's really driving me crazy - I have been troubleshooting the dryer for a while - I think if I can get this SMT component it will be a fix and my wife will be happy as it been not working for a while!

Appreciate any help offered.

Rgds
lpmurphy1
 

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Irving

Joined Jan 30, 2016
820
That's a catastrophic failure. It's likely there are other failed parts on the board. Replacing the damaged part may not resolve the issue and you'll just end up with another of the same.
 

ZCochran98

Joined Jul 24, 2018
83
I suspect it is a component by STMicroelectronics. Based on a file from ST micro, I suspect it is is a Z7S-type triac (specifically Z0107SN). The G and F642 appears, to me, to possibly be manufacture location/date codes (how to decipher those, I have no idea). But the device appears to be an SOT-223-4 Z0107SN triac (Mouser link).

And yes: that part is rated for very high power (up to 700V at 8.5A), so if it failed, there's likely other parts failed too.
 

Thread Starter

lpmurphy1

Joined Jul 13, 2020
4
Thank you to everyone who replied to the thread. As it turns out, it's what I thought it wasn't - it's a triac. I described it by mistake as a three terminal device but of course as shown it has four terminals - sorry about that!

Interesting description from Irving - catastrophic failure - yes indeed it was! Unfortunately, that failure was down to a rookie mistake on my part - a lookalike molex female connector allowed me to insert the male connector 180 degrees out - that is what caused this failure. It's likely that there are other issues on the board as a result of this but I may be lucky.
I had also replaced electro-mechanical relays on the board prior to this and replaced the starting capacitor on the motor.

However, I will try to replace the triac and see how it goes. It's difficult to get an exact replacement board with the same firmware.

Appreciate all the help you have given me to ID the component - couldn't have done it without the help :)

Rgds

lpmurphy1
 

Thread Starter

lpmurphy1

Joined Jul 13, 2020
4
[Edit] As I can't edit posts as such this is the only way I can do it. I'm curious as to why a Triac (3 terminals) in a SOT-223 package has 4 terminals externally?
 

ZCochran98

Joined Jul 24, 2018
83
If I'm not mistaken, the 4-pin triac has a redundant pin - the middle and the back pins are both the A2 (or MT2, depending on who you ask) pin. The remaining two pins are A1 (or MT1) and G.
 

Thread Starter

lpmurphy1

Joined Jul 13, 2020
4
Thanks again guys :)

If I can seek your opinion on an alternate triac? The one that is suggested is Z0107SN which is fine if I could easily get it locally.
I can get it via Mouser but the mailing charge is €20 so I won't be doing that :oops:
The nearest to Z0107SN I can get locally is Z0107MN - https://ie.rs-online.com/web/p/triacs/4865205/- question is, what really are the significant differences between a SN and MN?

For example, I can see that max peak reverse voltage for a SN is 700V and the MN is 600V - this should still be well within the peak voltage of 325V on 230V RMS. However, does the peak reverse voltage refer to just peak only or peak to peak? If peak only then the 600V should be ok?

Comments appreciated.

Rgds
lpmurphy1
 
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