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Photocoupler , Ic TNY264PN DIP 7 both have exploded Cause

Thread starter #1
Smart battery charger
What can cause to blow the legs of the photocoupler P621
Close by is a Ic TNY264PN Dip7 that had also blown up.
Is there any thing that may have caused this
 

kubeek

Well-Known Member
#2
My guess is that the TNY died first and took the optocoupler with itself, but without any more information it is just a guess.
 

Les Jones

Well-Known Member
#3
Post the schematic then we may have some idea of possible causes. There are many clever people on this forum but we don't have crystal balls.

Les.
 

crutschow

Well-Known Member
Most Helpful Member
#5
The main fumes 240 volt 6 amp also blew
If the mains' fuse blew, then there's a serious short somewhere in the circuit.
 
Thread starter #6
The charger is 12vv 30 Amp
3 Stage Switch Mode
Battery Charger
Number BC - 1230.
Can any one supply me with a circuit diagram
As you can see the IC 7 dip is damaged
And the photo coupler is also damaged
That’s may help you to help me. As I am not very good at fault finding except the components that are damaged.
 

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ronsimpson

Well-Known Member
Most Helpful Member
#8
It is typical for the TNY264 to blow up. I can see it was real hot.
I can not see if the photocoupler is dead. It should be hard to kill. The black smoke on the coupler may have come from the TNY264.
1544495993823.png
I do not have your schematic but here is one that is close.
D5 on my schematic might be shorted. Very typical. That will heat U1 and maybe kill it.
Also D6, C3&R2 might be bad and that will U1.
 
#10
Based on the schematic, my guess that there may have been a voltage spike on the AC line, passed thru T1 to the Tinyswitch and blew that. In the process of blowing the Tinyswitch, voltage went from the D pin to the EN/UV pin which then blew the opto isolator.
This assumes the opto isolator pins blown are the detector. If the other LED side is blown, then the "safety" capacitor across the transformer possibly shorted, and blew things on the output side (and LED emitter of optic isolator).
Pin 5 of the Tiny is what seems to have popped, that is the "D" pin, suggesting that is where the high voltage or current occurred...
If the Drain of the device is shorted to the Source, that will be the reason for a fuse blowing.

Just my hunch, maybe someone with better experience with these types of supplies can suggest better options.
 
Thread starter #11
Could you explain from the power input how it travels around the circuit as I am trying to understand the circuit and how the components work .Where no better to start than with this circuit.I understand what the components.
Thank you
 

Les Jones

Well-Known Member
#12
I think this may be a two stage converter. The first part being for power factor correction. This is based on the fact that there are two transformers. I could be wrong and the smaller transformer could be a common mode filter but it does not look like one.
Gregory, Are you sure that the picture of the underside of a board is the same board as I can't match up the hole pattern of the 8 pin dip package ? I don't think a switch mode power supply is the place to start learning electronics. I suggest that you start with something much simpler. If you intend to continue I suggest that you start by tracing out the schematic of the device and posting it.

Les.
 
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dr pepper

Well-Known Member
Most Helpful Member
#13
The tny chip is often used as an aux supply in Tv's, I suspect its an aux supply in your charger.
I've found the equivalent of R2 to be shorted on a circuit I repaired (open circuit is more common but that stope the thing from powering up).
I agree with ron the opto might be ok, just blasted with magic smoke from the tny.
 
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Les Jones

Well-Known Member
#14
I think dr pepper's suggestion of it being the aux power supply is more likely than than suggestion I made of it being the power factor correction part.

Les.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
#16
I think dr pepper's suggestion of it being the aux power supply is more likely than than suggestion I made of it being the power factor correction part.

Les.
I would agree, the transformer is far too small for PFC.

Presumably there must be some specific reason for the aux supply, such as a standard system (like on a TV).
 

dr pepper

Well-Known Member
Most Helpful Member
#18
I can think of 2 reasons why they'd go for an aux supply, 1 so the regulation electronics can be on the secondary side and still be isolated from the mains, and 2 the o/p of this thing presumably is on big croc clips, theres a high chance that these would be shorted during operation, if that removed power from the control electronics bad things might happen.
 

ronsimpson

Well-Known Member
Most Helpful Member
#20
My first "green power supplies" .... I did not know how to do that. 250 watts when on and <1 watt when off and must wake up to a IR signal and software buttons. I had to keep a micro powered up all the time. So I added an aux supply.

For a battery charger where the output gets shorted or connected backwards an aux supply might be worth the extra parts.
 

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