Hi folks,
I was trying to build a amp based on stk 4192 II chip. Since 4192 accepts 8ohm loads.I connected two 4ohm full range speakers in series just to test the amp.
As soon as I turned the power the transformer went to smokes!!
But I could hear some music for 20sec or so. It sounded horrible. It was more noise than music.!
I used a 20-0-20,5amps rating transformer. I think it could not deliver sufficeint current hence got burnt out.
Any ideas what could be the reason and possible solutions.
Somehow I am not very sure of stk 4192's capability. Data sheet looks fine but I havent met anyone who tried using 4192.
Any suggestions??
Thanks,
I was trying to build a amp based on stk 4192 II chip. Since 4192 accepts 8ohm loads.I connected two 4ohm full range speakers in series just to test the amp.
As soon as I turned the power the transformer went to smokes!!
But I could hear some music for 20sec or so. It sounded horrible. It was more noise than music.!
I used a 20-0-20,5amps rating transformer. I think it could not deliver sufficeint current hence got burnt out.
Any ideas what could be the reason and possible solutions.
Somehow I am not very sure of stk 4192's capability. Data sheet looks fine but I havent met anyone who tried using 4192.
Any suggestions??
Thanks,
rs1026 said:
It is almost impossible to blow a transformer by overloading an amp. It really, really is extremely unlikely. Most probably there was either a problem with the transformer wiring or the rectifier (or the amp), in such a way that there was a dead short across the secondaries.
I would suggest to take out the transformer and see if it really is blown. 20 secs or so is not enough to blow a transformer, which can only be blown by thermal overload (and high-voltage overload, but that will not be the case here). And transformers have BIG thermal capacity. Take the naked transformer, separate out the wires to be sure there are no shorts, and apply mains (to the right terminals!) and measure the AC secondary voltage. Chances are it is OK. Then of course the real fun starts....
Jan Didden
carlosfm said:If you messed up the PSU connections to the chip, that is, you invert + with -, you may kill the trafo in seconds.
That's why you should always use a fuse in the primary, with the correct value.
The fuse would blow before the trafo.
Beg to differ Carlos, you CANNOT blow a transformer in seconds. No way. Even a dead short on the secondaries (which as about as bad as it can get) will not do that. It takes time.
Jan Didden
Rated transformer primary volatge is OK and it is in line with the local distirbution network.There can be no problems with that. I also checked the rectifier diodes. They were also OK.
Also the transformer did not go to smokes immediately.It so happened that initially I started noticing smoke on the primary side of the transformer.So immediately I diconnected the amp and then switched on the power with just transformer and bridge rectifier.But this time it got burnt completly. I could see a flash on the primary side of the transformer.
Also the transformer did not go to smokes immediately.It so happened that initially I started noticing smoke on the primary side of the transformer.So immediately I diconnected the amp and then switched on the power with just transformer and bridge rectifier.But this time it got burnt completly. I could see a flash on the primary side of the transformer.
rs1026 said:
It would seem that you either wired the rectifier incorrectly, or that the transformer was bad. However, if the diodes were shorting the secondary, chances are your diodes would have started glowing long before the transformer broke.
I'd strongly advise using fuses (I do most of the time - honest
), and also wiring a light bulb in series with the primary when testing. The bulb will light if something is wrong, and absorb most of the power.Rune
Aha,
I remember you said there was a little sound, and now it seems that there was fire on the primary side? It could be a problem with the insulation of the primary winding. That would explain the fire, but it would also still allow a small secondary voltage so you had some sound.
If this was the case, the rectifiers and the amp would still be OK, but the transformer not unfortunately.
Jan Didden
I remember you said there was a little sound, and now it seems that there was fire on the primary side? It could be a problem with the insulation of the primary winding. That would explain the fire, but it would also still allow a small secondary voltage so you had some sound.
If this was the case, the rectifiers and the amp would still be OK, but the transformer not unfortunately.
Jan Didden
If the primary caught fire due to an overload that would suggest the primary was faulty in the first place. i once cooked a transformer by wiring it incorrectly to the rectifier (hey, i was 10 at the time !) and the primary insulation melted under the overload heat and blew - but it took a good minute or more to happen, and it was smoking before that
I would say the transformer was faulty before it was used.
I would say the transformer was faulty before it was used.
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