.51 ohms? Really?

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Tom Whitworth:
Yup I really borked it this time.  ::)

A voltage divider on the output of an audio amp has two .51 ohm 2 watt resistors  ???

Does not seem like much more than a piece of wire to me but... where in the world am I going to find such a thing??

Clark McDonald:
I've never seen that on the output of any audio amp and I've seen thousands of audio amps. 

More than likely those are the Emitter Resistors for a complementary pair audio output amp that are fried. 

These are available labeled as such from outfits like MCM, Mouser, etc.  MCM is a good source IMO. 

BUT -- if the emitter resistors are open, you likely need to replace both output transistors as well, as they are likely shorted. 

Shorting the output of a TransformerLess Output solid state power amp should never be done, as you've found out, Ohm's law again, the amp sees that short as a load only the devices in the amp can't pass enough current for such a low impedance and something has to give.  It is the device which fails. 


Tom Whitworth:
You are absolutely right they 'were' emitter resistors. They are not open but test out at 1 ohm each and are swelled and cracked. Yup the transistor pair are both shorted from what I could tell using a diode checker.

I am having a hard time finding an replacement.  :P

Bob Lewis:
Here's one that should work that I quickly found from a Bing search:


Clark McDonald:
I gave a link to the exact replacement in one of your other threads. 

twenty seven cents each. 


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