Simple trick to find a bad transistor (part) in an audio amplifier!

I was just pocking my finger here and there to find out the the problem and i cam across how to find bad part in an amplifier! this technique is used in tube amp to find bad tube with a stick but in a solid state it works with bare fingers and even without touching the part, just bringing the finger near part makes increases the intensity of sound and that is how you can make out where is the problem! if i am wrong correct me, i will learn!

[williampreston]

Thank you for this video, all the "correct" ways to diag did nothing, tried your way and found it in seconds!

[fullwaverecked]

Good info, but when I'm using my finger as a signal tracer, I would wear rubber gloves and have a buddy nearby ready to call an ambulance... Cheers!

[Sven_]

Can I use the finger method to check if my wall socket is live?

[Wunderdogg]

Some transistors with metal tabs can have high voltage on their collectors
In higher power amps the rail voltage can be 100 volts DC or more which are directly connected to filter capacitors with huge amounts of stored energy
If you touch one of those and another part of your body is grounded, it could be the final test you ever make
Please DO NOT physically touch anywhere inside an amplifier if you are not highly knowledgeable in electronics

[jeffberwick]

Could be that you just found the highest sensitivity part of the circuit, where you have the most gain picking up the AC noise from your fingers. That's also where a noisy transistor happens to matter the most, so you could have a good point there.

[pete]

Much better to use your tongue on these electrical components. The noise increases exponentially when you hit the live circuit!

[muneebkhan]

I don't understand your touching an electrolyte capacitor and calling it a transistor....plus it's really dangerous to touch it with bare hands use rubber gloves

[mtcemngr]

A Signal Tracer & Signal Injector would be sufficient.

[mrBDeye]

Do u think it good idea to test bad transistor in the circuit with my wet tongue ? Should I do it or no ?

[coolbee]

DON'T GO STICKING YOUR FINGERS IN LIVE ELECTRONICS. The humming might be due to ground-loop...Put ferrite beads on the speaker component you pointed/touched looks like a capacitor..?

[martinez]

excellent method to get electrocuted: D

[trenenpierskalla]

would a completely bad output transistor cause the amp to still power on but have zero audio (not even a hum or when I touch the aux jack)?

[rawhorley]

Freon in spray can, applied to resistors will work !

[fickfehler]

your soldering is very messy. Use 37/63 no clean solder with lower iron temp.

[MrTalaue]

I am sorry, but you can´t find bad parts with your methode.

[NKDA]

A home brew signal tracer would be faster. Also, there are some really bad looking solider joints there.

[ssbbearcat]

Set to the phono mode and turn the volume control to max, tough touch phono input. The side that blows up your speaker is the working one.

[robtitheridge]

I think the reason this works is because these old germinium transistors grow tin whiskers that end up touching the can.

[KBUIF]

I think this video should be taken down because its unsafe to poke inside any mains powered equipment.

[Luke-V]

Hello, when the transistor is changed to the same one, it is necessary to set the block current, or in what case to adjust it, thanks for the possible explanation