Energy audio mighty 1200.1

[Aqeeb127]

bcae1.com - Car Amplifier Repair Tutorial - The Basics thats the link

 

[Perry Babin]

Must be below ~3v. Pin 3 varies but pin 4 is virtually always very near 0v when the amp is operating.

 

[Aqeeb127]

Ok both of those voltages was almost zero

 

[Aqeeb127]

Maybe i should try other buffer transistors

 

[Perry Babin]

What are you using for the NPN driver?

 

[Aqeeb127]

The MMBTA42

 

[Perry Babin]

When you check them, does the probe to terminal configuration show the reading expected for each type?

I've seen mismarked parts so I have to ask.

 

[Aqeeb127]

Yes it does

 

[Aqeeb127]

Let i just double check

 

[Perry Babin]

What's the resistance from the collector pad for each A92 to pin 7 of the 494?

 

[Aqeeb127]

Im going to have to install a fresh set then to let you know the readings

 

[Aqeeb127]

It is 0.4ohms but thats my test leads ohmage but ok im going to clean everything up then going to put fresh transistors in then will check the voltages again

 

[Aqeeb127]

Sorry for waisting your time mr perry but the supplier gave me both pnp transistors thats why its not working

 

[Aqeeb127]

I am extremely angry right now for them going to phone them tomorrow and sort this out

 

[Perry Babin]

Are they marked MMBTA42?

 

[Aqeeb127]

I used a lcr tester and it shows pnp when its supposed to be a npn thats how i found out and the codes dont match up on the surface mount transistor

 

[Perry Babin]

You need to stop using that 'tester' and learn what your meter is telling you. The first time you tested the transistor with a multimeter it would have told you what the problem was. You are not alone. FAR too many people are relying on these cheap little testers and aren't learning to test with a multimeter.

 

[Aqeeb127]

I tried the multimeter first but the probes on my meter are to big to probe properly on these small chip transistors so it is a bit of a struggle for me thats why i tested with the lcr tester and thats how i found out its a pnp and not a npn

 

[Perry Babin]

You can sharpen the probes. If you don't want to sharpen the ones you have buy a cheap set to sharpen or use clip leads to connect to small solid wires that you can sharpen and use as probes.

The attached image shows one being used for ground but the idea is the same.

 

[Aqeeb127]

Thanks for the idea i will see to buy a cheap set tomorrow and sharpen them