100W Ultimate Fidelity Amplifier

[jaagut]

Picture can't show faliture, post voltage measurements on resistors, transistors and diodes.

Hi Apex,

Here's the measurements I gathered.

 

[jaagut]

Bro... Consider also to double check pin orientation of MJE's 340/350 by meter, be sure you inserted correctly, this is one of the case if you have huge offset when inserted inverted pins one of your pre-drivers.
It happens to me in middle east MJE340 by ON semiconductor as per datasheet pins are ECB but in actual check by meter it’s BCE.
Good luck...
Regards,

Thanks, I'll check.

 

[thimios]

AX11 under....test!

Telios.

congratulations belongs to mr Apex.
Mr Apex thanks for this.https://www.facebook.com/APEXaudio.MileSlakovic

 

[overall feedback]

Hi Apex,

Here's the measurements I gathered.

Maybe you should decrease R4 to about 280 ohm.

 

[apexaudio]

Hi Apex,

Here's the measurements I gathered.

Vbe on Q2 must be about 0.5V, replace Q2 for start.

 

[AndrewT]

.........
It happens to me in middle east MJE340 by ON semiconductor as per datasheet pins are ECB but in actual check by meter it’s BCE.
........

this sounds more like a fake.
To126 is ecb.
I am not aware of any exceptions.
If Onsemi state their To126 is ecb, then it is ecb.

 

[wiljj78]

this sounds more like a fake.

Could be... but it happens and with ON logo on it and the device still work till now.

 

[AndrewT]

If Onsemi state it is ecb and your version is bce then whether it has Onsemi on it or not, it cannot be Their To126 transistor.

 

[clovi_kate]

Hi Apex,

Here's the measurements I gathered.

i built this amp 6 months ago and i had 1 problem during testing. its the pcb, some traces are cut off and stick with other traces. try to double check your traces and make sure d2 and d3 is on right position

 

[clovi_kate]

Bro... Consider also to double check pin orientation of MJE's 340/350 by meter, be sure you inserted correctly, this is one of the case if you have huge offset when inserted inverted pins one of your pre-drivers.
It happens to me in middle east MJE340 by ON semiconductor as per datasheet pins are ECB but in actual check by meter it’s BCE.
Good luck...
Regards,

yeap.. i experienced this ecb and bce issue in MJE345/350.. use analog mulitmeter to check and loacte what pin is base and emitter.

 

[overall feedback]

Yes it is Q8 fault. Maybe wrong orientation (pins), maybe base-emiter open circuit.

 

[caglarm]

I think shematic is wrong..marked point should be disconnected.

 

[jaagut]

Bro... Consider also to double check pin orientation of MJE's 340/350 by meter, be sure you inserted correctly, this is one of the case if you have huge offset when inserted inverted pins one of your pre-drivers.
It happens to me in middle east MJE340 by ON semiconductor as per datasheet pins are ECB but in actual check by meter it’s BCE.
Good luck...
Regards,

Thanks Bro, I did what you told and sure the MJE340 Motorola make has BCE pins!

Issue resolved when I rotate the transistor 180 degrees.

DC offset has gone from 59V to -16mV.


I tested loading input with music, and it works!

 

[jaagut]

If Onsemi state it is ecb and your version is bce then whether it has Onsemi on it or not, it cannot be Their To126 transistor.

My other transistor in this setup was MJE350 from OnSemi. When I tested, pins are ECB.

 

[thimios]

AX11 under....test!

I think shematic is wrong..marked point should be disconnected.

Yes shematic in this point is wrong but pcb is o.k.
By the way this is shematic for AX11.

 

[dobrivoje]

Actually there is one more wrong dot - emitter of MPSA13 is not connected to GND.
I warned Apex on our local forum, so he gave corrected schematic.
Here it is:

 

[tinitus]

things started to get messy, and very confusing
I removed a few posts

please try to keep it clean for now, thanks


moderation

 

[shravanth]

Hello apex sir i need to add NFB for ax-14 or no need

 

[joeyt]

hello sir apex,
what is the possible substitute of bd 139, bc639 and bc640 for ax11, i cannot find this transistor here in our place.

 

[apexaudio]

2SC2383, 2SA1013 instead BC639, BC640 and 2SB649, 2SD669 instead BD139, BD140.