100W Ultimate Fidelity Amplifier

[jamesjbrookes]

Hi James, I did not, I just checked it and its not grounded on the PCB. Strange, I have never seen this before. Is it possible that has caused the thing to go into meltdown?

I not sure how it would behave in such a situation but I'm suprised by the damage it suffered. Have you managed to get the boards working now?

 

[Rick G]

Hi Terry,
I have tried to measure the Voltage across the .33R resistors i have installed & it is always 0V. If i put the gnd lead to gnd, i get same reading as the SPK Out. My MA meter also says 0.00ma on the V+ & V- tabs. Getting weirder..

 

[still4given]

If you have 0V across the 0R33 resistors then you have no bias. Difficult to achieve without a trimmer on the VBE multiplier. I temporarily installed a 5k trimmer in place of the 4k7 resistor so I could adjust the bias. Then I measured the trimmer and installed the closest value resistor. In my case it was a 3k9. However, I built mine per the attached schematic. You used different transistors so you will likely end up with a different value.

It is possible that your offset may improve if you can get the bias up where it belongs.

There are not too many transistors. Maybe you could post the voltages you are getting. That would help us help you.

Blessings, Terry

 

[Luke]

I not sure how it would behave in such a situation but I'm suprised by the damage it suffered. Have you managed to get the boards working now?

No where i live its a total pain getting semis and they are expensive. I am just going to look around for some outputs. I think the other channels outputs are not dead, but it still has the same problem as one with dead outputs before it lost its outputs if that makes sense So the other channel exhibits these symptoms:

http://www.diyaudio.com/forums/soli...imate-fidelity-amplifier-103.html#post4377943

 

[apexaudio]

Hi, I started with the VX120 because I wanted to build a hybrid amplifier. The part with the tube I have separated from the amplifier. Comes next. The transistor amplifier running with +- 50V, 40mA bias, sine wave looks good, gain is 30.
Unfortunately, I have -1V offset.

Can anyone give a hint where I start with the adjustment?

Regards Olaf

Nice work, use 1k resistor in series with 1k pot instead 1k5 and set DC offset,
Regards

 

[bimo]

If you have 0V across the 0R33 resistors then you have no bias. Difficult to achieve without a trimmer on the VBE multiplier. I temporarily installed a 5k trimmer in place of the 4k7 resistor so I could adjust the bias. Then I measured the trimmer and installed the closest value resistor. In my case it was a 3k9. However, I built mine per the attached schematic. You used different transistors so you will likely end up with a different value.

It is possible that your offset may improve if you can get the bias up where it belongs.

There are not too many transistors. Maybe you could post the voltages you are getting. That would help us help you.

Blessings, Terry

I make AX11 simulation and modified it.

 

[AndrewT]

Hi Terry,
I have tried to measure the Voltage across the .33R resistors i have installed & it is always 0V. If i put the gnd lead to gnd, i get same reading as the SPK Out. My MA meter also says 0.00ma on the V+ & V- tabs. Getting weirder..

measuring in Vdc is not sensitive enough.
You need to set your voltmeter to 2000mVdc, or preferably 200.0mVdc.

 

[apexaudio]

I make AX11 simulation and modified it.

Nice work,
Regards

 

[olafk]

Nice work, use 1k resistor in series with 1k pot instead 1k5 and set DC offset,
Regards

Hi Mile, thanks for the advice. I will check this at weekend. To late this evening


regards Olaf

 

[olafk]

Just for fun - A2

You have my attention. Layout?

Hi Terry,

if you want to test it, I can finalise this board at weekend. I can not build itself, have too many unfinished projects

regards olaf

 

[still4given]

Sure, post it. Can I get the sprint file?

Thanks, Terry

 

[Rick G]

It is possible that your offset may improve if you can get the bias up where it belongs.

There are not too many transistors. Maybe you could post the voltages you are getting. That would help us help you.

Blessings, Terry

Terry,See attached for Voltages. ALL ref: to GND. Looks like i blew up another transistor i guess. I will get back to it in a couple days as i have eye surgery scheduled for tomorrow. Thanks to All
Rick

 

[still4given]

Your fuses are blown.

EDIT; Looks like the 10R resistor is blown on the + side also. I see you relabeled the pins of the transistors. You can't do that. E is E, C is C and B is B. All you did was spin the transistor.

 

[apexaudio]

Hi Terry,

if you want to test it, I can finalise this board at weekend. I can not build itself, have too many unfinished projects

regards olaf

+/-15V is ref to amp out not to gnd
Regards

 

[olafk]

+/-15V is ref to amp out not to gnd
Regards

Yes, I have seen. Comes right in finished layout.
Thanks.

 

[olafk]

Layout A2

Hi, here is the layout for the A2. Would be nice if someone could check again. The layout is based on the circuit of post #5194. The Sprint-File is also uploaded.
I am very curious.

regards Olaf

 

[c08bm]

Should base 4148 diodes be on heatsink, for like bias compensation?

 

[rinku]

Hi,i assemble AX14P cuircuit but it is not start good and on the relay ther not goes suplly.so relay become not on,why

 

[rinku]

Hi,i assemble AX14P cuircuit but it is not start good and on the relay ther not goes suplly.so relay become not on,why and 15 volt supply comes on speaker

 

[apexaudio]

Should base 4148 diodes be on heatsink, for like bias compensation?

Yes diodes must be on heatsink or use SAP15P and SAP15N in OS.