Right now I have a DC voltage
At the exit of the amplifier speakers ARCAM FMJ 32
100 millivolts
The tension starts from 5 millivolts and increases gradually up to about 100 millivolts
* Right channel as soon as I raise the volume
There is a jump in voltage that is balanced
* Left channel the voltage rise does not affect the DC voltage
What could be the reason?
At the exit of the amplifier speakers ARCAM FMJ 32
100 millivolts
The tension starts from 5 millivolts and increases gradually up to about 100 millivolts
* Right channel as soon as I raise the volume
There is a jump in voltage that is balanced
* Left channel the voltage rise does not affect the DC voltage
What could be the reason?
I thought well until yesterday I connected the amp it had the DC voltage
Speaker port
After half an hour I exploded two power transistors SAP15
I need to fix the amplifier
Replace transistors
Two diodes BAS16
Potentiometer 100 OHM
Three transistors FMMT497
diode Zener 15 V
And resistors
SMD 100 OHM
Rail voltage
And Resistors 33 OHM in pre drive to power transistor
And all this because I thought that 100 millivolts DC voltage is fine
Before the DC voltage amplifier was 2 to 4 millivolts
I've been racking my brain to find the problem in 😕
http://www.diyaudio.com/forums/solid-state/248632-my-diy-arcam-fmj-32-amp-mod.html
It seems you recently modified/upgraded the receiver using various replacement parts as per the above link. You should have mentioned it, as it's probably the most important reason behind the problem.
Apparently you replaced the output darlingtons too, though these parts are obsolete. Where did you purchase the replacements? Genuine NOS parts would likely be quite expensive. There seems to be 2 or more sources of SAP15 fakes that I'm aware of and these show various instabilities but all have wound up in early failure. I haven't investigated this but there is little point when components don't work reliably in the same circuit as the originals.
It seems you recently modified/upgraded the receiver using various replacement parts as per the above link. You should have mentioned it, as it's probably the most important reason behind the problem.
Apparently you replaced the output darlingtons too, though these parts are obsolete. Where did you purchase the replacements? Genuine NOS parts would likely be quite expensive. There seems to be 2 or more sources of SAP15 fakes that I'm aware of and these show various instabilities but all have wound up in early failure. I haven't investigated this but there is little point when components don't work reliably in the same circuit as the originals.
SAP15 transistors
Normal I replaced them early in the project and the amp worked perfectly
I had some problem Now once I changed the resistors SMD
100 OHM
Rail voltage
Current mirror
And SMD resistors from the FRE DRIVE
to the Power transistor
The transistors I ordered from here lucky that I ordered a pair of spare
I probably would invite a few more future
SAP15P Sanken Audio Semiconductor SAP15PY | eBay
I need an answer why change volume button
Causes a momentary jump
The DC voltage left channel
This is what I suspect the problem now?
Causes a momentary jump
The DC voltage left channel
This is what I suspect the problem now?
I do not describe output offset of 100mVdc as normal, unless I know the amplifier and why it needs that much offset to perform properly.
After Work
At the end I solved the problem of the DC OFFSET
Now the amp stable even after an hour of work without a signal
The DC OFFSET about 13 millivolts
Another thing that has improved Halafta film capacitors RIFA
470NF film makers of VISHAY V730P
They were very helpful stabilize the voltage
(Reducing the DC circuit consists of an amplifier Server LT072 .
The circuit DC SERVO running as a inverter .
The DC voltage rises . Output in the OP AMP becomes negative
it raises the Current Negative Supply foot .
circuit consists of resistor 1 MEGA OHM
And Film Capacitor 470NF )
the BIOS voltage is Stable 16 millivolts
During the calibration i passed back forward
Between Measuring Voltage DC OFFSET to measure voltages BIOS
A few more measurements and then I'll turn it to the speakers 😉
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