my diy arcam fmj 32 amp mod

[dazzz]

After 3 weeks I got the transistors I ordered of SAP 16


I could not find SAP15 transistors
so I ordered the SAP16.

While I was waiting to the output transistors
I replaced all the burnt parts

In addition also bought Cooling paste
of arctic cooling mx-4
When I did this project did not put
Paste on the output transistors.

I installed all the part 🙂
I set the voltage bios
To 14 millivolts.

The DC voltage on the speakers output is Very Low Between
0.5 millivolte to 1.5 millivolte.

after cold Running of A few hours.

I hooked up to speakers
And everything works Perfect 😀

 

[dazzz]

An important lesson learned this week
Never replace JFET op amp with bipolar op amp in dc servo

After the preamp switched four units the LT072
In OPA1662
With a significant improvement in performance.
I decided to do an experiment it would have been risky because of the input current.
i change the lt072 in the power amp dc servo with lm4562
and boommmmmmmmm dc offset fo 1.5 volt on the output
The 15V rail Resistor R300
Ben burned by shorting the + to -
I saw a lot of lightning This week
I put the LT072
I did a course of strengthening the tracks of the +
By replacing SMD resistors
R300
R400
Resistors through hole
10K 1 watt
In addition, I discovered crack in the circuit of the OP AMP
So I've bypass surgery with spiders i created on the two OP AMP
And the amplifier back to life
Calibrate the BIOS to 16 mV
And DC OFFSET
Better before blast