MTX JH1200 repair

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
That establishes the fact that the transistors are pre-regulators. I don't know if they are the voltage source for any other components.

If not, use a zener value that causes the heat to be distributed evenly between the regulators and the pre-regulator transistors. The voltage between the input and output of the individual regulators can't be more than 40v. Anything below that is safe.
 
Why my tip29 and tip30 can warm up as soon as you install lm317 lm337. Operational amplifiers are not soldered, lm317 337 are cold. Here is my wiring diagram
 

Attachments

  • IMG_20201124_142113.jpg
    IMG_20201124_142113.jpg
    447 KB · Views: 45
I may be wrong, but here is a diagram of the preliminary stabilizers, I made them at 22 volts. Input 80, Zener diode 22. The minimum zener current is 0.001, the maximum is 0.018, we take the average value of 0.0095. I consider the resistor 58 / 0.018 ~ 6.2kOhm. It turns out that 22 volts with a current of 0.0095 A arrive at the base of the transistor. Seemingly 0.0095 x average h21e tip31 (32) c which I put in, which is about 40, at the output I should have 0.38A (this transistor has 3A max) .0.38x22 = 8.4W at 30 max. Either I'm confusing something, or everything should work. The only thing that confuses me is the high h21e of these transistors .. 50 should be the maximum and the Chinese pribluda shows 200+. Maybe that's the whole problem?
 

Attachments

  • 01.gif
    01.gif
    3.2 KB · Views: 40
I did + -15v. I wound 2 additional windings on transformers. I threw out the transformers, put 2 diodes instead of them, and instead of zener diodes, capacitors 50v 220mkf and cut the tracks from the collectors. As a result, 24v began to come to lm317,337 and everything worked. But another problem appeared, there is a quadratic impulse, there is sound, but the irf640n burns out very quickly ... maybe there are some guesses about what?
 
I wound 2 additional windings, put 2 diodes and 2 capacitors in front of the lm317,337 and +-15V appeared . All this instead of tip29 tip30 and Zener diodes. lm317, 337 are cold. Now another problem is burn irf640n . I turned it on, checked the pulses on the gates . It seems everything was fine, the amplifier played for 2 minutes and then the hum from the speaker . I checked the meander again and turned it on. Again, the same thing. After 2 failures on 1 shoulder, the meander remained, on 2 direct current . Pre-swing transistors (PZTA42) on the driver Board are intact. There are no burnt resistors . Where to dig I do not know( I do not like that the power in the shoulders is different, can this be due to the fact that the irf640 is not soldered ?
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.