MTX JH1200 repair

[tobyret2]

Good evening. Please help me with the repair of Mtx jh12000. He came to me without many complete sets and I am trying to restore them. Can anyone know what resistors should be in the allocated places? And another problem is + -15v. put new lm317 lm337 but they heat up even without load, 70 volts come to their input after tip29 tip30 ..
Tip29c and Tip30c I replaced with bd911 bd912 Did I do it right? I could not buy original spare parts in our city. I also attached a photo of the pulse on the shutters of the power supply, is everything good there? Thanks in advance to everyone who responds ...

 

[Perry Babin]

R4 is a 100 ohm. Marked 1000.

What do you mean that the 317/337 have no load?

What is the voltage on all 3 terminals of each regulator?

 

[tobyret2]

I installed new operational amplifiers tl074 tl072, a sound appeared and after 5 seconds everything burned out .... I evaporated them .. as I understand it, these + -15 are needed to power them ... but even without them lm337 and lm317 are hot .. Tomorrow I will take a photo ... Maybe there is a circuit of this amplifier? are the resistors between the base and the collector on bd911 and bd912 correct? I was embarrassed that one had 3.32 Kom and the other had 12Kom

 

[tobyret2]

I didn't have these details. I assumed that there should be diodes here? Am I right, should I have zener diodes installed?

 

[tobyret2]

R4 is a 100 ohm. Marked 1000.

What do you mean that the 317/337 have no load?

What is the voltage on all 3 terminals of each regulator?

I installed new operational amplifiers tl074 tl072, a sound appeared and after 5 seconds everything burned out .... I evaporated them .. as I understand it, these + -15 are needed to power them ... but even without them lm337 and lm317 are hot .. Tomorrow I will take a photo ... Maybe there is a circuit of this amplifier? are the resistors between the base and the collector on bd911 and bd912 correct? I was embarrassed that one had 3.32 Kom and the other had 12Kom

 

[Perry Babin]

MTX diagrams are virtually impossible to find.

Contact MTX to see if they will help with component values. At one time they would but now it's questionable. At least try.

 

[tobyret2]

already wrote to technical support. What causes the voltage in the shoulders to float? in 1 arm 72 in the other 88. Then it can become the other way around ... Is the oscillogram normal?

 

[Perry Babin]

There is a translation problem.

Shutter?

Shoulder?

I can guess but there's no point in wasting time if you can clarify.

 

[tobyret2]

This q116 q119 very hot... This is normal or no ?

 

[tobyret2]

There is a translation problem.

Shutter?

Shoulder?

shoulder good work now +-70v
+-15v normal

my problem now very hot q116 q119 This is normal or no ?

Graph out shoulder 1 and out shoulder 2 bad...

 

[Perry Babin]

Shoulder can't be rail voltage AND the waveforms you posted. Maybe someone else can help.

 

[tobyret2]

Shoulder can't be rail voltage AND the waveforms you posted. Maybe someone else can help.

it's all google translator) the amplifier turned on, there is sound. The only thing that confuses me is the hot tip29 tip30 lm337 lm317 and two A92 transistors on the output stage driver. Is it normal that these elements get warm?

 

[Perry Babin]

It's normal for voltage regulators to heat up.

Are the TIP transistors generally clamped to the heatsink?

Try a different translator (try several). Convert from your language to English and then back to your language to see which translator gets the closest to the original statement after the second translation.

 

[tobyret2]

they are all in TO-220 and without heatsink. I think to put radiators, they get very hot. I also don't like how the coolers work, they spin very slowly.

 

[Perry Babin]

How many LM317s and how many LM337 do you have in the amp?

In other MTX amps, the fans are controlled by output level as well as heat. Have you tried driving the amp to clipping (no load necessary) to see if the fans ran faster?

 

[tobyret2]

1pc lm317 and lm327. I tried to warm up, the revolutions did not change. As for the level, I have not tried it.

 

[Perry Babin]

Did you answer this question?

What is the voltage on all 3 terminals of each regulator?


How did you heat up the heatsink to test the thermal response?

Are you sure that it was sufficiently hot?

Did you try heating the thermistor itself?

 

[tobyret2]

lm317 1-13.8v 2-15v 3-60v
lm337 1--13.7v 2--51v 3--15v

 

[Perry Babin]

What about the other questions?

 

[tobyret2]

Just probed tip29c .... After removing tip29c tip30c lm317 lm337, the cooler started to rotate as expected. The volume level and heating of the thermistor with a soldering iron did not give a result. Maybe there should be zener diodes instead of diodes?