Stetsom EQ13500EX

Goodnight,

Today I got a stetsom 13500 for repair comes from another workshop where the outputs and the control circuits changed, and they told me that I was now in protection I proceeded to connect it and the amplifier only turns on the red LED and blinks 3 times so I read in Your manual indicates low battery I supplied several input voltages but the status did not change anyone has seen these amplifiers to tell me where to start?
 
I’m not familiar with that particular amp and I have limited experience with Stetsom amps but I have worked on a few.

Those amps use a PIC16 programmable microcontroller that produces the drive pulses for the power supply on pins 9 and 10.

When probing that IC for voltage readings, do not probe the pins connected to the oscillation crystal. Generally they will be pins 2 and 3.

Those amps also pass the B+ voltage that you connect the amp to, to the rail caps to become part of the rail voltage.

You should see your B+ input voltage at the outputs and the rail caps as well as the center legs of your power supply mosfets. Pin 8 of PIC16 IC should be the one that is connected to the undervolt protection circuit. It should be close to ground if everything is OK. But since you’re getting the undervolt fault I suspect it won’t be at ground. Try to follow that circuit back from pin 8 and troubleshoot that protection circuit. You may have a SMD resistor, SMD capacitor, or smd Diode that is open or shorted.

Also check any resistors, caps or diodes in the B+ line. Also check the traces on the bottom of the amp board for breaks in the traces.

Hope this helps.
 
With the amp in protection you may not cause any damage. Probing these pins with the amp working could cause damage to the power supply. I just got into the habit of staying away from them. If you have oscillation in pins 9 and 10 when the amp is working then the oscillator is working as it should.
 
Good Morning,
I just checked what you told me but I do not see 12V at the output and attached you will find the voltages that the pic has on its pins to see if you help me track the fault

pin 1 4.97 v
pin 2
pin 3
pin 4 2.52 V
pin 5 3.22 V
pin 6 4.59 V
pin 7 0 V
pin 8 0 V
pin 9 0 V
pin 10 0 V
pin 11 0 V
pin 12 0 V
pin 13 4.63 V
pin 14 0 V
pin 15 0 V
pin 16 0 V
 
According to those measurements the amp is going into protection due to over voltage.

Pin 13 is high and is connected to the over voltage protection circuit which is connected to the remote turn on circuit so troubleshoot that circuit.

Pin 4 is also high and that is over voltage protection and over current protection. They are both fed into that pin.

Over voltage protection is fed from the primary windings of the transformer through a diode.
Over current protection is fed into that pin from the speaker terminals through a couple of diodes.

Hope that helps a little.
 
apologize for my mistake before I sent you the wrong number of pins is a PIC16F616 which only has 14 pins I guess I must then follow pin4 only for verification
Thank you
pin 1 4.97 v
pin 2
pin 3
pin 4 2.52 V
pin 5 3.22 V
pin 6 4.59 V
pin 7 0 V
pin 8 0 V
pin 9 0 V
pin 10 0 V
pin 11 4.63 V
pin 12 0 V
pin 13 0 V
pin 14 0 V
 
Good night I checked the subvoltage circuit as you indicated and I did not find anything defective. What I saw was that the voltage on pin 11 went down to 0 by flickering, that is to say 4.67 and when flashing 0.67 what else do you suggest me to check, I saw a forum where you speak of an 8k stetsom and from what I could appreciate the circuit is quite similar to the one I am seeing
 
I would double check the previous tech’s work. Look for solder bridges on the outputs and driver ICs. Look for damaged via’s or damaged pads on the ICs. Check the diodes around the output mosfets for shorts. Look for missing paths back to ground. Try connecting the amp to a speaker or static load and see if the amp protects.

Since you found that other post about the 8k then you can see how to over ride the protection circuit. Do so with caution and be very attentive to everything and only after you check for the above mentioned problems. Power up the amp to get the green LED for a few seconds at a time and look for anything over heating. If nothing is overheating and the amp isn’t drawing excessive current (above 5 amps) then you may be able to power the amp up longer and look for proper or missing voltages on the board.

Only power the amp up longer with all of the mosfets clamped to the heat sink.
 
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How about David, I am retaking this amplifier again since the original problem was that it was protected by low voltage and it turns out that it turned on well with a switched source for 120 amp audio car, I made the measurements of the wave signals and as far as I left there was a signal on one of the two ir25607 the other was defective, I made the order and now that the parts arrived when I installed them the amplifier jumped to protection now turns blue and the seconds goes to protection and flashes once per second that according its manual is short circuit or overload on the output now I don't know what caused this if it turned on well before without one of the controllers
 
Reinstall the driver ICs and if the output mosfets check good, reinstall them and the inductors. Remove the gate resistors to the output mosfets so you don’t short the outputs while probing around in the preamp section and the output section.

If you fire it up and you still get a short fault then remove the rectifiers and fire it up and see if you still get a short fault. If you do, then the problem is in the power supply. If you don’t then you’ll know the problem is in the output section, so that could be from the rail caps, preamp section and all the way to the speaker terminals.