Sinus live SLA1500 protection (Help needed)

[WolFking]

Hi!

My Sla1500 recently broke down and wonder if i can get some help trying to fix it.
It goes straight into protection when starting it up and power light is flashing. Noticed that 2 mos fet pins of Q3 was broken so soldered them back but still in protection so started measuring the TL494 chip and accidently brigded pin 1 & 2 and the amp stopped going into protection but still unable to play any music.

Here's full read out.

Pin 1 : 0
Pin 2 : 5V
Pin 3 : 4,10V
Pin 4 : 0
Pin 5 : 1,520V
Pin 6 : 3,675V
Pin 7 : 0
Pin 8 : 12,22V
Pin 9 : 0,021V
Pin 10 : 1,718V
Pin 11 : 12,16V
Pin 12 : 12,16V
Pin 13 : 5V
Pin 14 : 0
Pin 15 : 2,068V
Pin 16 : 3,591V
I dont have a manual so dont know if this is good or not.
Also accidently touched pin 9 & 10 togheter due to fat pins on the multimeter so it burnt mosfet Q29,Q30,Q31
P60NF06 7sanx V6, I have purchased a few P60NF06 Gk11 V6 to my sla 3000 that broke down and wonder if i can use them on the 1500?

Using a multimeter.

 

[Perry Babin]

You can use those FETs to replace the ones that failed in the power supply.

You need to re-check the voltages on the 494. At least one voltage is almost certainly wrong.

Q43 may have been damaged when the FETs failed. Check Q42 as well. Check for shorts, leakage and open junctions.

You stated that the amp stopped going into protection. Do you mean that the amp went completely dead or that it was powering up normally?

 

[WolFking]

You can use those FETs to replace the ones that failed in the power supply.

You need to re-check the voltages on the 494. At least one voltage is almost certainly wrong.

Q43 may have been damaged when the FETs failed. Check Q42 as well. Check for shorts, leakage and open junctions.

You stated that the amp stopped going into protection. Do you mean that the amp went completely dead or that it was powering up normally?

The amp went on powering as nothing have happened ( Protection went off and power lamp glowed like normal), connected a speaker to the terminal and rca to my phone's headphone connection via 2-1 cable but still no sound.

 

[WolFking]

Test 2 of TL494 amp connected to a battery at 12.16V
Pin 1 : 0 (no readout on mV)
Pin 2 : 4.98V
Pin 3 : 4.10V
Pin 4 : 0.6mV
Pin 5 : 1.506V
Pin 6 : 3.640V
Pin 7 : 0.001V (no readout on mV)
Pin 8 : 12.13V
Pin 9 : 0.103V
Pin 10 : 1.715V
Pin 11 : 12.13/14V
Pin 12 : 12.13/14V
Pin 13 : 4.97V
Pin 14 : 4.97V
Pin 15 : 2.061V
Pin 16 : 3.595V

 

[Perry Babin]

Have you replaced the power supply FETs?

Is the amp producing rail voltage?

 

[WolFking]

I have not replaced anything yet im to shakey to solder so have to call my brother for that, Q43 & 42 look good, no visible damage on them, and i dont have any spares for them. T or +2 thingys.
Rail voltage? mind explaining that a bit?

 

[Perry Babin]

You absolutely cannot tell if semiconductors are in good condition by their physical appearance. they have to be carefully tested.

What do you mean by: T or +2 thingys

When you get the power supply repaired, measure the DC voltage on the middle leg of Q4 and the 3rd leg of Q5. Black probe on ground terminal of the amplifier.

 

[WolFking]

Q43 & 42 are marked X 2 on top of them, at first glance i thought i saw T or + 2 marking, sorry about that.
But i might have the fet's replaced tomorrow if we can get the time for it, il get back when they have been replaced.

 

[Perry Babin]

Are you sure that you're looking at the right transistors?

They cannot have the same part numbers. The originals are typically marked L6 and M6. In the photos below, the PNP driver failed and has been replaced with an MMBT3906 (2A).

 

[WolFking]

Quite positive. But was marked Q42 - 2X and Q43 - 2 T>

 

[WolFking]

Exchanged the 3 P60NF06 7sanx V6 with the P60NF06 Gk11 V6 i had, but when i was going to power it up to check the TL494 they broke again (burned up making the holding metal glow red hot) So i consider this amp quite dead.

 

[Perry Babin]

Please read the basic amp repair page (link in sig line below). Read all of it but pay special attention to the text in the yellow box.