Skar Audio T1400.1 protection light flashes fast on/off?

[8LayerJunky]

Ok guys, this amp is really frustrating me. I am use to old school amps. This is a 2014 model. At first when I would bench test it would be solid protect mode. Now it flashes really fast in/out of protect mode? ? Here's when I found wrong with it. ...

1. Big green Emitter Resistors had a broken leg , 1 broken leg on each, there where 2.

2. Replaced all output transistors.

I checked all emitter resistors and diodes, my head hurts from scratching ,dumb founded. Someone plz suggest something or point me in a direction? ? Can't add a photo for some reason???

 

[Perry Babin]

If you tried using the 'go advanced' and 'manage attachments', the file may be too large (there is an error message but sometimes not obvious).

 

[8LayerJunky]

K I think I got it. Thank you sir!

 

[Perry Babin]

This is a class D amp. Emitter resistors are resistors connected to the emitter terminal of a bipolar transistor, typically an output transistor. None of that applies to this amp.

This amp appears to use the driver board with transistors Q7, 11, 19 and 22 across the top of the board. Those commonly fail. If it uses a different board, post a photo of the component side of the audio driver board.

Did the output transistors fail or did you simply replace them?

 

[8LayerJunky]

I always thought emitter transistors were just the "bigger round ones w/ low values n higher wattage, not necessarily in conjuction with transistors. " See, still learning something new everyday!! So you want pics of the smaller boards that are vertical and check there values? Thought those smaller boards were for bass boost, low & high pass gains and etc. I have not tested any of those componets.....

 

[8LayerJunky]

Sorry, forgot to add, I replaced em on out put side bc one was cracked in black casing and another one looked burnt. I bought this amp and many others like it from store that had these shipped back to em , under warranty I'm guessing. But knowing what commonly fail on these amps is great knowledge for the other ones. Some of the other amps have smd resistors and capacitors, so they will be a new learning curve as well. Any input or trade secrets for smd mounted component would be greatly appreciated.

 

[Perry Babin]

The vertical boards are typically driver boards. One for the power supply and the other for audio.

The removal of SMD components varies depending on the location and the type of component. For the most part, I get enough molten solder on all terminals to free it and push it to a safe place (NOT on top of other unprotected components).

 

[8LayerJunky]

Sorry Perry, son had soccer practice today. Can these Lil boards lift out after removing the goop crap? It was a pain just getting readings. K I wrote down readings I got for each Q driver. Do you know what size these are? All they say are AG QQ, DK QK, DK QKI?? But your were dead on , on guessing. You can fix an amp in like 5 min can't you??

 

[Perry Babin]

The driver boards are soldered into the main board and should not be removed unless absolutely necessary.

When these amps simply stop working and none of the heatsink-mounted components have failed, the 4 transistors along the top of the board should be replaced. They regularly fail.

The larger transistors marked AG and DK are 2SA17927 and 2SC4672. They sometimes fail when the output transistors fail.

I'd suggest replacing the 4 transistors along the top of the board to see if that solves the protection fault.

You need to check the 470 ohm resistors clustered above the larger driver transistors on that board.

If the amp is in protect mode, you probably won't have voltage on the driver board. If you need to check components or measure voltage and cannot get to the terminals, make something like you see below. Someone posted a photo where they simply wrapped wire around their probe to do the same thing.

 

[8LayerJunky]

Thanks Perry, I really appreciate it. Yeah it was hard to reach with probes, can't imagine having to solder them. The ones on the top aren't to bad. I do have another question, I was checking out smd capacitors and resistors, bc the other skar amps I have yet to fix, have mainly smd components. Do you recommend those supercapacitors? Or just use regular smd caps? Don't know if they store more and longer? Or if it's a marketing stunt? Thank you sir!

 

[Perry Babin]

I recommend using exact replacements where available. Don't try to modify or 'upgrade' anything unless you have a legitimate reason for it.

 

[8LayerJunky]

Ok will do sir!! Thank you for your help sir. Greatly appreciated, just ordered the smd transistors. I'll keep you updated, have a feeling this will fix it, bc everything else check out ok. Thank you Perry!!

 

[8LayerJunky]

Ok Perry, got the new transistors, was taking the 4th one off the top like you said and all the solder n pad came off with it? I about capped my pants! ! Now what? ? And I checked the pack of 470 ohm resistors and all checked out good. Don't know what to do now. I'm about to just send it to you Perry and have you fix it.

 

[Perry Babin]

I no longer take in repairs except from one shop. No exceptions.

Post a 'good quality' photo of the damaged part of the pad/trace. Clean the area with cotton swabs and either alcohol or acetone.

 

[8LayerJunky]

K sorry Perry been swamped at work and sons soccer. K I got solder to stick after acetone, but b4 the acetone I was getting good reading off input and output transistors. Now that I got Q12 to stick on the 3rd leg, I tested input and output b4 powering up and I'm back where I was? ? Any ideas?

 

[Perry Babin]

Precisely, what do you mean by 'back where I was'?

 

[8LayerJunky]

At the beginning. I thought I was moving forward, following what you said I was getting closer to being fixed. When I 1st made this thread, I had installed new input and out put transistors. After that I was getting same reading, only 1 reading off all transistors. Then u mentioned the card. I found 4 bad smd transistors at the top like you said. I installed all 4 but 4th wouldn't stick on 3rd leg bc all solder came off. While waiting for you to reply I tested in/output transistors and got all 3 legs to give me a reading. Then you told me about acetone, it worked, finished that up, re tested input and output transistors, now it's back to only 1 good reading. Hope this helps understand more.

 

[Perry Babin]

Which transistor had the bad pad?

 

[8LayerJunky]

Q11 on driver board. And now I'm not getting positive polarity both ways on diodes on driver boards too. I'm definitely not liking these skar audio amps. I've still got a LP1000.1 and LP1500.1 amp to fix for my collection. Hope non of those are as hard as this one.

 

[Perry Babin]

Photo of the damaged area, after cleaning the flux with alcohol and cotton swabs. I need an in-focus photo.