Is a SVT Pro 7 supposed to hiss this much?

[DGBass]

52 minutes ago, Downunderwonder said:

I wouldn't expect output from a power stage that's had a capacitor go MIA

Agreed, and sure I mentioned that when reffering to the driver chip circuit caps of potentially the value on the burnt remains of the component in the picture. C25 on the power board looks the most likely possibility to me, its a de-coupling cap and sits on its own between two parts of the amplifier. If it blew i'm sure the amp would still work as the driver circuits each have independent voltage feeds. As the cap would be gone, any harmful voltage wouldn't get anywhere else, you would more than likely just loose the de-coupling effect which might increase background noise rather than total amp failure. I'm pretty sure its not the pre-amp as I don't see any component value with a 47 or 25 on it. It's forum diagnosis at its best or worst if you like. The only way to know for sure would be to pop the hood and start taking high res photos of the SVT7 Pro mainboard. I don't recall coming across an amp guts reference library thread here on BC? Happy to attach schematics if you fancy a look at them🙂

[Marcus Cornall]

Wow! So it actually even accounts for the precise fault I had! 

I'm amazed at how much time and effort you have put it here .

I feel bad ! I had hoped for help, but I never expected free technical analysis and diagnostics to this level!

You guys are fantastic  thanks again so much .

It's even helping the seller get it repaired, so you're saving an amp too.

I sort of feel bad I haven't photographed the circuit boards so you can confirm it for your own satisfaction!

 

 But I already feel like I have impinges a lot on your time.

 

DGBsss you've done an amazing job with forum diagnosis.

[Marcus Cornall]

actually Gents, I am going to take the lid off before I package it up today,and attempt to find C25 and photograph it. I bet I find a gap there! 

It's for 'closure for you,. I know sometimes you work a thing out for someone, and you remain interested to see if you were right! 

So I'll be back with a pic in a few hours.

It's the least I can do.

And I want to know myself now

[Downunderwonder]

Nobody else noticed your rattle report. You didn't come back and nobody bothered raising it again. So you're lucky I don't like being ignored!!!

 

The foundation of forums like this one is folks giving free help and getting the satisfaction of problems being solved. Without the back and forth all you have is a forum full of "what's the best bass for.." threads and cat videos.

 

You're welcome, happy to help. DUW.

[DGBass]

3 hours ago, Marcus Cornall said:

I am going to take the lid off before I package it up today,and attempt to find C25 and photograph it. I bet I find a gap there! 

 I will say diagnosing an issue without actually having the amp on a bench is always tricky. Expect the unexpected, especially if the amp is still working after a fashion. It will though be interesting to see if you can spot anything from a photo. There are a lot of high voltage caps in the SVT7 pro so be very careful when the lid is off not to touch or short anything and make sure it isn't plugged in 😬

[Downunderwonder]

I am sure the fine folk who worked out which cap remains you found will be equally dead against you doing any more than removing the cover to take a photo.

 

If the cap location can't be seen DO NOT go removing anything from inside to get a better look!!!!!! We would rather you left that to the tech who is going to be much happier if you have left it alone.

[Marcus Cornall]

Hello and dont worry I didn't touch anything or do any more than remove the lid.

I looked with a magnifier and a torch.

 

I couldn't see anything untoward.No obvious sticking out legs or connections,no outlined numbered area without a component there.

In the bits that I could see.

There were caps behind things I could just make out,so it could have come from there somewhere.

I couldn't find c25 despite scouring the visible areas for half an hour.

I also realised that tonget a zoomable resolution I would have to take a good few pictures.

At that point I am afraid I gave up, put the lid back on and packaged it.

I figured that if I couldn't see it ,you probably couldn't, given the  ore limited viewpoints of pictures.

And anyway past a certain point I am sure you have better things to do than scouring pictures of circuit boards looking for problems.

 

[BassmanPaul]

True dat!

[Downunderwonder]

Post the pics anyway, some of us are locked up at home with a nasty virus, too weak to leave the couch, and too cheap to pay for Netfix so scouring photos of amp gizzards counts as entertainment.

[Marcus Cornall]

I'm sorry to hear you are not wel,and may you get better soon.

I was packing it up but just for you I got it out and opened it again.

But i just can't get it to focus enough on the little component numbers so they are legible.

My hands shake quite a lot I'm afraid ,so that adds difficulty.

I just couldn't get good enough shots.

Sorry to disappoint you, and get well soon

And thanks once again for your highly valued input.

12 hours ago, Downunderwonder said:

Post the pics anyway, some of us are locked up at home with a nasty virus, too weak to leave the couch, and too cheap to pay for Netfix so scouring photos of amp gizzards counts as entertainment.

 

[BassmanPaul]

@Downunderwonder Get well soon brother!