Ampre Audio 7.5k

[mnhiphop101]

When I power the amp up it starts switching until the relay kicks in. Then it stops. Any ideas?

 

[Perry Babin]

What happens if you are driving a signal into it?

 

[mnhiphop101]

Same thing

 

[mnhiphop101]

I got it to switching but as soon as I put fets in one of the chips blew

 

[Perry Babin]

Photo of driver board (or 'type')?

Which IC failed?

 

[mnhiphop101]

It was a 21844s. One of the drive transistors failed. Ive got it back to When I start the amp up the relays click and the drive disappears. No fets are in the output section

 

[Perry Babin]

Does the drive stop, even when driving a strong signal into the amp?

 

[mnhiphop101]

Yep

 

[Perry Babin]

What's the DC voltage on the larger output filter inductor before the relay closes?

Do you get modulation of the carrier before the relay closes when the amp is driven with a signal?

 

[mnhiphop101]

Yes but only if there is still rail voltage when I fire it up. If I turn it on with empty rails I get no drive wave at all

I get 0v on the inductor

 

[Perry Babin]

Does it build rail voltage if you power it up with discharged rail caps?

 

[mnhiphop101]

Yes

 

[Perry Babin]

When it starts from 0 rail voltage and builds rail voltage but no rail-rail carrier, can you see the audio drive signal on the input pin of the driver board?

 

[mnhiphop101]

Yes

 

[mnhiphop101]

The rail voltage is jumping around while it builds. I know u hate video but I attached a video of what it's doing.

 

[Perry Babin]

Well... I used to watch video but I can't remember seeing a single one being of any use. I appreciate you trying to reduce the trauma for me by using an analog scope.

Which question (post #) was this supposed to answer.

Some of these self-oscillating amps need a bit of a kick to get them to start oscillating. I asked about the drive at the driver board when it refused to go rail-rail to know if it was possibly not starting because it was not seeing a signal, at the driver board input.

 

[mnhiphop101]

Feeding a signal doesn't have any effect

 

[mnhiphop101]

The rail voltage jumps around as it's building. I've never seen that before.

 

[Perry Babin]

Is that signal reaching the driver board when it will not start?

 

[mnhiphop101]

I put new 21844s chips it and it starts up every time now. it looks like it's trying to start with little blips