CAB 2000.1 Protection Flashing

[40HRZZ]

I'll have to look at schematic again. I had one questionable solder joint so I reflowed it. Still no continuity to center pad.

 

[40HRZZ]

I only see 3 single strands off of the transformer on this could you highlight where you see one going to the center pad?
Thanks!

 

[40HRZZ]

Rereading that schematic and the more ive worked on this board the power section is very similar but the output section doesnt look the same

 

[Perry Babin]

See attached.

 

[40HRZZ]

ok i do have that strand. it is OL to center pad on the amp. But it is 0 ohms to the windings that would be soldered in to the center pad. so if i soldered the windings back in that would have ~0 ohms to the center pad.

 

[40HRZZ]

That strand seems to control the 15 regulators should i check those for a short?

 

[Perry Babin]

If it was shorted to anything, I'd expect C53 and C54 to fail. If the lamp wasn't lighting up, it's not likely a short. If you desolder that wire from the board and reconnect your jumpers to the power supply secondary, does the amp still shut down (go into protect)?

 

[40HRZZ]

I lifted the strand and now the amp builds square waves. I do not get a green or red led now.

 

[Perry Babin]

If you reconnect the jumpers between the large windings and the board, will it power up?

 

[40HRZZ]

I already connected them

 

[Perry Babin]

Is this the winding that goes to the two capacitors and then eventually to the two regulators?

 

[40HRZZ]

See attached.

It is the highlighted trace in the picture you sent. Following the traces it does go to C53 and C54

 

[40HRZZ]

C53 and C54 appear to be ok. Just a heads up. Diodes check ok too.

 

[Perry Babin]

As of now, you read 0 ohms from that winding to the secondary of the transformer, correct?

If so, remove the two capacitors and solder the winding back into the board and confirm that the amp still powers up.

 

[40HRZZ]

Ok jumpers in single winding back in. C53 and 54 out it still Powers up.

 

[Perry Babin]

Install one cap at a time to see if you can narrow down the problem area.

 

[40HRZZ]

With C53 in it protects. With 54 in it powers up.

 

[Perry Babin]

Reinstall the cap and pull the 7815. Does it power up?

 

[40HRZZ]

It powers on with both caps in and the 7815 out.

 

[Perry Babin]

Is the 7815 shorted?

If it appears to be OK, the problem may be with something that's being supplied by that regulator. One thing that's being fed is the 7805 regulator. If the 7815 seems OK, reinstall it and pull the 7805.