Kenwood KA-3500 takes puts DC on speaker while powering on

Raccoon1400

Raccoon1400

Super Member
When I turn the unit on, it puts the rail voltage on the output for about 3-4 seconds. Both channels do this. What could cause this? The regulated and non regulated voltage supplies for the power amp look fine from what I can tell. I'm worried about this damaging someone's speaker.
 
So, is there a corresponding big 'thump' coming from the woofers?

The 3500 has an odd little muting mechanism via Qe26 and Qe27 in the pwr amp section. Two transistors, a couple of diodes, and a 47uf cap. Last 3500 I had here with a problem like you describe (but apparently not so severe), swapping those parts out cured it, and it powers up nearly silently.
 
EchoWars said:
So, is there a corresponding big 'thump' coming from the woofers?

The 3500 has an odd little muting mechanism via Qe26 and Qe27 in the pwr amp section. Two transistors, a couple of diodes, and a 47uf cap. Last 3500 I had here with a problem like you describe (but apparently not so severe), swapping those parts out cured it, and it powers up nearly silently.
Click to expand...

Not so much a thump, but a hum. The same hum I heard while experimenting with sending DC to speakers though my DC protection circuit, just before the test woofer coil toasted.

I'll try swapping those parts and report back soon.
 
That worked, thanks! I changed the two diodes and two transistors. I left the cap because I don't have any 47/100V caps kicking around.
 
You must log in or register to reply here.

Similar threads

chicks
Kenwood KA-3500 Integrated
Replies
19
Views
14K
Jcricket
Jcricket
rickl
KA-3500 cleanup
Replies
3
Views
553
hopjohn
hopjohn
R
Kenwood KA-3500 becomes distorted?
Replies
9
Views
4K
Uncle Bambi
Uncle Bambi
S
Another KA-3500 with some issues
Replies
6
Views
1K
Mayank
Mayank
rossm
Kenwood ka-9100 help
2
Replies
38
Views
3K
rossm
rossm
Back
Top Bottom