View previous topic :: View next topic |
Author |
Message |
irobot
Joined: 13 Mar 2009 Posts: 49
|
Posted: Tue Apr 06, 2010 8:10 am Post subject: YAMAHA RX-V2500 PA Problem |
|
|
Hi All
I hope someone can help with this:
I have a RX-V2500 on the bench with what I believe to be a strange bias problem on the SL channel output stage. DIAG mode displays DC Protect fault.
So here's the scoop -
Upon power up I read about -1.5V on the speaker output, which climbs to about -3.1V volts after about 20 seconds, then of course the DC protect kicks in and shuts it down.
I see this same -1.5V ~ -3.0V on the input to the PA (this is the "VSL" signal). It also too slowly climbs up to about -3.0.
The same voltages (-1.5V ~ -3.5V) show up on both emitters of the complementary transistor pair prior to the finals.
I replaced almost every component in the bias and output stage including the finals and .22Ohm pair. I checked for any possible floating grounds.
I also checked and rechecked components on the preamp/driver board.
The other channels are all fine.
By now I'm pulling my hair out!
Any ideas?
Thanks! |
|
Back to top |
|
|
|
|
|
You can post new topics in this forum You can reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
|
eServiceInfo on FB -
Service Manuals Free Download -
Service Diagrams
Free TV Schematics Download -
HARDW.net -
Pinout Master -
Jabse Service Manual Search -
Jabse.InK -
onTap.bg
SnimkiOt.com -
Poblizo.com : пътешествия
Latest Service Manuals :
GA26-1589-5 2835 2305 Reference Oct83 IB • hfe pioneer djm-800 service prov en Pion • la schematic set1 . Various • SR7-79~2 LG • AZ3010 Philips • Canon LBP-2460 Service Manual CANON • 11 Electrical Part List Samsung • 2sc3547b Toshiba • Compaq A900 (JBW00 LA-3981P) R0.2 HP • HP 4396A Performance test 2 Agilent •
|