[TechAssist] Re: Yamaha Receiver Model# RX-V85- Hums & turns off after 5 minutes.

A lot of new product doesn't necessarily have protect indicators, I do a
fair bit of audio service and have found this to more true as audio
companies try to shave the prices down. Your unit is almost definitely going
to some sort of over current mode. I would do this first : Hook the item up
to a 8 ohm load and an ac ammeter to monitor the AC input current. Most
receivers today idle drawing less than 1 amp at 120VAC. When the thing
starts to hum watch the ac current and quickly check for DC voltage at the
speaker terminals. It should be pretty much 0V when operating correctly. If
you find there is 1 volt or more on one of the speaker outputs, that channel
is the problem. If you find the same condition on both speakers, then you
have a problem common to the output stage, probably power supply.

Also, look for screws going thru the PCBs that act as grounding points. Sony
was famous for this one, critical grounds routed thru the chassis via a
SCREW !  Pretty dumb if you ask me, but hey we need stuff to fix right ? If
you find you have a bad ground like this, I would hard wire it with some 18g
stranded wire in a point to point fashion.

IF this receiver is a 5 channel surround type, the above still applies, put
the unit in Church, 5 channel stereo, Hall or Matrix mode. This will make
all 5 channels output audio without having to input a Dolby type signal (if
you had it in DD or DTS mode)  Check all 5 channels for dc on the output !
You can remove the cover and locate the output coils (usually near protect
relays) and check for DC there.
BTW, if your AC ammeter starts to climb above 1 amp shut the unit off and do
the "Finger test" look for something hot ! Don't lose your prints in the
process !
HTH
Keith Trumbla
BEM Electronics
Winnipeg, MB
Canada
Phone. 204-832-6237
----- Original Message -----
From: <HarrisTV50010@xxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Monday, January 31, 2005 1:45 PM
Subject: [TechAssist] Yamaha Receiver Model# RX-V85- Hums & turns off after
5 minutes.


> I have a friend that has a Yamaha receiver Model# RX-V85. This unit works
OK
> for about 5 minutes then gets a hum and turns off. I am a little confused
> because he says there is no protect indicator on. Normally with the hum I
would
> thing it would be going into a protect mode. Maybe this unit doesn't have
a
> visible protect indicator. Any thoughts would be appreciated.
> TIA,
> Dale
>
> Dale A. Lubow... HarrisTV50010@xxxxxxx ..515-232-1109..(Fax)515-232-3356
> Harris TV & Appliance..........335 Lincoln
> Way.....Ames.....Iowa.....50010-3384
>
>
>
> --------------------------------------------------------------------------
---
> Lost Password:
> http://www.tech-assist.org  and select "Login Problems?".
> Email Archives:
> http://www.freelists.org/archives/techassist/
>
>


-----------------------------------------------------------------------------
Lost Password:
http://www.tech-assist.org  and select "Login Problems?".
Email Archives:
http://www.freelists.org/archives/techassist/

Other related posts: