[TechAssist] Re: [Intrepid] Mitsubishi M-AV1, Audio
- From: joe872@xxxxxxxxx (Tech / 2002)
- To: techassist@xxxxxxxxxxxxx
- Date: Wed, 2 Jan 2002 20:01:45 -0500 (EST)
Thanks Frank,
If you do come across any service info. let me know. No mute switch,
most all switching is done digitally, except for a couple. Eliminated
relays, going to try to check out STK4132. If anyone has any service
info on this unit, would appreciate letting me know. Thanks All "joe"
joe872@xxxxxxxxx
From: wb7elc@xxxxxxxxxxxxx (Frank=A0Burnham) Date: Wed, Jan 2, 2002,
12:52am (EST-3) To: joe872@xxxxxxxxx (Tech / 2002) Subject: Re:
[Intrepid] Mitsubishi M-AV1, Audio
Joe,
If this unit has a mute switch, check it,( they get dirty & do some
REALLY
strange things also if it has a tape monitor switch that is another high
failure area. Got had a few times by those areas
Not familiar with the unit you are working on.
Also check for bad solder on the switches.
Have you tried injecting a signal into the output Ic's input pin? I
suspect a cross ref book would have the IC pin out. Those also use a +&-
b supply. Typically around 40-60V check the ic for those voltages.
=A0=A0=A0=A0If the signal is present to the input of the STK's, and the
voltages are what is shown in the cross ref book, I would suspect the
STK. You can remove the STK. from the board and put your signal tracer
there. If you do have voltages & signal- I think I would seriously
suspect the STK's.
=A0=A0Of course, I have been fooled once or twice over the last 30+
years....................
Don't forget to double check the relay contacts. Whap them with a
screwdriver handle on top of the relay.
=A0=A0If your sound suddenly appears- you found it. Those cotton'pickin
relay contacts will pass signal at some levels and not at others.- or
sometimes none at all.
=A0=A0There is lots of discussion on cleaning the contacts or replacing
the relay. I favor the latter. Remember- if there is room, you do not
have to have the exact relay to do the job. I have out boarded relays
when the OEM was NLA. Just match up the coil voltage & current. Have
used 4PDT for DPDT & SPST relays too.
=A0=A0On the SPDT replacing the DPDT, I paralleled the contacts for
greater reliability.
=A0=A0Its 1:30 here & have to be at work at 9:00 so gotta run. I just
picked up literally 1/2 cord of svc manuals & a lot of mits stuff in
the pile. for TV, haven't gone through for audio yet. If I get time I'll
try to see if I have a schematic I can peruse for you to help out. Frank
Tech / 2002 wrote:
Frank & Anyone
thats knows audio,
Frank I started with your suggestions below, come to discover that if I
almost max to max volume I have low volume, very clear but very low, IC
301 which i believe is pre amp gets quite warm understandably when
running near max vol, then unit has 4 pre outputs, 4 outputs, then
STK4132 stereo amp which i some what suspect, or could AB switch
headphone jack both mounted on same board cause this, also same with
headphones plugged in, max vol, vol still clear & still low. Baffled for
now, gonna call it a night, hopefully wake up to some additional
leads.Thanks for the starter "joe" joe872@xxxxxxxxx
=A0=A0=A0=A0=A0=A0=A0=A0From: wb7elc@xxxxxxxxxxxxx (Frank Burnham) Date:
Tue, Jan 1, 2002,
6:10pm (EST-3) To: joe872@xxxxxxxxx (Tech / 2002) Subject: Re:
[Intrepid] Mitsubishi M-AV1, Audio
Joe,
=A0=A0=A0=A0Check to see if this unit uses a relay to switch the
speakers on. I have had them go bad. Just put a signal tracer on the
relay contacts to test.
Don't overlook a defective headphone jack, A/B speaker switch, or hidden
output stage fuses. Frank
"Dr. Digital"
Tech / 2002 wrote:
Mitsubishi model M-AV1, quite an elbrate audio sound system. DR62 of ac
bridge shorted, F11 8 amp ac fuse blown. Replaced, unit now fires, both
relays click on, all funtions on display panel work fine, put in FM/AM
mode to check audio, tune in station to where display shows tuned, yet
no audio from speakers or headphones. When 1st turn unit on, yellow mute
light flashes until 2nd relay kicks on then shows normal display, just
wondering if i'm overlooking a mode, has numerous selections, but I
don't think so. No print. Any help would be greatly appreciated. Thank
you, joe872@xxxxxxxxx
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0"joe"
=A0=A0=A0Tech/2002
Otsego,49078
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