HS-U580 Mitsubishi RF output issue
bob u
I set it up in his house and it was fine
2 weeks latter he is having issues
i got it back and tested it.
through the line outputs it seems to work fine
through the RF CH4 modulated output, its a blue screen
It seems the modulator is putting out a carrier,
but no information. If i do the TV/VCR switch, i can see
the TV channels OK on the TV with pass through mode.
I don't have the manual on this beast.
I checked the menu, and there is a way to disable the RF mod
in the set up menu. I double checked it, and its enabled.
I even toggled it for good measure.
This does not sound like a modulator issue, but i am kind of
stumped on this without further information. Anybody got any ideas
on this or have a PDF manual on the HS-U580?
bob
David Farber
Hi Bob,
I'd check the caps first. Maybe a few are leaking and wreaking havoc on the
circuit board. Is the audio missing as well? Just to make sure I understand
your problem, is the screen also blue when playing a tape as well as going
through the tuner?
--
David Farber
Los Osos, CA
bob u
But they both work on the Video line output jacks.
bob
Bruce Esquibel
> yes, its blue with no audio on both VCR tuner and VCR tape.
> But they both work on the Video line output jacks.
You said earlier, "This does not sound like a modulator issue", but it seems
to be one to me. I'm not familar with that model but many vcr's get the
audio/video feed into the modulator from the a/v jacks, or the same path.
So generally if you have composite working but no r/f, it's something with
the modulator.
Also, are you sure the vcr is the one producing the blue screen? Most tv's
within the last couple decades go to blue screen if no rf signal is present
on a channel.
If the modulator is dead, or not getting power, would make sense with the
blue screen.
Generally modulators have a switched 5 or 12 volts fed to them when "on".
Usually only 5 or 6 pins.
Without a schematic, I'd just use a volt meter, touch each pin while
switching it from "tv" to "vcr" mode, one of them should swing from
next-to-nothing to +5 or +12.
If none do, it's in the switch circuit (schematic needed at this point), if
one pin does, it's probably the modulator. Would only take a few seconds at
this point with a scope to see if video and audio is present at the other
pins.
Basically, if you have power, video and audio going into the modulator and
nothing out, it's a bad modulator.
My guess is, if it was working and stopped working after a couple weeks with
the new owner, likely there is something he isn't telling you.
Many "bad" modulators went bad right after the owner tried to do something,
forced a cable in, bent pin, yanked the cable hard.
Many a modulator gets the center of the "out" jack cracked or broken off the
circuit board inside of it. Too little pad for too big of a connection. Any
abnormal force breaks it.
The hardest part to all of this is just gaining access to the modulator,
some are a peice of cake, some a pain in the ass.
But I'd still guess "something happend" when "it just quit working".
-bruce
b...@ripco.com
Brenda Ann
"Bruce Esquibel" wrote in message
news:id8e1a$jr4$1...@remote5bge0.ripco.com...
bob u <so...@inetnebr.com> wrote:
-bruce
b...@ripco.com
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Have you tried it with more than one television? If using a current model
equipped with an ATSC tuner, the NTSC is an afterthought, and often requires
a "perfect" signal to operate. VCR modulators are very crude devices, with
no appreciable filtering (the audio signal can be seen on both sides of the
carrier, there is no vestigial sideband filtering) which can cause the TV to
lock in to the wrong part of the signal (i.e. lock onto the first carrier it
sees: the audio carrier that shows up at the bottom of the 10 MHz wide
output channel).
Lots of incompatibility issues with the new generation of TV's..