had this nice VCR i sold to a customer 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?
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?
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".
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".
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..
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