GD70
Lunatic Member
Looks like it was well taken care of. Nice!
Let's See Your Great JVC Gear!
- Thread starter GD70
- Start date
Ashraf Hamza
New Member
Hi there,
I have bought this JVC RM- 505 control unit (cost me about $20) missing its remote control. It says all system control unit/ central controller. Does it work as a receiver or as a pre- amp?
lm a newbie I’m not sure what exactly its function is, So please help me out!
Ash
I have bought this JVC RM- 505 control unit (cost me about $20) missing its remote control. It says all system control unit/ central controller. Does it work as a receiver or as a pre- amp?
lm a newbie I’m not sure what exactly its function is, So please help me out!
Ash
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Okke 70s
Super Member
That looks to me as a "control unit" in the sense that is can control other units. Basically an external hub to allow for the use of a remote control. It is not going to amplify anything, other that the "wow!" factor of your stereo. Well, back in the day when wireless remotes where uncommon anyway.. Without the actual remote however, it would seem of little use.
Ashraf Hamza
New Member
Thank you for your swift reply
Schurkey
Well-Known Member
It'd still work as a non-remote-controlled preamp. It's got switching for a limited range of source components, and some sort of volume control. It's the volume control that would be the most-questionable; maybe it has to have the remote for that.
NOT a receiver, there's no on-board tuner or power amplifier.
NOT a receiver, there's no on-board tuner or power amplifier.
Okke 70s
Super Member
NP Ashraf!
. I suppose you could turn it in to a usable pre-amp with some modification. If you dive in and find the right contact points you might be able to fit a "volume up" and "volume down" button in the front. Which then makes me wonder: why did they but up buttons for the input selector in the frontpanel but not volume control? You would still have no tone control, but there does appear to be a phone stage in there. So I was mistaking about that, it amplifies at least your phone signal up to line level.
I was looking at that, but I don't think there is any way to control volume. Accept for that "volume clear" button, but I suppose that is a solution for not having any way to see how high the volume is set right now.. I can see JVC was trying to make something interesting here, but it really seems all a bit clumsy
. I suppose you could turn it in to a usable pre-amp with some modification. If you dive in and find the right contact points you might be able to fit a "volume up" and "volume down" button in the front. Which then makes me wonder: why did they but up buttons for the input selector in the frontpanel but not volume control? You would still have no tone control, but there does appear to be a phone stage in there. So I was mistaking about that, it amplifies at least your phone signal up to line level.
Ashraf Hamza
New Member
NP Ashraf!
I was looking at that, but I don't think there is any way to control volume. Accept for that "volume clear" button, but I suppose that is a solution for not having any way to see how high the volume is set right now.. I can see JVC was trying to make something interesting here, but it really seems all a bit clumsy
Ashraf Hamza
New Member
Thank you guys for your consideration, I think it is a real thought provoking vintage hifi unit!!!
You need the original cables and remote control, it works with some JVC tuner and tapedecks. You can control all functions, it is very nice with a tapedeck, you can change level if audio goes through the RM-505.
Ashraf Hamza
New Member
Thanks for the info, but do you know where to find them remote control and cables?
Funny ..... I think the remote you need for that unit, was posted above https://audiokarma.org/forums/index...r-great-jvc-gear.561107/page-43#post-16051762
Byron Boldt
Active Member
I bought this for $20. It was in rough shape but worked. A lot of bulbs were burned out and it was missing some veneer. I replaced a bunch of bulbs, built new sides from hardwood, painted the top and recapped all but the tuner sections. I also replaced some transistors in the phono stage. It's not worth a lot but I gave it a new life.
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Oldsansui441
Super Member
Nice work Byron. As you say, you have given it a new life and it is now a very functional and great looking piece.
gera2k5
Member
Hello everyone! I'm new to the JVC's world, and I think I'll belong to it for a long long time... still enjoying and very happy with a JVC JA-s77 just acquired.
It's been sleeping for +30 years on a garage, pretty dirty and filthy... but as you all know, when those devices came to our hands, they come for a reason... and it's to wake up the monster once again, and probably not to sleep again.
I never heard a JVC from 70's before, but I read a lot on here and other places that they were pretty decent, with a unique/signature sound, and I've been so curious about it, I know how good JVC was at that time, and also on Video related stuff, as VHS, etc..
I can't believe how good this amplifier is, I knew I was chasing a JVC JA-S71 but it's a bit expensive and I dont really know besides the transformer and 8 transistors at the output instead of 4, which are the big differences... so I went with this one at a decent value, since it was abandoned...
Owner told me he turned it on (without cleaning ANYTHING AT ALL), and it turned on, couldn't confirm if relay clicked or not, so I gambled a bit buying it... lucky it was 100% fully functional, of course potentiometers and switches were stuck and channels were distorted, etc... it was impossible to hear. Even though it was that ugly values (offset and bias) were very very decent 5 or 8mv offset, and bias was 10mV on a channel and 2 on the other, so at that point I knew it was something serious that worth resurrecting...
I still have to clean the faceplate even more, can't remove some grease or marks it still has, and also I want to replace the thermal paste and mica on the output transistors. I always recap an amplifier from this age when I buy them, but it's not the case, I see it's very very good, no leaking on capacitors on the boards, so I will try to keep its signature until the end (if possible).
For whoever still didn't hear a JVC from this era... dont think it twice, go ahead and get one, if you have good ear... you won't regret 100% guaranteed.
By the way, it's been adjusted exactly as the service manual recommends, BIAS and offset.. very very accurate and stable along the time when warm... so it plays lovely at very low volumes as it should.
It's been sleeping for +30 years on a garage, pretty dirty and filthy... but as you all know, when those devices came to our hands, they come for a reason... and it's to wake up the monster once again, and probably not to sleep again.
I never heard a JVC from 70's before, but I read a lot on here and other places that they were pretty decent, with a unique/signature sound, and I've been so curious about it, I know how good JVC was at that time, and also on Video related stuff, as VHS, etc..
I can't believe how good this amplifier is, I knew I was chasing a JVC JA-S71 but it's a bit expensive and I dont really know besides the transformer and 8 transistors at the output instead of 4, which are the big differences... so I went with this one at a decent value, since it was abandoned...
Owner told me he turned it on (without cleaning ANYTHING AT ALL), and it turned on, couldn't confirm if relay clicked or not, so I gambled a bit buying it... lucky it was 100% fully functional, of course potentiometers and switches were stuck and channels were distorted, etc... it was impossible to hear. Even though it was that ugly values (offset and bias) were very very decent 5 or 8mv offset, and bias was 10mV on a channel and 2 on the other, so at that point I knew it was something serious that worth resurrecting...
I still have to clean the faceplate even more, can't remove some grease or marks it still has, and also I want to replace the thermal paste and mica on the output transistors. I always recap an amplifier from this age when I buy them, but it's not the case, I see it's very very good, no leaking on capacitors on the boards, so I will try to keep its signature until the end (if possible).
For whoever still didn't hear a JVC from this era... dont think it twice, go ahead and get one, if you have good ear... you won't regret 100% guaranteed.
By the way, it's been adjusted exactly as the service manual recommends, BIAS and offset.. very very accurate and stable along the time when warm... so it plays lovely at very low volumes as it should.
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Dude you really scored on that one. Those JVC amps from the late 70s were waaayyy underrated in power output and IMO they're just damn cool! I'd say carefully clean it up and out then replace the electrolytics, that amp will go another 40+ years without a problem.
gera2k5
Member
Thank you ! I'll try to re-paint the metal cover tomorrow, didn't get that light gray, but a bit darker, since it has no texture it's just a normal painting, I'll give it a try tomorrow and see how it goes, it has some rust right now, so it will be look much better. I am still thinking about recap, I always recap every amp that I get, but in this case.... I love the "signature" sound SO MUCH that I fear to change it a little bit by replacing caps on the audio chain, even though I go with nichicon audio grade, ELNA or panasonic... so maybe I'll check ESR and leaking (at first sight they didn't leak), and decide.
Okke 70s
Super Member
You can always save the old caps, in case you want to role it back. But I would be jolly surprised. This amp uses film caps for anything delicate, so elcos are just for the crude PS related stuff. I don't even see any low-noise in there. Panasonic FC would suffice for an improvement. FM for whatever is at the signal path (if any). The magic is in other components here. I bet you'll love it even more when done!