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Roberts Electronics Model 770 Help Request

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posted on Jan, 7 2018 @ 04:27 PM
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Hello Music Enthusiasts!

I have a 1964 Roberts Electronics Model 770 reel-to-reel that appears to be new or hardly used. However, it has been in storage for decades and I am a bit worried about firing it up because I have heard that tube devices such as these need to be treated carefully if they haven't been used in awhile. I am wondering if any of you have experience with this or other similar devices and could either tell me what I need to do or point me in the right direction.


Thanks in advance!!!
edit on 172018 by seattlerat because: (no reason given)




posted on Jan, 7 2018 @ 04:48 PM
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a reply to: seattlerat

If you can take it apart and feel comfortable putting it back together right, do that. One piece at a time and dust off that area. Especially the moving parts. When you're done with all that, configure everything to where, when you turn it on, it isn't working that hard. I have no working familiarity with that make and model, but this is kind of the standard operating procedure for anything with moving parts that hasn't been fired up for a few decades. Treat it with kid gloves in other words. And if there are parts that need lubrication, go light with it.

What's the worst that happen? Keep in mind that this make and model is only worth about 100 dollars on a good day.

BTW.......that looks to be in REALLY good shape.

Good luck

edit on 7-1-2018 by DeepImpactX because: (no reason given)



posted on Jan, 7 2018 @ 05:03 PM
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Does it have a 'standby' mode?
If so let the tubes warm up in standby and warm up for about 10 minutes before you kick it on.



posted on Jan, 7 2018 @ 05:46 PM
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a reply to: seattlerat

Some audiophiles recommend slowly
upping the voltage on old tube gear.
I had some old McIntosh C20 and MC30
pre-amp/amp blocks and that's what was
suggested to me.

I just went ahead and plugged them in,
connected, and they were fine.

The things to be concerned about on your
recorder are the Capacitors , all rubber belts,
and the rubber pinch rollers for the capstans.

Your recorder may be Solid State and not Vacuum
Tube style. Regardless, I always have a can of De-Oxit
on hand for cleaning potentiometers,etc. Just make sure
to avoid spraying the pinch rollers/belts to avoid tape
contamination and slippage.
You have a fine project there.

S&F


edit on 7-1-2018 by Wildmanimal because: typo

edit on 7-1-2018 by Wildmanimal because: add content



posted on Jan, 7 2018 @ 07:53 PM
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a reply to: seattlerat

This guy's YT channel has all kinds of electronic tube repair stuff . You might find what you are looking for or you might be able to send him off a note ...he is a good guy and his name id Brad
eta you could take the unit to a electronic shop and have them slowly bring the voltage up with a Variac

edit on 7-1-2018 by the2ofusr1 because: (no reason given)



posted on Jan, 7 2018 @ 08:30 PM
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Thank you for all of the great replies- it has been awhile since I looked into getting it playing again- the suggestions you have all made seem like stuff I can handle, taking it to shop to have voltage slowly increased with VARIAC is what I thought I needed to do, I just couldn't remember that. I sure appreciate the time you all took to reply! I will post here again in a couple weeks after it is up and running.

Happy New Year!!!



posted on Jan, 19 2018 @ 07:10 AM
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I build and repair tube guitar amps.

You don't need a Variac to re-form the filter capacitors--you can easily make your own voltage ramp if you can solder and know how to be safe around mains voltages.

The voltage ramp is made with an incandescent bulb (60 watts is good) and a socket for it. Wire up the socket so it is in series with the hot leg of your AC mains supply. When you switch on your device, the light bulb's filament acts as a load and prevents a voltage spike from hitting the filter caps.

Speaking of filter caps: if you crack open the unit, be extremely careful because filter caps can retain lethal DC voltage even when the unit is not plugged into the AC mains supply.

Additionally--if the unit's AC mains cable is a 2-wire (no ground) which was common prior to the late 1960s, you will be in danger of a serious shock because depending on how you plug that into the wall socket, the chassis may be live. If there's a ground reversal switch on the rear panel near where the AC mains cable enters the unit, that's another indication that the metal case might be live (depending on the position of the switch).

If that were mine, the first thing I'd do is install a 3-wire mains cable to ensure the chassis/metal case is always referenced to ground.


edit on 19-1-2018 by TheTruthRocks because: (no reason given)




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