5050 buzzing problem

nh36000

Too many notes!!!
I have a random and intermittent buzzing from the take up reel motor when I first turn on the deck. It takes about five minutes to stop but it finally does.

I can tap around, with the butt end of a screw driver, on anything inside to no remedy. I have an idea that it's an electronic problem.

Might that be a bad electrical connection or something? Any help to fix that, please.

I've been hearing that for better than six months. I don't know what's doing that.

Lu.
 
4-2-7;

Yeah, the capstan motor is well oiled.

And no, I can take digital photos but not video. I'll do my best to relate anything, though.

And thanks for the interest, glad you wrote in.

Lu.
 
Wait, wait, wait!

I just remembered, there is a camera on the laptop, here. 'Don't know how good the recording will be but, I'll give it a shot.

I just got done reading your Westwood One thread. Maybe I can link a YT video.

Lu.
 
All, I'm bringing this one to the top, again;

My not knowing just what to do, and all the mention of how clean 5050s are to be kept, I dropped the amp board and cleaned all the connectors. It helped but didn't solve the issue.

This morning I dropped the transport board and cleaned up the front switches. The micros should be OK.

I've got an early model, a -2HD. These weren't sold to the consumer but to studios and record makers. I can imagine that a problem would prompt a call to a repair tech for service. That guy would probably have all he needed.

The owners manual I have, does not have a capstan motor control board schematic to it. Nor, a parts list. I open up an SM for a -Blll, on HiFi Engine, for that.

Now, there is a guy that started a four page thread, on Gear Slutz, that was rebuilding his capstan motor. Doing that, when it came to looking for a motor board schematic, there is none. A guy, out in California, wrote in to say that he used to work for Otari and had a schematic for the control board, he attached it to the post. I saved it to my computer.

The buzzing hasn't stopped but I could pass the schematic on if anyone could help me figure this 'buzzing' out.

And along with that, I started up the deck this morning, pressed play and no tape transport. ??? I turned it off, waited a minute, then turned it back on. With some persuasion, the reels were turning but it was jerky, like 60Hz. wall current. I stopped it, put it in FF and then Rew., and after that, reels were spinning normally. That would tell me it's just dirty. And it's why I cleaned in there.

While it's open, I could clearly hear that the noise is coming from the control board. I could unplug it, dismount it, and go over it for out of spec. components, if someone would tell me what to look for.

Any help, please. And yeah, that transport issue sure gave me a start!

Lu.
 
4-2-7;

Is the capstan motor oiled?

Yeah, yeah, it's spinning like there's snake oil there. I wrote that in post #4.

I'll give the link a look.

Lu.
 
Hi guys,

I am having a problem with a Revox A700. On first switch on, the take up motor does not drive at all initially. The motor can then feel to buzz and the power (Torque) can be felt to increase. When the torque is at a max, the buzz then tails off and all is well again.

I am expecting this problem to be a leaky capacitor which is level shifting the AC signal to a rail or ground.

May be this could be applicable to your fault. Go over the Servo for the reel in question and look for suspect caps on the schematic. I don't have any experience on a 5050 but I am happy with sorting electronics.

Cheers.

GPS16
 
Yeah, thank you very much for the idea. I had another look inside the deck this morning and thought I heard a buzzing from a big, silver, oil can looking, cap.

A quick look at a schematic referenced a 6.5 mf./ 250 v. capacitor. It's soldered to a board that is next to the transformer, and powers the take up reel motor.

The buzzing is 60 Hz. and along with that, I can hear a high pitched noise, along with the buzz, that sounds almost metallic, in the back ground. A strong sound that made me think that there are lots of volts there. The cap is on a board that can be wired for 100 to 240 v. for input from wall current. Not very loud, but just listening to it suggested that there is big power there. Maybe a replacement cap would solve it. It looks like it would be a pricey cap.

I've re oiled, re floated solder, No cure yet though.

Hope this helps to figure it out,

Lu.
 
Here's the latest;

I have the back off and I looked inside.

With the deck 'on', I moved the take up tension arm up and the random buzzing started.

While listening to it, the buzz is coming from the take up reel motor and the high pitch noise is from the capstan motor control board.

Also, when the deck is in either FF or RW, the noise is constant.

I have no idea what's doing that, and it's not getting any better. It's messing up tape speed, too, for about ten minutes until it warms up.

Help!

Lu.
 
I have no idea what's doing that, and it's not getting any better. It's messing up tape speed, too, for about ten minutes until it warms up.

What about your interconnects? Did you see what wee where talking about in my thread?
 
4-2-7;

Actually, the interconnects I'm using now are brand new. I just bought a line leveler/ converter and all the cable I needed to patch all that in. In fact, liking the cables that Skywavebe recommended, I bought ten more. They should be here in a couple of days. I'm going to trade out the GEs and the Evergreens, I have, with new.

I first have two RCAs. (more on the way) I plugged one of them into the out of the deck and then into the pre amps 'play' port. The other went from the pre amps out and then to the power amps in. I then played a tape and instantly noticed an improvement in the sound. Much more detailed and cleaner sounding highs and low frequencies. I bought more cables.

No, it's not the cables.

Lu.
 
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