equipment buzz...Help!

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tcb1

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Hi!
I am transferring several recordings created in 1964 and 1965 to wave files on my pc's hard drive and then to cdr. I am using an early 1970'2 model Akai gx-4000D reel to reel tape deck to play the tapes and a Creative Audigy 2 card as the input to the pc. The tape deck has rca jacks for line out and I am using an inexpensive adapter cable with rca plugs on one end and a stereo miniplug on the other.
The problem is a consistant buzzing that is created when plugging into the sound card and this buzz is then captured along with the recording. I have tried plugging the tape deck into another source but it does not help. The buzz can not be heard when using the headphone jack on the tape deck but is quite audible from either the headphone or the speakers on the pc.
If you can help a newbie resolve this problem it will be much appreciated.
 
My first guess is that the tape deck is not well grounded.

If you have a voltmeter, measure the dc potential between the tape deck chassis and your house ground. You might have to be somewhat ingeneous to do this, for instance, plug the tape deck into an outlet near a water pipe, then connect one voltmeter lead to the water pipe and the other to some surface on the tape deck that you suspect is connected to chassis ground. If the voltage measured is anything other than zero, the tape deck chassis has a lousy (or non-existent) connection to ground. Depending on how familiar you are with electronics, you might try fixing this yourself. It might be as simple as connecting a piece of wire from the tape deck chassis to the computer chassis, but be careful, if the tape deck chassis is indeed floating and has a significant potential, you could harm the computer by doing this. It might be worthwhile taking it to an electronics shop.

Another possibility is that the cabling you've cobbled together is causing the problem, but from what you've described it sounds like it should work.

Let us know what you find out.
 
Does the deck have a three wire grounding plug? Or at least a two wire, polarized pug with one blade wider than the other?
 
Also make sure to plug the tape deck into the same power strip as the computer.
 
Thanks for the responses.
I have done the following: using a multimeter taped the neg lead to incoming copper water supply and then tested various chassis points on the tape deck:
In dc voltage mode there were no readings beyond 0. In ac voltage mode there was a four volt reading at all chasis points.

The unit was manufactured prior to required use of the grounded three prong plug.

I removed an electrical plug socket from the wall housing an attached a wire lead to the ground using the same screw. I carried the insulated wire to the tape deck chassis and connected it with another screw.

That relieved all of the buzz at the low to mid high levels. It is still there at full volume, especially with the sub woofer cranked up, but since I won't be recording at that volume I am hopeful it will not be apparent.
Is there likely to be any negative consequence from this grounding experiment to the heads or to the tape when it is loaded?
 
I also failed to note that I am using that same wall socket to plug in an outlet strip for all of the components.
 
At full volume and with no input, almost all AC powered gear will pick up some 60 Hz hum. It comes through the air and sneaks into unshielded high impedance circuits. Don't worry about it if it is not apparent at normal levels.
 
tcb1 said:
Thanks for the responses.
I have done the following: using a multimeter taped the neg lead to incoming copper water supply and then tested various chassis points on the tape deck:
In dc voltage mode there were no readings beyond 0. In ac voltage mode there was a four volt reading at all chasis points.

The unit was manufactured prior to required use of the grounded three prong plug.

I removed an electrical plug socket from the wall housing an attached a wire lead to the ground using the same screw. I carried the insulated wire to the tape deck chassis and connected it with another screw.

That relieved all of the buzz at the low to mid high levels. It is still there at full volume, especially with the sub woofer cranked up, but since I won't be recording at that volume I am hopeful it will not be apparent.
Is there likely to be any negative consequence from this grounding experiment to the heads or to the tape when it is loaded?
Click to expand...


It would be interesting to see what the frequency of that AC voltage is - probably 60 or 120 cycles, ripple voltage from the power supply rectifier - in any case, nice detective work!

Hard to say if there will be any negative consequences, the deck probably needs to go into the shop so someone can take a serious look at the power supply. You could probably take a crack at it yourself, start by replacing the filter capacitors, and then check the ground connections from the power supply section to the chassis.

Any chance you could borrow a good tape deck just long to transfer your tracks to the computer?
 
I can't take credit for the detective work on this as it belongs to you and the other members of this forum. I have two reel to reel decks but the one I am using has less buzz than the other, both were aquired via ebay which proved to be a handy source for 30+ year old technology. I am going to transfer from tape to pc using less critical recordings to check the results. I will post the results when completed.
Thanks to all for your responses.
 
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