Adding three-prong cable to old reel to reels?

peritus

peritus

The not fountain head
Hi.

I have an old reel to reel that I want to use to bounce stereo mixes for tape compression (and dirt). It's an old 7.5 ips Uher deck with two-prong cable. Should I, and is there any value to, replacing this cable with a three-prong grounded cable?

Mine looks like this, but is different:

Mine has a two-prong US tail cable instead of the Euro style.
 
As a rule of thumb, if a product needs a ground (which of course is for safety, not noise purposes) it will have one. In Europe we have two classes of equipment. One needs a ground - an absolute essential designed in feature. Operating it without the ground is dangerous. Remember we have 220/240V power here.On the other hand there is double insulated equipment that is electrically safe without a ground. Connecting the chassis of these to ground removes the built in separation the double insulation provides so again, is not recommended. If it has a two conductor mains cable, leave it alone. These Uhers were not the nicest recorders - some of their range were superb, others were quite domestic in quality - but as you are dirtying the audio up, I guess that's what you are after?
 
I'll go with it does not need a ground. The power transformer isolates the AC mains from the chassis ground of the deck so there is nothing hot from the mains that would normally get through to the chassis and create a shock hazard. Not sure if you may have issues with hum depending on if the gear you're connecting the deck to is or isn't grounded well. I had some problems with an older Tascam USB interface that had a poor ground through a computer via the USB connection and had hum/noise issues.
 

Attachments

  • uher.jpg
    uher.jpg
    152 KB · Views: 2
I just want to emphasize the point that was already made, that a 3-prong power cable vs a 2-prong power cable has nothing to do with sound quality. It is all about safety, though it does provide a way to neutralize any voltage potential between the chassis of your different devices. But this all gets pretty complicated pretty quick. I say if you are not having issues with ground loops/hum, and there is otherwise something in the design of the 2-prong power cable device that addresses the safety issue, then it is not time well spent to change the power cable. I had an issue where a Tascam BR-20T had issues with the chassis being hot…voltage-wise…enough current to feel it when I touched it. I didn’t get to the bottom of why this was happening, but I changed the power cable to 3-prong, consulted others for the best way to do this, and took all precautions in the process. It took care of the issue. But it was really masking a symptom of some other problem. So…that was lame of me. The way I ensure all devices in my setup have a single path to a common ground is through the power cable or some means of strapping the chassis to the common ground through only one path. Then there’s a whole investigative process to determine how signal ground is handled in each device and rectify disparities with that. But if the easiest way to strap the chassis through a single path to a common ground is by incorporating a 3-prong power cable, then I do that. I think I’m your case if the device is safe with the 2-prong cable, and it should be, and you are not having noise issues that are the result of the 2-prong plug, rest well and leave well enough alone.
 
I think I'm a little sensitive to volts where they shouldn't be. I seem to detect 'tingles' quite easily - continuous and static discharges. I've still got the scar on one hand caused by a grounded surface touched by my left hand and the skin on the back of my other hand touching the 'ground' of the case on another bit of dodgy kit. Years ago I was found commonly grounding everything case and screen wise mainly to stop the tingles and cure hums. Later on I started to think a bit more. One day with a tingle I was bonding two bits of kit together with my favourite problem solver - a jack to jack cable wired with ONLY the ground wire connected. I could plug this into any jack socket on an amp, and into any other bit of kit - or a mixer aux in or line input - it conveniently cured hums and stopped the tingle, until one day when I plugged it in, I heard a quiet pop? Inside one of the jacks, the thin cable inside the plug had melted! Investigations showed there was over a hundred Volts and half an Amp on the meter between the two units. A dodgy turn on a transformer in a guitar amp - half of the mains Voltage was on the ground of them that had a two wire mains cable. That's heart stopping stuff! Usually it's leakage current so milliamps - and grounding hides, not cures the problem. I never fixed my grounding cable - safety now is in my head in a way it wasn't before.
 
The only reason I put IEC sockets on older Teac decks is to get away from that hard to find two prong cable they sold. The IEC cables due to computers and broadcast equipment are everywhere and when I wire up a Teac with IEC I do NOT use the ground terminal as there is no reason to do that. The deck runs on an isolated transformer winding and the chassis is referenced to the ground of the DC power supply. I had only been stung by one deck in 47 years and it was a A4010S that had a pinched wire under a motor mount that finnally went through. It burned a 1/4 watt 1K resistor in half as I measured leakage from chassis to bench ground- that is when I knew it was a serious problem but was resolved. The unit is working well in Amarillo TX. I think he was the Mayor there.
 
You must log in or register to reply here.
Back
Top