Disabling erase head on Reel to Reel (sound on sound)

[Casey Jones]

Hi all,
I need some tips regarding this modification I am looking to do on my UHER 4000 Report Monitor. So I need to bypass the erase head by adding a switch ..or alternatively a potentiometer so I can turn the erase head on and off smoothly so I can achieve an endless loop of sound on sound. This is possible as I have seen somebody do this before. I am just not sure where to do the mod - or if I need to consider the BIAS and stuff in the circuit diagram. (I am a bit of an electronics newbie)
If anyone has any advice or experience in doing this themselves I could use a couple of pointers. There are a couple of people on blogs who have shown off their modifications yet offer no real instruction how to do this.
Thanks if anyone has a few pointers!
CJ
]

 

[ecc83]

Hi all,
I need some tips regarding this modification I am looking to do on my UHER 4000 Report Monitor. So I need to bypass the erase head by adding a switch ..or alternatively a potentiometer so I can turn the erase head on and off smoothly so I can achieve an endless loop of sound on sound. This is possible as I have seen somebody do this before. I am just not sure where to do the mod - or if I need to consider the BIAS and stuff in the circuit diagram. (I am a bit of an electronics newbie)
If anyone has any advice or experience in doing this themselves I could use a couple of pointers. There are a couple of people on blogs who have shown off their modifications yet offer no real instruction how to do this.
Thanks if anyone has a few pointers!
CJ
]

Hmm, tricky. If you take the load off some transistor oscillators they destroy themselves! You could try to find the exact erase head and connect that away from the tape (not too far!). Another problem is that forking with the bias osc' will change its frequency and that will change the bias current.
You could try a mechanical method to move the tape away from the head.

Whatever you do buy a head de-fluxer first because all these shennanegins are sure to mag them up!

Dave.

 

[Beck]

You could try a mechanical method to move the tape away from the head.

This is the easiest way to go. Think tape lifters, but for the erase head only. It doesn't take much, even a piece of electrical tape over the head. Not that you'd want to do that exactly, its just an example of how little one needs to lift the tape away from the head before it won't erase. It's not very much.