Otari MX5050 mkiii Questions

thehammondman

New member
Hi all, I've just about got my Otari MX5050 1/2" 8 track dialed in, but I'm having 2 problems. Hoping someone can help:

1. Channel 7 is not erasing properly. If I have something already recorded on that track, it only gets about 50% erased when I try to re-record over it. This doesn't happen at all with any other channel, and I even have a spare head stack that I've hooked up. Same thing. Just Channel 7. Is this an issue with the electronics? Strange that's it's only happening on channel 7.

2. When adjusting the repro levels using the built in oscillator, the VU meter on Channel 8 is very wobbly. When I apply a little pressure to the reel, it stabilizes, leading me to believe I have an issue with the "brake" tension. How do I adjust this?

Other than that, my VU meters are all aligned to zero for the line input, 1k, 10k, and everything is working quite well. I'd appreciate any feedback.

Thanks, everyone!
 
1. Each track uses bias signal for erase operations. So that's where I would start, to check the bias signal amplitude to track 7 during record mode. Have you tried re-seating the channel 7 amp card or swapped a pair of cards to see if the problem follows the card?

2. Edge tracks can be less stable. Your "wobbly" response on track 8 wouldn't have anything to do with the brakes, because the brakes are not engaged in PLAY or fast wind modes, but it may mean you have a holdback or takeup tension issue in PLAY mode. Look in the service manual for how to adjust the tensions and check and adjust and see if that resolves your issue.

Out of curiosity, what's the swing on track 8, and is it more prevalent at 1k vs 10k?
 
Okay. That’s normal. Your machine will always have less stable amplitude response at higher frequencies.

How much is track 8 modulating at 10k?
 
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