Yes the tape is bad, 456 from probably 2005-ish. I bought a few rolls from Coast Recording when I first got the machine. I did put on a newer roll of RMGI 911 and the tape is much smoother. Once I get the kinks out of the machine I'll get some new tape. The RMGI is fairly new with little use, probably a few years old. All my tape is stored in a conditioned space. The MRL tape is stored in it's original case in a closet, conditioned space. It's pretty clean as far as operation etc....
I could probably demag the machine. I'll look for that in my box of stuff. How often should I demag?
My alignment procedures are as follows @15ips. This was taught to me by a local tech hear in the LA area when I got the machine from the CBC in 2005. I'm going on the notes I took.
Repro/Playback Alignment: MRL Tape
-set all tracks to safe mode
-play 1k tone and adjust repro adjustment to 0vu.
-play 10k tone and adjust low speed/high frequency adjust on repro card
-play 100hz tone and adjust low speed/low frequency adjust on repro card
Record Alignment:
-set all tracks to ready mode
-send 1k (1.23vac) tone to channels
-record and adjust each record adjustment to 0vu.
-stop tape/switch to input and adjust rec cal on record card to 0vu.
-switch back to normal mode and send 10k (1.23vac) tone to channels
-record and adjust low speed adjust on record card to 0vu.
-send 42hz (1.23vac) tone to channels
-record and adjust low speed/low frequency on repro card to +1vu for extra low end.
Yes the hum is most prominent on channels 3,4,7,8,11,12,15,16 which are on the right side of the machine under the take up reel. The other channels have a marginal amount of hum. I'm not sure if it has something to do with the power supply transformers when the reels are under load. Not sure if it is inducing some kind of hum into those tracks closest.
Incoming AC ground is nice and tight and other surrounding grounds near that first ground connections/star ground? No visible straps on any of the motors so those must be internally grounded to chassis already.
Just trying to tackle this 60hz issue before any of the other various issues with my deck. I've got a few.
Thanks for the assistance here. Is the Ampex mailing list still in service?
I haven't aligned an MM1100 in a long time, but I'm almost positive that this step is out of sequence in your procedure: "set stop tape/switch to input and adjust rec cal on the record card to 0 vu."
On the MM1200, record cal affects record level. The MM1100 is probably the same. I would set record (input) cal as the last step in the record alignment.
At 15 ips, bias is generally 3db over peak level @ 10k on either machine. As Walrus pointed out, this should be the first step in your record alignment.
For the hum problem, you might try leaving the transport stopped in repro/tape mode with tape loaded on it and the head gate open. Now try rotating the entire machine 45 to 180 degrees... you might be near a strong AC magnetic field and it's being picked up by the heads.
Yes the hum is most prominent on channels 3,4,7,8,11,12,15,16 which are on the right side of the machine under the take up reel. The other channels have a marginal amount of hum. I'm not sure if it has something to do with the power supply transformers when the reels are under load. Not sure if it is inducing some kind of hum into those tracks closest.
I find steel plate is helpful for hum shielding. If you can get your hands on a piece of steel and insert it between the underside of the motor and the top of the electronics cage, you should be able to either prove or reject this theory in short order. I have used things like steel rack panels, steel lids off of electrical back boxes, the steel angel brackets that you get at building supply stores to aid in wood-frame construction and angle-iron. Typically, thicker steel will have more effect than thinner steel, but the quality of the steel makes a difference too. The plate does not need to be grounded to have a shielding effect. It occurs to me that a steel mixing bowl might go around the bottom of the motor, but I'm way more familiar with the MM-1200, and haven't even seen one of those in aeons...so no idea if that would fit.
