tilt?

[FALKEN]

So I think the playback head and to a lesser degree the record head on my 2-track have a bit of tilt to them...tilting back away from the tape very slightly. I noticed with a flashlight shined on the heads that they are starting to wear less on the top and more on the bottom. Also I noticed a difference in the amount of low frequency between the 2 channels. I have read a bunch on here about phase alignment and azimuth, but how do you check that your tilt is correct?

[Tim Gillett]

If the tilt has been incorrect for some time and head wear is now uneven as a result, probably not a good idea to just fix the tilt. The head(s) should be relapped or replaced and installed correctly.
Depending on the model, tilt can be adjusted using a jig, basically a squared piece of metal or plastic, referenced to the head base plate or the chassis plate.
I've sometimes done it by eye, referenced to the fixed tape guides or even the capstan shaft, which should be fairly true. On some machines I've used the technique of looking along the tape itself and watching for any slight twist in it from the guide to the head.
The classic error is to set the tilt wrong and then compensate for the resulting vertical tape skew by raising or lowering the head height. It looks fine but you get weak tape pressure on one edge, with the risk of dropouts, and long term uneven wear (keystoning). With the standard 3 screw adjustment, once you have tilt correct you need to avoid putting this adjustment out when you adjust height, by varying the two height screws by exactly the same amount.
Cassettes are easier as the tape path is standardised and so there's one jig fits any and every machine.
Whatever, if you do it yourself take time, be patient, use lots of light and if your eyesight isnt what it used to be, like mine, use magnifiers.
Cheers Tim

[FALKEN]

Thanks, Tim. Here is a picture of what I am talking about. You can see the trapezoid in the center of the head on the right. It seems as though the heads have never been adjusted since leaving the factory because the screws are still marked in their original positions. (with wax or glue or whatever that stuff is they put on at the factory)

[Slowrider]

To me, it looks like the capstan rubber idler needs cleaned. Glazed at the bottom, which would cause an uneven pull. Could just be my eyes?

[Tim Gillett]

Hard to tell much from the photo. I think you need a macro or a close up lens.
Yes I've seen a number of machines with keystoned wear pattern and apparently set like that from the factory. But then what a job for some poor sucker to do all day every day...

Cheers Tim