Otari MX-5050BII Help--Playback Heads Funny During MRL Calibration Tape

[woody23]

So I picked up an Otari MX-5050BII recently and finally got around to calibrating it. . My problem: As I start playing the azimuth section of the MRL tape, it starts fine, but gets to certain frequencies and channel 2 stops playing back until the announcer comes back. There is no levels coming into the oscilloscope at all. The werid part is, when I switch the head to 4T (four track mode) the frequencies are there, even louder overall. Anybody familiar with this problem or maybe there's something about the heads I don't understand?

[docb]

Which certain frequencies? The highest ones? If so, the head is probably worn or gunked up, maybe in a corner where you might not have spotted it. Give it a really good cleaning and try it again.

[woody23]

Thanks for replying. It is definitely the higher frequencies. I just cleaned and demaged it very thoroughly and the level went up a bit but not anywhere near where it should be. 

[steveidosound]

Check the lower gap on the 2 track head for wear.
Does the wear pattern on the 2 track head look asymmetrical top to bottom?
How  does it look compared to the wear on the other heads?
Check that the tape path is smooth over the head.
With an unimportant  2 track tape (in case something happens)
listen for decreased high frequencies on the right channel.
Gently press the tape against the head, particularly the lower half, as it runs (sometimes I use the back of my small finger nail) and see if the level of the high frequencies increases through the speaker on that channel.
Any gunk on a guide or edge of a head can cause a ripple in the tape contact in that area.
The head may have to be re-lapped or even replaced if it comes down to gap wear.

[woody23]

Thanks I'll check that out tonight and post some pictures. How much would it cost to relap?

[docb]

(sometimes I use the back of my small finger nail)

[jcmusic]

What a sense of humor!!!! Great stuff Doc.

Jay

[steveidosound]

I resemble that remark !

[woody23]

For those following this saga, I'm sending the heads back to the guy I bought the deck off of and he's going to look at it. I noticed that channel 2 was much quieter overall and the highest reading I could get off the 1k mrl test tone was  about 1.5db while the manual called for 4db...so clearly something is wrong...