Measuring Tape Head Wear

[Jeremy H]

Hey Guys,

I recently got my hands on a Tascam 85-16B - (16 track, one inch.)

The unit is original and has obviously done a lot of work. ( I didn't pay a lot for it either)

There is obvious wear on the heads - Can anyone advise me in the following;
1. If I do nothing about this - how exactly is the sound compromised by worn heads? Does realignment or recalibration help much in this regard?
2. How do I determine if the heads are too worn for a relap?

If I am correct in assuming that a new head is the same radius above and below the track segments (the part of the head the tape doesn't contact) as it is where the tape runs, I would estimate the wear at around .004" (4 thou.)

Or as another indication, the shiny flat spot down the middle of the head measures about 3.5 mm wide.

Both the erase head and the playback head (and the tape lift pegs) look to be similarly worn. However, the record head looks pretty good. I guess that makes sense. All of them appear to be original.

I have heard of people referring to head condition as "50%" etc. How exactly is this established.
Thanks for your help
Jeremy

 

[guitarmaker]

The only way to really determine whether the recorder needs work done to the heads is to get an alignment tape and see if it will calibrate to the manual's specs. That's a pretty big investment for 1" tape (about $300 or a little less). You'll need to check both reprduce and record alignment. Clean everythung really well first and demag. The pinch roller might also need new rubber (about $50 from Terry's Rubber Rollers).

If the heads need lapping it will cost about $400 from a place like JRF. They will give you a complete head report.

I guess you need to decide if this is something you want to get serious about. The initial cost to get a machine back in good shape can be pretty large. You're dealing with other people's years of neglect.

Steve

 

[DrFrankencopter]

Is there a keystone pattern to the wear shape on the heads? If so this can be a sign of trouble...it can be very difficult to mechanically align a deck with worn heads. It tends to require more pressure on the tape head (I forget the name of the adjustment brings the head more into contact with the tape...maybe zenith), which exaggerates the wear problem. Eventually, you can get wow problems as the tape slides up and down the wear pattern.

Cheers,

Kris

 

[CalavoBob]

(I forget the name of the adjustment brings the head more into contact with the tape...maybe zenith),

That's the wrap. When the head gets a fair groove worn into it by the tape, it will pop in and out of the groove on the top or bottom causing serious intermittent high frequency loss because of the contact spacing loss. That's the beauty of newer heads that have the notches above and below the tape path. It allows the tape to gently ride over the heads and not get caught in the wear pattern, even if the tape's slit width slightly varies.

 

[jeffbro]

For not much money JRF can usually cut relief slots into a head that doesn't have them. I always have this done when I have them relap heads that don't have slots.