Determining Head Wear - Tascam 38

[fstrat76]

For head replacement, I understand that when a gap starts showing up, that its definitely time to replace them.

I've included two images. The first image is from my almost working 38, the one I am in the middle of aligning and calibrating. The second image is from a very cheap 38 I picked up recently to either restore or use for spare parts.

However, I'm not experienced enough to know how good the heads actually are. One tech service guy told me the head in image 1 was in excellent condition, although the photograph reveals scratches and marks.

Besides the calibration procedures revealing issues, so how does one determine how worn the heads are, when its time to relap or replace?

 

[Blue Jinn]

Take a look at these two articles:

http://www.jrfmagnetics.com/tapeheadintro.html

http://www.jrfmagnetics.com/headtrip.html

The first head seems to have slightly uneven wear pattern and a lot of oxide built up.

 

[sweetbeats]

It looks like BOTH heads have some uneven wear but not major...its not keystoning really...its almost like something wasn't setup quite right in the tape paths and the tension was higher at the bottom of the tape vs the top. Anyway...

Both heads appear to have about the same wear and you can tell by the length of the edge slots.

Both have plenty of life left IMO.

head #1 has that NASTY scratch down at track 8...that would be taken care of in a lap.

Head #1 ALSO looks almost like there is a crack going through the left end of the top edge slot? Is that what I'm seeing or is that just another crack or even a fiber or some debris?

Head #2 looks yucky at the bottom.

Here's the answer I've gotten to your really big question:

Yes once the gap opens up the wear material is gone and the head is no good. Otherwise the big test of a head is can you get the machine to calibrate to spec? If you can't and its an impediment to what you are doing then its time to relap if the heads are worn. And then of course if the head CAN'T be lapped its time to replace. That's the ticket is whether or not the deck cal's up, and if it doesn't and you know its not the electronics and the rest of the tape path is setup right and the heads are worn then its time to consider a relap.

 

[fstrat76]

OK, so for my own learning experience, how is it you can tell there is uneven wear?

I mean, aside from the camera flash and light not being exact or perfect, what is it you are looking at to determine uneven wear or oxide buildup?

Edit:

OK, I think I see what you are talking about in the wear after looking at those jrf links and slowing re-reading your posts. The longer edge slot at the bottom indicates that the bottom portion of head 1 has more wear than the top? Is that what Im seeing?

I'm not seeing a crack at the top edge slot or scratch at the bottom at track 8 so I'm not sure what I'm looking at.

As long as these heads have some life, and not causing any sound or shed or tape issues, I'm ok to go?

 

[sweetbeats]

I'm just looking at the flat spot...the wear path...it flares out a little at the bottom.

The edge slot comment I made is just comparing the two heads to each other...It looks like they haven't been relapped...can' tell for sure without seeing some other angles and can't REALLY know for sure without measuring the material remaining to the gap. Edge slots aren't typically recut so as a head is relapped those get shorter.

Yeah go ahead and use them but clean them up good first, and that scratch along the bottom of head #1...check and make sure that isn't going to contact the tape.

 

[fstrat76]

Yeah go ahead and use them but clean them up good first, and that scratch along the bottom of head #1...check and make sure that isn't going to contact the tape.

I'm not sure about this scratch you are seeing. Are you talking about the squiggly line at the bottom to the left on track 8?

It looks like a cotton thread if we're looking at the same thing. I checked with a magnifying glass and can't see anything there now.

I'm cleaning these heads as best I can with 100% cotton makeup removers and 91% isopropyl alcohol. Its coming back clean but I'll keep at it.

 

[sweetbeats]

Mmmmmokay strat...I think that's what I'm seeing alright.

Okay. Sounds like you're doing the right thing. May be sticky shed crud and that does take some time to remove. I've found hat sometimes I can use my fingernail to dislodge sticky shed crud and then get the residue with the iso alcohol.

Keep at it and if you can put up some pics of the heads after cleaning.

 

[fstrat76]

OK, I've kept at this thing trying to clean the oxide from the heads and don't seem to be making any progress. I've used the makeup pads, 91% iso, and fingernails as suggested.

Any other suggestions to get this stuff off short of taking 60 grit sandpaper to it?


(only kidding, just some frustration as there are only 168 hours in a week)

 

[sweetbeats]

Can you put up a pic of how they look at present? Sometimes there is just staining or oxidation that may not effect performance and is just...there. Do they feel smooth?

 

[fstrat76]

Can you put up a pic of how they look at present? Sometimes there is just staining or oxidation that may not effect performance and is just...there. Do they feel smooth?

Finally got a chance to take more pics. One is a shot in natural light, the other with a flash so you can see there is a lot of something. It just won't come off the sides the "regular" way of cleaning. They do feel smooth, no bumps.

Relapping is an expensive option.


Let me know your thoughts.

 

[sweetbeats]

Strat, my friend, it is my humble opinion that that head looks excellent.

Check out this shot of the head on my 388...same kind of wierd hazy appearance over tracks 1&2 and 7&8...not on the surface, no way no how it comes off but it works just fine. If yours feels smooth and based on the non-flash picture in which you can't see the marks I think what you are seeing is IN the metal composition and not anything to worry about. You've done a nice job cleaning it up. Time to try it and see what you have.