Yikes !!!


    the AnalogRules "BAD HEADS page   !!!    



Here are some pics of heads that have worn down so much that the head-gap is opening up...

We're still updating these older pages so come back soon for other pictures  !!

Note that not all bad heads will look like these....
Heads can burn out inside the head due to DC currents or severe voltages...
they can have small breaks in the coil wires - usually at the soldering posts
- often just due to expansion and contraction with heat and age -
and there can be other problems that you won't see visually.


But the most common problem with tape recorder heads is just simple wear..
magnetic tape can be considered a form of sandpaper...
wearing out the head with each inch of tape that passes over the heads
  (one reason why you should use 15 ips rather than 30 ips   !! )
In time the heads will wear out due to use

Little BLACK LINES at the gap area indicates the head is opening up....
that the very small normal 'gap' is now turning into a huge gap
effectivly making that track unuseable.

Nothing can be done.... there is no way to 'rebuild' a head
once the head is so worn the gaps are opening up.  
You can't replace worn-off metal  !!!


An AMPEX MM1200 24 track head with a bad track # 23

  (outlined with the black marks)

You can see from the wear-pattern that the head has a large flat area where the tape hits the head...
AND the small black line in the Gap area on track #23
indicates the head gap on that channel is opening up...
meaning that track is bad and will not record or playback just about anything.
== odds are other tracks will soon open up because this head is so worn out ==
this head is WORTHLESS


Here is a Tascam 16 track head with tracks 15 and 16 opening up...

Note that the alignment of the head was NOT correct on the machine...
the wear-pattern is NOT a nice straight pattern.... it is a trapizoid
which means the lower part of the head was sticking out more than the top edge...
thus there has to be more tape tension on the lower area than the upper area
The area with more tension will wear faster than the area with less tension
this head is WORTHLESS


Here's a bad MCI JH-16 16 track head...

And saddly a too common story about buying a tape machine without a
written head report from Sprague Magnetics in the LA area
or John french on the East Cost....
 
Note that this was another yet deal that went sour....
the buyer asked for a head report, but the seller just lowered his price and
gave excuses... saying the heads 'looked' as if they had lots of life on them.
and he didn't have the time to send the heads off to Sprague Magnetics in LA
(the seller IS in LA !!)     The buyer felt the seller was a 'nice guy'
and wouldn't lie to him....  So he bought the machine only to find out
the Repro head was shot.

another view...

another view

 

 

 


I've drawn (poorly) what the heads and Gaps are like as the head wears down:
NOTE that in this next drawing - a 'new' head - the LOW Frequency signal "A"
doesn't have much of a difference between the signals at each side of the gap....
as frequencies get lower the difference between the gap get smaller and smaller.
 
The Higher frequency signal "B" has a much larger difference signal between the edges
of the gap - resulting in a good strong signal.
 
The very high frequency signal - "C" is so small in wave-length that the
gap 'sees' no signal difference between the edges of the gap
resulting in no signal output at all   !!!
 
Head Gaps are very small... heads normally have gaps of about 0.25 mils (0.00025 of an inch wide)

 

 

  Now here is what happens as your head wears down...

 

 

  And finally what happens when the head 'Opens Up'...
as in the pictures of heads above.   The 'black' line you see
in the gap is the epoxy inside the head to hold the pieces together
- in a good head all you will see is the extreemly small gap -
almost too small to see without a Magnifing Glass   !!!

 

  as the head wears, the gap will get larger and larger and do so quickly....
ALL high frequencies will 'fit' inside the gap (wave-lengths of the signals
are smaller than the size of the gap) resulting in no output of high freqencies !!

 
Here are pics of a bad quarter-track head - with a huge gap !
 

 
Also you can see that this head is very worn out - the large flat area
indicates this head has seen lots of use.     It looks as if
this head was properly installed - the wear pattern looks good.
Note the ridge at the top and bottom of the head.... this head doesn't
have 'edge-slots' which are grooves cut at the top and bottom of the head
at the upper and lower sections of the tape path... so the edges of the
tape rides in the grooved-out area and will not cut ridges in the heads.
The ridges in this image will collect tape oxide, get dirty and if the
tape was cut slightly larger than the wear pattern has been cut into the
head, the tape could not ride in the groove correctly....
causing all sorts of problems.
 
Here is a head with Edge and track slots !!!!
 
 

  The edges of the tape should ride in the slots, thus causing no ridges
but if you look close you can see a small ridge.... showing that the tape path
on this head was incorrectly adjusted !!!   The head was set too high
so the edge of the tape was on the track and not where it should have been !!!
 
 
Finally here is apicture of an Very Old Ampex Mono head
Showing the components found in every magnetic head:
 
 
 

 
Here's another Tascam tape recorder with BAD HEADS...
and once gain the seller said "It was working fine when I put it into
storage."       And once again the buyer got ripped off!
 


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