I performed a mod on my Roberts 808D and Akai 81D- this mod will make the
program track switch work reliably every time. It's a proprietary mod and
procedure I developed myself, after giving it much thought- so I can't share
it at this time. I will upgrade any Akai deck for $20 plus shipping both
ways, if you want this done.

The graphite problem, will also trick the auto stop circuit in the Pioneer
HR-99/100 decks- causing them to auto stop in the middle of a program,
instead of at the end. The Pioneers will also crackle with an old tape with
playside loose graphite- but not as bad.

Static problem- you really can't eliminate that entirely. It is caused by
loose graphite hitting the tape head, on a high-end deck that was designed
to give an upper limit of 15khz-18khz high end response. The tape deck
circuit responds to little pieces of graphite, as if they are part of the
music recorded as static, if you get my drift. The static will reoccur
exactly the same way, at the same part of the tape- just like music. If
you listen to the tapes that have static, you'll find that it makes the
static in the same place, and the same type of static- i.e. it's on the
tape- i.e. it's loose graphite on the FRONT play side of the tape, hitting
the head.

This same loose graphite, is slightly conductive and is what drains the Akai
program switch capacitor prematurely, causing the 80-81-82 decks not to
switch tracks. A close inspection will reveal, the 82 deck system was
modified further to try to solve this problem, but even the 82 may not
switch tracks on an old tape, with lots of graphite transferred to the front
of the tape.

The key to getting rid of the static, is clean the FRONT SIDE of the tape
thoroughly. One way is to de-spool all the tape, and wipe both sides with
alcohol and a rag. This not only cleans the front play side, but also the
back side- and removes LOOSE graphite, that is no longer adhered to the
tape.

Another mod is, put new pads in the tape, that are foam with no slick
surface on them (cut your own, or buy mine on Ebay, $10 per 100, plus $5
shipping)- the foam pads will act as scrubbers and clean off the loose
graphite from the back of the tape. Graphite that is properly adhered,
will not, and should not, come off the back of the tape in the first place.

If you put foam pads in without slick surface, they will actually "clean"
the tape, the more you play it- a transfer will occur, where loose graphite
that is on the front playside of the tape, will return/transfer to the
backside of the tape, then be picked up by the foam pads and removed. Radio
Shack had a similar machine that was made to clean tapes, but no one was
ever sharp enough to realize how it worked- and used it on new tapes that
didn't need it. If you find one of those RS cleaning machines, playing a
crackling tape in it long enough, will get rid of the crackling on the tape.

Crappy low-end decks with limited 12khz-14khz top end, won't crackle-
because of their limited upper bandwidth, the head cannot reproduce a
crackle, from the loose graphite- so they basically play muffled even when
working correctly- and you don't here the crackle.

get it ?




"still_trackin" wrote in message
ups.com...
Anyone have success in eliminating the static/crackling problem in
Akai/Roberts decks by using the Akai mod? I know there is a ton of
archive info regarding this issue, and one theory is to add 1 uF cap
in parallel to the sensing poles by the recording head.
I own a Roberts 808D that crackles in the right channel on most tapes
after it auto changes tracks. When the tape is first inserted and
tracks are manually changed the problem is not apparent. Only when the
player auto changes does the static appear.
I also read that the problem could be attributed to a loose ground
wire connected to the screw that holds the head in place. By
tightening the screw the ground wire will then make proper contact and
eliminate the static.
Do either of these procedures really correct the problem? I'd use this
Roberts deck alot more if I could eliminate the crackling! BTW....this
deck has a cool after mod, the previous owner had a pause mode added
on using a toggle switch and an extra light that comes on when
engaged! I would really like to get this deck to play the way it
should. The sound is very nice otherwise.