HP 82161A - mini cassette



#6

Hi and happy new year to everybody!

As promised, I return with the results of trying to fix my digital cassetes.
I'll use the Diego's message to compare to my experiments:

" (...) Regarding the length of the tape, I used my audio tape recorder timer to count the 8min 44sec. needed for the task. This is the result of calculating how much time a standar tape recorder needs to run 24'384m (80feet) between the holes, plus 2 x 25cm extra tape to reach the leaders at both ends."

Well, I've tryed this and I believe my cassette recorder isn't so accurate. So, I wasted my time and precious tape, because the length wasn't enough to the task.

After many tryings, I decided to measure by hand the HP actual tapes length = 25.08m .
So, by hand, I measured the CrO2 tape and cut it. This time it worked well.

"I've also wound the old defective HP tape into a standard audio tape shell... and of course played it!! The saturation is farily high >+8dB!! (I'm sure that my neibourghs' son is still wondering where the hell have I got this amazing new beat!!!! ;-)"

I've done this with another tape I've already replaced with chrome new midia and hadn't worked. I took it from the HP case and filled into a standard cassette. Again, using my cassette recorder, the signal was not so strong. May be incorrect tape type?

"Then conected an oscilloscope to the phones output and took a look... It's a 1'85Khz. (approx.) carrier with phase/amplitude modulation, as stated in the 82161 manual, separated in brusts and silences of 1'16s/0'6s ratio (approx.). "

"Translating this into 82161's read/write speed of 9inches (22'86cm) it results in a 8'9KHz (approx.) carrier. Those are "approx." due to the 82161's constant ANGULAR speed while standard audio tapes runs at 4'75cm. constant LINEAR speed."

"I decided to made my first attempt with a CrO2 TDK tape as I assumed a standard FeOxide tape would have some difficulties in handling the required saturation level and Metal tapes trend to be highly abbrassive."

Using normal tape - FeO2 - the digital cassette even couldn't rewind it. Using 60min chrome tape demonstrated again it is thicker than the HP one. I could find a source for a 60min Metal Tape. It seens to be even thicker than normal tape. Resuming, only the 90min tape could be filled in the HP's case.

"Cutted the tape, made the holes in their corresponding places with a 0'8mm drill bit, taped the leaders, wound it back into the HP Mini Cassette shell and insert it into the drive."

"NEWM 256.... and... IT WORKS!!!!!!!!!! ;-) (...)"

I could restore 5 tapes up to now. One is intermittent. other didn't work any way ... my basis material it's all over and
90min Crhome tapes are becoming hard to find (at least in my city if someone in Brazil find one, send it to me!).
Also, if you don't pay atenction and let the end go into the case, it's very hard to open it without breaking, as the parts are glued togheter.
It is not an easy task and the results may not be the expected!
(Just forgive my English mistakes!)

Thanks Tony, Diego, Garth, David, Etienne and Dave for precious support!

01/01/2006 - Artur


#7

Hi Artur,

Seems that you've gone thru several troubles while following my experiments.

However, it's not clear for me if you finally succeeded in recovering some of the tapes you've tried... (hope you did :-)

Certainly I didn't mention I used C90 TDK CrO2 tape. Yes, C60 are not suitable as they're much thicker. I haven't tried with Metal tapes (I simply *guess* they are too abrasive for the 82161A head... they should work anyhow)

The tape length didn't was a trouble at all... I measured it with a Technics RS-275M tape deck (a very accurate device, I must say)... The reported saturation level (>8dB) was *measured* using the tape deck Vu-meters (not so accurate indeed) and EQ set to Normal Bias (Type I) FeO2 tape. Values will vary depending on different EQ settings.

Thanks a lot for the feedback and report whichever other info you may get from futher experiments (if any...)

All the best for the new year.

Diego.


#8

Yes, Diego.

Five tapes worked fine and one intermittent. Unfortunatelly, my old Chrome cassettes have gone and 4 HP tapes will have to wait new replacements!

Thanks a lot the help!
Artur


#9

Hi all,

Five tapes recovered!! These are great news indeed!! For the remaining "intermitent" one, I suppose you've followed Tony's advice regarding pressure pad rebuild, double check it otherwise, see "Tony's document" down in this same trhead (Thanks Etienne and credits to Tony for the unvaluable knowledge "database" he shares with us)

It may also be caused by tape wear. Was/is the CrO2 tape used or new??

Can you get more CrO2 tapes to recover the remaining 4 mini-cassettes?

Are you going to give a go to the Metal tape approach?

Congrats on your success and best wishes for your future jobs!!

Diego.

Edited: 4 Jan 2006, 5:14 a.m.

#10

Hello Artur, Diego, Tony et al,

To complement Diego's useful information, I have Pdf-ed Tony's Tex document on the tape restoration: 49 Kb pdf. You'll need Acrobat Reader 5.0 or later.

I've put it online on the support section of my site: Tony's document

Thank you Tony and best wishes for 2006 to all!

Etienne


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