HP 82161A - digital cassette drive

[Artur-Brazil]

Hi,
Does anybody have the electronic schematic of HP82161A or any material about how to service it?
Best regards
Artur

[Tony Duell]

I have the HP service manual for the 82161, which includes a schematic.

Unfortunately I have no easy way to get a copy to you, but I can answer any questions about repairing it..

[Artur-Brazil]

Hi, Tony

What a pit... is this manual too big?

Well, I would like to know if is there any adjustments like gain, speed, bias, etc.
I could see some trimpots inside the drive, but no indication what they are for.
Also, how I can measure the signal sent and readen from magnetic head.
I believe as the tapes are getting old now, they may are loosing their capacity of recording. So, increasing in some way the signal this could help in improving the reading.
Any way to get a simple photocopy and posting it in USPS?
Best regards
Artur

[Garth Wilson]

I don't have a service manual for the 82161A, but hopefully this will interest you anyway.

Age alone will not deteriorate the tapes' ability to take new data or hold old data. The characteristics of a head will change somewhat as it wears, possibly requiring an adjustment of the trimmers. I doubt that you've used it that much though. The settings don't change much even for high-end audio equipment until the head is near the end of its life. After the machine is initially aligned correctly, being dirty (especially for the head) is the only real enemy to performance before actual wear-out or damage. Even head demagnetization is a myth. I've done very little tape-recorder design work, but I did service nearly a thousand high-end audio tape recorders in a prior life, over 20 years ago. Bringing a tape recorder back up to new-machine spec.s never involved demagnetizing.

The 82161A records digitally and does not use bias. Its record circuit gives the head about 150% of the DC current needed to saturate the tape (according to the May 1983 Hewlett-Packard Journal), so even an erase head is not needed.

[David Smith]

The number one cause of tape failures is the backing to the pressure pad rots out. You can replace the pressure pad with either sticky back felt disks used on the bottom of pottery or sticky back nose pads used on eyeglasses. Walgreens sells a brand that is just the right thickness. The pottery felt is a bit coarser than the original stuff, but it seems to work just fine.

[Artur-Brazil]

Thanks to everybody who is helping me.
I've already replaced the felts that makes the pressure. I'm still getting or Drive ERR or Midia Invalid (I don't remember the exact message) after initializing them with HP41 command.
If the head, even used for a few times, is bad, there would be a replacement? I have worked with tape recorderes only once or twice before.
Also, there would be neccessity for cleaning and lubricating the internal motors?
Best regards,
Artur

[Diego Diaz]

Hi Artur,

It's a long while since I tried this:

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv009.cgi?read=24244#24244

but the tape is still working fine. You may want to give it a go... not much to lose since you can't have the current tape working.

Best wishes.

[Tony Duell]

Incidentally, my offer to make that DataFile (HPCC Journal) article available still stands (I am sure I have it somewhere).

Unfortunately (for most of you), I use LaTeX, and can't produce pdfs, proprietary word processor files, etc. But then LaTeX is a text file with readable commands, so you should be able to understand it. And if you are able to translate it into other formats, that's fine too, just give me credit for the original.

[Etienne Victoria]

Hello Tony,

I run TexShop on OS X.

If you email me your LaTex file, I'll try send you back a secured pdf.

Just let me know.

Etienne

[Tony Duell]

Remind me to send you the LaTeX file... But there's no point in sending me a pdf (secured or otherwise) because it's a lot easier for me to read the original LaTeX. You are welcome to make the pdf available on a suitable web site, though.

[Etienne Victoria]

Hello Tony et al,

As promised, 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

[Artur-Brazil]

Hi, Diego
You are always helping us!

Well, last year I tryied to replace the tape using normal midia (but CrO2) found in market.
I was surprised, because the 60min tapes are ticker than HP tapes and 90 min seens to work.
Any way, I didn't make a precise cutting in the length. I'll try to use your time - 8min 44sec - to get a precise length.
I'll let all of you to know the results! I really hope it works!

Best regards,

Artur

[Etienne Victoria]

Hello Artur,

You can get the 82161A service manual here.

Best regards

Etienne

Edited: 20 Dec 2005, 7:56 p.m.