AMI R-81 Memory Unit

Still looking for one of these. If anyone has a good one, give me a
holler. Thanks.

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Try he

http://www.rowejukeboxrepair.com/

He is the one that told me mine is bad. He could repair mine, but is
kinda pricey. Was looking for one a bit cheaper in price. He wanted 3
times what I paid for the whole jukebox to repair one module, Jim

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On Mar 27, 2:50*am, (James McClave) wrote:
He is the one that told me mine is bad. He could repair mine, but is
kinda pricey. *Was looking for one a bit cheaper in price. He wanted 3
times what I paid for the whole jukebox to repair one module, *Jim

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It sux, but even when the special IC (which is the cause of problems
with these units) was last still available, in the early 1990s it was
about $120 from rowe distributors.


You then have to fit it, etc.

That unit used some special/custom components that have long since
been obsolete/discontinued. When you can find them, the price is very
high.

If they are obsolete /discontinued , etc. Where is he finding them? He
seemed to have a good supply. I bet there is some substitute out there
somewhere. Jim

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On Mar 27, 4:41*pm, (James McClave) wrote:
If they are obsolete /discontinued , etc. Where is he finding them? *He
seemed to have a good supply. I bet there is some substitute out there
somewhere. Jim

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You would need something like a PIC, AVR, CPLD to substitute, and
someone has to write the software for it, this is the hard part. The
chip ROWE used is not a simple logic gate, the IC has internal RAM -
that's also battery backed up, bidirectional serial comms (sort of)
port, (though probably more like an I2 squared design).
The only good news is that the communication protocol is described in
some detail in the service manual.

The same applies to the selector logic, Memorec unit and credit
computer. Each is a special custom IC.
(for home use you can probably do without the Memorec and credit
computer if they fail) but you need the memory unit and selector logic
for the machine to function.

Also the IC (and the whole system) is designed around negative supply
voltage (-17v) which, while possible to do, is a pain in the arse to
design around with modern chips. Modern microcontrollers use +5v (or
in some cases 3.3v). You would have to look at a replacement board,
or rider board rather than just the chip.

Remember too that this system is VERY old - the earliest date stamp I
have seen on these boards is 1974.
The design probably dates back to the early days of this sort of
technology coming into more common use, they probably paid an absolute
fortune back then to have these chips and modules designed and
manufactured, specially for just this purpose and nothing else. It was
probably took a huge risk going to this technology, I wonder what the
operators thought when they saw a totally silent black box replace a
search unit, button bank, etc ? It probably scared the **** out of
them, as to what to do if anything went wrong.

Being straight MOS technology, they are very sensitive to static
electricity also.

Also note in the manual where they discuss desoldering IC's, there is
nothing at all mentioned about anti-static procedures - except
attatching a ground wire to the iron, or touching it to a grounded
surface before using (shudder).

Good info! Thanks . I will keep looking for a memory unit thats good or
will end up parting out my R-81 . Jim

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On Apr 1, 2:29*pm, (James McClave) wrote:
Good info! *Thanks . I will keep looking for a memory unit thats good or
will end up parting out my R-81 . Jim

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what exactly is the problem you are having with it ?

When you make a selection , it just scans past it and wont select any
record. Memory unit is bad , had it tested by the guy in new england ,
The micro processor chip is bad. Jim

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