Yamaha R-8 receiver drops memory at power off

[Mickey Trageser]

I'd like to know what component holds the memory so I can replace it. Before I get started on it, I thought I'd ask what is likely considering it is a 1985 vintage device. Thanks!

 

[Harald Kapp]

It's probably not the memory that's gone, it is the battery that backs up the memory. A comparatively inexpensive way of storing data even with the mains power turned of is by using a static RAM and a battery to keep the RAM powerede. This is called NVRAM. Look for a battery in your receiver and replace it.

A modern way of buffering such an SRAM for a medium long time is by using a high cpacity gold cap, but I doubt that this was used in your over 30 year old receiver.

 

[dave9]

I found a topic that suggests they used a (albeit old school low capacity by today's standards) supercapacitor for memory, located "buried near the edge of the vertical circuit board, where it meets the adjacent horizontal circuit board. Look for it on the horizontal CB, near the edge." Part 0.047F/5.5v, #WD292000

You probably wouldn't have any problem substituting a modern higher capacitance cap, just look at the existing one and see what your mounting options are, whether soldered on or on leads then mounted wherever however.

Here's that topic:
https://www.houzz.com/discussions/2359482/yamaha-receiver-memory-problem

 

[73's de Edd]

Sir Mickey Trageser . . . . .

IT"s IN THE BOOK . . . . . .By Johnny Standley . . . .and I just happen to have THAT relevant Yamaha book !

One each .047 FARAD 5.5 VDC Super Cap, being needed, and I would replace the old C179 shunting it.
Just find 42 pin IC108's . . . . . pin 40 and track it down.
It probably will be available at both Digi-key or Mousers.

The tuning system is using an old four bit / banger CMOS San- YOOOOOW LC6510c-695 u/p, clocking at a staggering 800 Khz, and its 256x4 bits of static memory storage SERVES for all of your tuning memory function.

RELEVANT SURROUND SCHEMATIC SNIPPETS REFERENCING . . . . .

73's de Edd
.....