Memory Forgets

I have one about that old. Any minor power glitch and the memory goes. I just plain gave up because I get a minor power glitch every few days and it's not worth putting the thing on a battery backup.

Hi...

It's likely that there's one filter cap whose sole purpose is to hold those settings for a while... you may want to consider changing it.

Take care.

Ken

In many of these types of receivers, there is either a gold leaf capacitor, or a battery backup.

For the gold leaf capacitor they are usually in the order of about 0.4 Farad to about 0.5 Farad. The voltage rating can be from about 3.5 VDC to about

5.5 VDC.

If the set uses a battery for the memory backup, it may be very similar to that is used in many of the mother boards of computers. They are usually in the range of 3 VDC.

You have to be careful when changing parts in these receivers. Most of the time, the battery may be with hard contacts and soldered to the circuit board.

--

JANA
_____


"Greg Esres"  wrote in message 
news:1186265694.866128.242830@k79g2000hse.googlegroups.com...
I have a 20-year-old Onkyo receiver that has some radio presets that
have *never* held their settings for more than a couple of days.  Is
it likely there are any user-serviceable parts inside that I might
could replace to make this function correctly?

Thanks

capacitor,

Farad

in

You had me worried there for a moment - that I'd been throwing gold leaf in the trash. Anyone know what the construction is of these fractional farad memory retention caps ?

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Onkyo's generally use a memory backup cap. May not be readily accessible. A model number would help...

Mark Z.

One of the trade names for them was "Goldcaps" I think - it's certainly a name that I use for them - but I wasn't aware that gold was in any way part of the construction. Even if it is, gold leaf, or gold in such tiny quantities as would be in such an item, is valueless, unless you have a lot of it passing through your hands, as the recyclers of computer mother boards do. I saw a programme on that brilliant "How do they do that ?" series on Sky the other day, where they were removing all the gold plating from the connectors and CPU pins. They were dealing in skip-loads of the stuff, and recovering a very respectable amount of gold, but it was hard work ...

Arfa

about

usually

farad

part

lot

boards

But how do they separate the gold surface film from the underlay of bronze or whatever that goes between base metal core and the gold?

I used to know someone who cropped the edge connectors off old computer boards from the 60s and 70s whan there was serious gold plating.

2 and 1/2 small tubs abot 10 inch diameter x 18 inch high bought him a new Transit van.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

They used a combination of heating/melting and chemical separation, which resulted in some gold salt or other, I think. Further chemical treatment at a secret location, finished the job off. The final recovered product was just about as pure as when it went on in the first place.

Arfa

Mark Z. wrote:

vey wrote:

That's what I was afraid of. If it requires soldering, then I'm I'm not going to try it myself.

Thanks

Hi...

Didn't find you a free one - perhaps someone else can, but if you're willing to pay a little for a repro of the service manual, here's where you can find and order one...

Take care.

Ken

Hi yet again...

Everyone has someone in their life - a relative, friend, neighbor that's competent at that level - ask around. Offer a soft drink or a beer :)

Take care.

Ken

The backup cap is C715, a .047F located on the digital pcb near the TC9147BP tuning control IC. Although my service manual is not really clear where that board is situated, it seems that it's somewhat buried in the front panel ass'y.

Mark Z.

Ken wrote:

I'll take a look and see if something jumps out at me. Perhaps there are labels.

Thanks for looking that up!

Ken wrote: