Denon - is there a back up battery?

[Sainthunter]

I recently bought a Denon 'Personal Component System/AM-FM Stereo Receiver DRA-F100' unit from a charity shop - sold for spares or repair. Apart from a tuner issue the main fault is that after a while in standby mode it switches off completely from standby as though the mains has been switched off/a power cut.
Is there a back-up memory battery somewhere, I have tried leaving the unit powered up and switched on for at least 24 hours kidding myself that it will recharge the memory battery, if there is one?

[Michael Black[_2_]]

On Thu, 13 Feb 2014, Sainthunter wrote:

>
> I recently bought a Denon 'Personal Component System/AM-FM Stereo
> Receiver DRA-F100' unit from a charity shop - sold for spares or repair.
> Apart from a tuner issue the main fault is that after a while in standby
> mode it switches off completely from standby as though the mains has
> been switched off/a power cut.
> Is there a back-up memory battery somewhere, I have tried leaving the
> unit powered up and switched on for at least 24 hours kidding myself
> that it will recharge the memory battery, if there is one?
>
It would depend on the vintage. After a certain point, there were high
value capacitors in very small packages that were used to keep memory
alive.

Don't leave it in standby, let it run for a decent amount of time at low
volume and see if that solves the problem, which isn't really stated but
would seem to be that the memory doesn't keep remembering.

The weird thing is, a lot of recent equipment never turns off. The on/off
switch controls the secondary of the power transformer (one reason being
that it avoids bringing the 120VAC from the wall to the on/off switch and
then back to the transformer), and so those can keep memory alive with a
trickle of power from the power transformer.

Michael

[David L. Martel[_3_]]

The user manual makes no mention of a backup battery.

Dave M.

[Trevor Wilson]

On 13/02/2014 7:57 PM, Sainthunter wrote:
> I recently bought a Denon 'Personal Component System/AM-FM Stereo
> Receiver DRA-F100' unit from a charity shop - sold for spares or repair.
> Apart from a tuner issue the main fault is that after a while in standby
> mode it switches off completely from standby as though the mains has
> been switched off/a power cut.
> Is there a back-up memory battery somewhere, I have tried leaving the
> unit powered up and switched on for at least 24 hours kidding myself
> that it will recharge the memory battery, if there is one?
>

**I don't have the service manual for that model, but most machines of
that vintage use a large, low leakage electrolytic cap of approximately
20,000uF @ 6.3Volts. It will likely be near the main microprocessor.


--
Trevor Wilson www.rageaudio.com.au

[Trevor Wilson]

On 29/03/2014 10:32 AM, Trevor Wilson wrote:
> On 13/02/2014 7:57 PM, Sainthunter wrote:
>> I recently bought a Denon 'Personal Component System/AM-FM Stereo
>> Receiver DRA-F100' unit from a charity shop - sold for spares or repair.
>> Apart from a tuner issue the main fault is that after a while in standby
>> mode it switches off completely from standby as though the mains has
>> been switched off/a power cut.
>> Is there a back-up memory battery somewhere, I have tried leaving the
>> unit powered up and switched on for at least 24 hours kidding myself
>> that it will recharge the memory battery, if there is one?
>>
>
> **I don't have the service manual for that model, but most machines of
> that vintage use a large, low leakage electrolytic cap of approximately
> 20,000uF @ 6.3Volts. It will likely be near the main microprocessor.
>
>

**BTW: By "large", I mean in capacity. The physical size is likely to be
approximately 20 ~ 25mm high and 15mm in diameter.It may also use a
'supercap', which could be in the range of 0.1F ~ 1F @ 5.5 Volts, but I
doubt it.

--
Trevor Wilson www.rageaudio.com.au

[Michael Black[_2_]]

On Sat, 29 Mar 2014, Trevor Wilson wrote:

> On 29/03/2014 10:32 AM, Trevor Wilson wrote:
>> On 13/02/2014 7:57 PM, Sainthunter wrote:
>>> I recently bought a Denon 'Personal Component System/AM-FM Stereo
>>> Receiver DRA-F100' unit from a charity shop - sold for spares or repair.
>>> Apart from a tuner issue the main fault is that after a while in standby
>>> mode it switches off completely from standby as though the mains has
>>> been switched off/a power cut.
>>> Is there a back-up memory battery somewhere, I have tried leaving the
>>> unit powered up and switched on for at least 24 hours kidding myself
>>> that it will recharge the memory battery, if there is one?
>>>
>>
>> **I don't have the service manual for that model, but most machines of
>> that vintage use a large, low leakage electrolytic cap of approximately
>> 20,000uF @ 6.3Volts. It will likely be near the main microprocessor.
>>
>>
>
> **BTW: By "large", I mean in capacity. The physical size is likely to be
> approximately 20 ~ 25mm high and 15mm in diameter.It may also use a
> 'supercap', which could be in the range of 0.1F ~ 1F @ 5.5 Volts, but I doubt
> it.
>
That's a good point. I remember the cartoons in hobby magazines about
what a Farad capacitor would look like, usually the single unit delivered
ont he back of a truck.

If such large capacitors existed, they sure weren't at the hobby or
consumer level forty years ago. I remember buying a 'computer grade"
electrolytic, the size of a Coke can, 15,000uF at about 16V. Barely high
enough voltage rating for my purposes, but it was what I could get
surplus.

Now you can get even higher capacitance electrolytics in a much smaller
package.

ANd yes, by physical size, you'd never grasp that those backup capacitors
in more recent equipment had such large capacitance values.

Michael