Denon DRA-275RD Supercapacitor and Service Manual

[paul_g_787]

Hi everyone. I am wondering if anyone is able to provide some advice?

I have a Denon DRA-275RD Receiver/Amplifier which has a problem remembering the presets radio stations.

I have done a little research and I am assuming that it is likely the supercapacitor that is faulty. As show in this video here with the same model!!!


The value of the capacitor on my receiver is 0.1F 5.5V (See attached image). However I cannot easily / cheaply get this value.

What would be the effect of replacing this with a higher value 0.22F 5.5V capacitor? (This value is very readily and cheaply available for me).
Am I correct in assuming that this would just increase the charge/discharge time?
Are there any other effects I should be aware of? 

And also, if anyone is able to point me in the direction of the service manual, I would very much appreciate it.  I have not had success 2 hours into my search.

It is this one shown here:https://www.manual-buddy.com/p/denon/dra275rdr-service-manual.html

[Manul]

In my opinion 0.22F will be ok. And just for the interested I would check if old one is getting charged at all while on the board (small chance, but maybe charging circuit failed).

[coromonadalix]

You can find theses caps at gogikey, mouser  etc ....  it need to be a 5.5 volt part,  0.1 farad 0.22farad   0.33 farad  are not too difficult to find, but the casing may or will be different ?

You could check if you have an 5.5 volt if you're able to probe on the pins  when your receiver is powered on, if yes, it could be only the supercap ..... 

[PKTKS]

Probably none besides the SIZE of the piece.
Done that several times on diff models wo problems

And nothing prevents you putting right value
using 2 or 3 pieces  but expense of a mounting
hassle.

Should be fine
Paul

[Chris56000]

Hi!

Not over brilliant in quality I'm afraid – the original I suspect had colour printing in it!

Too big to post on here but get it from my Dropbox:–

https://www.dropbox.com/s/7ph5f1bejv6pghj/DRA275RDR_SM_DENON.pdf?dl=0

Chris Williams

[paul_g_787]

Thanks a lot. That is going to help me out loads! 

[paul_g_787]

You can find theses caps at gogikey, mouser  etc ....  it need to be a 5.5 volt part,  0.1 farad 0.22farad   0.33 farad  are not too difficult to find, but the casing may or will be different ?

You could check if you have an 5.5 volt if you're able to probe on the pins  when your receiver is powered on, if yes, it could be only the supercap .....

I have found one which should just squeeze in place. Will have to bend the legs a little though.

Thanks for the suggestion. Will try to measure the voltage when the unit is on, then switch it off and take readings over time.

The memory used to last for weeks, but now only a few hours, so I would assume I will see the voltage across the capacitor dropping if I take readings every few minutes.

There is a little white ooze nearby though on the PCB. Could be the electrolyte from the cap.

[coromonadalix]

There is a little white ooze nearby though on the PCB. Could be the electrolyte from the cap.

It could be a badly cleaned pcb when it was fabricated, i've seen this in the past, it never created any problems. To my knowledge i never saw an leaking supercap in home appliances ?
only in a fluke 189 meter (known bug)   never elsewhere,  i may be wrong.

On your photo the pcb seems pretty dusty ?

[paul_g_787]

Well it turns out that it is indeed the capacitor. Measuring the voltage over time shows it is not holding a charge at all.

It is now de-soldered and the source of the ooze is indeed the capacitor. (See cap1.JPG attached).

With this better view you can clearly see it is slightly swollen and has a small crack which I expect is due to venting out all it's capacitor-ey goodness. 
After peeling it open and you can clearly see how it has failed in cap2.JPG. Yuck!

So new one is on order. 0.22F 5.5V is the cheapest.

Will post results post-replacement.

[paul_g_787]

There is a little white ooze nearby though on the PCB. Could be the electrolyte from the cap.

It could be a badly cleaned pcb when it was fabricated, i've seen this in the past, it never created any problems. To my knowledge i never saw an leaking supercap in home appliances ?
only in a fluke 189 meter (known bug)   never elsewhere,  i may be wrong.

On your photo the pcb seems pretty dusty ?

The PCB was very dusty. After a good going-over with the air compressor. It is now squeaky clean. See attached photos. The super capacitor is C401 next to the white ribbon-cable socket.