Restoring a Mis-voltaged Denon

[nintendoeats]

The story: My girlfriend's dad used to live in Qatar which is on 220 volts. About 8 years ago he bought a 120V Denon AVR 3808ci which his friend promptly plugged in. Bang.

He brought it in to a repair place and they told him that a small piece needed to be replaced. The part was cheap, labour wasn't. In the end he was impatient and just bought another reciever. Upon his return the old one was put, in the box, in the garage.

Over the weekend he offered it to me and said to either repair it or chuck it.

What I have looked at: I started by checking the fuses with a multimeter but those all still conduct. I then looked at the relays, but those are rated at 250V so they shouldn't blow under this load. From what I gather the same transformer part number is used for both voltages (which seems odd). There is still a burnt smell in the machine, but everything looks perfect. The part I'm currently suspecting is one of the bridge rectifiers (S4VB-20) since they have a voltage limit of 200V, but the ones I can reach without beginning to dismantle the machine appear to be conducting correctly. Some of them have heatsinks and those are the ones I really suspect, but I cannot reach them reliably with the probes.

We live in a small apartment so I can't start taking it apart until I have some confidence that I'll be putting it back together again. I was wondering if anybody here had any ideas about where I should start looking. I have basic electronics knowledge and DIY skills but I am by no means an electrical engineer.

Thanks!

 

[knockbill]

If the transformer has a multi tap primary and was set for 110V,,, 220V may have burned out the primary coil,,, there may be a jumper or switch to set the line voltage.... you can read thru the primary winding with a DMM on ohms setting, to see if the winding is shorted or burned out(open)...not sure what the "inexpensive" part the tech mentioned is...
Good luck...

 

[nintendoeats]

I actually looked for that transformer and it doesn't seem like a particularly easy thing to get ahold of on its own. I would probably have to buy a dead reciever and start pulling bits out of it.

 

[petehall347]

i have only seen this situation once on some equipment and all it did was blow a fuse and the bridge rectifier .
that was lucky i suppose .
rectifier diodes generally go short circuit when they fail .so any that test short whilst still in circuit pull out and test again . if ok look further at it .

 

[nintendoeats]

Thanks, that's handy to know. I actually think I may have found the problem though. I went through the circuit diagram and discovered that the transformer for standby mode was missing. The place where it should be has burn marks on it. My guess is that the shop removed it. I have a new one ordered, I'm hoping that will be the only problem. If not I'll start checking those rectifiers. Of course it's a special order so I may not have it for a month.

 

[OMGCat!]

I can see the standby transformer immediately popping upon being plugged into the incorrect voltage before anything else has a chance to go the same way so maybe you got lucky. If, after you get the replacement parts installed, it still doesn't work then I'd definitely check the trafo windings and then the rectifiers. Either way it looks like you're definitely heading in the right direction. Good luck

 

[nintendoeats]

I can see the standby transformer immediately popping upon being plugged into the incorrect voltage before anything else has a chance to go the same way so maybe you got lucky. If, after you get the replacement parts installed, it still doesn't work then I'd definitely check the trafo windings and then the rectifiers. Either way it looks like you're definitely heading in the right direction. Good luck

Thanks! I will report back with further developments.

 

[nintendoeats]

I just installed the new transformer and it appears to work! I won't know for sure until tomorrow when I hook it up. However, it boots into standby and shows text on the display when I turn it all the way on.

 

[nintendoeats]

Just a final update, I've been using the 3808 for a few days now and it works perfectly. I hope that somebody, one day, finds this post and is able to use it to solve a similar problem.

 

[N8Nagel]

I love a happy ending

Good to know that it stood up to abuse too, have a 3310ci (if I understand this correctly that means it's two years newer than yours) that I've already fixed once (bad network board) didn't know if it was a "long haul" unit or not.

 

[nintendoeats]

I love a happy ending

Good to know that it stood up to abuse too, have a 3310ci (if I understand this correctly that means it's two years newer than yours) that I've already fixed once (bad network board) didn't know if it was a "long haul" unit or not.

On the one hand, it travelled overseas and sat in a garage which endured both Canadian summers and winters free of any temperature or humidity control for 6 or 7 years. On the other hand, it was stored in the box wrapped in a thick plastic bag and was never used. I don't know how much this can really tell you about the overall longevity of the unit.

Oh, just FYI the repair tag on this unit said August of 2008.

 

[fendray26]

I know this is an older thread but my search didn't return many results. I got an AVR-3808CI with the cool touch screen remote for $20. When you plug it in it gets power......and that's it. It's goes directly into protection mode. Do any of you know of common issues with this model I could start with? I see nothing obvious but you can't see a lot of the internal components in this model.

 

[mbz]

Download the service manual from hifiengine.
Need to register, it's safe, no spam, used by 90+%(*) of AK diy'ers
(*) made up, but you get the drift...

The service manual shows how to do some basic diagnostics and fault finding.

Suggest start with test mode(page 7)



If you want to take a punt, you could try a reset


More computing power than the early apollo missions and just as difficult to repair.

 

[fendray26]

Well that’s just great. I’m so excited to spend hours feeling unaccomplished.

I do really appreciate you taking the time to send me all that info.

I already tried the reset. It looks like it works but then it’s right back into protect mode.

 

[mbz]

Did you try the test mode. This should give you diagnostics, undoubtably cryptic, but it should be a start.

 

[nintendoeats]

I love a happy ending

Good to know that it stood up to abuse too, have a 3310ci (if I understand this correctly that means it's two years newer than yours) that I've already fixed once (bad network board) didn't know if it was a "long haul" unit or not.

I popped back into Audio Karma for an entirely unrelated stereo repair, and I happened to see my old thread. I thought I'd update you, I am STILL using this receiver. I got a ThenAudio Sharc so I can use it with a 4K TV, before they were bought by private equity and the cost of that device went through the roof.

So yes, it is absolutely a long haul unit.