NAD 7140 tuner section won't hold presets

Pastor Bill

My NAD 7140 loses the preset stations every time it is powered off. What causes this problem and how do I fix it? Remember, speak plainly and simply. I'm not very savvy with all this stuff yet so couch your recommendations in language suitable for a tyro. Thanks in advance.

The tuner still sounds fine...but losing the presets is inconvenient.

Pastor Bill

While I was eating dinner (lovingly prepared and served by my beautiful bride) I received a few answers from AudioKarma as well. A slow leak capacitor is the likely culprit...I wish it was a battery. If it's a capacitor, I'd have to purchase one of matching values and solder it in. Don't know if I'm that good or steady with a soldering pencil. I was kindly presented with a schematic that located the capacitor.

Pastor Bill

Here's the schematic:
(Fellow said that it was the C213 5.5V - .047F mounted near the circled location) Almost all of that is Greek to me...

"It's C213, a 0.047F, 5.5v super capacitor, mounted very close to the TC9147P IC."

BlueFox

Pastor Bill wrote: »

I was kindly presented with a schematic that located the capacitor.

The schematic shows its location in the circuit. Physically, it can be harder to find.

Pastor Bill

I just fired off an email to the local hi-end audio shop here in Gainesville - Sound Ideas. Hopefully, they'll respond to my request for a ball park estimate to repair this. Attached the info and schematic as well.

[Deleted User]

Hello,
This is what they usually look like and can be ordered from Newark parts:

http://www.newark.com/cornell-dubilier/edlsd473h5r5c/capacitor-super-0-047f-5-5v-120/dp/27M9822

However, it looks like they have a high minimum order, but maybe it will give you a start to identify the part inside the tuner.
Regards, Ken

Pastor Bill

Thank you, Ken. Now, at least I know what I'm looking at/for.

[Deleted User]

You're welcome, if you can take a photo of the tuner's insides we can help you locate things.

Pastor Bill

I've contacted the hi-fi shop, as well as an electronics repair vendor. Both say it should be an easy fix...one wants a $65 bench fee and the other wants $100. Both say it will be two to three days to research and then make the repair. I'm beginning to think that I'll just live with the lack of presets and manually tune each time just like an analog tuner. What sayest thou? Is it worth it? Should I bravely and resolutely forge ahead and at least try to locate the cap myself?

pitdogg2

Pastor Bill wrote: »

I've contacted the hi-fi shop, as well as an electronics repair vendor. Both say it should be an easy fix...one wants a $65 bench fee and the other wants $100. Both say it will be two to three days to research and then make the repair. I'm beginning to think that I'll just live with the lack of presets and manually tune each time just like an analog tuner. What sayest thou? Is it worth it? Should I bravely and resolutely forge ahead and at least try to locate the cap myself?

Yes but chances are it will look nothing like the one Ken linked to. That is what they look like now. They are usually close to the power caps as in the past they were very tall. Look for a 5volt cap that will say .47F 5volt that IIRC what mine said in my Sony CD player. Same function hold the memory of CD's that I had a program for so I would not have to program each time I played it.

found this
http://www.amazon.com/Supercapacitors-Ultracapacitors-47F-5-5V-EDLC/dp/B00HKJ2ELC


http://www.pridmore.com/Capacitors-EDLC-and-Supercapcitors/.47F-5.5V-21.5X8-ELEC-DOUBLE-LAYER-CAP.html

http://www.mouser.com/Power/Supercapacitors/_/N-6uivw

Pastor Bill

Thanks for the information and the links, Pitdogg2.

billbillw

On the NADs, its probably a big green cap, very obvious because it looks much different than the other caps. It will say NEC (or Tokin), 5.5V, .047F. Measure the size and lead spacing and order a comparable replacement from Mouser or DigiKey.
Here are your choices from Mouser:
http://www.mouser.com/Passive-Components/Capacitors/Supercapacitors-Ultracapacitors/_/N-5x76s?P=1z0sia5Z1z0wug0



EDIT: I've added a photo showing you the exact cap on the 7140 that you need to replace

billbillw

After looking at the choices at Mouser, I'm guessing this would be the closest, drop in replacement:

http://www.mouser.com/ProductDetail/KEMET-NEC-TOKIN/FYL0H473ZF/?qs=sGAEpiMZZMuDCPMZUZ%252bYl5h6rep0zAk%2fyr9hp6j9Iwo%3d

$1.72 and probably ~$5 to ship it by 1st class mail. I'd give it a try. Soldering through hole components is relatively easy. The hardest part is getting the tuner board off to access the bottom side.

Pastor Bill

You guys are really helpful...thanks for the additional information and especially the photo, billbillw.

Now...I've only seen a capacitor soldered onto a small board that was completely free and outside of the component. Think you could talk me through the process? The picture has lowered my fear level by about half. Again, thanks.

Pastor Bill

I'm assuming that the tuner board is the smaller green colored board that covers about the front third of this area? Think I'd better hike over to HiFi Engine and see if I can download a service pamphlet.

Pastor Bill

I'm assuming that the tuner board is the smaller green colored board that covers about the front third of this area? Think I'd better hike over to HiFi Engine and see if I can download a service pamphlet.

(small amount of time passes)

Well, that didn't help as much as I thought. But if I move slowly and carefully, make a lot of drawings and label everything...I ought to be able to do this.

Pastor Bill

Before I get into this...is there anything I shouldn't touch? (As in fully charged capacitor)

billbillw

Pastor Bill wrote: »

Before I get into this...is there anything I shouldn't touch? (As in fully charged capacitor)

Obviously you want to have it power off/unplugged when you do this. Maybe let it sit unplugged overnight before you attempt repair. Really the only ones that you might need to worry about are the biggest power supply caps (the tall black ones). The others drain pretty quick and/or don't hold enough charge to hurt you. You probably need to be more careful that you don't break off any components, plugs, etc.

The tuner board is the entire top horizontal layer that you see in the photo with the green 'supercap'. The main amp board is underneath and you probably don't need to do anything to that. The vertical board on the front is for the display.

As far as removing/replacing the capacitor, you need to carefully identify the correct two leads from the bottom of the board. Circle them with a marker. Then heat up your soldering iron for about 10 minutes. I recommend getting some de-solder tape (radio shack probably carries it). It is a copper mesh that wicks away melted solder. It is easier to use and more thorough than a solder pump. Just press a section of the tape on the lead that you want to desolder, then place the iron on it until you see the tape wick up the solder. Then do it for the other lead and the old capacitor should be loose enough to pull out from the top.

To put in the new one, just orient the black (or white) stripes to match the orientation of the one you removed, put the leads through the holes and bend them out slightly. Resolder by putting the iron on the lead for about 10 seconds, then touch the solder to the lead and let it flow. After you do both, let them cool for a minute and cut the leads short to the board with wire snips. That's it.

Pastor Bill

My confidence has grown slightly. So I have to remove this tuner board...are there many connections? I know I'm being a pain...but this is how I learn best. I'm seeing at least four screws and a number of plug in connections.

pitdogg2

billbillw wrote: »

To put in the new one, just orient the black (or white) stripes to match the orientation of the one you removed, put the leads through the holes and bend them out slightly

Some boards have the holes labeled +/- but as bill states get a good look at that strip as it denotes negative hole. IF you get it backwards you will know when you turn it on as that cap will come apart quick like POW.....been there done that:redface:

billbillw

Yes, you have to get access to the bottom side of the tuner board to remove the old cap and solder the new one. Can't tell you exactly what to do because I don't have the exact receiver. You'll just have to work your way through it. Take a photo of 'before' in case you have trouble getting it back together.

Pastor Bill

Howdy all! I'm back after a long hiatus. Finally bit the bullet and took the NAD to a pro for repair. It was expensive but worth it. A lot of solder joints needed to be "re-flowed" and a handful of capacitors (including the station preset) were replaced. All controls cleaned. The fellow that did the work said that it was a real challenge to get to everything that needed work...apparently this particular receiver isn't real "user friendly" when it comes to working on the boards and pots. Works like a champ, now. Should be good for a long while. Thanks to all that tried to help me out when I was considering trying to do it myself.

pitdogg2

DANG Holy resurrection! Thanks for letting us know. I've myself had the pleasure of replacing one of those super caps. Mine was super simple in and out in 20 minutes.

Pastor Bill

I'm glad yours was very simple. For the life of me, I couldn't figure out how to get one board off that was blocking my access to the pots and caps. I removed all visible screws...yet something was holding it firmly in place. Since I didn't know the answer, I was loathe to try to go any farther. Fellow that did the work was temporarily stymied by it, also. He did say that this particular receiver was worth repairing and had power output far in excess of its published specs. I could have bought two "low-end" Sony or Yamaha receivers for the cost...but today's stuff just doesn't "sound" the same. All power and no warmth.

BlueBirdMusic

2/22/22