Hello! Grundig KS 680 U

[providence]

I am new to the forum and vintage audio in general. I've been taking in a lot of the literature in this forum the past week or so. Thanks for the cache of info.

Was wondering if anyone could provide info on what we have?

I'm a bit of tinkerer (rebuild and collect vintage racing bicycles) and DIY guy at heart and we've been looking for a nice piece for a wall in our living room. Happened across this console and the size and design was what we were looking for. It was very neglected and had layers of film all over it. Looked in rough shape. Looking through the console, it appeared most everything was there. Just a lot not set up properly. We figured if the exterior ended up not cleaning up, we'd strip and refinish. Went to work on it and it actually cleaned up extremely well, appears the nasty build-up protected it for the most part (see this in bikes sometimes) so the exterior is safe. Exterior as it sits, needing a little more love but saving that for now:

As for the interior, well, that's another matter. I'm still reading up on a lot of info stored on the site so I'm not ready to jump in yet. Getting into the project, our thought was if the audio was shot, we'd retrofit modern and call it a day. Of course, in bikes, the moment someone starts to modernize something somewhat sought after or better, some of the crowd starts to cringe. Not entirely sure if this console is worth fretting over in those terms but it does seem nicely constructed for it's age (60's or 70's I'm guessing?).

I haven't touched any of the electronics yet outside of clearing our the large dust collections and spiderwebs. I did plug it in, but only the light illuminating the TT showed any life. I'm sure there's several issues at play there. Below are pictures of the interior and back of console.

Mainly looking for thoughts on how to proceed.
1. Is this sought after enough where it would be a shame to modernize it?
2. Is bringing this back to working original form likely too much to handle for a relative newbie who is young enough to have not grown up with any of this equipment?
3. What sort of money am I going to invest into this on the low and high end with doing it on my home as well as finding a shop to do it? (I have no real set budget, into it for cheap, and likely looking somewhere in the $1k range for modern equipment.

I appreciate the input. Sorry for the long post...

 

[quiet]

It certainly is pretty. As for bringing the old electronics up to speed for everyday use and keeping them that way, I don't know.
A good case can be made for different innards, vintage or new.

 

[Patrice B]

Push-pull EL84, tube tuner and stereo FM decoder, worth to restore in my opinion... The amplifier section is separated from the tuner chassis, a plus!

 

[Dswankey]

First of all, welcome aboard, that is one nice looking console you have there. Are you in Providence RI? if so maybe check around to see if there are any audio repair shops around and have them look at it.

I would reach out to one of our locals here at AK, @buglegirl and hopefully Frannie can shed some light if any on what she did or didn't do with hers.

http://audiokarma.org/forums/index....-karma-is-a-bitch-if-you-mess-with-it.517464/

https://www.radiomuseum.org/r/grundig_ks690_hi_fi.html

First thing to consider is that "tinkering" with tube related gear not knowing what you're doing is not advised. If you have a local to you shop or know someone who has good knowledge of tube gear have them look at it.

Question # 2

Yes!!! with regards "likely too much to handle for a relative newbie"

I could be wrong but in the 3rd picture if that is the tuner note that some of the tubes are missing. You can check against the tube placement chart in the first pic.

The power amp* in pic # 6 looks unmolested which could mean it's been sitting dormant for many many years ie not being abused which could be a good thing as they seem to be highly thought of

*Grundig NF-20

http://www.tube-classics.de/TC/GermanTubeHifi/Poweramps/Grundig NF2/NF2.htm

https://www.radiomuseum.org/r/grundig_nf20nf_2.html

http://www.w-e-s-t-e-r-w-e-l-l-e.de/grundig-nf20.htm

I've attached a schematic too

 

[providence]

Appreciate the info. Thanks all.

I’m actually in Minnesota and there’s an audio shop (mainly specializing in amps and vintage) a few miles from my house so I may check in with them.

Around what ranges would I expect to pay a shop for what I would imagine would be a pretty complete overhaul?

 

[Dswankey]

Everything looks pretty intact and all the dust leads me to believe it's still stock. Definitely check in with the local tech and bring the pics to show them what you have. They should be able to give you a rough estimate and depending on your budget go from there. I will say that power amp is VERY nice!!!!

 

[primosounds]

Actually , that amp is known for very good sound quality. You have a lot of unknowns yet. If you want to keep the console the speakers need to all be in good shape with no holes or tears in the cones, and open coils in the motors. They usually are but another thing to check. The cabinet is nice so it might be worthwhile restoring the unit.The tubes are probably original and most likely good so your tech should have the tubes tested and make sure he returns everything to you. Some techs will summarily throw out the tubes and charge you for some new ones. But secretly they will keep the vintage tubes for their own stash.

 

[gadget73]

The NF-20 amp is probably the single biggest prize in the box. I expect the speakers pair with it fairly nicely. If your intent is to keep the cabinet, honestly I'd restore the electronics and keep the whole thing together.

 

[Dswankey]

The tubes are probably original and most likely good so your tech should have the tubes tested and make sure he returns everything to you. Some techs will summarily throw out the tubes and charge you for some new ones. But secretly they will keep the vintage tubes for their own stash.

Good call @gadget73 I couldn't agree more!!!!!! and it looks like they're Valvo's if not Telefunkens too.

To the OP, FWIW Valvo's & Telefunkens are West German made tubes that are quite revered & desirable.

Also maybe create a new thread seeking advice from fellow AK'ers in your part of Mini Soda asking if they have any experience with the shop you mentioned.

 

[RWood]

Agree, that's at or near the top of the line for Grundig, just before they started using solid state components. Their best power amp, stereo FM, Dual turntable........ very nice.

In my opinion you will enjoy it even more if you get it running yourself. BUT this is not the rig to learn on. If you can afford to take the time to learn on something simpler like a Magnavox, RCA or similar console, become familiar with schematics, soldering techniques, component identification, acquiring tools, you will be in a better position to bring the Grundig back. It sounds like you already have the required gene for tinkering, which along with it comes troubleshooting and attention to detail. You'll need all of that, with a little bit more of the 'trying to not die' instinct that comes with working on high voltage electronics.

An alternative if you are hell bent now would be to remove and work on just the power amp. There are some good threads here on the NF-20. The power supply, a critical part of what needs to be refurbished, is a part of the power amp.

 

[providence]

Thanks for the advice all. It is appreciated.

I'm still looking into everything I have and reading up here before really touching anything. I'm comfortable enough with wiring and soldering (to be dangerous...). I don't really want to do anything quite yet until I have a good grasp as to what I'm looking at.

Good call @gadget73 I couldn't agree more!!!!!! and it looks like they're Valvo's if not Telefunkens too.

To the OP, FWIW Valvo's & Telefunkens are West German made tubes that are quite revered & desirable.

Also maybe create a new thread seeking advice from fellow AK'ers in your part of Mini Soda asking if they have any experience with the shop you mentioned.

Of the tubes I can see/see through the dust, they appear to be marked Valvo.

I've reached out to two shops in my area regarding repair. Both have declined due to the size of the console. I can't blame them, it is a big piece of furniture.

Is there a particular part of the forum to post in to get an idea as to what shop would be willing to work on it in my area? One of the shops I spoke with gave me a number for a museum to contact as they might have an idea of someone in the area.

As an aside, I'm a pretty big into tools so any recommendations on necessities would be welcome.

 

[gadget73]

You'd have to pull the guts and take them. The complete cabinet is just too big and difficult to deal with.

 

[Dswankey]

I'm comfortable enough with wiring and soldering (to be dangerous...).

I've reached out to two shops in my area regarding repair. Both have declined due to the size of the console. I can't blame them, it is a big piece of furniture.

Wiring & soldering is one thing, wiring & soldering with tube gear can be very dangerous if one is not knowledgeable.

I feel for you on the one hand I can totally agree with the shops you called not wanting to have to deal with size of console on the other hand pulling the components and bringing them in would be great but are you comfortable pulling everything correctly and being able to reinstall correctly.

Maybe start a thread in the regional clubs section of AK, titled something to the affect "Tube repair help in the (your) area" and in the post link back to this thread and spell out your predicament. Or maybe check out this thread to glean some info.

http://www.audiokarma.org/forums/index.php?forums/regional-clubs.202/

http://www.audiokarma.org/forums/index.php?threads/twin-cities.768558/

Did I mention that is one nice piece of furniture!!!

 

[Dswankey]

Maybe try here

https://www.facebook.com/audiosocietyofmn

 

[providence]

Thanks again for the advice. For whatever reason pulling the tube amp and stereo didn't dawn on me initially. Those are the two more daunting projects in this console for my abilities, I believe, so if I can find someone to take this on locally I think I could manage with most everything else.

 

[gadget73]

I imagine it all comes out with a couple of screws. In the 60s you might call a repair guy out, but if he couldn't fix it on the spot the parts would just be removed and taken back to the shop for repair.

 

[knockbill]

Seems there are different connectors attaching the separate chassis together,,, DIN jack may be for the PS to amp,,, and some RCA s for TT and tuner connections, speakers may have special connectors also,,, Take lots of pictures, and drawings of the cable connections, you can even use paint dots (I use nail polish) or cable tags to identify them... Looks like a few screws are holding the chassis to the console... One of the techs in your area may be interested in the rebuild if you are OK dissembling it...
Good luck with your decision...

 

[Alfonsol]

It have the magnetic phono preamp and reverb unit!!!

I repaired a similar console. If the transformers are good, the repair is cheap in parts, but long, because everything is cramped inside. the turntable lamps is working because this is connected directly to mains. The amplifier( the big one with 3 transformers and 6 tubes is also the power supply for the tuner, so neither will work if the fuse of the amplifier is open. the fuse is usually open because the electrolytics in the power supply or the selenium rectifiers failed. hopefully your power transformer is not toasted. If it is not everything is lost. On mine it was missing and i made one from scratch . On mine i ended making a complete recap, and changed several resistors that were out of spec. same story with the tuner and reverb unit.

 

[MCM Marvin]

Hey there - I just purchased a Grundig KS 680 U the other day. http://audiokarma.org/forums/index....-stereo-console-looking-for-more-info.842185/

I am still sorting mine out. I also have 20-years in the electronics service biz but I've been out of the racket for 20 years now, so I can help but I don't have a lot of equipment to test things as I used to.

Looking at your pics, it appears your unit has been meddled with a bit and as a few have mentioned, you're missing some tubes. You probably do need professional help, and as you've gotten some really good advice here, my recommendation is to tree carefully, document EVERYTHING, and clean up what you can. Remember too, sometimes technicians get difficult to work with when people have messed with things or tried fixing things themselves, as it can make their job more difficult.

As I said, I'm just getting started on mine. I have power, my amp appears to be working, my tuner is somewhat operational, yet my system sounds horrific.

My final thought about yours (and mine as I look through your pics), I'm going to carefully check out the condition of the large "woofers" before going too far. Maybe just inject a signal with them disconnected from the amp, as with that fabric over the back, it's hard to tell if the cones or surrounds have deteriorated.

Anyhow, feel free to reach out at any point - I'm more than happy to help, share info.