View Full Version : Grundig Console


Dave_Amels
07-16-2011, 11:32 AM
I'm in the process of restoring Grundig KS 500 U. Would anyone happen to know where I could get a schematic for the radio/amp chassis? I've tried Cicone electronics which has one listed on their online store without luck.

I've started without the schematic and was able to free the stuck AM / SW tuning cap. The grease had frozen the bearings.

Next problem: The glue holding the pivot in the tuning meter separated. I've found a similar triplette on the web. I'll either transfer the innards or adapt the flange. It's possible I may try to reglue the meter as well.

BTW - anyone know how to clean the grillcloth on this unit. I was almost able to get the grill off entirely but the bottom of the turntable compartment (masonite in a slot) extends to a groove cut in the rear of the grill. If I could pull the masonite back a 1/4", I could release the entire front grill. Your thoughts would be appreciated here.

Turntable: The ceramic cartridge seems to have little or no bottom end. Is this a symptom of a dying ceramic cartridge? The radio has great bottom end.

I've cleaned all the bearings and idlers... the turntable runs a bit slow. The motor had been seized... same grease as the tuning cap?

Speakers: I'll need to do the weather stripping trick on the rim. The foam turns to dust upon contact.

Any ideas?

Best,

/Dave

RWood
07-16-2011, 12:35 PM
Here are some KS 5xx schemas (http://83.117.57.34/nvhr/zip/Grundig_Locarno.zip)that might get you close. Yours is probably an export-to-USA model; these are domestic.

Does yours have ECL86 tubes in the audio amp?

For the other questions, you might get more responses if you post pictures.

RWood

fiftywatt
07-16-2011, 09:56 PM
You might try calling Antique Radio Supply of Arizona.I purchased one for my 302US model,they also have speaker/grill cloth.Oh,they also have a website too.

DaLarry
07-17-2011, 01:11 AM
Pictures would definitely help. I searched for that model on RadioMuseum.org. I have found models over there with just a photo. The "KS 500" series starts with "520 " and goes through "590". Ordinarily RM.org can be counted on to have all things Grundig but no joy this time. The "U" in the model number is almost certainly an indicator that it was made for the US Market.

Dave_Amels
07-18-2011, 12:06 PM
Hi Folks,

Here are some photos (http://tinyurl.com/3b9p9zu)... sorry about the quality. I'll try to shoot some better ones later but these should give you an idea. The output tubes are the expensive ECLL 800s.

Best,

/Dave

DaLarry
07-18-2011, 03:33 PM
seen a Grundig receiver quite like that one; but that isn't saying. I'm an admitted toob poseur. However, it does look like it is mono; is that correct? I have some photos from RM.org which I will either sennd to you by PM or post online in the next hour or so. I didn't see anything that looks a lot like yours except a KS400 for the mid 60's that definitely would be stereo.

Dave_Amels
07-18-2011, 04:19 PM
It's stereo, complete with external fm mux and stereo ceramic cartridge. There's two oval speakers and two electrostatic or piezo tweeters on the sides.

DaLarry
07-18-2011, 05:39 PM
I only saw the one transformer which I took to be the PT. It wasn't a very clear picture but i couldn't see the OPT's. Ergo, I thought it was probably mono.

Dave_Amels
07-18-2011, 09:26 PM
There are two at right angles on the top of the chassis. I guess the outputs are single ended pentode stages.

Dave_Amels
07-19-2011, 04:43 PM
make the the bottom of the chassis

Dave_Amels
07-19-2011, 05:46 PM
Thank you for the radio museum tip. The guts seem to be identical to ks550 models listed there. Only the cabinet is different. Could someone who's a member download the schematics? It would be greatly appreciated.

Best,

Dave

Dave_Amels
07-20-2011, 01:08 AM
I've found a copy on a French site. Would anyone happen to have a copy of the stereo mux schematic?

tri-comp
07-20-2011, 01:35 AM
This is not the MUX-schematics but rather the adjustment instructions.
Beware, that this decoder does not fit the KS-550 socket; different pin-out.
It's all I have about the Grundig decoders and hopefully it will be of some help.

rgds,

/tri-comp

larryderouin
07-20-2011, 03:17 AM
http://www.audiokarma.org/forums/showthread.php?t=377533&page=2

See Posts #20 & #21. These are for a KS590 and the Version 5 Multiplexer. Check the tube in the MPX and if it's an ECC81 its a version 5. 6BH6 it's a version 6.

Larry

Dave_Amels
07-20-2011, 11:33 AM
Thanks everyone... Here are some photos of the reassembled chassis. I've replaced the stereo meter with the same model only it had mounting tabs instead of being side mounted. I've removed the tabs and you can see the cardboard shims which hold it in place in the rear photo. Also the resistance of the original meter was 430 ohms and this is 1750 ohms. I've shunted the meter with a 610 ohm resistor (didn't have a 560).

Should I replace the cathode electrolytics?

Dave_Amels
07-28-2011, 03:57 PM
Still having problems cleaning the grill cloth. The console was owned by a smoker and it was quite stained. I've been sponging it with oxyclean and applying paper towels over top to draw out the tar. It's worked well but after several applications I believe it's drawing out dirt from the baffle. Anyone know how to remove the baffle. I've removed all the screws but the baffle, it's loose but it's locked in place via groove and a piece of masonite which forms the bottom of the turntable compartment.

DaLarry
07-28-2011, 06:48 PM
My grill cloth is also dirty. Oddly enough, it's not that noticeable in person but looks far worse in photographs. I've thought about but not attempted to clean it. As my daddy used to say; "If it don't stink, don't stir it."

Similarly, it's almost impossible to get in there and do other things like recapping the crossovers at each extreme end. It sounds pretty good as is. I guess I'll never know what it'd sound like completely updated.:scratch2:

Dave_Amels
07-31-2011, 09:52 PM
Yep... Best not to mess with things too much... Unfortunately I've already started the process.

Fimger
08-25-2011, 08:01 PM
Hi Dave and Forum,

not to hijack your thread, but i am also restoring a grundig radio from the same era and mine looks very similar to yours.

You see the iron bar with the thin copper wiring wound around in two places in the left end of your picture? (i have no idea what it is - sorry i am new to this)
mine is broken off its pedestel and the copper wiring is broken (three loose ends).

could anyone tell me what this is, how important is it that i fix it, and how do i fix it? (my radio is working somewhat. i do pick up some stations, and the magic eye is working, i'm just not sure what role this thing plays).

thanks much for any advice.

RWood
08-25-2011, 11:14 PM
I can't view the picture but what you're describing sounds like the speaker crossover networks. It divides the frequencies so that the lows go to the woofers and the highs go tweeters. Yours might have midrange speakers too.

You could try to repair the wires or you could rebuild with modern crossover components.

RWood

Scuzzer
08-26-2011, 01:30 AM
You see the iron bar with the thin copper wiring wound around in two places in the left end of your picture?

Yep.

could anyone tell me what this is

It's the ferrite bar AM antenna.

Fimger
08-26-2011, 07:58 AM
its amazing with all the posts to this forum that beginner questions get answered so promptly. it could have taken me a month of sundays to try to identify this piece, but overnight i have my answer.

i don't have much call for AM radio, so i think i will leave this as is.

thanks again,

Fimger

Scuzzer
08-26-2011, 03:40 PM
i don't have much call for AM radio, so i think i will leave this as is.

If you ever did have a need for it you could hook an external AM antenna to the appropriate two jacks on the antenna connector panel. That's assuming that nothing else was damaged when the ferrite bar broke off.

steerpike2
08-26-2011, 05:13 PM
Turntable: The ceramic cartridge seems to have little or no bottom end. Is this a symptom of a dying ceramic cartridge? The radio has great bottom end.

I suspect it has a Dutch made Philips auto-changer, with a GP200 cartridge. Those cartridges are generally reliable and survive well long-term. Good performance for a ceramic too. Maybe failing capacitors giving it poor bass?