1956 Grundig 3028 Hi-Fi Zauberklang AM/FM 6 valve radio

[howard]

Hello again,

I bought this great big Grundig set at the last Wootton Bassett meet at the Bring & Buy table for £22. It immediately appealed to me as it is in remarkably good cosmetic condition and came complete with its original dust cover which had obviously protected it well from bumps and scrapes all its life. A couple of stations were audible on FM but I couldn't test AM as the AM cord was broken ; also its EM34 magic eye was dead. Inside it was dusty, with the remains of the steel AM cord coiled up on top of the chassis and the cord for the rotating antenna was falling off as well. Removal of the damaged cover under the set revealed evidence of previous work done to the set as there were a three old Radiospares capacitors fitted and one of the smoothing caps had been replaced.

This is a German spec set (220 volts and German lettering) and I found a circuit diagram for it described as AM/FM-Super 3028, and other useful documentation for the 3028 Musikgerat series, on RMOrg, and later bought a copy of the service data from Paul Stenning's website for the Grundig Marlborough 3028/W/3D which is the UK version of this set, and that proved to be almost identical to the German set even down to the 468 khz AM IF frequency.

These are not easy sets to work on as they're big and heavy and often fiddly and the worst job is putting the chassis back in its case. I also made a mental note to keep well away from the unprotected fuse on the back when the chassis was out of the case and plugged into the mains. The hefty chassis comes out after detaching four wires to a tag board on the rear of the front baffle board wired to the three loudspeakers (I made a note of the position of these to ensure correct reconnection later), removal of the bottom cover and earth wire, and removal of four bolts underneath. If pulled straight out the glass dial will foul the side speakers so it's necessary to pull one side partly out to clear the speaker and then slide it slides out OK. Watch out for the four loose thick rubber washers that the chassis sits on.

On the underside of the chassis were still in place several blue and green lozenge shaped caps and four of these and the output valve coupling capacitor were taken out and Ron Bryan tested them and all were leaky. So I replaced those and then all the other lozenge shaped capacitors (Ron tested a few more of these later and they were all leaky). I also replaced three old grey RS caps as those I gather can be troublesome.

The cord to the rotating ferrite rod aerial I simply shortened and that then worked fine. The pulley on the end of the tuning capacitor was broken in half so I stuck that back together with superglue. The AM cord on these sets is part steel wire and part cord and it was the steel wire that had broken. It had been repaired before as the steel wire was shorter than in the documentation and indeed a piece of cord had been tied in to replace a piece broken off. I tried to find some suitable steel cable like the original but couldn't find any so I ended up replacing the lot with cord of US origin - quite easy in fact, the documentation specifies the length of the two cords so I made them up and fitted them in about 30 minutes. I was then able to check the operation of the AM clutch (the FM clutch was fine), it is obviously worn but once engaged it holds fine and so I left it at that. This set has a 'graphic equalizer' display under the dial, just above and operated by the four tone wheels, which is simply a red rubber band. The original band had completely disintegrated so I replaced it with a new white piece of rubber band extracted from some knicker elastic .... unfortunately it wouldn't accept a red dye or paint so it remains white.

I switched the set on and it was now working quite well on MW, on VHF it was picking up only one or two stations down one end of the waveband, on SW it was working OK but very softly but on LW it was picking up just a couple of MW stations. I replaced the ECC85 and that brought FM back to life and that was now working well and sounded very good. The EM34 was still dead so I fitted a secondhand £10 replacement which is a nice bright one but it wasn't closing properly when tuning on AM. And then the set wouldn't switch on .... so I took it over to Ron Bryan to take a look at. He quickly found the problem, there is an internal on/off toggle switch in these bolted onto the end of the switch assembly and operated by a bar that comes out the side of it ... it wasn't working as it was clogged with dust so I cleaned that out and sprayed it with switch cleaner and away it went again.

Ron then investigated the LW problem and found that a wire to the LW loading coil was broken and also the core inside it was disintegrating and the top of it was damaged. So the coil assembly was removed from the chassis, its crumbling core was removed, the thread inside retapped and a new core fitted, the coil replaced on the chassis and the wire reconnected - a very
tricky job as the wire is very fine (38swg = 0.006") and only a tiny piece remained on the coil to solder onto - and the coil then adjusted OK. This restored LW operation, but LW was still weak compared with MW and the dial calibration was well out, so the 468kHz AM IF was realigned. It was during the IF realignment procedure that an error in the documentation was discovered, the docs incorrectly indicate the position of the first AM IFT which in fact it turned out to be an FM IFT so the FM IF then had to be realigned. MW and LW RF realignment then followed. This improved MW significantly but LW remained around 10% weaker but still perfectly listenable. The condition of a few resistors and other small red polystyrene capacitors were checked and they all proved to be fine, and voltages to the valves were all checked and they too were fine. The 10uF crossover network capacitor on top of the output transformer was tested and that was found to be leaky so that was replaced.

The set then came back to me for cosmetic restoration and finishing off. The case only had one or two tiny marks on it so I simply polished it with Topps medium wood scratch cover. The trim and knobs were cleaned with upholstery cleaner and I stuck the bottom cover back together again using some wood glue and then placed a heavy weight on it over some greaseproof paper. When playing a slight rattling sound was coming from the main loudspeaker - I discovered that the badge was loose and so its tabs were pointing inwards at the loudspeaker the other side of the baffle. So out came the loudspeaker ... a tricky job which also entailed the removal of the adjacent side speaker .... I removed and polished the brass badge, painted in the white 'Zauberklang' text, revarnished it and then refitted it firmly. The sponge around the inside rim of the loudspeaker was disintegrating so I brushed that off and replaced it with draught excluder and refitted it and the side speaker. Also evident when playing was an occasional high pitched ringing noise at first thought to be AF instability but which I found stopped when pressing on the EL84. So I replaced that with a brand new EL84 obtained at Tonbridge on Sunday (£2) and that cured that problem.

This is a very fine radio indeed, the best sounding set by far that I have acquired to date. On FM it sounds wonderful, crystal clear and with great bass. It's also sensitive on all bands except for LW where it has lost some gain due its worn and probably unreplaceable loading coil but it's still perfectly acceptable. And it looks absolutely fabulous. And 52 years after it was built, still a hard act to follow ...........

Howard

[howard]

And three more pics of the restored badge, graphic equalizer and loudspeaker. If anyone knows where red knicker elastic, wire cord and a spare LW loading coil can be obtained, please let me know.

Howard

[JoshWard]

Another outstanding job Howard! These big German sets are lovely, I've got a Telefunken which cost me £4 from an antiques fair which I use quite often and works brilliantly even in it's unrestored state, I also have a Grundig 2035 'Hastings' which needs alot of work and I have a very very big Grundig radiogram which I will be starting work on soon, it does work a bit though! Congratulations on this job, they certainly aren't the easiest sets to work on. Josh.

[howard]

Hello Josh,

I am very impressed with this set which along with my Philips Reverbeo and PYE VHF2D Continental is one of my big radios. It seems the bigger the radio the better the sound quality, and if I had the room I would have more of them ...........

Howard

[JoshWard]

I noticed in another post that you're selling some sets soon, however I doubt you'll be selling this! (sadly ). I agree with the bigger the radio the better the sound, you need a Pye Fenman 2!

[Kat Manton]

Hi,

Originally Posted by howard

If anyone knows where [...] wire cord [...] can be obtained, please let me know.

I've yet to make a start on my 2035, which may have similar tuning arrangements, so I'm not sure what type of wire is needed. (Though your restoration may inspire me to move the 2035 further up the list )

However, you may be able to find some suitable wire at a fishing tackle shop; I remember my father using a wire "leader" on the end of his line when going after certain fish as some could bite through nylon line.

Cheers, Kat

[howard]

Originally Posted by Kat Manton

Hi,
..... you may be able to find some suitable wire at a fishing tackle shop; I remember my father using a wire "leader" on the end of his line when going after certain fish as some could bite through nylon line. Cheers, Kat

Thanks Kat, I never thought of that !

Howard

[yesnaby]

Howard,

Yes I saw you leaving WB with this set, I will not say what my thoughts were (too many *'s needed!)

Michael

[Tim]

Well done Howard. These big Germans can be tricky until one gets used to the engineering style. The last one I did had similar capacitor problems, and ISTR a gummed up ferrite aerial rotator mechanism. It also had an O/C output transformer and a couple of duff valves. I have sent the report to Paul Stenning but I don't know when he will be able to include it on his website. I was very pleased with the finised set, and will happily confess to "turning up the wick" whilst listening to "Rockin' with Suzie Q"!
These big Grundigs seem to be quite fussy when it comes to ECC85's. Every one I have had in has been dead or intermittent on FM and needed a change of ECC85 (although not always a NEW valve).

[geofy]

Originally Posted by howard

And three more pics of the restored badge, graphic equalizer and loudspeaker. If anyone knows where red knicker elastic, wire cord and a spare LW loading coil can be obtained, please let me know.

Howard

Another good restoration on an impressive radio. These must have sounded incredible when a customer went to try them out in the shops. The loudspeaker looks very modern. Not sure where you could get red knicker elastic, though being Valentines day we live in hope

If it is just red elastic bands, the post delivery drop them on the ground all the time here. I can send one of these.

Could you use a longwave coil from a scrap set, though the one you have looks repairable though the wire is on the short side. Can it be slide up and down on the former; this can improve the coupling.

Geof

[yestertech]

Nice one Howard !

These are truly wunnerful sets especially if you're lucky enough to get one in good cosmetic condition. I have done about 6 of these, although if I'm honest I prefer the VHF94 as it has the extra IF stage. The EM34 is always a problem but I've been lucky enough not to have any defective wound components.
Both sets sound truly superb though and the Grundig sounds so nice with the extended bass you just HAVE to crank the volume up and rattle the windows.

Andy

[Walterh]

Hi Tim

Dead (not weak) ECC85 indicate, that a radio was mainly used on the AM bands and therefore the B+ to the ECC85 cut - cathode poisoning is the (long time) result. Often seen in addition to blocked tuning mechanism on the FM part (caused by hardened grease).

Kind regards, Walter Haring, Switzerland

[don2233]

Hi howard,i've just got one of these sets complete with the owners manual,the top of the set was badly water marked,so i'm having to strip the entire set as the finish they used is coloured.I also note that my english models badge just says 3D SOUND but the grundig badge is the same,any ideas what colour they were,cheers don.

[howard]

Originally Posted by don2233

......I also note that my english models badge just says 3D SOUND but the grundig badge is the same,any ideas what colour they were,cheers don.

Hello Don,

The 'Grundig' badge is plain brass and the '3028' (if fitted) and '3D Sound' white/brass badges are the same as on this set, the only difference is the name 'HI FI Zauberklang' is replaced with '3D Sound'.

Howard

https://www.vintage-radio.net/forum/...8&d=1202916848

[don2233]

Thanks for that howard,i'll let you know how i go on with my set,i've had to strip the cabinet as it was water marked,but the laquer came off ok with nitromors.

[don2233]

Hi tony,i have restored my marlborough,the chassais went to richard at past times radio and apart from the wave change buttons onthe front not working because of filth ,somebody cutting the tuning cords and the usual caps replacement the chassis now sounds superb apart from after a day ot two the original EL84 went soft and i replaced it ,the cabinet was a different matter,i had to nitromorse the cabinet due to water damage, i then sanded to 1200's and then stained it walnut,grain sealed and true oiled it,i then 0000 grade wire wooled the whole cabinet after a week and bri waxed it,the brass trim came next and i was delighted to find it solid brass laquered, which i polished,the speaker cloth was washed and re glued in plaice after ironing.The zauberklang on the german models means clean sound according to my german frirnd and the 3D SOUND badge is painted black according to his dad who had who worked there,it looks and sounds superb and with it's NOS em34 is original,i asked richard if he could fit a switch to the valve heater circuit to save the 34 which he did.I have another 34 as a spare,ATB Don.