Grundig 7060 WE/3D

[Colin Boggis]

Unusual chassis with odd valve line up. EBC41, ECH81, EF89, EBC41, EM80, EL84 and Selenium rectifier. Covers MW and 4 SW bands.
I can't find a schematic anywhere, not even on Radiomuseum.
Whilst the radio is working well I'd like to see what the front end EBC41 is doing!
Does anyone happen to have the circuit?

PS: 7060 W/3D is NOT the same!

[Herald1360]

I suppose it could be a grounded grid RF stage. I can't think of any other way it could be any use. Do you know it's the right valve and not a cuckoo?

[ukcol]

Originally Posted by Herald1360

I suppose it could be a grounded grid RF stage.

If Chris is right it is likely to only be used on short wave. Why not remove it and see if any or all of the short wave ranges stop working?

[Colin Boggis]

It's the correct valve - types are marked on back panel and, no, it's not for SW. Interestingly I've found that it's used as a preamp for the pick up input! Not sure what the diodes do - still need that elusive circuit! When I've more time I'll sketch out the circuit if I have to. Thanks guys for the suggestions.

[roffe]

Found this circuit diagram:
http://www.dampfradioforum.de/downlo...5976&mode=view
and this where Hans M Knoll talks about the EBC41 as RIAA stage:
http://www.radiomuseum.org/r/grundig_3050wf3dph.html

[Herald1360]

That makes the set rather special!

Pity they didn't go the whole hog with a push pull output.

[Colin Boggis]

Thanks for all your help! I have drawn out the circuit of the amplifier in my radio - it's very similar to that mentioned by Hans M Knoll. Pictures and circuit attached. All the capacitors were faulty, but resistors within 10%. I've just finished replacing the caps. and I'll test out the repaired amplifier tomorrow.

[Colin Boggis]

Whoops, just noticed my diagram has a 10 Meg from grid to ground missing!.

[Colin Boggis]

Here's my corrected circuit alongside that of Hans Knoll for comparison.

[bobbyball]

I've noticed that a few manufacturers used the EBC41 as a "single triode" stage, just grounding the diode connections. Philips used them as a (non RIAA) "tone booster" (their description) stage in some of their radiograms, the type that used the crystal pick ups.

Sometimes the EBC41 is also used as an extra triode stage in a push-pull output: the Grundig 5080 radio uses it in this configuration.

I think the "/WE" suffix meant that it was an export version. I have a streogram that has this suffix and instead of LW it has two SW bands and the FM coverage is up to 108 MHz.

When restoring a set like this it goes without saying that allthe wax caps need changing as well as as most if not all of the electrolytics unless they will re-form. They are often made by "ERO" who seem still to be in business as the "modern" ones I have are also made by them.

Does your set have the built in record deck then? Grundig were among many that did this.

[Colin Boggis]

Yes it has an early Perpetuum Ebner deck, with very unusual auto function - literally a weight that sits on top of the stack to push the records down! It too has issues which will be sorted in due course (I hope!).
At present I haven't replaced any caps in the main chassis but it seems to be working OK. Obviously I will check them though. They aren't Wima or ERO - I don't recognise the maker -the are in shiny finish hard shells, tapered at the leads, with KS together with what looks like RR or KR markings.

[bobbyball]

Colin I would definitely replace all the coupling and decoupling capacitors. Not worth wasting time checking them, just replace them. I am doing the same in my big stereo chassis, have just run out of 0.022 uF at the minute! The small value ones used in the radio circuity for the tuned circuits etc should be OK and would upset the alignment anyway if disturbed

The record changer will be called the "REX". The plate sits on top of the records to hold them in place, there was a version of the deck (which I have!) that uses the more usual record steady arm. There were 3 speed and 4 speed versions and some, yours included I presume, that have a removeable headshell: the cartridge may well be an ELAC.

The deck is unusual and clever in how it detects the record size. The first record in the stack will be lowered down a couple of cm or so and then "measured" by the edge of the pick up head; it will then drop and be played. The deck can be used on manual by using a short spindle that should (or would have been) mounted on a clip.

[Colin Boggis]

I shall replace all caps: I usually do! Just hadn't yet as radio works well. Out of interest do you know the manufacturer of these caps - picture attached.

Regarding deck, yes it is a REX, 3 speed and I do have the short spindle too. I suspect the cartridge is faulty as output is very low and connections are fine including the sliding contacts. Shame because it's quite unusual.

Being a mercenary kind of chap, I'll probably sell the deck as I think it's very collectable. I have a later PE deck I could replace it with that has a good cartridge although I'll then have to modify the RIAA stage as it isn't magnetic.

[bobbyball]

Can't say I have seen that make before, but have replaced ones of a similar style in a NordMende chassis I was rebuilding.

I'm not sure whethere those early turnover cartridges (usually made by Elac) weren't an early "variable reluctance" type.

[Colin Boggis]

A stroke of luck - amongst a pile of 78 rpm records that came with the gram, in a sleeve, was the circuit diagram of both the radio and the RIAA stage plus the user manuals for the gram & the PE Deck! So I'm no longer searching for them.

Circuits attached for those who want them.