Schematic Needed Telefunken Opus 5430MX

9/9/2013 8:55:54 AMBrianC

Recently picked this radio, Telefunken Opus 5430MX, up at a local consignment shop. Not getting any deflection on the eye tube with the AM band. FM is OK. Just looking for a schematic so I can fix that problem, and go over the whole set. Beautiful set. It has two output channels. Thanks in advance.

9/9/2013 11:04:49 AMCV

Try testing or just replacing the ECH81 tube first. This is the converter/osc tube. Its oscillator section is only used in AM mode (the FM section uses half of another tube, the ECC85 I believe, to generate the mix frequency for FM). Most people who originally owned these sets bought them for their hi-fi chops and so operated them pretty much exclusively in FM mode; consequently the AM oscillator half of the ECH81 tube eventually went bad due to "cathode poisoning" (the plate bias for the oscillator being cut off for FM operation).

Of course, the problem could be anywhere else in the AM section's RF or IF string... but the ECH81 tube fault is a very common one.

9/9/2013 11:47:23 PMBrianC

I didn't try the tube swap yet, but wanted to make clear that I am getting decent AM stations across the band...just no deflection on the eye tube on that band.

9/10/2013 9:16:48 AMCV

On this set the eye tube is switched between AM and FM AVC. I think that the actual switching is done on the FM sliding switch strip- if FM is selected, the eye is switched over to the FM discrim/AVC circuit; otherwise if any other band (BC, SW) is selected the connection defaults to the AM demod/AVC. A nonresponsive eye tube on AM is probably due to an oxidized contact on the FM selector slide switch (part of the bandswitch array). Could also be a broken connection on one end of the jumper wire between the FM slide switch and the AM AVC bus. Really bad luck would be for the linear switch to be broken internally.

I own this model but haven't needed to work on it for several years, so my memory is a little foggy as to its innards. But I seem to recall that, while the lift-off case was a nice service feature, the jam-packed linear switch array was semi-daunting. Great sounding radio, however, and well worth the effort to repair. Close to the last of the awesome Opus series.

9/10/2013 4:34:50 PMBrianC

Thanks for the help CV...I have some space on the bench to get back to working on this set and try your ideas. It came with only 1 Telefunken (Klangbox) 2402 speaker box..I am looking for another in your travels...

9/10/2013 6:09:00 PM*** Edd ***

Sir . . . Brian Ceeeeeeeeeeeeeee

With all of THIS info, how can you now fail in your efforts ?

Here is your signal flow with color coded referencing:
You have a combined AF and DC mix coming from your FM detector section, via the FUCHSIA ARROWED LINE

downwards and connecting into # 7
of mode switch UIIb

You have a combined AF and DC mix coming out of the AM detector, via the BLUE ARROWED LINE, its DC AVC

portion component is branching off as the BLUE-RED ARROWED LINE path, while another path with AF and DC

is moving on up to make connection on into # 5 of mode switch UIIb

The rotor of of mode switch UIIb at its # 5 connection, is being positioned in accordance to whether being in its AM

or FM mode, is taking off signal to then pass down the
GREEN ARROWED LINE to pass over to the right and then

downwards .
It then reaches a branch where the DC component swings to the left, continuing on as the same GREEN ARROWED LINE

until it reaches the control grid of the tuning eye tube.

Back at that branch, the AC component continues downward as the GREEN-RED ARROWED LINE , and as the audio input

into # 10 of the St switch.

Thassssit . . . .

As far as the different signal routings, the GREEN ARROWED LINE is importing the negative DC samplings of EITHER
of the AM and FM sections. as grid drive for your EM84 eye tubes control grid.

Sooooooooo ...... monitor its DC levels in both the sets AM and FM modes

Now with only the AM not driving the eye tube, one would immediately want to suspicion switch UIIb at its # 5 contact

BUT you said that you HAD AM audio, so it must be connecting . . . . .along with its passing of the DC component.

Sort of makes you want to suspect the detected level / or amplified RF output prior to the detector stage.

Inspect / Meter the possibilities and feedback to us.

73's de Edd

I don't think I've done a system update on my computer since 1998,
but I've clicked on "Remind me later" 1,887 times.

TELEFUNKEN OPUS 5430MX Schematic:

:Thanks for the help CV...I have some space on the bench to get back to working on this set and try your ideas. It came with only 1 Telefunken (Klangbox) 2402 speaker box..I am looking for another in your travels...
:

9/11/2013 8:40:43 AMBrianC

Thanks for the ske-ma-tic Edd!!! Got into the radio last night...Turned out to be a non-insulated wire on the movable ferrite antenna was shorting against the wound part..causing some signal loss. Also did some IF coil tuning and we're back in business.