I just got a beautiful Dirigent 610K which doesn't work. Although the user interface is far from self explanatory, I believe I tried every proper way but no sound at all came out.

I took it open and found it to be very clean inside, with no signs of heat or other damage. All the tubes glow. However, the 1000 ohm safety resistor on the main cap has popped, so I suppose there's no anode voltage now, explaining the silence... I know it can't be fixed with usual soldering, but would it be safe at all to just melt it back together, after checking for other obvious faults of course?

Wonderful piece !

Those resistors are safety components, acting as slow blowing fuses.
If they open their solder joint, they should be considered defect and a replacement will be needed.

Having said that, you can of course solder the tab back onto the resistor as a temporary solution but
I suggest you put a voltmeter across the resistor to monitor the current flow when you power it up again.
If it works and everything looks normal, I will be happy to see if I can find a replacement resistor of the
correct type for you.

Martin

Thanks, I'll try that, hope I can take you up on your kind offer   I suppose the normal current at little/no load should be in the ballpark of tens of milliamps?

I'm in no hurry so I guess it won't hurt if I check first that all resistors are about in spec. There are no apparently leaking caps. The only signs of heat are around the power output valves (the PCB has slightly darkened).

I remember dismantling old radios as a kid and had a lot of those resistors... and many of the exact same component types I see in this radio. I think they have of course been junked ages ago  

Oh yes, the MPX decoder... if I have it, where is it? There's a suspicious empty slot for a PCB between the power amp and the speaker connector panel, but I can't see any provisions for connecting one anywhere.

The Stereo decoder is located to the left of the amplifier section, like this:

This particular one is a Dirigent 609 but your 610 is very similar.
This one will also need a new pair of output valve sockets. I've found some ceramic ones
at Ebay that are very good if you cut the solder pins down to half their supplied width.

Martin

Check also the output valve grid coupling capacitors. If they are leaky, they will allow
DC onto the grid, causing the valve to draw excess anode current. That could cause an
overload of the power supply and also the burned resistor.
Those caps are normally of a very reliable type (mustard colored dry type) but
I have seen cases where they were replaced by something "audiophile" and "modern"...

You have email.

Martin

No decoder installed then... but at least the valve sockets are in much better shape than the ones in your pic!

Everything seems original, but I'll check those caps as well before powering up. I'll delve deeper into the unit tomorrow - I was so happy with my other new arrival (see the "Flash your B&O" thread) that I'm now well into a bottle of red

I wussed out, and instead of soldering the fusible resistor together, I replaced the missing connection with a fused ammeter.

Then I powered up - first nothing, but as the tubes started to warm up, the current slowly rose to ~40 mA and stopped there.

I already had a makeshift antenna connected, so I plugged in the S80.2s that happened to sit nearby on the same floor next to my workdesk, pushed the inexplicable speaker selectors at random until I heard some hiss, then started to turn the frequency selector... MUSIC!

Extremely bass heavy, although fixable with the tone controls... and then it sounds really good. Cleaning needed at the control pots perhaps - and definitely at the valve sockets, as the entire receiver is extremely microphonic. I will continue with that after it has cooled down and the supply voltages have bled down

Now that I know this works, I have plans for the missing stereo decoder...

Microphonics is almost always caused by either hardened rubber insulators where the
FM screened can is mounted to the chassis or the front-end valve itself (where a screen or grid may have losened
inside the valve in transport or similar).
If extreme, as in your case, my bet is on the valve.

(Microphonics is an unwanted side-effect where you can hear what is best described as a kind of hall-effect to
the reproduced sound when you tap your finger on the set. Sometimes you can even hear the tap itself
as you would on a microphone).

I may be able to document the decoder in my set if that would be of interest.

Martin

Oh, I guess I used the wrong term then - it was just very sensitive to tapping anywhere. I simply removed and reseated all the valves, and that problem disappeared so it was apparently just bad contacts at the sockets.

I connected my CD50 to it (how's that for a combo?) and played it for about two hours straight without any problems, and the sound is awesome! The boomy bass - I set the knob at about 8 o'clock before it sounded right - may have flattened a bit, but I'll need to judge the frequency response better tomorrow... I live in a flat and can't use any real volume at these hours.

Hold a bit on the decoder

Meanwhile, it's time for some cosmetic work.

The woodwork on the Dirigent is so beautifully made. Good condition too, so all it will need is a makeover with some teak oil.

While it was apart, I of course cleaned the front plate as well. There is a thick plexiglass(?) window in front of the tuning indicator valve, and it had dropped down. Hot glue to the rescue again.

The chipboard bottom plate has a thermal protection(?) foil on it. The bottom had some damage due to a hit from below, and the foil was sticking up. We don't want any short circuits, and some heat resistant Kapton tape should take care of that.

The metal case was basically scratchless and straight. There were remains of some tape, felt pen markings, and some skid marks on the top. I managed to remove them all with some isopropanol and elbow grease.

And now the front is nice as well! There's a spot to the right of the tuning indicator where the gray paint has flaked off. I'll fix that once I find some suitable coloured paint.

A wonderful set, a great thread and lovely work ! 

The foil on top of the bottom plate is for screening under the sensitive IF circuits.

For the grey part of the dial, I've found a mix of Humbrol colors 129 & 67
in a mix ratio of apprx 10 to 1 to be a fairly good match.
Note that Humbrol colors dry up fairly different from wet so make a couple of tests mixes first.

Martin

Off to the model shop then! Thanks

I've been playing it all afternoon and love it. Might be my new favourite amp for acoustic music. Even with its mighty 2x4W, it has no problem filling the room with my passive Pentas, the volume setting halfway up. And I'm sure the neighbours would agree!

Do you have any theory on the bass issue? It sounds just as if the bass knob was a quarter of a turn off it's correct alignment. First I thought it might be a problem at either the bass EQ network or the "physio" network on the volume pot, but it seems to be the same on both channels...

Sigh, bliss isn't eternal. While I enjoyed my CDs, the tuner developed a fault - perhaps something gave due to the heat. Couple of stations come through everywhere on the dial seemingly regardless where I turn it.

Some valve socket problems remain, so I'll clean them properly and redo some solderings. Meanwhile, I'm all ears for possible causes for the above... I'm already looking at getting some spare valves I'll probably need sooner or later anyway.

The bass knob; Is that based on the position on the potentiometers track or the position of the knob ?
The thing is, that the knobs have little markers. The markers position differs according to the knobs use.
What I mean is that all of the small knobs should be of the same type on your set but a knob from
a wrong set could have been fitted at some point, one with a marker 90 deg off.

The tuning fault sounds like an oscillator problem. I think I'd clean valve pins and replace the frontend valve first.

Martin

The knob seems correct, the end stops of the travel are where they are supposed to be. Just that the pot needs to be set at about 8 o'clock for the frequency response to sound natural. Not a showstopper, but there's not much usable range

If cleaning doesn't restore the tuner I'll get a new ECC85 to try. Already found a local source for 17 euros, which doesn't sound like outright robbery, but I'll shop around a bit more...

EDIT: a couple of tested excellent Telefunkens coming this way from fleaBay.

Have to say that is quite a nice looking set, and I am not normally interested in pre-70's sets! I can't believe it would drive your Pentas without distortion though!

Keep up the good work :)

WOW.

I want one!

One problem though, I think I like the look of the back more! So nice looking, clean and pefect! I mean don't get me worng - great look on the front too! Hmmmm... would that be hard to use? With the controls facing the wall?

Wonderful to see this restored (and saved.)

And I agree with Evman that it looks good both coming and going, so a rectangular mirror behind the unit seems called. for.

As I always say, the Pentas are just another 8 ohm speaker and not some mythical sea monster born to eat amplifiers... As I understand these valve sets would be most efficient with 3-6 ohms, but otherwise no problem there. I'm sure that if you put a distortion meter on the output at large volumes, it would show something awful, but 3% of harmonic valve distortion is still like honey to the ears compared to the same figure from a transistor set.

Thanks for the compliments - I'll consider the mirror setup once I'm able to screw the top down for good

All right, despite the best efforts of our strike-ridden postal service I finally got my new valves.

I tried two measured good ECC85's in the front end, with practically no change - a couple of stations are heard on top of each other everywhere, with the tuning knob having very little effect. AFC on/off doesn't change anything either.

Should I still concentrate on the front end, or could it be an IF problem? The front end has been boxed annoyingly well and there is no access to the solder side without removing it...

Sounds like it could be allowing both the added and subtracted frequencies
in from the mixer or the local oscillator is way off.
Alternatively a heavy spurious.
Could be an adjustment issue, a too widely tuned LC circuit, maybe even a broken
coil, ferrite core or similar but check first anode voltages from the frontend and through
the IF stages to make sure that all valves are operating correctly.
If you cannot get to the solder side (admittedly difficult in the Dirigent), try finding
components attached to the anodes that you can reach from the component side.

Can you tell if one of the stations are correct on its frequency ?
If so, can you tell if the other station lies the frequency of the IF higher or lower ?

Martin