seibt: 5L Spezial; Roland - Chassis connections

Esteemed colleagues,

Could some member explain the jack inputs (2) on the rear chassis, immediately below the loudspeaker L ein-aus switch, which are designated with the  letter T.
From the underside of the chassis there is a 50uF at 50 WVDC elko which connects to one of the 2 "T" terminals?

I understand from the historical pages" of the Museum of Sound Recording that a gentleman named Herr Kurt Stille was instrumental in patenting a "wire audio recorder" - the Telegraphone; and he also  developed  the Textophon (a wire dictation machine) in the early 1930s. I apologize if I have used inappropraite terminolgy for the instruments.

In early 1934 I believe the manufacturing firm C Lorenz (aided by radio engineer Semi Begun), had developed a "tape-type" recorder.

Is it possible that some of the Seibt Roland 5 series radios had the capability to "play back" the output signals from the early Textophon devices or the earliest AEG recorder/players?

Respectfully,
Robert
 

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Esteemed friend Roberto,

It is difficult to interpret the exact function that complies the 50uF 50 WVDC elko without the Roland 5L Spez. schematics . 

I have read your numerous interventions in the forum expecting a valuable information that help to restore the nice Roland 5L Spez.  I know your persistent attitude and surely you will find the necessary information. 

We expect that some member that have the schematic want to share it with you.  It is probable that your comment have a more generous reception if you presents it in German language. 

Best regards, Bruno.

 

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Hi folks,

I have a suggestion, if this is the same company that makes Roland musical instruments,perhaps you could contact them for the schematics and even consult with their tech engineers.  I think they would even appreciate it.

It sure is worth a try!

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Dear Colleagues,

And to Omer,
Lack of schematics are NOT the problem - sometimes too many schematics seriously hinder problem resolution . . . . . .as in the Roland 5 variations.

I will try to clarify my primary dilemma  -  were some of the Roland 5 radios of the TRF design?
 
I have been somewhat confused with Seibt Roland 5L Spezial that I am restoring. . . .
- Every Roland 5 in the RMorg database is described as being of Superhet design.
However, I have what appears to be some peculiar type of "superhet". I had submitted several
very detailed photos of the chassis (top and bottom) to several eminent members. I received different responses but 2 eminent members stated definitely it is the TRF design!

In the rear corner of the chassis there is a potentiometer which does control the point at which oscillation begins.

There are several small components which I am totally unfamiliar with; however,
I believe they are an early type of "bi-metallic" capacitor (appears to be copper and silver in color) within a small glass envelope (they appear to be vacuum sealed), and have markings with different ratings
D.S.Loewe A.8
5000cm
VC145
I believe it to be the 5000pf capacitor.

There are several others. 
D.S.Loewe A.8
300cm

and one which has only a small piece of white tape and the marking 1400cm - I assumed someone may have attempted to clean it many years ago, and obliterated the original markings.

I would be most appreciative for any comments.

As a matter of interest, I am receiving local stations on MW from 280meters up to 470meters, and strangely at night the reception greatly diminishes.

Is it possible that I need to  replace the bottom plate after each repair/troubleshooting session?

Please note that I am trying to maintain as many original components as I can and still achieve somewhat distortion-free reception.

Respectfully,
Robert
NB: I have taken MANY high resolution photos of the chassis.

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Dear Robert,

Your assumption is right, the D.S.Loewe parts are the famous Loewe vacuum capacitors.
The value given in the (old) unit "cm" is indeed the capacity.
Conversion factor: 1 cm ~ 1.1 pF or in detail: 4πε₀ with ε₀ = 8.8542*10^-12 F/m.

Concerning the "T" is my assumption - without having checked the schematics - that it could be the output for earphones:
In most of the 1920ies and early 1930ies radios "T" stands for "Telefon" (= telephone) which means actually earphones.

I hope this is helpful for you!
Best regards
Jürgen

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Dear Robert,

first of all your Roland 5 L spez is a superheterodyne, no doubt. The spez ( = special) refers to an extra double selection filter in the first stage of the radio. It has a so called "Bandfilter" in the first Hf stage followed by a Hf amplification tube RENS 1214. The REN 704d is the mixer also supplied with a Hf filter in the grid and the fourth variable condenser package is dedicated to the oszilator. This is the reason for the four package condenser in the Roland 5 spez.

The Radio has the typical superhet construction style in Germany of that time. The REN 704d has been used only for a short period and 1932 was the first year when superhets became more poplar in Germany.  But this principle was used at that time only in "high end" devices, so superhets of that time are quite rare in Germany.

The resistors and condensers you decribed have already been explained by Jürgen Stichling. I tried to identify this 50 µF condenser on your picture. If it is the orange one below right it is definitely not original. The explanation for T can also be "Tonabnehmer" ( = pick up). So possibly an old owner of the receiver wants to isolate his pick up from the voltage in the radio. In this case one of the terminals should be connected to a switch the other via 4 kOhm to the cathode of the RENS 1204.

The potentiometer on the chassis has been quite common in early superhets in Germany. In your case it is obviously an adjustment for the grid bias of the HF and IF amplifier valves. The REN 904 amplifies the grid bias to the necessary level for the two RENS 1214. In other cases the regeneration of the IF amplifier was adjusted. In Germany valves have been very expensive and companies tried to build up radios using the minimum amount of valves as possible. So they built in a regeneration, which has to be adjusted after change of the valves.

What me suprises are the terminals in the diagram in parallel to the bias resistor in the cathode line of the output valve RENS 1374d. E.g. these make only sense if you have the possiblity to switch to a more powerful valve which needs a different bias resistor value.

All other parts in your radio look original. It is in a very good condition. Congratulations. Outside it can be restored to original condition despite of the bubbles in the veneer.

Regards

Rüdiger Walz

 

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Dear Jurgen and Rudiger,

I thank you gentlemen so very much.  I  have completed the cabinet restoration about as well as I can after using some products referred to me by some elderly woodworkers. I used the glycerin solution for softening the veneer, and then used a very fine needle syringe to inject small amounts of the original animal hide glue. 

All of the blisters are gone, but I have not attempted to fill in the small gouge on the upper front edge - apparently many years ago someone forgot and left a cigarette on the radio, causing a short burn mark. Most all of the mark had been "dressed up" - but Kobi offered the suggestion (and I totally agreed) thatit would enhance its appeal if left that way. Almost like a scar that we sometimes wear with fond remembrance. And in some places around the very base, I decided not to replace every one of the many pieces that had broken off over the last 72 years - as though it still wears its original shoes . . . .somewhat ragged in places but still presentable as Dr Seibt would have it!

I have replaced  the orange 50uF elko with a much elko of 5uF and is discreetly placed.

Since I have been unable to locate one of the original Seibt B4 sockets (I have an NOS Telefunken RGN2004 - thanks to Bruno Gandolfo), I have this afternoon created a dual thick  phenolic based socket  for the B4 based rectifier. I could not have accomplished this without a like-new B4 socket and a very good used B4 socket that Herr Konrad Birkner so generously offered to me. 

Someone had also installed a model 80 full-wave rectifier mounted on top of a Remler type 50 baseplate (with exposed high voltage leads). The tube filament requires 5 volts and draws a nominal 2 amps.
 
I hope the retrofit will be of some positive benefit - at least, it will be nearer to authentic than a model 80 rectifier and a Remler mount protruding above the chassis.

I will attempt to "close" the existing 6 added holes drilled for that modification with some J-B Weld material and return the chassis to a near original condition.

I will add some photos soon of the various processes in this endeavor.

I can honestly state that the 5L Spezial is slowly being restored similar to a "group effort"  - with the knowledge, and help and parts offered by a number of RMorg members. 

My research was less than complete, and I have added the "Loewe Story" data to my folder on the Roland 5L Spezial - again I offer thanks for the reminders.  


Respectfully,
Robert

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Robert,

 

Would you be able to show us some pictures of the veneer repair you did on the cabinet?   Also, did you find out if the  cabinet is shellacked or varnished?

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Hello Omer,

It appeared to be a Shellac finish. I will reduce some of the photos I recently took outside to show the beauty of the veneers; and I will submit the photos of the socket "retrofit" (with the new TFK RGN2004 rectifier)  after I have finished them sometime this weekend.

Of some importance is a request  or consensus of knowledge from the members who may know positively if the final finish was either a "Gloss" or "Satin" type.

The original grille cloth will be neatly placed in a sealed pouch inside the radio. I found some very elegant looking fabric (comparable in quality) which tends to enhance the appearance of the Seibt radios - and there is a faint rhombus pattern in the weave.

Respectfully,
Robert Attachments:

• Cabinet Restoration (128 KB)

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To my knowledge and what I have seen of well conserved radios of that time it has to be a gloss surface. It is difficult to distinguish how glossy these old laquers have been. I would expect due to the fact that they have been nitrocellulosis-based that the surface was not as glossy as of radios of the 50ies which have been thick coated with modern resin based laquers and polished.

Martin Renz decribed it very well, but unfortunately only in German.

I personally would recommend a polished shellac not to thick coated. Your foto showed it already in a good condition.

Best regards

Rüdiger Walz

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Dear Rüdiger,

As a matter of fact, I hand rubbed about 5 coats of the Zinsser French Polish - which is really a flake shellac. Then the old woodworker at the Rockler Woodworker suggested (as you have mentioned, just a few light coats of the Zinsser spray Shellac film to use as a lovely top coat.

He stated it should not have to look like "glass",  but it will be absolutely elegant. He is white-haired, and 88years old - name is Karl Apfel. He pronounces the name as "apple".  His father came to Wyoming in 1899 from Germany.

I believe the finish looks quite nice. The original B4 socket has been re-installed and 6 of the extra holes have been closed with the J-B Weld material. It also looks quite nice - not perfect, because the original Seibt B4 socket with number 6 --- I have never located one. But my "clone" has the slightly enlarged white number 6 pressed on with the transfers.

One last item I am still searching for - onthe rear chassis are 2 input jacks for the item "Err" - I am thinking it is for an external receiver of type like the Seibt KL45 or some other adapter!

Respectfully,
Robert
NB: I read nearly every German posting, and I have particularly enjoyed Martin Renz' articles - as well as many other members.
 

  Attachments:

• Final Shellac coatings (120 KB)

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Wow!

They have sure simplified the French polish technique!

The question of gloss/no gloss can easily be answered by looking at a violin or a guitar.  French polish means a smooth gloss finish..  Even though this radio was sprayed, it is always a good idea to go over each coat with #0000 steel wool. After a week, it should then be polished with beeswax (applied with #0000 steel wool).  That way if someone places a martini on the cabinet , it won't leave a ring.

For post war radios, using a dark walnut shade latex nail filler, one coat of clear shellac, and then three coats of nitrocellulose lacquer will give you a piano finish.

There still is nothing like a good French polished cabinet!

That radio now belongs in a museum!

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Yes, I agree, it should not look like "glass" as the surface of radios in the 50ies. When I use a French Polish I do the last polish with a few drops of oil on the shellac/alcohol wet cloth I use for polishing.

"Err" means "Erregung" (here: generation of magnetic field, sometimes also called "Feld") and is an extra terminal with high voltage for the magnetic field of an external electromagnetic loudspeaker. These terminals are not shown in the circuit of the Roland 5 spez. but as already known Seibt built a lot of modifications of Rolands which are not all shown in the circuit collections.

By the way, the extra terminals parallel to the cathode resitor of the power pentode are terminals for extra headphones (Hörer) . In other circuits they are marked as "Hörer".

Best regards

Rüdiger Walz

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Rüdiger and Omer,

Thank you both so much. I have plenty of the #0000 steel wool; and the FP "wet cloth" is still in the air tight container.

The new RGN2004 rectifier performs magnificently. I must admit that I still have an annoying slight distortion from what sounds like a small bad cap. I am going slowly through them, because even the original small parts are NOT exactly the same as any of the schematics.

I wil add another view of the replaced Socket and rectifier after final minor detailing; and I have the opportunity to record a new set of voltage readings. Keep in mind that I have not been able locate the small brass rivets.

And I would certainly hope that a member may have either one of the 2 outer knobs. I believe the Wellenschalter and the ON-OFF/Volume knobs are identical except for the color marking of the indicator dot on the knob.

Respectfully,
Robert

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Hi Robert,

 

I believe, if worse comes to worse, see if a local plastics shop can either make a copy for you or sell you materials to make a copy.

All you need to do is use an injectable silicone for making molds, slightly block the screw hole on the side, and then make an impression enveloping the whole knob.  Upon hardening and fully curing, carefully cut open the impression and remove the knob.

Now, after getting the right polymer and monomer with right coloring, you can proceed to place the liquidy plastic into the mold and wait for it to fully cure.

Then, with a razor, you can remove all the flashing from the knob

After making the knob, you can cannibalize a tightening screw out of another knob, and have a machine shop drill a hole and thread the hole for your screw.

I hope this helps.

Is there a chance Robert that you can show us how you repaired the veneer, step by step. 

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