TO-R S15, Do I really need a new Project ?

[tri-comp]

Hi,

I came across the very nice FM-only dual-channel output receiver in a 2nd. hand shop.
It was sitting on a shelf right up under the ceiling hardly in view.
On the frontscale it says stereo and immediately I was sold on the idea of owning and restoring this beauty.
Believe me, restoring is very much in demand; have a look at the pictures.
I even believe that underneath the filth lurks several black Hunts capacitors and we all know where they should go.
At least one of the cathode decoupling electrolytics is leaky but I expect that won't be the only one in need of replacement.
The main electrolytic cap has extremely low ESR and possibly only needs to be resurrected somewhat slowly.
Now, where did I put that air-gun...?

More to come as the project advances.

[tri-comp]

A few more pix.

[tri-comp]

Last ones for now.

I do have a full service-manual for the set, in colour even

[Nuvistor]

That looks nice, hope the ECL86's are good.

Frank

[tri-comp]

Frank,

I didn't have too high hopes for the ECL's to be in a good shape.
With the black Hunts as 'That Cap' it would be a miracle if they survived.
One did the other didn't. It shows severe grid leakage most likely caused by a leaky Hunts cap.
I have a lot of used ECL86' and they measure fully up to a NOS Raytheon specimen on hand.
Somewhat strange that Raytheon would label the valve like that and NOT 6GW8 but there you are. The labelling even states mfd. in the US.

It would be a much bigger problem if the EF89's were gone as I don't have any.
They are remote cut-off types and not very suitable for LF applications that I do most.
It would also be a downer if the ECC85 in the tuner was weak as it's becomming quite expensive.
Same goes for the ECC83 but happily all valves measure to be in mint condition save the one ECL86.

[Herald1360]

Is there an optional multiplex decoder plug in facility or is the radio strictly mono?

[tri-comp]

No, the receiver-section is strictly Mono and strictly FM, 87~100MHz

The Noval-socket on the rear-panel is for connecting external speakers.
All very well described in the service-manual.
The manual mentions that there is room for a multiplex decoder inside but has no instructions on how too retrofit it or even a schematic diagram.

I once owned a Philips FM-tuner, valve-type build like a car-radio.
No LF-section; just the tuner.
I put a MC1310 stereo decoder inside and it worked just with a somewhat limited channel separation.
The quality of the IF and/or Detector in an older valve-set probably isn't up to passing the pilot tone in good shape.

EDIT:
I searched a couple of domestic forums and it seems that the stereo-decoder actually existed.
It was built around a single ECC85, so I guess it was hard pressed to perform
I'm trying to obtain the schematic.

[julie_m]

You could always rob the FM stereo decoder chip out of just about any 1980s "boom box", just to keep you going in the meantime ..... There should be enough power available from the output valves' cathode bias.

[Nuvistor]

I did not see many sets with the Foster Seely discriminator, I would think the last IF is designed to be a limiter.

Frank

[Nickthedentist]

Who were TO-R? They're not a brand we ever encounter here.

Nick.

[tri-comp]

TO-R started producing radios in 1930 and were at one time among the top-3 Radio- and TV producing companies in Denmark.
The factory was placed in Copenhagen but from one of the above pictures you'll notice that the cabinet of my S15 was produced by Hadsten Træindustri.
Hadsten is a village to the north-west of Aarhus in Jutland, actually no more than a good 80 km's from where I live.
Træindustri means Wooden Industry.
The name TO-R originates in the founders name: Rasmus Rudholt.
TO is the Danish word for 2
So TO-R simply means 2 'R's
How simple can it be ?
The factory closed in 1966. They didn't really make the switch to semiconductors except for producing A LOT of portable transistor radios from the late 50'ies on.
You may also find the name Superphone in relation to TO-R as they bought that factory in the 60'ies and kept using the name for marketing, especially their B/W TV's.
Here's a web-page with some pictures of TO-R radios.
http://www.olepiil-radioer.dk/75.%20...diofabrik.html
It's in Danish; probably Google Translate will come in handy.

[turretslug]

That's a rather nice radio, hopefully it will work well. Always good to see what got made outside the UK. I bet it gets quite hot though, all those valves in a compact box! Interesting to see the comprehensive fusing around the transformer, there seemed to be almost an aversion to fitting fuses with some British designs.

[SteveCG]

tri-comp, a nice find.

I wish I could come across such a thing in a second hand shop, sigh....

I take it that VHF/ FM is still going in Denmark - and you've not been DABed yet?

[tri-comp]

Oh yes, we're DAB'ed all right. Have been for many years. Still clinging on to FM though.
In a relatively short period of time we went from Mpeg2 to Mpeg4/T and then further into Mpeg4/T2.
It cost the consumer an arm and a leg to keep up and public opinions MAY have persuaded some to go a bit slower with getting rid of trusty FM.

I'll renovate this beauty and keep my fingers crossed

Today I gave the S15 a firm workover with the compressed-air gun and found what was residing under the thick layer of dirt.
Hunts of course and good evidence of leaking electrolytic cap's.
Further more a ceramic cap. in the IF has split open and God only knows how many carbon resistors needs to be replaced.
To keep up the interest I'll point you in the direction of the volume-pot (R103/R153). Did you ever see anything like it ?
I'm posting a better quality schematic.

[Nuvistor]

That's different, hope it's a good one.
In answer to the title of the post, I think you have a project whether wanted or not.

Looking forward to following the thread, as turret slug says, it's good to see what is produced in other countries.
Frank

[tri-comp]

The volume-pot seems to measure OK except that the ground-side of both sections are connected to the rear potentiometer-casing for grounding.
They should have selected the front section as that measures only an Ohm or two against the chassis, not several 100 Ohms as the rear section does.
Obviously that's a minor problem.
The sections measures quite equal, so I'm optimistic about the carbon inside hasn't gone wild.
It's a Vitrohm btw. and they MAY develop problems with the pertinax base upon which the carbon is deposited.
The base may become conductive and upset balancing of the channels.

About the Hunts in the pictures. I'm a bit puzzled as they're absolutely not conducting DC/Leaky (At low voltages as with my Ohm-meter) They're all cracked open and way off rated value but otherwise good.
Rated 10nF/400V and now they're anything between 12nF and 42nF !
Under no circumstances will they be going back in.
What ever persuaded TO-R to use these as anode-to-grid coupling cap's ?
The set is full with 400V Philips/Mullard mustard-cap's but they HAD to go with Hunts for the critical parts

EDIT:
Spotted 2 more Hunts under the OPT's. Very well hidden !
Rated 5nF/400V and now about twice the nF's.
Also showing no leakage.
Do I have it wrong about Hunts ? In my world they are 'Shoot on Sight'.

[Nuvistor]

If the value as gone up, presume you are using a modern capacitor tester, they will be leaky. It seems a common thing with the old paper caps. See various threads.

Frank

[SteveCG]

I would say that cracked case capacitors are 'replace on sight'. As for non cracked ones, well that depends on where they are in the circuit. Certainly, any coupling capacitors to the audio output valves need careful checking. Most types are likely to be electrically leaky by now.

[tri-comp]

I checked out the carbon resistors and it was depressing.
Actually everything but the two 10MOhm grid resistors were way off value.
In my experience you always start by suspecting the high-value resistors of being off. Not so in this set !
Obviously the cathode-elektrolytics were gone, one leaking all over the PCB.
Anyway, I decided to remove all components around the ECL's to replace them after giving the PCB a good cleaning.

So, Gunk be off !!

I remember these generation 1 or 2 PCS's and how easily you could damage the pads when replacing the parts. I hated working with them in the old B/W TV-sets when I was an apprentice. Well, that was in the OLD days before Solder Wick & Weller Stations. Now everything came apart just fine, not a scratch to the pads.

In the 2nd. picture you'll see the TO-R factory owners name on the soldering side of the PCB.
At least I know now I got the spelling right

[tri-comp]

Here are a few pic's showing the LF-output amp. after a full 're-cap' and 're-sist'

This HAS to be a first; TO-R S15 with ELNA Starget cathode decoupling cap's !

I further need to check all components around the ECC83 pre-amp.
They're probably in the same sorry state as those surrounding the ECL's.
That part of the PCB also needs de-gunking but strangely enough the volume-pot and the speaker and input switches were fine. Bass, Treble and Balance pots needed a very small amt. of contact-spray to get in line.
The main-cap formed fine. About 15 min's running the receiver on 150VAC input and I turned the Variac up to 230VAC. The cap is not heating after running the receiver for about an hour, so it'll be OK. B+ voltages are exactly following the schematic so all is well.

The receiver is now working admirably receiving a 'local' FM-station about 40Km from here using just a 50cm piece of wire. Absolutely NO FM-noise, but were of course doing Mono, for lack of the MPX-decoder.
I hope to rectify that situation

The scale illumination bulbs are both OK and so is the EM84 Magic Eye.
It's not in mint condition but even w/o cleaning it has sufficient output to be of normal use. Following a cleaning of the scale and the Eye, I'm confident it will do. Otherwise I have several NOS on hand.

Then there an added bonus doing these kinds of renovations. The SMELL of the set when warm is just right and will set you back about 40~50 years, aaaaah !