Firestone 13G3 Television

[rogerdup]

Hello everybody,
I just receive my TV Firestone from the ETF auction. As usual, it has certainly had better times. A lot of restoration to do on it. Does somebody have the schematic of it? It looks very similar to the Tele-tone tv149. Same chassis and tubes.
Thank you ! Merci..
Roger

[Jac]

Roger,

I have the schematic of the Teletone 149.
Let me know your email address (PM or send me an email) and I'll send it to you.

Jac

addition:

Here: http://www.earlytelevision.org/tv_sc...iagrams_t.html you can find some data as well.
Hope this helps.

[dseymo1]

That is surely the tyremakers' logo. What's their connection with consumer electronics?

[FERNSEH]

Possibly a Philco clone?

DFWB.

[Argus25]

The set looks very similar to the Teletone. Looks like a 7JP4 crt, and its associated RF power supply, probably with a 6V6 and 1B3. I have heard that the EHT of these drops over time due to moisture absorption in the tuned winding, but mine did not do this, I replaced the tuning capacitor though with a mil spec dipped silver mica type.

Possibly, this set also uses the line scan deflection generator designed by Faudell & White with two transformers and 1/2 a 6SN7, it might not be obvious from the schematic due to the way it is drawn, this circuit is discussed on page 4 here in a set with a 7JP4:

http://worldphaco.com/uploads/Admiral_TV..pdf

Normally , in these sorts of sets, the high voltage required to run the vertical scan output valve, often a 6SL7, is acquired in the lower end of the EHT & focus chain. There were quite a few innovations in these types of sets.

Note that the missing 3 rear controls on the right back of the chassis, would have originally have been mounted on an insulating panel behind and have had plastic shafts or plastic knobs as they are close to EHT potential.

Sometimes, also the insulating material in the 7JP4 socket degrades and the socket gives problems. Easy to get new sockets now on ebay. When I restored my Admiral set there was no ebay I couldn't find a socket in NZ at the time, I had to machine a new socket out of nylon using octal socket pins retained by fiberglass pcb material, it was quite an extravaganza.


Hugo.

[usradcoll1]

Originally Posted by dseymo1

That is surely the tyremakers' logo. What's their connection with consumer electronics?

Their tyre and auto repair stores had a showroom where they sold TV's Radios and other home appliances, branded with their trademark.
They did that for many years, from the mid-30's.
They didn't build any of those products themselves, but they were contracted out to the larger manufacturers.

[rogerdup]

Hello Gentlemen,
I recently bought a Firestone 13G3 tv from the ETF may auction. It arrived yesterday, and I immediately noticed (sadly)that it has been "visited" for (a poor)repair at some time. The high voltage box was floating unscrewed and so the plate supporting the back potentiometers.. Hopefully the line transfo is not open, and I could begin restoring that part.
Unfortunately the front knobs are all missing..
Steve kindly check the 7JP4 for me before sending the set. The crt survived the trip..
If somebody has experience on restoring this set comments will be welcome!
Take care !
Roger

[usradcoll1]

Of all the early sets I worked on through the years, I never had any exposure to that particular set, either the Firestone or the Tele-Tone.
Teletone is the manufacturer of the set.
The schematics for both sets are available from the ETF website. The Tele-Tone model is TV149.

[rogerdup]

I got the schematic from the ETF data base. Steve told me He is going to look for the missing knobs as they are common to many sets there..
Anyway, I will be glad to share my experience in restoring that set. A real challenge for now.. about 30 wax capacitors to replace.
Roger

[Argus25]

Roger,

The deflection circuitry is quite different in the Teletone 149 than in my Admiral set with the same CRT. The Teletone (and your set) has very straightforward oscillators and para-phase amplifiers, so it should be easy to get the deflection working well.

Also unlike the Admiral, the Teletone is a hot chassis set, so best to run it from an isolating transformer and ground its chassis before attaching test instruments to it, but don't forget the isolating transformer defeats your dwelling's breaker box RCD.

Hugo.

[rogerdup]

Thanks for your replies everybody!
For Hugo, I always use an isolating transformer for apparatus with hot chassis as it is the case for my recently restored LV30 PYE.
In fact, I plan to use the same toroidal transformer for this one and put an inverter at the output, for 235v or 115 volts depending on the set connected.
Roger

[rogerdup]

Here photo of the cabling before I put a hand on it (somebody did it before but badly ). See on the control pot plate, the two holders I put to fix it again on the rear chassis. I was wrong in my measurement, so the axis of the pot are too far at the right. I will correct that.
Hopefully, the chassis had two holes already placed for me to fix the holders..
When I receive the TV, I first thought that all the back pots were missing ! Too bad, until I found their plate 'floating underneath..

[Argus25]

Roger,

It is great that it looks all original with the wax paper caps (waxies), and you know the CRT is good so there is no logic in trying to power it initially for a CRT test. (I tend never to power a vintage set with its original waxies & electros anyway, I wait until they are attended to)

My advice is to rebuild every waxy initially. This is because they will all be leaky to some extent and play havoc with the circuitry, especially the coupling cap into the grid of the audio driver (with a 10M grid resistor) and the deflection plate coupling caps into the high load resistors.

Heat the waxies in an oven until the wax just melts, it makes it easier to withdraw the contents from the cardboard tubes. Then wipe off all the wax while its hot and melted.

When you put the poly caps inside (with the same value & often higher voltage rating) wrap tape around each one near its center to make them a firm push fit into the tube. Then on alternate days pour polyester resin into each end (Photo attached). This way the resin doesn't leak past and out the other end. Get a cardboard box and push in small holes for the leads to keep the capacitors stable while the resin sets.

Also, you will find when the hot wax is wiped off each capacitor's tube, the surface will later accept varnish (I use marine spar varnish). This way when it drys, it looks good, but dust does not stick to it unlike the wax.So I do this rather than re-waxing them (Photo of some caps under the chassis of a set being restored attached, the varnish is why the capacitors look a tad shinier than usual).


Mostly I replace the resistors with 2W MF types, but you could check what is there and replace those out of spec. In the RF circuitry (IF's etc) largely its best to use silver mica types. Try to avoid replacing any of the small ceramic capacitors ,such as dogbone caps, in the tuner section, they are mostly special types & usually they are ok.

Replace all the electrolytics with new manufacture ones, the types used in this set, twist lock I think, are available from AES (USA). Then when all that work is done it will be ready to power up & align.

Have fun !

[rogerdup]

Hello everybody,
I need some advice on my Firestone TV set. I replaced all capacitors and faulty resistors. All voltages are corrects on the tubes but I think the high voltage is too low. I put the picture with the raster I get on the crt. No focus working but difficult to see because the picture is too small and concentrated. The height pot. doesn't work despite the voltages are corrects.
The centering controls H and V are functioning as well as the brightness.
I have no probe to check the full high voltage. But when additioning across the various 2,2meg resistors chain from the end up to the rectifier filter, I get 3518 volts. That appear to be too low. On the schematic is it indicated 5500 volts. Perhaps the 1B3GT is faulty? I hope that it is not the crt bad..

[FERNSEH]

Hi Roger, Does your Firestone TV employ an RF EHT system? That's how it is in my 7" CRT Admiral and Motorola TVs which are of a similar design.

DFWB.

[rogerdup]

Hi David,
Yes the Firestone use that RF system. Today, I replaced all components in this compartment resistors and cap. It looks like I got correct HV (not quite sure). Brightness control is good as all the centering H and V controls. I don't understand why I get this wide horizontal band and a cannot expand it in the vertical sense.
Of course, I check the vertical stage and all the voltages are corrects on the 12sn7 and 6sl7 tubes. For now, I don't know what to do.

[peter_scott]

I hate to suggest it but vertical deflection plates shorted together? Sounds unlikely, I know, so hopefully not that .

Peter

[FERNSEH]

It's likely that Roger's Firestone 13G3 is electrically similar to the Teletone TV149.
The EHT supply is positive with respect to chassis which means that the deflector plates are close to full EHT potential.
The attachment shows the THT generator and the picture shift circuits.

DFWB.

[rogerdup]

Hi Peter and David,
Not good news. When disconnecting the wires to the vertical deflection plates, the same raster appear instead having a nice horizontal line. Have checked with the ohmeter and found no short between the V plates. I am sure there is something wrong inside the crt. it seems not having survived well the trip from USA to France..Too bad,I'm sad..
Roger

[buggies]

In post #4 you said focus is not working. Could your horizontal line not be just a single line but well out of focus?
I see lots of 2.2M resistors to check if so...