unknown: LS-4; Sterling

I recently purchased this model to help start my collection. It is almost all knew on the inside except for the battery uptake, which is corroaded and rusted. I was wondering if anyone could suggest the best way to clean this without harming the original parts still in there. Also does anyone know if it will run without the second battery, It's the 1,5 V battery and I think it just powers the headphone jack, but didn't want to put a battery in if it was dangerous.

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The 1.5V cell is for the valve filament. It won't work without it assuming the Model page is correct.

What are you using for the other HT battery? I think could be 67V or more, does it say?

Does it have tubes (valves) like this?

I use Rustin's Rust Remover very carefully brushed on the corroded parts after using very fine grade wire wool or Dremel grinder for severe rust. Remove all loose material before using the Rust remover (it's Methanol. Ethanol, water and Phosphoric acid as the active ingredient).

Can you upload 933 pixel 3/4 view of front and straight views of the rear with cover on and off so we can see what you mean?

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Thanks, yes those very closely resemble the tubes, I bought the model on Saturday, so I haven't had much time to tinker. It does use a 67,5 V battery on the second battery, according to the intact tag inside. All the parts are in beautiful condition, if I can get second battery port cleaned and working this radio should come to life.

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I presume you need to make a 67V battery out of PP3 as I don't think they are made, which part number?

With age some capacitors go leaky with DC, the final tube needs its grid about -4.5V compared to filament and a capacitor connects from there to the preceding tube Anode with about 40V. If this capacitor is faulty then the output transformer and/or valve (tube) can be destroyed.

Read what numbers are on the tubes?

Common 67V batteries no longer made (since about 1970)

B101 (BB501, L5500, 45F40, NEDA 200, 08, 145X, 501, 1734, 4367, A467, BA51, KL1, S101, VS016, XX45, B139, Pertrix Nr. 57

Eight off PP3 is close enough to 67V

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Thanks for all your advice, I appreciate the help as I start my new hobby. I have a picture which is displayed above which shows the model. As you can see everything on the left side is shot. My theories are rust or corrosion though it also looks a little burnt, any input would be appreciated.

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Also according to the box it has 1R5, 1T4, I'm assuming the third is 1D5 (it's a little hard to read and 3S4 tubes.

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Anything with 1D5 in it seems to be much larger types, or not even suitable at all.

More likely is

DAF91 = 1S5 = ZD17 = 1B2 = 1FD9

The corrosion is mostly likely due to a battery that has leaked. It will need cleaned off and any damaged wires replaced.

On my German Philips LD452AB I had this. I'll upload pictures there.

A similar radio is likely the Ever Ready Personal B you can download its schematic. It's using the same tubes with alternate UK numbers. It has the 1.5V and the 67V combined in one box. But otherwise very similar.

The most critical part probably to replace is the capacitor between 1S5 (or what ever is 3rd tube) detector / preamp Anode  and the 3S3 audio output grid.

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I have the schematics for this model, but it's only what's on the back panel, what is the best way to upload that.

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Michael,

I have access to a oscilloscope, can I use that to check my tubes?

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Hi Josh,

No - an oscilloscope is generally not a good instrument to use for testing tubes.  For that you'll want to get a tube tester, as I mentioned in my response to another post of yours.

Regarding the schematic:  If you can temporarily remove the label with the schematic and scan it in a scanner, that is the best way to capture the image.  If that isn't possible, a good digital camera can be used to take a pretty good image of the schematic.  That's just the first step, however.  Uploading schematics to RMorg requires you to get the schematic into a very specific format.  It takes a bit of time and effort to learn the procedure, but if you are willing to give it a try, you can find excellent instructions on how to process the image and get it into the correct format here.

Tom

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A DMM is useful
1) Ohms: Test the filament. Note pin can be tarnished and it seem high when it is not. Clean pins with ink eraser or PCB cleaning block gently as any stress or bending can crack glass

2) Volts. Measure grid, Anode and Screen volts and voltage on cathode/filment series resistors. Find out if DMM is a fixed 10M or 1M impedance to load the circuit.

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According to radio shack you can still get the 67.5 volt battery, it is called a "hobby" battery. Is this at all accurate.

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I checked the Radio Shack website, and indeed they do have a 67.5 volt battery for $59 each.  If you are willing to spend that much, it should work fine.  It will last a fairly long time.  A separate battery is used for the tube filaments, and that one will need to be replaced more often (but is not so expensive).

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