Restoring my Philips Magnetband Schreiber.

[mrmagnetophon]

I am working on my Philips Magnetband Schreiber machines.
Problem is I can't manage to get the reel tables off.
Anyone out there have a Turnbuckle style machines and removDe the tables from it?
Thank you,
Chris

[david winter]

Hi Chris,

It depends on how they are put together. On my HTS for example, the two tape locks have a large screw (around 1cm large on the top part) attaching them to the tables. They are "severely" screwed by design: the end of the axis has two cuts forming a +. Thus, the end of the axis has four parts which can be spread against the table hole to lock it. The screw starts with a constant thread diameter (like 3mm) and finishes with a conical shape which, as far as you screw, will spread the four parts of the axis against the hole of the tables, thus locking them. On my HTS I really had to lock the motor using a screw driver toward the bottom fly wheel in order to unscrew using the appropriate screw driver. Don't think about using anything smaller than the screw, you really need full "force" to unscrew.
I think this design was used on almost every AEG Magnetophon model.

[mrmagnetophon]

Hi David,
I figured them out last night after my post.
My tables are held on exactly the same way your magnetophon HTS holds its tables.

The picture is my current progress on it.

-Chris

[david winter]

Beware of the material used on that bedplate. If it's zamac, it will definitely break soon or later somewhere else. This material, when not properly made, does not age well and becomes too brittle against weight. You should dismantle everyting to separate the bedplate itself, and ask a professional to mould one for you, and use the shape of the other hole to remake the broken one. Quite some work, but the only reliable solution in my opinion.

[mrmagnetophon]

I'm using aluminum weld and building it up. It's the strongest type for casting, it's from a company called Devcon.
It's for cast aluminum which is what mine are made of.

Chris

[mrmagnetophon]

Now the hard part comes, one of the motors has a bent shaft and the table moves up and down as it rotates.
Does anyone know how to rebuild the motor and unbend the shaft without snapping and denting it?

-Chris

[mrmagnetophon]

I need some serious help with this, the shaft is nearly straight, but I need someone who could help me get it exactly straight.
Is there a service out there to do this?
-Chris

[mrmagnetophon]

Now, I have this transport finished but need to run a test on it, I would like to power it up via my variac. Is it safe to do this with the motors? I think the caps should be reformed, there is a rather large bank of them.
-Chris

[ben]

Should be ok via a variac, just be ready to yank the plug if any smoke or noise comes.

[mrmagnetophon]

So using 75 watt current limiter, then variac, then 120volt to 220 volt step up transformer (provides isolation too) all plugged into a RCD(GFI)
-Chris

[mrmagnetophon]

With 75 watts I can only get 40 volts out of my variac, the load is so much the bulb is glowing full on.
-Chris

[Station X]

The limiter needs to be in the secondary circuit of the step up transformer. The current there will be half that in the primary.

[Station X]

The limiter will need to be 220V, or you could use two 110V types in series.

[mrmagnetophon]

The machine runs, i wasn't using the limiter with the machine, i was limiting with 500 watts the amount of power going to the variac, and it worked quite well in that setup.
-Chris

[Station X]

So you've changed the limiter from 75W to 500W?

[mrmagnetophon]

75 to 150, to 500 watts.
-Chris

[mrmagnetophon]

Now, for powering up the Preamps, i have inspected them for any loose connections and mended the faults.
How should i power these up, via variac with 75 watt limit again?
With 75 watts i can achieve 35 volts, 150 watts around 55 volts, and 500 watts around 100 volts, so should i power them up that way, without the valves in place first?
Or should i not take the risk and put the valves in.
What of the tape heads, don't they have to be plugged in so it doesn't damage the amplifier? (don't valve amps need the load?)
-Chris

[Station X]

I'm not familiar with the circuit for these devices, but generally, unless the rectifier is plugged in the smoothers won't get reformed. By all means progressively increase the wattage of the limiters.

I assume the voltages you're quoting are for the output of the variac which is the same point as the input to the step up transformer? It's the voltage at the output from the step up transformer that matters though. I still think the limiters should be in the 220V side. Their brightness or lack of it will then give you an idea as to what's going on.