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This is the Telefunken Jubilate 1651 L
it belongs to a friend of mine
and he asked me to look at it
He played this radio for years
it was his kitchen radio
But now it has a bad hum
it used to be good but now it hums
Lets see what we can find out
I turned it on to have a listen
Yes, that hums
I just turned this one on because I know the history of this radio
I know the owner has used this for years and only recently turned it off
If you do not know the history of the radio, you should never just turn it on like this
even with the volume down all the way, you still hear the hum
If I turn the volume up, the hum does not change much
Check this out
nice
this is the original schematic
I also downloaded it from the internet
But this is great
here is a small compartment for the schematic
Lets take out the chassis and see what we can find out
Ok, it seems I have a new challenge. The tuner cord broke!
I am not touching this any further so I can remember how the cord goes on.
we need to replace the cord later
I did not count on that but it needs to be done now
I bought this new cord on line. So lets do this
well, this took me an hour but I did it
Nice and tight
It works as it should again.
This is the ripple on the main filter capacitor
It is a 50 Hertz ripple, because this is a single rectifier
I have the scope on 2 millisecond per division
10 boxes means 20 milliseconds, makes 50 Hz
the hight of the ripple is almost 50 volts
The scope is on 1 volt per division but the probe has a 10 to 1 reduction
10 20 30 40, almost 50 volts
So this is before I change the filter capacitors
So, now I replaced those capacitors, three of them in total
This was a 3 in 1 unit, containing 3 capacitors
The ripple looks a lot better now
The scope is set on 5 volt per division, no reduction on the probe.
15 volt ripple
Remember it was 50 volts before. That is an improvement!
So far I replaced this 63 uF
that is the main filter cap
From that point, power goes directly to the main amplifier valve
and this capacitor, 50 uF
and this one, 16 uF
Also, this capacitor on the main amplifier valve
and this small one
Next I will replace these small caps in the power supply
And then I will test the radio again.
I am putting it back together. It needs to go in from the front.
But the tuner indicator, needs to go trough this slot
to the front of the scale
and lets see if it works
OK, another issue
The chassis is back in the box and this side looks fine
The shaft lines up with the hole,
But not on this side.
So this *** will not fit like this.
the issue is with these rubber rings that go between the bottom and the chassis
the rings are flat and lost all damping.
So when I tighten the screws, I pull the chassis all the way to the bottom.
So I need to put some rubber rings between there.
That is much better
The first *** goes on with pressure
and the second *** screws on to the shaft
Well. the first test was a great success..
Because it did not work at all
These two wires broke. They should connect to the on/off switch
She isolation has gone hard and dry. So the wires lost all flexibility
So the wires broke when I manoeuvred the transformer into place
I will replace the wires.
One side is connected.
this is shrink tube
They need to connect to these two points
lets try again