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Re: schema's van philips versterkers

Geschreven door Thierry Magis om 11. Jan 2002 21:52:44:

In reactie op: schema's van philips versterkers geschreven door Martin Loots om 10. Jan 2002 20:42:42:

Hello,

I'm also owner of two 2844 amps. Photographs are on my website... those
are very destroyed, but works... I'm gonna rebuild the two final stages
with other preamp on a new frame, stereo block. A hi-fi project?
Certainly not!! But it remains me the sound of my first amp, a Geloso
with 807 tubes. I like this (so special) sound...
The two power supply transformers are out of use, leakages problems between
primary and ground. The 10mA differential switch (protects AC plugs of
my lab) cut off when using amps... I must put an insulation transformer!
I'm gonna re-wind a 600VA industrial transformer to have the voltages i
need for my stereo project... A lot of work for the next months!!
When done, I put photographs on my site. Now, the two are totally
dismantled!

I own the schematics of the 2844, but perhaps have you already receive
it from other Forum-users? If no, tell me. I'll send you, no problem.

You can connect 8 ohm speakers with the output voltage selector on 20V
position. In this case power is about 50W. Do not remove the "neon" tube
connected at secondary winding of the output transformer (under the
frame)! It protects output tubes if no loudspeaker is connected at the
amp. Perhaps, if broken, use varistors? I don't know...
Be also careful at smoothing capacitors: if there are in shortcut, the
AX50 valve will be quickly destroyed... First, blue flashes inside, and
after... Bang! And there are expensive! I've seen it into EL6420 amps...
Nota: in normal use, there is a little blue glow inside this kind of
gas-filled tubes. It's beautiful, enjoy it...
I suggest you to put on your amp(for the first time) by means of a
variac, increasing slowly the supply voltage. Leave a couple of hours on
with a very low (40-50V) voltage, in order to dry up the transformers
and the wiring.

Those amps are from 1948-50... If you need other data, ask me. Before
dismantling, I've made a few drawings and measures.

I don't have any info about the 284503 amp.

Friendly greetings,
Thierry







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