• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

First time with 1959 tube amp. Need help

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I have this Magnavox console that has a turntable and amplifier in it and that’s it when I turn the volume on or the unit on all I hear is crackling and popping sound I’m going to attach some photos
So some people could give me some advice on what to do
I would like to get the TT working but mostly get the amp working right. The tubes all glow
IMG_2001.JPG IMG_2007.JPG IMG_2004.JPG IMG_1994.JPG IMG_1995.JPG IMG_2008.JPG IMG_1993.JPG
 
Hopefully, you did no damage, when you applied power. It is a matter of routine to replace all electrolytic capacitors in units that old, before attempting power on.

As it stands, that amp violates forum rules. Please observe the absence of a power transformer, which is an absolute no/no. That can be corrected easily enough. Buy a Triad N-68X isolation transformer, along with the other parts needed for refurbishment.

You are dealing with a very bottom of the line unit. The TT and associated piezoelectric cartridge will damage LPs. :mad: No power trafo and series heater string = cheap as cheap can be. Some "maggotbox" console amps are OK. That specimen is a POS, sorry.

Hopefully, some member will point us at the schematic. In the meantime, I strongly suspect the presence of a ticking toxic time bomb selenium rectifier.
 
Go to VintageHiFi.net - Index, lots of Magnavox service manuals there for console components.

You'll have to join to get access to downloads, yours looks similar to one used in a portable phono player. The amplifier chassis is numbered, and you'll need the complete number to find the info you need.

You'll find plenty of Magnavox console knowledge there as well.

BTW, I would heed Eli's advice on the isolation transformer.
 
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When I got to the persons home to pick it up they had already plugged it in and Lowery it up. So any damage that would or will happen is done. I’ll just pull it out and go over all the parts and replace them. I know it’s only one watt and I have speakers that will work very well with that
Thanks for the info
 

PRR

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To echo what Eli said:

This is a Hot Chassis amplifier. One side of the wall-power connects TO the circuit.

It was sold in an enclosed console with insulated pickup leads, permanently wired speakers, and plastic knobs. In that form it was "reasonably safe" by 1959 standards. It would not be allowed today.

Your plan to make input and speaker connections (and chassis?) user-touchable makes it VERY dangerous!

Yes, we all used such things back in the day and many of us lived. But we got many shocks, and some people were killed.

Get the isolation transformer FIRST.
 
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It appears to be a Magnavox 800200 chassis, described in Sams Photofacts Set 508 folder 13, date 11-60. I don't have direct experience on this chassis but I have restored a few similar ones. This is not a Hi-Fi chassis and will never sound good, but it may be restored as-is for fun, or rebuilt with a different schematic with a slightly better sound. Do this if you are confortable to work with the high voltages inside - they are dangerous. Either way you must add the insulation transformer and a fuse on the mains before any further test. This will reduce the shock and fire hazards, and also will add some protection to the expensive components. I suspect that the crackling is mostly due to oxidation and thin wiskers inside the potentiometers. Try with spray contact cleaner first. The paper C5 and C10 coupling capacitors must be replaced. The M1 diode must be replaced with a bridge rectifier - change the main supply connections accordingly. The multisection main filter capacitor C1 must be replaced, but to retain the vintage look of the amplifier I suggest to keep it in place and simply disconnect from the circuit. Add a terminal strip to anchor 3 modern capacitors with increased value such as 330uF, 120uF and 47uF. There will still be a residual hum due to the cheap parts and construction. The piezo turntable is a nostalgic item only, will sound bad and damage discs.
 

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Please correct me if what follows is in error.

The documentation "pcan" so kindly provided indicates that there are 2 versions of the O/P trafo. The version with a separate NFB winding is preferable. The OP needs to determine which "iron" version is present.

My guess about selenium was wrong. The setup is recent enough to use a silicon diode.

The series heater string draws 150 mA. A Triad N-68X isolation trafo is good for 435 mA. So, 285 mA. are available to energize the B+ PSU. Half of that 285 mA. will be available as DC, which is quite ample.

Bridge rectify the B+, for both lower hum and no "standing" DC on the N-68X.

R21 is a peak surge limiter and can be dropped, if the essential N-68X is added.

C13 and C14 should be rated for connection to an AC power main and the specified working voltage can't be too "tall".
 
Well tell you what. If anyone wants the amp its your for free. Just pay shipping. Let me know. I know it’s out of my tech knowledge so why risk blowing it apart

Carl, don't give up so easily. You can acquire the knowledge you currently lack and plenty of help is available from the members. Whether it was decades ago or yesterday, every last 1 of us started out as a "nube".

Check for which version of O/P "iron" is present in your unit. The version with a separate NFB winding is definitely worth your time and the other version may not be totally hopeless.
 
You have the separate NFB winding O/P trafo version. :up: That gives you something to work with, even if you threw everything else away.

Get those tubes properly tested. Just because the heaters are intact doesn't mean they are up to snuff. Tubes are a consumable item and wear out, even if the heaters don't go open. Replacement tubes should not be problematic. ;) 12AX7s are currently being produced. RES shows the 50EH5 at $4 each.

There is no law requiring the retention of the OEM schematic. FWIW, I'd ditch the (IMO) wretched tone control. I'd also go to a simple 2 pot., L/R, volume control setup.

I'd take advantage of the chassis opening occupied by the multi-section cap. and put a clamp mounted modern part there.

Oh yeah, black carbonized plate tubes are highly desirable. I hope those specimens test strong.
 
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Guys, I have some ideas for improving the series heater string. Feel free to critique my thinking. I've taken symmetry and higher average AC mains voltage into account. Of course, all of this presumes the presence of a N-68X isolation trafo.

Connect each leg of the N-68X's O/P to a 2 W./27 Ω resistor. Connect the resistors to the 50EH5 heaters. Connect the 50EH5 heaters to the 12AX7 heater (pins 4/5). Connect pin 9 of the 'X7 (heater CT) to ground via an AC line rated ceramic cap. whose WVDC is at least 2 KV. This part must survive, regardless of any mishap.
 
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