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 Post subject: Magnavox Model 2ST673
PostPosted: Mar Wed 07, 2018 1:18 am 
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Joined: Mar Wed 07, 2018 12:58 am
Posts: 3
I have a Magnavox Console Stereo Model 2ST673, and it appears that one side of the speaker circuit has some bad components. I know this because by swapping the speaker wires the non-working side, now works and the side that was working does not. The components are on a small board with what looks like one capacitor resistor, and coil? (magnet wrapped with copper wire) for each speaker. The cap I can read as an 8mfd 25 vnp. The resistor however, only has a part number and the number 15 on it. A search of the part number came up nada, and as for the coil (if that's what it is) I have no idea how to proceed with that. Any help would be appreciated so that I can breathe some life into this gorgeous Maggie. Thanks in advance!

MaggieLover


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 Post subject: Re: Magnavox Model 2ST673
PostPosted: Mar Wed 07, 2018 4:03 pm 
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Joined: May Sat 06, 2006 4:03 am
Posts: 3176
Location: ZIP 23831 South of Richmond, VA 25 miles down the pike.
That would be a crossover. Very unlikely your problem. You will need to troubleshoot the side which isn't working. Most times capacitor replacement will solve the problem. If output transistors, well that's something more troublesome.

Bill J.


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 Post subject: Re: Magnavox Model 2ST673
PostPosted: Mar Thu 08, 2018 6:14 am 
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Joined: Mar Wed 07, 2018 12:58 am
Posts: 3
Thanks for the reply so; when you say crossover, exactly what are you referring to? That whole board is called a crossover? I'm in agreement that it is likely the cap. Like I said when I swapped the speaker control wires over with each other, the other side worked fine. Telling me there is nothing wrong with anything downstream from the board, and likely the cap on the side that is not working. Can you tell me what purpose the copper wrapped magnet serves. Some sort of coil? As for the resistor, how can I determine the ohms and watt rating? Especially if it's bad. I suppose I could start with replacing the caps and see if that solves the problem which it likely will. I just figured if I'm going to go through the trouble to replace the caps, why not just do it all.

Thanks


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 Post subject: Re: Magnavox Model 2ST673
PostPosted: Mar Thu 08, 2018 8:07 am 
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Joined: Jan Mon 16, 2012 4:15 pm
Posts: 4897
Location: Near Brandon, Iowa
It's very unlikely that the inductors or resistors are bad in any crossover network. However, you can assure yourself of this by ohming across them (using an ohmmeter): each inductor will have a very low resistance (a few ohms or less). You can repeat this for the resistors: ohm across each resistor from the "good" side and note the resistance- the "bad" side resistors should be very close in value to the readings taken.

The electrolytic caps are another matter; one or more may have "gone bad" just sitting around due to internal chemical decomposition. These caps can't be accurately tested without special equipment, but that's OK- just assume that if they aren't bad now, they eventually will be, replace them all, and move on.

Be sure to use "non polarized" electrolytics, not standard caps, since they will be passing audio AC, not being used to smooth pulsating DC.


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 Post subject: Re: Magnavox Model 2ST673
PostPosted: Mar Fri 09, 2018 5:22 pm 
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Joined: Mar Wed 07, 2018 12:58 am
Posts: 3
Thanks for the insight. It did not occur to me to ohm the good side to determine the ohms on the resistors and inductors. Good grief, sometimes I'm just a rock. I have a fluke multimeter that reads mfds so no problems there. Yes, I noted that the caps are non-polarized so I'll be sure to use the right ones, but I noticed that 8uf 25v is not very common. I was able to find some 8uf 100v and if I remember my schooling on caps, voltage the same or greater is fine. Thanks for helping the light bulb come on with this project. My brother is moving in to his first house with his new bride at the end of the month, and this was the only thing holding me up from finishing the work on a spectacular Maggie. The cabinet looks brand new. It just needed some tlc on the inside. Thanks so much again for your help. I called several shops and they either didn't even want to look at it, or they wanted a kings ransom for ten dollars worth of parts and 20 minutes of soldering, lol

Thanks
Daniel


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