Author Topic: Magnavox portable TP 235B  (Read 1507 times)

TC Chris

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Magnavox portable TP 235B
« on: March 08, 2015, 04:48:50 PM »
I've got an old mono Magnavox portable TP235B (B = brown?),  It's designated Style P242 R4 and has a Shure PC 6 cartridge.  When I lived in Ann Arbor many years ago, I would go to an annual charity sale, a kind of large-scale garage sale, and buy a few cheap electronic items that looked like fun.  I replaced the filter caps a couple years back but the sound is too bass-heavy so I'll need to do some more cap and resistor replacement, I think.  I also need a new turntable mat.  Let's try for photos.

Chris Campbell

Consoleman

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Re: Magnavox portable TP 235B
« Reply #1 on: March 08, 2015, 06:27:23 PM »
Very cool. I like these old portables.
Mark

bastardbus

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Re: Magnavox portable TP 235B
« Reply #2 on: March 08, 2015, 08:32:37 PM »
What is the amp in it?  If it is something like P-P 6V6s or 6AQ5s that is a lotta power to be running through a small speaker.  I know RCA had this in the SHF-7 and if you cranked it up you would surely blow the speakers outta the front of the player.

BUT if you have not re-capped the unit it needs to be done.  Leaky and drifting cap values will change your frequency response up or down.  This could add to the boominess...

T

TC Chris

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Re: Magnavox portable TP 235B
« Reply #3 on: March 09, 2015, 11:06:24 PM »
I just took the old thing apart again.  It's like a Chinese puzzle, and every time I do it I have to re-learn the sequence.  It's completely counter-intuitive.   Much bad language ensues.  Well, I finally got it apart.  The amplifier uses two 35C5 output tubes, a 12AX7, and a 35W4 rectifier.  The AMP number on the amplifier chassis is not there--it just says AMP.  Well, duh.  There's a tube chart with no identifying info for the number.  There are two speakers, 6" and 4".  Changer is the RC-54. As long as I've got it apart again I'll replace the capacitors and check the resistors.  Right now I'm gluing one of the plastic feet that broke and that I had ignored since it's so hard to get the device apart.  I'm going to write up the sequence so I'll have a break the next time I have to do it after memory has failed.

Chris Campbell

bastardbus

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Re: Magnavox portable TP 235B
« Reply #4 on: March 10, 2015, 02:00:25 AM »
If I recall right Magnavox use AMP-150, AMP-148, etc as model numbers not to point out HEY THIS IS THE AMP!    ;D

I am guessing the stamp was done lightly and you can see the numbers that should follow the AMP- stamp.  Looks closer...it might be there...

T

TC Chris

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Re: Magnavox portable TP 235B
« Reply #5 on: March 11, 2015, 10:30:15 PM »
I looked extra hard on the theory that it MUST be stamped there--MODEL is very clearly stamped, and AMP, but then it's just plain blank.  No amount of staring at it improved the situation.  There's also the licensing stamp, but it was smeared and partially missing. 

I decided not to replace the amplifier's capacitors now.  First of all, when I replaced the electrolytics, the other components covered up one of the four paper caps.  There are a bunch of ceramics, but they aren't noted for failing (or sounding very good, either, but I don't have a schematic  to figure out what is what).  This little amp has no power transformer, just a 35W4 half-wave rectifier, so we're not dealing with ultra-high voltages anyway.  Maybe if I find a schematic I'll get ambitious and do some more replacing.  I'm wondering if the relatively low fidelity on playing records is from a superannuated cartridge--I may try running another music source into it and see what things sound like. 

Chris Campbell