Birch Manhattan 78 rpm record player
 

I picked up this Birch Manhattan 78 rpm portable record player at the flea market and the main reason I bought it was because it is in good cosmetic condition. Most of these that I find have beat up cabinets; but, this one survived in good shape. I suspect that part of the reason for that is because this record player was probably bought shortly before 33 and 45 rpm records were introduced and this one probably went in a closet when slower speed records came along.

This record player uses a rectifier tube and an output tube; so, that means it uses a high output crystal cartridge. Of course, it will need a mechanical and electronic overhaul. I'm also happy that the chassis is not used for the electrical ground.

http://i538.photobucket.com/albums/f...t/birch001.jpg

http://i538.photobucket.com/albums/f...t/birch002.jpg

http://i538.photobucket.com/albums/f...t/birch003.jpg

http://i538.photobucket.com/albums/f...t/birch004.jpg

http://i538.photobucket.com/albums/f...t/birch005.jpg

I'm old enough to remember when folks would happily have something like that as their only source of music entertainment.
Well, along with an AM tube table radio and one small TV set. Nice catch!

It seems that one side of the power line goes to ground when it's switched on. Is that not the chassis? The diagram says no, but what does the ground symbol mean?

The motor looks like either an Alliance or General Industries.

Also, no value given for the volume control but it's probably 1 megohm.

Whoa..... that isn't just a phonograph. It's an AIRPLANE !

http://videokarma.org/attachment.php...1&d=1345767501

I only took a quick look; but, it looks like the electrical ground terminates at one side of the power switch and there is a wire going to a blank pin on a tube socket where some more things are grounded.

I'll add that the entire motorboard is made of metal; so, it probably would be a good idea to not use the chassis for an electrical ground.

I wonder if that 2451 is the date, mid 1951?

It could be a date code. I figured that 78-only record players stopped being made when microgroove records came out in '48; but, I suppose some children's record players with 78-rpm only speed were made into the '50's.

Did anyone calculate the power dissipation of the heater resistor? It's 300 Ohms rated 5 Watts. It has 150 mA running through it, so that translates to 6.75 Watts continuous power dissipation at 125 Volts line, a little less at more normal voltage.

That is super nice and rare as hens teeth in that condition. Most are beat to shit.

I saw a mid-sixties Decca mono portable record player. The model designation was " Conway II ". I guess it was named after Conway Twiddy. Decca named their phonos after some of their main recording artists.
Very nice condition with instruction book and 45 spindle. Schematic in instruction book shows 25EH5 super one tube amp. BSR changer. :yes:

I think there's one of those Decca's, with a BSR mini-changer, on ebay for a BIN of $45 in non working condition. I'd like to have it; but, not for $45.

I relented and went back to the thrift and bought the Decca.
For the most part, it's in decent comdition, but one of the corners is bashed in a bit from careless handling. Naturally, it hums from bad 'lytics, but the cartridge appears to be good. The changer is a standard size BSR.
Also the oil is dried up in the motor and is seized a bit. :sigh:

I removed the cartridge, a Shure P30, that's the standard flat metal crystal type that's always bad. This cartridge is not screwed to the tonearm. Instead, the cartridge fits in the tonearm just tight enough to hold it.

So, my options are to either have the old cartridge rebuilt or use some type of velcro or double-sided tape to mount a more modern ceramic cartridge. Of course, a more modern cartridge won't have enough output for full volume and there's really not much extra room on the chassis to add a preamp stage. So, I may have the original cartridge rebuilt.

There should be a high output ceramic cartridge out there somewhere. Most of the lower end phonos out later were all single stage output amps, needing a high output cartridge.

It seems odd that they bundled the pickup wires with the AC line cord, right where hum could be picked up.