{"id":335,"date":"2014-09-25T16:49:29","date_gmt":"2014-09-25T22:49:29","guid":{"rendered":"https:\/\/txsound.com\/blog\/?p=335"},"modified":"2014-11-15T19:25:22","modified_gmt":"2014-11-16T01:25:22","slug":"16-transcription-turntable-restoration-prestopickering","status":"publish","type":"post","link":"https:\/\/txsound.com\/blog\/16-transcription-turntable-restoration-prestopickering\/","title":{"rendered":"Presto T-68 16″ Transcription Turntable Restoration"},"content":{"rendered":"

\u00a0About 3 years ago, I saved\u00a0the pieces of this\u00a016″ transcription player & cabinet from a dusty internment.<\/h1>\n
\"The<\/a>

The 16″ platter, stripped, cleaned and ready for re-felting<\/p><\/div>\n

\"presto<\/a>

cabinet as found<\/p><\/div>\n

\"16"<\/a>

Project in pieces before restoration<\/p><\/div>\n

\"Presto<\/a>

Presto top plate with idlers removed.<\/p><\/div>\n

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\"busy<\/a>

busy day at txsound<\/p><\/div>\n

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(Click the thumbnails above for a larger “before” view). , \u00a0This Presto T-68 Transcription Turntable with Pickering 190D Tonearms<\/strong>\u00a0was used at an Air Force base<\/strong> in Fort Worth. Found inside the cabinet was a\u00a016″ acetate record, with the lacquer falling off the aluminum substrate. The disc labels indicated the acetate had various\u00a0Reveille bugle\u00a0calls, marching\u00a0and teletype\u00a0sound effects. The military base\u00a0had its own radio station, or perhaps they used these effects over the public address system for PT!<\/p>\n

\"acetate<\/a>

The acetate found in the cabinet.<\/p><\/div>\n

\"acetate<\/a>

Old Acetate disc labels from in bottom of turntable cabinet<\/p><\/div>\n

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Upon complete disassembly, work started\u00a0on the motor\u00a0&\u00a0start capacitor, with a gentle variac power-up to check for shorts in the windings, or a bad capacitor. \u00a0It’s an\u00a0an Ashland Hysteresis Synchronous<\/strong> motor of 1\/100 horsepower. after a complete overhaul, the motor ran continuously for a couple of days to observe operating temperature, let the bearings settle in, \u00a0and discover any latent noise or vibration issues. \u00a0New motor mounts were installed as well.<\/p>\n

\"Ashland<\/a>

Motor removed for teardown, old lubricant removal, reassemble and re-lubricate. Slow power up with variac.<\/p><\/div>\n

Three rubber idler wheels transfer the motor’s energy to the platter at 78, 45 or 33 1\/3rpm, depending on which plane\u00a0of the\u00a0spinning motor shaft is engaged (see photo below).<\/p>\n

\"presto<\/a>

Transport with Terry’s new idler wheels installed.<\/p><\/div>\n

The existing idler wheels (above) were hardened and crumbling. The brass hubs were re-surfaced by Terry’s Rubber Rollers<\/strong><\/a>. The motor and idlers get the platter up to speed in about 1\/4 of a platter rotation<\/strong>. Pretty quick, which was important for the operators\u00a0ability to tightly cue<\/strong> the audio tracks.\u00a0\u00a0<\/strong><\/p>\n

The tonearms are type Pickering 190D<\/strong>, originally wired for mono. \u00a0BTW, Mr. Pickering<\/strong><\/a> holds the original patent on the moving magnetic phono cartridge!<\/strong>\u00a0 These tonearms were heralded for extremely low vertical to lateral moments of intertia<\/strong>, and minimal vertical mass. \u00a0Because of the big swing<\/strong> of a long tonearm, the tracking error is less than 2.5 degrees.<\/p>\n

\"pickering<\/a>

Pickering 190D tonearms, mono wiring &\u00a0magnetic arm rest.<\/p><\/div>\n

\"pickering<\/a>

The Pickering 190D (click\/enlarge)<\/p><\/div>\n

The tonearm’s\u00a0extremely low head-mass\u00a0 can deftly\u00a0<\/strong>handle\u00a0a\u00a0warped record very nicely. \u00a0The rear tonearm is intended for a 78 rpm<\/strong> cartridge\/stylus. \u00a0The front\u00a0arm is for a microgroove<\/strong> cartridge. \u00a0A top-\u00a0mounted\u00a0rotary switch<\/strong>\u00a0selects which arm is fed to the pre-amp.\u00a0 Before restoration, the signal passed through a Pickering model 132E\u00a0passive equalizer<\/strong> before being pre-amplified by a mono model 230H\u00a0<\/strong>Pickering tube preamp.<\/p>\n

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\"pickering<\/a>

Ad for the original preamp. (click\/enlarge)<\/p><\/div>\n

\"pickering<\/a>

Pickering passive cartridge equalizer.<\/p><\/div>\n

\"presto<\/a>

78- LP tonearm selector<\/p><\/div>\n

\"presto<\/a>

Power switch with a\u00a0hand-made\u00a0plastic mount-plate<\/p><\/div>\n

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Both \u00a0tonearms get re-wired\u00a0for stereo, no small task with hair-thin oxygenated tonearm wire<\/strong>.\u00a0The rotary switch was replaced to enable stereo switching between tonearms. The mono\u00a0Pickering equalizer<\/strong>\u00a0was removed(which will fetch about $100 on ebay) and the resulting empty hole\u00a0with a bat-handle<\/strong> power switch<\/strong> for the motor, a more practical use of the space. \u00a0 The turntable previously was powered-up when the speed selector was enabled. A\u00a0\u00a0black switch mounting plate<\/strong>\u00a0was created to match the other label plates on the\u00a0plinth.<\/p>\n

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A new\u00a0stereo tube preamplifer is now required inside the cabinet, so a<\/a><\/span> Little Bear Stereo Valve Preamp<\/a>\u00a0<\/strong>was shipped in from Hong Kong. \u00a0(below)<\/p>\n

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\"Little<\/p>\n

The popular Little Bear stereo tube pre-amp from Hong Kong. \u00a0Very nicely designed!<\/p>\n

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\"presto<\/a>

RCA patchbay on rear panel.<\/p><\/div>\n

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To allow the user to select the internal or an external preamp,<\/strong>\u00a0An RCA\u00a0patch bay <\/strong>\u00a0is added on the rear cabinet panel. Also shown is the ground lift switch, power connector and chassis ground terminal.<\/p>\n

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\"pickering<\/a>

Assembly and wiring of tonearms. Individual Channel signal\/ground wires eventually made into twisted pairs for hum suppression.<\/p><\/div>\n

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The cabinet<\/strong> was a challenge, especially the plinth. The 3\/4″\u00a0plywood base\u00a0surface\u00a0was\u00a0covered in a thick, ancient, funky, dull- green laminate. The surrounding metal was painted industrial\u00a0grey with a good deal of chipping & corrosion. The metal surrounding the laminate was refinished in hammer-tone grey . \u00a0<\/strong>The funky-green clashed with the other colors, so the wood top was refinished in\u00a0<\/strong>solid satin<\/strong>\u00a0black<\/strong>. \u00a0The platter had plenty-enough green in it after the re-felting,\u00a0<\/strong>which is done with felt, spray adhesive, and careful lathe-style trimming with a razor.\u00a0The plinth’s vertical edges were stripped down to the bare metal<\/strong> and polished to a bright shine, almost chrome. The polishing process was observed\u00a0in a motorcycle restoration shop<\/strong>, and has been sucessfully used\u00a0here\u00a0on lots of projects. \u00a0(Enlargable thumbnails below)<\/p>\n

\"2014-07-03_13-08-52_159\"<\/a><\/p>\n

\"2014-07-04_13-36-10_96\"<\/a> \"2014-07-04_13-36-41_12\"<\/a> \"2014-07-04_13-41-56_855\"<\/a> \"2014-07-03_12-46-10_159\"<\/a> \"2014-07-17_21-07-16_881\"<\/a><\/p>\n

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\"cabinet7\"<\/a> \"cabinet8\"<\/a> \"cabinet9\"<\/a><\/p>\n

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\"presto24bh\"<\/a>

Collection of 16″ transcription records are stored inside the cabinet. Those suckers are heavy.<\/p><\/div>\n

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The Presto- DuKane cabinet, preamp and associated wiring came together as pictured. The tonearms get fitted \u00a0with \u00a0Shure M91ED cartridges, the rear cartridge with a 78rpm stylus. The unit is extremely well grounded, including the motor shell, and cabinet ground is independent of signal ground. Wether using the internal or an external preamp<\/strong>,\u00a0there are no hum issues. As a precaution, a ground lift switch was added to the rear panel. \u00a0Power lines are capacitor bypassed\u00a0at the entry points and at the power switch. \u00a0(below pics are enlargeable)
\n\"P1030664h\"<\/a> \"presto4h\"<\/a> \"presto17H\"<\/a> \"presto19h\"<\/a> \"presto20h\"<\/a><\/p>\n

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The table adds a special allure to\u00a0vinyl activities. A heretofore ignored \u00a0pile of 78\u00a0rpm records\u00a0have provided some very interesting listening! \u00a0It’s the record industry in its infancy. Various recording techniques can be discerned, qualities,\u00a0different\u00a0equipment eras, groove depth variances, etc can all be heard.<\/p>\n

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\"presto<\/a><\/p>\n

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There’s a million cheap 78s, lps and 45s<\/strong>\u00a0still floating around out there, in thrift stores, estate sales, and flea markets. \u00a0Many found 78s \u00a0have\u00a0never been played<\/strong>, and those make for\u00a0remarkable\u00a0listening.\u00a0Back in the day, the commonly used steel needles would destroy a 78 after 20 plays.\u00a0Many\u00a0outstanding\u00a0shellac records are still out there, They are\u00a0remarkable examples of\u00a0recording skills and standards through the era.<\/p>\n

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\"presto<\/a> \"pickering<\/a><\/p>\n

The 60’s produced some remarkably well mastered LP’s as well. \u00a0I particularly like the Command 35mm<\/strong>\u00a0series, which are still in plentiful supply\u00a0at the above mentioned sources. See you at the Goodwill<\/strong>!<\/p>\n

MORE ABOUT TRANSCRIPTION TURNTABLES….<\/h1>\n

In the US, professional\u00a0transcription\u00a0turntables were primarily made by RCA, Gates, Fairchild, Presto, <\/strong>and McCurdy<\/strong> in Canada.\u00a0They also required a separately purchased \u00a0“transcription” tonearm, about 3″ longer than a standard tonearm. The extra “swing room” these arms create also reduce stylus tracking error, especially on 7″-12″ records.<\/p>\n

I’d been searching\u00a0<\/em>for a 16″ transcription turntable for many years. These tables are a unique and dissappearing part of broadcasting history.\u00a0\u00a0Unlike a 12″ platter, they can\u00a0\u00a0accommodate vintage 16″ transcription vinyl records<\/strong>, popular in the radio industry<\/strong> through the 50’s, 60’s, and 70’s. Amazingly, for their size, these records only contain about 15 minutes of program material per side!\u00a0 That’s because the grooves are spaced far apart. The discs\u00a0typically cannot fit on a standard 12″ turntable platter without hitting the tonearm base. The US Armed Forces and Veterans Administration used these records extensively to distribute their radio programs. The records also were popular for distributing library music, jingles and commercials.<\/h5>\n
\"70-D_001\"<\/a>

RCA 70 transcription turntable. Thousands of these used to reside US radio and TV stations.<\/p><\/div>\n

\"Beardsley.press\"<\/a>

A 16 inch record press<\/p><\/div>\n

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\"Gates<\/a>

Earliest version of the Gates CB-500 Transcription turntable.<\/p><\/div>\n

The\u00a0big turntables\u00a0often came mounted on a cabinet, the size of a dishwasher. The earliest tables\u00a0used this space for a complex, gear driven, flywheel-stabilized motor, These motors provided the necessary torque required for slip-cueing records and fast startup rotation. \u00a0Eventually, the torque came from smaller, hysteresis sync motors with\u00a0idler\/puck drives. \u00a0By the early 60’s these became\u00a0the standard turntable design for radio\/tv stations. In the early 80’s,\u00a0Technics Corp. introduced\u00a0powerful, direct drive, crystal controlled motors. They were adopted quickly by radio stations and used\u00a0until CD’s replaced vinyl entirely…<\/h2>\n
\n
\"rcaTTunderside\"<\/a><\/dt>\n
Huge flywheel motor affair that is under the platter of the early RCA transcription turntables.<\/dd>\n<\/dl>\n
\"Maybe<\/a>

Maybe there’s still some of these hiding out there, somewhere?<\/p><\/div>\n

<\/h2>\n
\"RCA<\/a>

A more recent underside of a transcription turntable, the RCA BQ-2B. I do not recommend placing a tube amp in the cabinet!<\/p><\/div>\n

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If you’ve got room in your listening area for one of these behemoths, you’ll find them few and far between, and priced outrageously. And that’s before the freight shipping required to send to your place. \u00a0The most current and popular transcription unit is the Gates CB-500 , \u00a0<\/strong>and the cabinet (if you can find it).<\/p>\n

\"The<\/a>

The Gates CB-500 and cabinet. The Holy Grail? The front panel controls are a sloppy, abortive add-on.<\/p><\/div>\n

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\"gray-research-model-206-12-1<\/a>

Grey Research Viscous Damped Tonearm with installation template.<\/p><\/div>\n

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\u00a0Personal Story Time:<\/strong> In my college days<\/strong> of Radio and Television (circa 1980), the school\u00a0had a large, 3 camera TV Studio<\/strong>, with a huge cyclorama curtain surrounding the walls. \u00a0One day, while scrounging behind the curtain, I found two of the huge RCA transcription turntables, in their massive cabinets. They had the coveted\u00a0Grey Research Damped Transcription Tonearms<\/strong>, so named, as the arm rode on a layer of oil<\/strong> to\u00a0isolate it from the turntable’s vibrations. And also to minimize lateral friction. The RCA tables were in deplorable, but restorable condition. Piles of 16″ records cluttered the space around the machines. I had little interest in vintage gear in those days, and forgot about them. \u00a020 years\u00a0later, I \u00a0learned l that when the TV studio was renovated into a dance studio, the\u00a0turntables had\u00a0been unceremoniously trashed. \u00a0Truthfully, over 30 years later<\/strong>, I still have lucid dreams<\/strong> about finding vintage broadcast equipment in the bunkers and catwalks of my alma-mater’s fine arts building. \u00a0– by Pete Verrando\"Meadows_School_of_the_Arts\"<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

\u00a0About 3 years ago, I saved\u00a0the pieces of this\u00a016″ transcription player & cabinet from a dusty internment.           (Click the thumbnails above for a larger “before” view). , \u00a0This Presto T-68 Transcription Turntable with Pickering 190D Tonearms\u00a0was used at an Air Force base in Fort Worth. Found inside the cabinet was […]<\/p>\n","protected":false},"author":1,"featured_media":371,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[8],"tags":[85,30,83,80,81,86,48,82,84],"_links":{"self":[{"href":"https:\/\/txsound.com\/blog\/wp-json\/wp\/v2\/posts\/335"}],"collection":[{"href":"https:\/\/txsound.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/txsound.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/txsound.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/txsound.com\/blog\/wp-json\/wp\/v2\/comments?post=335"}],"version-history":[{"count":81,"href":"https:\/\/txsound.com\/blog\/wp-json\/wp\/v2\/posts\/335\/revisions"}],"predecessor-version":[{"id":480,"href":"https:\/\/txsound.com\/blog\/wp-json\/wp\/v2\/posts\/335\/revisions\/480"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/txsound.com\/blog\/wp-json\/wp\/v2\/media\/371"}],"wp:attachment":[{"href":"https:\/\/txsound.com\/blog\/wp-json\/wp\/v2\/media?parent=335"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/txsound.com\/blog\/wp-json\/wp\/v2\/categories?post=335"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/txsound.com\/blog\/wp-json\/wp\/v2\/tags?post=335"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}