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Topics - Motorola Minion

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Sightings / 1960 Concert Grand - Chicago
« on: October 04, 2018, 04:05:09 PM »
I saw this on videokarma and figured it would look good here. I thought it said $100 but I must be hallucinating :-[ again .

Chat / Few consoles in vintage CU books
« on: October 01, 2018, 03:15:20 PM »
Consumer Reports tested many products but I could not find stereo consoles in their reviews, even after I bought a dozen year-end issued "buying guides" on fleabay.

Then I saw a side bar discussion in the 1961 issue, under the listing High Fidelity equipment, where a selection of low-mid priced consoles were tested...and deemed unacceptable, mostly due to the record changers that came in them. It seemed that a Webcor Coronet and a few others were barely-acceptable consoles.

CU also stated that true stereo realism cannot be achieved when speakers are only 3 feet apart. 6-10 feet of separation was only possible with two-cabinet consoles (none reviewed), with separate components or with only the largest custom and some Curtis Mathes "aircraft carrier" consoles.

I offer a few questions for discussion:

1. Was CU biased toward picking the best individual components, assuming they all can play well together, as opposed to a group of components from one manufacturer designed to work well together :-\ (yes - I am thinking Magnavox speakers and amplifiers here)

2. CU reviews of record players (single-play ) included tone-arms rated ala carte, and separate from the turntables. Didn't Rek-o-kut, Grado and others make good enough tone arms ???

3. CU was a value guide, so were more expensive consoles simply ignored? In earlier buying guides, kits by Heath and Dynaco, speakers by AR and Warfdale were rated very favorably.

4. Due to the relatively good record quality prior to the "give me convenience or give me death" or 8-track and cassette era, was the general preference for high-quality players diminished by then? An example is the fact BSR replaced Mag, RCA and Zenith console changers by this time

Fisher / 1964 Ambassador IV A-69 P
« on: September 27, 2018, 03:13:37 PM »
This was one of the hybrid models that is 85% tubes, with four output transistors for each channel. The 690 amp has the entire power supply for both tubes 300V and +/- 32 volts for the push-pull output transistors. I will recap the power supply first, before trying anything.

Before offering a reasonable sum at a well-known swap meet last Friday, I pulled all four fuses from the amp to confirm nothing bad went down. This amp is the type that direct-couples the push-pull output transistors to the speakers without a capacitor. From the schematic, it would seem a shorted transistor could fry the speakers. 

It definitely needs repairs to the legs before I can put it upright. The cabinet suffered through a few moves by the look of things. Fisher cabinets are one of the more damage prone, based on a lack of bracing found underneath. I have already used structural woodscrews to tie the rear legs into the base trim and glued one leg that split in half.
The legs and most of the "fruitwood" cabinet appear to be cherry, and like my 1964 Electra VII in "distressed walnut", will need to be stripped.

The amp and receiver chassis had all the 12AX7's swiped but the rare 6HU8 tubes were not ??? The Garrard type A record changer is complete and nothing else looks missing.

I was curious about the speakers first, so those are the photos below. Ill have to get a better picture of the tube map.

Zenith / 1958 Zenith HF1284 - just before stereo
« on: September 07, 2018, 12:59:52 PM »
Zenith HF1284 - I have two, limed oak model with E-suffix and the walnut with no changer and messed up speaker grill weave. Getting a record changer found on CL in a $10 beat-up portable near me.

These also have electrostatic tweeters like the Cantata posted. The tweets connect directly to the (PP 6V6) output transformer primary, as they need a few hundred volts to get started. 

I need to find them, both are buried in my garage and need to be moved to a new space so I remember to work on them someday :P

Sightings / Sylvania SC74 tube model - PA
« on: September 06, 2018, 10:27:27 AM »
This one has an owner that will not get back to me but I have a similar model a year newer. Its only an hour up north in the mountains, worth a drive.

These were all-tube, hand-wired and some (this is a single-ended 7868 ) had a push-pull 7868 output stage. That was a special Sylvania tube developed for Fisher and used in their 400 series   

Sightings / 1962 Normandy
« on: August 31, 2018, 04:06:00 PM »
I have one, a 1ST659 with the 93-series amp, horns and 12"woofs. This is noted as a sweet-sounding console yet mine is recapped but still apart as there is lot of connections including FM multiplex adaptor. The tuner-preamps only looked like this for a year or two but they were all-tube.

Sightings / 1962 Magnavox in PA
« on: August 31, 2018, 03:59:16 PM »
This looks similar to the other one I posted. The tuner-preamps only looked like this for a year or two but they were all-tube

Music / Aretha Franklin
« on: August 17, 2018, 08:08:54 AM »
As we have lost one more great talent, I was fortunate enough to hear the Queen of Soul cover "Long and winding road" in a way Paul and the Beatles probably never imagined. I had just missed her cover of "walk on By" unfortunately. So I'm looking on youtube now and imagining how it would have sounded.

Her vocal range was all the more sweet and nostalgic heard through a 1965 "last of all tubes" Zenith Console as I boxed in the speakers. Being one of the last all-Beatles songs, it was always bittersweet anyway, yesterday it was more so :'(

I want to preface this by saying that often, changers seem to work fine mechanically. When they don't, you need to mean business, so get down and dirty!

For oiling spinning metal parts, Zoom-Spout turbine oil must bein every record player toolkit. 3 in 1 type and sewing machine seems like appropriate vintage oil to use BUT it is generally sloppy and attracts dirt. Less is better, always.

I used to HATE doing record changers during the 80s, preferring the carried-in 9" to 20" TVs. The TV road tech pulled the changers from consoles and brought back to the shop for us bench toads, and as you can guess, peak season was October-December.

Doing changers was fun - like taking out the trash, so our service manager had a no-fail 8-step method we used on BSR, Magnavox and RCA units pulled from consoles and brought back to the shop by the road tech. "Just do it" I was often told when I verified it was operating correctly, and already looking for a new stylus (often in vain) in the dusty parts drawers.

Lubriplate or white lithium grease ( aka GC's Phono lube) is mandatory for all sliding parts. Go in ONCE with your best stuff and you'll own the repair. Just do it all, forgetting anything will make you repeat those annoying processes.

Isopropyl alcohol (IPA) and alternately, lacquer thinner, Q-tips and shop towels are all that is needed to clean off dirt-encrusted grease. it also does a great job on motor capstan "stepped shafts" plus the inside of the platter along idler track

Rubber-Renu is highly reactive oil of wintergreen and seems to work on most but NOT ALL idler pulleys to remove glaze. Only slightly more effective than IPA. If the pulley has deep fissures in the rubber, it probably overheated when the player motor was left on when it stalled, basically finishing off any chances for a lasting revival. Bite the bullet and replace it.

Bottoms-up work first

1- Mandatory motor maintenance - mark positions of every nut, 6-32 screw, washer, spacer and bearing bracket before you take ANYTHING apart. Soak those bearings first with IPA, using a cotton swab to pull the gunk out. Soak next with Zoom Spout or similar super-thin stuff.

2- Clean the changing mechanism with IPA and shop towels, and yes, you must take cycle gear-wheels off shafts or sliders out completely. Sliders on V-M players are tricky but you will not be successful without a thorough disassembly - cleaning and lube. trip levers that slide must be cleaned and having another player along side to compare whats out of place or bent cannot be understated.

Topside last

1- Pull off the platter from spindle. RCA's need a snap-ring pliers, Mags and BSR use a C-clip and V-M's use a small plastic O-ring and grooved center pin. Most are easy but on BSR's - spindle grease turns into JB weld, and must be soaked with lacquer thinner or worse to get it loose, spin-able and removable. I have yet to try "weasel piss" (WD40 or PB blaster) as it is hard to limit overspray.

2- Take idler pulley off and give it the business with IPA and oil the shaft/spring washers. Check alignment with the motor shaft thru all speed settings. If it does not land in the middle of a step, motor mount grommets are flat/gone OR if solid, it may be improper idle shaft washer placement.

3- Move center pin in/out, up and down while dousing with IPA to get ALL the crud out that causes it to drop two records or operate sluggishly. The tiniest bit of oil is all this part needs.

4- Platter spindle cage/ball bearings and washers need a thorough soaking and de-gumming, here we had success with lacquer thinner also. Pay attention to sandwiching the bearing between TWO thin washers. They like to stick and drop off during disassembly. To keep from hunting parts like those washers and center pin balls (V-M) that bounce off the bench, do your disassembling in a dishwashing tub or big cafeteria tray to catch anything that cuts loose.

5- The grand finale included checking speed with strobe disc under light from incandescent or fluorescent on magnetic ballasts. Try all record sizes/rpms and verify it worked on the 45 adapter, run through all cycles and at 78 (or 45) rpm to distribute all the oil and exercise every operation.

It always worked, no call backs, all the more reason to love Magnavox and RCA changers in particular.
About 5 years ago, I had to re-learn the whole process for Voice-of-Music changers, used in all my Motorola and Zenith tube sets.

I may post a thread on V-M by itself, renowned as rugged YET labor intensive to disassemble and re-assemble :P.

Astrosonic and Other SS Magnavox's / 1966 Imperial 2RP701 repairs
« on: June 28, 2018, 11:53:16 AM »
This tale is a short one but I thought it necessary to help anyone who is working on the better quality Astro-sonic chassis. This one has the R207 tuner-preamp and A575 100-watt amplifier. The record changer is a W603 Micromatic, a bit hard to remove from a cabinet with everything compartmentalized.

This console has a few doppelgangers, including the popular "Francisco" 1RP679, which has one set of horns, not a pair for each channel.

The repairs were very straightforward. About thirty 5 thru 500 uf black Nichicon capacitors were needed, with many of them testing open. As with most of this era Magnavox, the power supply positive is grounded to chassis. the amplifier has both positive and negative supply voltages.

Other Tube Console Brands / General Electric Tube console
« on: May 30, 2018, 01:57:32 PM »
I just picked this up on a trip upstate, from the original owner. It was probably bought at a small-town appliance store. As you can see from the photos, its pre-1964 due to conelrad marks on the AM scale. It claims FM stereo although it does it on the cheap, with one tube. I have seen this GE tuner in a few other models, like TV-stereo combos.

I was expecting a GE changer but this is a Voice of Music and appears original. The 8"/ 3" speakers are probably the most a single-ended 6AQ5 output tubes can drive.

Overall, this is a lightweight console but interesting nonetheless. GE had to make mid-priced and expensive consoles, but I have not seen one to date.

Motorola / Pre-stereophonic High Fidelity Motorola
« on: May 30, 2018, 01:42:55 PM »
I'm having a look at this. The seller is "moving and wants it gone". I have not seen a Mono HiFi from Motorola before.

Sightings / General Electric Tube console - PA
« on: April 27, 2018, 01:34:32 PM »
I'm going upstate next week and plan to stop and check this out. As it has been said elsewhere on this forum, you can never have too many tube consoles.

Right now, I have a tube stereo console from every major manufacturer except GE. This is the best example of a tubed GE I have seen to date. I'm sure there was a more deluxe model, but the lack of brochures and advertising makes that uncertain. Musaphonic was a name for such a model in the late 30s and 40s.

Since I am very familiar with GE televisions of this era, I am excited at the prospect of owning the HiFi equipment.

Motorola / Motorola Stereophonic SK107 - Phono with Vibrasonic
« on: April 20, 2018, 02:32:41 PM »
I picked up another Motorola on a trip upstate after seeing on CL and being the only one willing to pony up $25. Its the SK107 ($300 new), which has no radio but does have the "Hammond-licensed" vibrasonic unit built by Gibbs Manufacturing of Janesville Wisc. It is one of the more economical three-channel models having a 10" woofer, two 6" mids and two 3" cone tweeters. I am expecting to sell this one, as my other two are more expensive models, not to mention a tad LOUDER :P

I opened it up to see a the same pre-amp used in more expensive models, but an interesting amplifier that uses two SE 6BQ5 (Mullard OEMS) and the usual pair of 6V6GTA for the push-pull bass channel.

It looks similar to my SK112 ($605 new) but the amp is 20 watts versus the usual 51 watts. Both have the same early-American cherry veneer, not the sought-after Drexel cabinet models that many seem to have and are usually priced accordingly.

Tube Consoles / Missed it by "that much" - a recapping tale
« on: April 20, 2018, 01:56:50 PM »
After performing a full recapping on a mid-level 1964 Zenith stereo amplifier that uses SE6BQ5 and 1-12AX7 , I was greeted with a loud, irritating oscillation upon power-up.

Rather than hearing silence with the volume set at minimum, a loud 700 hertz (or thereabouts) blast filled the shop and beyond one early morning in February.
Turning up volume, audio from the restored tuner came through but still, I had just enough time to kill power to stop it.

Not fast enough, this prompted the upstairs tenant to complain to my normally patient landlord/owner (who is Amish) via a "building manager" (a demanding RE agent that he hired to manage tenants), prompting me to be banned from my shop before noon. Sheisse!!! I am preparing a new space in a barn on the same property. More on that in another post, probably in chat.

Coming back later that day when the coast was clear, the volume could not be reduced, the tone controls had little effect and neither did the bass-boost switch.

No usable clues except pulling the 12AX7 made it quiet. Not knowing where to start, both the Zenith factory and SAMs Schematics were double-checked to see if my nearly 100% re-cap missed any values.

Even the normally OK Zenith-made ceramic disc caps of .01 and .0033mf, 470 and 220 pf had cracks in them, prompting a replacement along with bumblebee, dipped paper caps and electrolytics including some resistors. I want this console to sound as good as possible, being the last of the all-tube Zeniths.

 Today, I thought to bring in the chassis and schemos and scrutinize it over my lunch break under very bright lights. The cause found was a capacitor in each channel being off by one order of magnitude, I used a .0033 instead of a .033 mf. This was in the feedback loop that runs through the bass-boost switch.

Lesson learned: Even though I wrap leads of replacement caps around the existing cap leads before soldering and clipping old caps out, I missed it somehow ???

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