Motorola SK29 - aka "gullwing" 3-channel

[Motorola minion]

Here is another one in my shop that I just got restored for my flea market stand customer. So far he keeps finding appreciative homes for these consoles and this one has some funny features of its own.

Back story: this was found in a rodent infested location, chock full of stuffing and crap when it arrived and was a PITA to get chassis out. The amp chassis had been used as a mouse "throne" right behind the power transformer and chassis was rusted away, two bolts were so bad I had to cut it apart to get it out. The tuner and preamp were very difficult to remove due to a very bulky cabinet.

Fortunately, I had an identical HS768 amp chassis that was missing two of it's output transformers as I had robbed it for parts. I decided to restore it for this set and found the three OPTs on the rusty chassis were good I also found an original defect in this amp, pins 6 and 7 on a 12AX7 feeding the PP bass output tubes were solder bridged from the day it was built. THAT explains the one open winding on the bass output transformer, the fatigued pin 7 on the affected 6BQ5, and teh fact it never made much bass for me (this was part of a consoles guts I got in 8th grade) but sounded good enough to get me VERY interested HiFi.

When I opened the panel under the preamp to get it out, I had a hard time getting up to the 11/32" nuts holding it in place. It took every extension I had in my craftsman 1/4" ratchet set and the nuts were so tight. This was only after I vacuumed extensively to get all the virulent crap out of there before I dared look up to remove it. Fortunately the Tape-Tuner switch has a stereo tape input though the AM-FM tuner is pre-mpx.

Probably the strangest thing I saw were the 6x9 midrange speakers (OEM 232 - Mag!) that appears to have no magnet. Has anyone seen this before?
The woofer is Motorola as well as the 4" cone tweeters, with 5 mf NP silver wrapped with clear plastic tubing caps made by Mag also, which actually tested good!!

[Motorola minion]

SK29M preamp r.jpg (60.55 KiB) Viewed 6601 times

[electra225]

If they put Magnavox speakers in your Motorola stereo, does that make it a Magnarola or a Motovox?

I don't remember seeing a speaker like that, come to think of it.

[TC Chris]

Those 6x9s may have had tiny magnets, but remember that they did not have to do any heavy lifting in the bass department. And the lack of gauss strength may have been intended as a way of rolling off lower frequencies--part of the crossover design.

Chris Campbell

[Firedome]

Perhaps part of the magnet is concealed by the basket stamping?

Weird those bridged tube-socket pins got by the Moto QC people, that's a pretty egregious goof.
But at least it helped to start interest in a new hobby!

I'm amazed at the level of success he has in selling these refurbed consoles, given how many seem to languish on CL and FBM, and given how younger people shop online for everything these days!

[TC Chris]

I'm amazed at the level of success he has in selling these refurbed consoles, given how many seem to languish on CL and FBM, and given how younger people shop online for everything these days!

My nephew and his wife, who both have PhD degrees in robotics, just bought a modern Crosley "record player." They are all excited. If I were out in CA I would shake them silly and tell them to buy something better. (Anything is better). I wonder of the console market may be people working their way up from Crosleys?

Chris Campbell

[William]

Being they live in California, and the price they get for consoles out there, maybe the Crosley was all they could afford.

Bill

[Hi-Fi-Mogul]

Staying on topic, I had one of these SK29s, and they
are really solid built and heavy.

IIRC, the speaker connections in the swing outs
are through the hinges.

Mine did not have Magnavox speakers in it.

[Firedome]

Confused...were the oval speakers in the fold-out speakers or the main cabinet?

[Motorola minion]

Confused...were the oval speakers in the fold-out speakers or the main cabinet?

The ovals and 3.5" tweets are in swing-out (not removable) doors, just the woofer is in the main cabinet.

The tuner is on my bench, I remember it working pretty well but it needs an alignment now. The 6DA6/EM81 scissors eye tube was so weak and others I tried were as well, so I found a Mullard NIB and boy is it bright now!

[Motorola minion]

Staying on topic, I had one of these SK29s, and they
are really solid built and heavy.

IIRC, the speaker connections in the swing outs
are through the hinges.

Mine did not have Magnavox speakers in it.

Im going by the 232 EIA number on the 6x9s, which are silver like all Mag speakers. The six digit number begins with 580, like Magnavox

[TC Chris]

The 6DA6/EM81 scissors eye tube was so weak and others I tried were as well, so I found a Mullard NIB and boy is it bright now!

Would it be worth inserting a resistor to drop the plate voltage some and extend the tube's life? Seems to me I've read about doing that.

Chris Campbell

[Motorola minion]

I tried three of the 6DA6 I had, all were dim and only that NIB Mullard looked decent. I had this tuner from long ago like that factory-defect amp. I was all over the FM dial in those days and the eye tube was always dim. It was a sensitive tuner using a simple 6BQ7/6BK7 and always selective just using rabbit ears. It just never tuned lower than 90 Mc and this could not be left unaddressed, considering that's where the good stuff is these days, IMHO .

A simple messing around with the tuning string and oscillator setting put it where it needed to be, that figures - its a Motorola . This is unlike experiences with an RCA using a 12DT8 and a Magnavox also using a 12DT8, where I needed to lay aluminum tape over a variable cap to lower the lowest osc frequency.