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 Post subject: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Fri 03, 2012 4:54 pm 
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Posts: 58
Location: Rhode Island, USA
Hello everyone

I don't consider myself a vintage audio collector, but I do dabble in it a bit here and there. I found a nice 1964 Motorola SP-29-E 3-Channel Portable Phonograph at an antique shop on Block Island, and I decided to pick it up. I asked to test it out with a record in the shop, but the platter was slowing at each revolution. The shop owner said that had the same result when he tried playing it. The price was $20 because of this, but I offered $15 because I figured it would just be a really nice (big) decoration for a while before I found out what was wrong with it. After lugging it back to the ferry (3/4 of a mile) and looking at it at home, I found that the turntable mounting screws weren't screwed down all the way, and the screw head was rubbing on the platter every time it made a revolution. It was spinning perfectly after that...

So now that its working fine, I have to do some more maintenance. I cleaned and greased the mechanism on the underside of the turntable. I have to replace the filter capacitors as I'm getting a bit of hum after it warms up. Even still, the sound is IMMENSELY better than my only other phono, a 1950's Decca Portable...

Also, when I have the dial set to STEREO, and I'm playing a stereo record, I'm getting inconsistent output from the left channel. It's going on and off. Once I turn the dial to MONO, I get equal output from both the right and left speakers. I'm thinking of replacing both the needle and cartridge. I'm not sure how to identify the existing cartridge, however, as I don't believe there are any markings on it. There was a spare needle (the old one) included in the new needle's box. The new needle is an 813-DS77.

Any ideas?

Thanks,
Nick

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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Fri 03, 2012 5:25 pm 
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Joined: Dec Sun 07, 2008 7:05 am
Posts: 4242
Location: MS
It could be an intermittent cartridge, or something intermittent in the amp.

When the switch is set to mono, the L and R channels are combined; so, even if one side of the cartridge was intermittent, you'd still get sound out of both channels.

Try www.thevoiceofmusic.com for a cartridge. That one looks like a later Sonotone cartridge; but, I could be wrong.

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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Fri 03, 2012 5:54 pm 
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Location: Minnesota
I used to have a '59 3 channel motorola portable (i use that term VERY loosely) I ended up selling it for $50. I regret it sooooo much because of how nice it sounded. I have yet to find a portable player that sounds as good.

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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Fri 03, 2012 6:06 pm 
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Joined: Aug Fri 03, 2012 4:28 pm
Posts: 58
Location: Rhode Island, USA
radiotvnut wrote:
It could be an intermittent cartridge, or something intermittent in the amp.

When the switch is set to mono, the L and R channels are combined; so, even if one side of the cartridge was intermittent, you'd still get sound out of both channels.

Try http://www.thevoiceofmusic.com for a cartridge. That one looks like a later Sonotone cartridge; but, I could be wrong.


Thank you for the link. After looking at their website, my Motorola appears to have a VM record changer, something like a 1258. I'll have to take the bottom cover off to get the actual model number of the changer.

13crhuber wrote:
I used to have a '59 3 channel motorola portable (i use that term VERY loosely) I ended up selling it for $50. I regret it sooooo much because of how nice it sounded. I have yet to find a portable player that sounds as good.


Yes, portable is definitely not the correct term. Maybe "luggable" is more appropriate. Reminds me of the early "portable" computers. Everything I've read so far about these 3-channels has mentioned their great sound. Hopefully I'll be able to get my issues ironed out so it'll sound as close to perfect as I can get it.

Thanks,
Nick


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Fri 03, 2012 8:24 pm 
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That's a good looking Motorola portable. I think that model is fairly potent. Welcome to our board!


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Fri 03, 2012 8:55 pm 
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unless you like spending a lot of money I would go with replacing the needle/stylus first. they need regular replacement if played regularly. then check connections all the way through the channel. sounds like a switch contact or other poor connection somewhere. if it is a tube unit check the tube seating. wiggle the tube

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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Fri 03, 2012 11:00 pm 
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Joined: Aug Fri 03, 2012 4:28 pm
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Location: Rhode Island, USA
Thanks for the replies.

The turntable is a V-M 1242-369. I took the 5 tubes out one at a time and cleaned the pins. I took the amp section cover off as well to see how the capacitors and resistors have held up.

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Everything looks untouched and original, which is great. I'm sure there are many more capacitors in the tone control box under all of the dials. Those will have to be checked as well. Also, there's another box where the main transformer is, along with a 6CA4 tube. I'm sure there are more caps there as well. This phonograph consumes 110 watts, that seems very high to me...

Nick


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Fri 03, 2012 11:13 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3130
Location: Boston, MA USA
Not sure that can-type electrolytic capacitor is original. It would be unusual to find on mounted like that. Plus the photo seems to show a rat's nest of wiring around it that should be cleaned up.

Most of the capacitors are ceramic disks and a ceramic couplate which will not give any trouble. A couple of electrolytic bypass capacitors should be changed.

The grease on the turntable looks bad, may be thickened with age.

-David


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Sat 04, 2012 12:32 am 
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Joined: Aug Fri 03, 2012 4:28 pm
Posts: 58
Location: Rhode Island, USA
Thanks David,

When I first got the turntable, I vacuumed out the cobwebs inside the chassis, and I lightly oiled some of the moving parts. Looking at the pictures, I really should remove that old grease. I get a bit nervous when oiling things like this. One misplaced drop and then the idler wheel starts slipping or something like that... What sort of grease or oil would you recommend? I don't think the extremely-light Hammond Tonewheel Oil that I have hanging around would be of much use here...

The wiring looked fine to me, but I haven't been around many of these... I wasn't sure what that metal can was. It looks like it has 6 or so spades coming out of the top. It doesn't appear to have any markings on it so I think that's going to be the hardest one to replace...

I switched the needle with the old one and the left channel is still in and out on STEREO, but fine on MONO. I swapped the left and right amplifier tubes, but still the same.

Are there any sources for obtaining a service manual for this?

Nick


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Sat 04, 2012 12:48 am 
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I just bought and received a 1960s Heathkit signal tracer that had all ceramic disc capacitors in it...there were no paper caps. The can electrolytics were original also, and they have absolutely NO hum. The tracer works perfectly and like a brand new one with 50 year old parts.


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Sat 04, 2012 3:33 am 
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Joined: Aug Fri 03, 2012 4:28 pm
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Location: Rhode Island, USA
Larry Hillis wrote:
I just bought and received a 1960s Heathkit signal tracer that had all ceramic disc capacitors in it...there were no paper caps. The can electrolytics were original also, and they have absolutely NO hum. The tracer works perfectly and like a brand new one with 50 year old parts.


Nice!

So I guess it would be smart if I replaced the easiest ones first... Get all the easily replaceable/identifiable paper caps out of the way, and then check and see if the can needs to be replaced as well. I know at least one of the tubes (a 12AX7) was replaced as the old was included with the player. I'm not sure where I could have the tubes checked. I don't think there are many drug stores with tube testers around... I should send a written request to CVS. Ha!
Nick


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Sat 04, 2012 4:03 am 
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Location: South of Richmond, VA 25 miles down the pike.
Tomorrow I will get the SAMS and scan it for you. Need a PM with email address. Good unit there and the electrolytic can is mounted the way shown. Problem comes with space to mount individual replacements for it. And a replacement one may not be available. You may get one with some values and and then use individual one for the balance. I've done that before. I wish I had kept my Motorola ones too.

Bill J.


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Sat 04, 2012 4:26 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Boston, MA USA
NTL1991 wrote:
So I guess it would be smart if I replaced the easiest ones first... Get all the easily replaceable/identifiable paper caps out of the way, and then check and see if the can needs to be replaced as well.

Not seeing any paper capacitors in the photos at all.

-David


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Sat 04, 2012 4:34 am 
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Joined: Aug Fri 03, 2012 4:28 pm
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Location: Rhode Island, USA
dberman51 wrote:
NTL1991 wrote:
So I guess it would be smart if I replaced the easiest ones first... Get all the easily replaceable/identifiable paper caps out of the way, and then check and see if the can needs to be replaced as well.

Not seeing any paper capacitors in the photos at all.

-David


Sorry, I was mistaking the electrolytic's for paper because of their sheathing. I'll also have to investigate for more caps in the tone control strip.

NumberMaj 1 wrote:
Tomorrow I will get the SAMS and scan it for you. Need a PM with email address. Good unit there and the electrolytic can is mounted the way shown. Problem comes with space to mount individual replacements for it. And a replacement one may not be available. You may get one with some values and and then use individual one for the balance. I've done that before. I wish I had kept my Motorola ones too.

Bill J.


Thank You, will do. I had that issue with my old Decca. There was a combo cap and I had to externally mount the replacement (also a combo cap). It was just too big to fit in the small (6" x 4" x 1.5") amplifier enclosure.

Nick


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Sat 04, 2012 4:38 am 
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NTL1991 wrote:
I'm not sure where I could have the tubes checked. I don't think there are many drug stores with tube testers around...
Nick

I doubt there is one single drug store in existence anywhere that still has a tube checker.


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Sat 04, 2012 4:41 am 
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I see two paper electrolytics in the amp that should certainly be replaced (the yellow ones). If your set doesn't have any hum to it after that, the can electrolytics may be just fine. You could leave that alone if they don't hum and not bother to replace them until hum starts to be heard.


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Sat 04, 2012 5:37 am 
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Here's a method I've used to check for an intermittent cartridge. Play an old record that means nothing to you and when one channel cuts out, lightly tap the top of the tonearm where the cartridge is located. If the cartridge is intermittent, the tapping will most likely make it work again. That's a common problem, especially on record players where the owner was careless in either dropping the tonearm on a record or forgot to lock down the tonearm during transit. If you dismount the old cartridge, there should be a make and/or model number for the cartridge. Take care not to break the fragile cartridge wires when working around or on the cartridge.

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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Sat 04, 2012 8:10 am 
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Joined: Aug Fri 03, 2012 4:28 pm
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Location: Rhode Island, USA
radiotvnut wrote:
Here's a method I've used to check for an intermittent cartridge. Play an old record that means nothing to you and when one channel cuts out, lightly tap the top of the tonearm where the cartridge is located. If the cartridge is intermittent, the tapping will most likely make it work again. That's a common problem, especially on record players where the owner was careless in either dropping the tonearm on a record or forgot to lock down the tonearm during transit. If you dismount the old cartridge, there should be a make and/or model number for the cartridge. Take care not to break the fragile cartridge wires when working around or on the cartridge.


Thanks! I have TONS of 45s hanging around and might try that. The phonograph sends the audio signals from the tonearm to the amp via an RCA connection. Couldn't I just plug an external known-good source, such as a CD changer or iPod into the RCA jacks to the amplifier? Wouldn't that rule out a bad cartridge/needle?

Nick


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Sat 04, 2012 8:59 am 
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NTL1991 wrote:
The phonograph sends the audio signals from the tonearm to the amp via an RCA connection. Couldn't I just plug an external known-good source, such as a CD changer or iPod into the RCA jacks to the amplifier? Wouldn't that rule out a bad cartridge/needle?

Nick

Give that a try. The impedence will not be the same, but it might enable you to verify whether both stereo channels in the amp are working right or not.


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 Post subject: Re: Found a Motorola 3-Channel Portable Phono
PostPosted: Aug Sat 04, 2012 12:51 pm 
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Location: Minnesota
One other thing you could try is to reverse the connections. If the bad channel switches to the other one, you know the cartridge or the wiring, is the culprit.


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