60s Magnavox Micromatic noise problem

johndvick · by **johndvick** » Tue Feb 03, 2009 8:36 am

Hi all,

I'm a newcomer to the forum, and it's my first time trying to fix up an older record player. I know next to nothing about electronics, so I'm really starting at the very beginning with all this. Any help or advice will be greatly appreciated.

I bought an early/mid 1960s Magnavox Micromatic record player in a cabinet a few weeks ago. There was a problem with the sound coming out of the left speaker. When playing a record, the volume was lower and it sort of pulsated. Not sure how else to describe it. After fiddling with the volume knob, I discovered that if I rotated the knob all the way clockwise, turning volume to 100%, then slowly turned the knob back to midpoint, about 50% volume, the left speaker sounded fine. I used it like that for a couple weeks without a problem. But when I was playing a record the other day, a loud humming started coming through all speakers, and the music was barely audible. Now, every time I turn on the record player, even if I don't play a record, all speakers hum.

Any ideas about how to fix this?

Thanks in advance for any help!

: 60s Magnavox Micromatic cabinet; magnavox.01 (Small).JPG (36.7 KiB) Viewed 3441 times

cabinet

: 60s Magnavox Micromatic record player; magnavox.02 (Small).JPG (55.94 KiB) Viewed 3441 times

record player

: 60s Magnavox Micromatic circuit board; magnavox.03 (Small).JPG (64.54 KiB) Viewed 3437 times

circuit board

Thom · by **Thom** » Fri Feb 06, 2009 1:01 am

That can in your photo is a capacitor with several values. It is a filter (electrolytic capacitor) for the power supply which quite possibly has gone bad. They usually do. This can be replaced but you will want to check in the archives and on the net on how it is done. It is not diffcult if you are handy with a soldering iron. In fact, in a unit of this vintage all the electrolytic capacitors should be replaced anyway. This should take care of your hum.

Thom

johndvick · by **johndvick** » Fri Feb 06, 2009 1:26 am

Thom wrote:That can in your photo is a capacitor with several values. It is a filter (electrolytic capacitor) for the power supply which quite possibly has gone bad. They usually do. This can be replaced but you will want to check in the archives and on the net on how it is done. It is not diffcult if you are handy with a soldering iron. In fact, in a unit of this vintage all the electrolytic capacitors should be replaced anyway. This should take care of your hum.

Thom

Thanks much Thom! I appreciate your help. I'll check archives and the net for more info on changing capacitor(s)...and where to find new ones. Then I'll have to get a soldering iron and start practicing.

Thom · by **Thom** » Fri Feb 06, 2009 11:30 pm

A word of caution: Never use a soldering iron while wearing shorts.

Just use your favorite search engine and look for "recapping vintage radios" or "Just Radios" " how to replace capacitors" etc. Take a small amount of time to learn the fundementals of capacitors which is not difficult . Good luck. Thom

johndvick · by **johndvick** » Sat Feb 07, 2009 5:01 pm

Thom wrote:A word of caution: Never use a soldering iron while wearing shorts.

Thanks for the clothing tip Thom. Long pants only when soldering.

Thom wrote:Just use your favorite search engine and look for "recapping vintage radios" or "Just Radios" " how to replace capacitors" etc. Take a small amount of time to learn the fundementals of capacitors which is not difficult . Good luck. Thom

I came across justradios.com the other day when searching for recap info and emailed them a photo of my Ecap to see if they had one in stock. Here's what they had to say:

You can replace that Ecaps with 2 new single Ecaps ....our 1000uF at 25V and 500uF 50V...........just disconnect the old Ecap and leave on chassis for looks....then install 2 new caps under the chassis.

[Ecap photo below]

So I guess that's the route I'll go, unless there's some affordable new old stock out there somewhere.

: electrolytic capacitor; 60s.Magnavox.capacitor (Small).JPG (46.9 KiB) Viewed 3382 times

It's going to take some time to get this done, but I'll let you know how it turns out.

Thanks again Thom!

Bobby Basham · by **Bobby Basham** » Sun Feb 08, 2009 7:48 am

I have a model very, very similar to that one. Mine does have a pair of brass knobs on the front and it looks like your turntable and amp are the same. Mine is tube, not solid state, with 10" woofers and 5" tweeters.

I would replace ALL the caps on something that old. My FM was dead, but new caps brought it back to life. If I'm in a adventurous mood, I may check all the resistors for tolerance.

And yes...do not wear shorts, Daisy-Dukes or other short-legged apparrel or be naked. You wanna keep your close relatives (cousins) safe...LOL Soldier is hot, but it cools quickly. --BB

Bobby Basham
Tucson, Arizona

johndvick · by **johndvick** » Sun Feb 08, 2009 7:53 pm

Hi Bobby. Thanks for your reply

I have a model very, very similar to that one. Mine does have a pair of brass knobs on the front and it looks like your turntable and amp are the same. Mine is tube, not solid state, with 10" woofers and 5" tweeters.

Just measured the speakers in mine. It has 8" woofers and 5" tweeters.

I would replace ALL the caps on something that old. My FM was dead, but new caps brought it back to life. If I'm in a adventurous mood, I may check all the resistors for tolerance.

Right now I'm in the process of figuring out all the caps I'm going to need...and trying to figure out how to remove the chassis. It's attached to a thin strip of wood that holds the pots, and it looks like the strip might be glued to three small blocks of wood that are glued to the cabinet. (You can see it in one of the above photos.)

Here's another photo so you can get a better idea of what I'm talking about:

: Chassis attached to thin strip of wood that holds pots; chassis.attachment.01 (Small).JPG (47.15 KiB) Viewed 3362 times

What's the best way to test resistors? I did a quick search of the net and all sites mentioned using a multimeter. Looks like something I can pick up at Radio Shack.

And yes...do not wear shorts, Daisy-Dukes or other short-legged apparrel or be naked. You wanna keep your close relatives (cousins) safe...LOL Soldier is hot, but it cools quickly. --BB

Darn. I usually enjoy doing repairs in the nude.

Bobby Basham · by **Bobby Basham** » Sun Feb 08, 2009 10:23 pm

Those little blocks of wood may just be spacers. I was just now looking at a spare Maggie out in the garage...weather beaten, so the bottom board is mostly rotten and I can see the insides...soon to be parted out and gutted.

If you can take a look-see at the other side of that vertical chasis board, there may be four long hidden screws supporting the chasis. It is not suspended from the top...too heavy. If you remove all the knobs and then those four screws on that board, the amp should slide right out (if you have the cabinet turned on its side vertically). Otherwise, it will drop straight down. It's been so long since I took one apart.

When I get my work room set up in the coming weeks. I'll start working on my units again. Some of them just need a little TLC and a few could use a Cap job. Isn't it fun working on these old things? Seems like I learn something new every time I open up one of these beasts. At least it keeps me out the streets....LOL!

Best to you,

Bobby Basham
Tucson, Arizona

johndvick · by **johndvick** » Mon Feb 09, 2009 6:50 pm

Thanks for the tips Bobby

Bobby Basham wrote:If you can take a look-see at the other side of that vertical chasis board, there may be four long hidden screws supporting the chasis. It is not suspended from the top...too heavy. If you remove all the knobs and then those four screws on that board, the amp should slide right out (if you have the cabinet turned on its side vertically). Otherwise, it will drop straight down. It's been so long since I took one apart.

I'd already removed the knobs and one long screw that attached bottom of chassis to support panel, but the chassis still wasn't sliding out. (You can see the screw bracket to the left of speaker wire connections in above photo of chassis.)

When I took a closer look at the topside of the pots, I found two of them were held in place by a sort of circular hexagonal nut, and it looks like those might be holding the chassis in place from the top:

: Right pot held in place by circular hexagonal nut. Left pot doesn't have the nut.; pots (Small).JPG (41.51 KiB) Viewed 3343 times

So I guess I have to find a tool to remove the nut. Not sure what it'd be called though...

Isn't it fun working on these old things? Seems like I learn something new every time I open up one of these beasts. At least it keeps me out the streets....LOL!

I agree. It's a lot of fun. And there's a lot to learn, especially for a newbie like me. I've already picked up three oldies - two Maggies (early 60s and early 70s) and a Soundesign from the 70s - so there's a lot to keep me off the streets and out of trouble for a while.

Bobby Basham · by **Bobby Basham** » Tue Feb 10, 2009 9:28 am

Like I said, it's been a long time since I removed one of those amps. I don't recall ever having to remove those bolts around the pots. Those are bolted directly to the chassis, and if they needed to be removed, you would use something deep like a spark plug socket.

Duh...looking at my unit, there are two more long screws inside near the turntable just above the 45 adapter storage and the on-off/speed selector knob...those are supporting the top part of the amp. I'm still thinking there's a fourth screw somewhere...two near the middle/bottom of the vertical chassis board and two inside where the turntable is. The whole thing should slide out then once you remove the knobs.

The face place should stay intact. On some of my models, the "face plate/cover" is directly attached to the amp/receiver and slides out as one piece. I would turn the cabinet on it's side...it's a little uncomfortable holding a screwdriver/wrench in one hand and trying to suspend the weight of the amp in the other when it drops down. --BB

Bobby Basham
Tucson, Arizona

orthophonic · by **orthophonic** » Sat Feb 21, 2009 3:53 am

I rebuilt this exact model two years ago for a gilfriend and i remember having to take those nuts off the knobs and remove the faceplate
to remove the amp.

johndvick · by **johndvick** » Sat Feb 21, 2009 10:54 am

orthophonic wrote:I rebuilt this exact model two years ago for a gilfriend and i remember having to take those nuts off the knobs and remove the faceplate
to remove the amp.

What sort of tool did you use to remove the nuts? I've done a little looking at local hardware stores, but haven't found anything that'll work.

Bobby Basham · by **Bobby Basham** » Mon Feb 23, 2009 12:17 am

My face plate stays intact. I just remove the knobs. Slide open the lid and there may be two phillips screws, one just above the 45 adapter storage and the other one near the speed selector knob. They are holding the top part of the amp in place, the other two screws are underneath on the back side of that vertical board holding the lower part of the amp in place. You shouldn't have to deal with the hex (or whatever) bolts on the chassis. They keep the controls bolted to the chassis. It should all slide out in one piece after removing the knobs and those four long screws.

Bobby Basham
Tucson, Arizona

magnabox · by **magnabox** » Wed Jan 20, 2010 3:11 am

Hello John,

I have the exact same console judging by your photos, and am about to undertake an electrolytic capacitor repair. I am to the point of removing the two hexagonal nuts on the faceplate to remove the chassis, I would appreciate anything you could tell me about how your repair went. Thanks!

Jim

MattTech · by **MattTech** » Fri Jan 22, 2010 9:52 am

Magnavox Authorized Service Centers were furnished a special tool for those inverted nuts.
I own one

No, I won't part with it

"No user-servicable parts inside"
"Please refer servicing to authorized personel"

60s Magnavox Micromatic noise problem

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60s Magnavox Micromatic noise problem

Electrically amplified phonographs or radio/phonographs and related components (approx. 1928-1990).

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