Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Sep Sun 23, 2018 5:37 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 35 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Wed 01, 2017 8:06 am 
Member

Joined: Sep Fri 02, 2016 10:07 pm
Posts: 40
Hello,

So I have recently learned that my amplifier is in need of restoration, specifically replacing the capacitors, does anyone have a diagram for this machine or should I just dive in and start taking pictures of the amplifier?

A little background: I brought this machine in "working" condition, I replaced the needles, did some cleaning, removed the turntable and oiled and greased many parts (I did this with no expierince with turntables rather experience with Antiques and mechanics, so if there's any specific points I should grease and oil that would help too) the record player works fine but has a hum, I was told this means I need to do some replacing on the amplifier. Also I should note that this is a tube set. I've also brought replacement speakers, but I will most likely go back to the originals if this amplifier restoration brings this baby back to life.

I have a manual for the micromatic turntable but not for the amplifier. I have experience with soldering and have done some research already but I still don't know if there's anything I need to ground out so I don't shock myself or if there's anything else I need to replace to get the optimal sound this player can have


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Wed 01, 2017 7:16 pm 
Member

Joined: May Sat 06, 2006 4:03 am
Posts: 3080
Location: ZIP 23831 South of Richmond, VA 25 miles down the pike.
Reading your prior posts I don't see where you have posted the amp number. Here's what you must do in regards to getting a schematic for the amplifier. As far as I know about Magnavox there will be an amp number on it. It may read AMP80-01 plus two more characters. You post the numbers and if I have it and most likely I do, I will provide a link to it unless someone gets to it first.
Bill J.


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Wed 01, 2017 8:28 pm 
Member

Joined: Sep Fri 02, 2016 10:07 pm
Posts: 40
I'm not with the record player right now, but from the one picture I have of the amp it says "M1" in a big square if that helps


Attachments:
IMG_0140.JPG
IMG_0140.JPG [ 122.81 KiB | Viewed 3229 times ]
Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Wed 01, 2017 11:56 pm 
Member

Joined: May Sat 06, 2006 4:03 am
Posts: 3080
Location: ZIP 23831 South of Richmond, VA 25 miles down the pike.
No Help.
Bill J.


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Thu 02, 2017 3:25 am 
Member

Joined: Sep Fri 02, 2016 10:07 pm
Posts: 40
Okay so I looks at the amplifier, it says "445936" and "8001-40" and then "M1"

Inside the record player there's a small wiring diagram that says "EL 1551-1"

Hope that helps


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Thu 02, 2017 4:07 am 
Member

Joined: May Sat 06, 2006 4:03 am
Posts: 3080
Location: ZIP 23831 South of Richmond, VA 25 miles down the pike.
Here's the link.
Bill J.

https://app.box.com/s/mbgqiyj0gbdi6radohqzfkxxqex1jyxe


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Thu 02, 2017 4:23 am 
Member

Joined: Sep Fri 02, 2016 10:07 pm
Posts: 40
Okay thanks, now that I have that, what parts am I replacing? I understand they are capacitors, so is that all of them starting with "C1" and so on?


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Thu 02, 2017 5:07 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4129
Location: Boston, MA USA
You need to replace at least the 3 electrolytic capacitors that are inside that black cardboard tube. You can either "stuff" the new ones inside the tube after cleaning out the old capacitor guts, or install them on terminal strips under the chassis if there is room.

Please post a clear photo of the underside of the chassis so we can advise if there are any other capacitors which should be replaced as well.

-David


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Thu 02, 2017 5:26 am 
Member

Joined: Sep Fri 02, 2016 10:07 pm
Posts: 40
Here's a photo from one 8001-40 amp that I found on eBay, if mines also a 8001-40 I'm assuming it's the same, otherwise I can open mine up, but before I take out the amp (which I essentially want to do once, replace the parts, test and put back) I wanted to know if there's anything that i need to discharge for safety precautions


Attachments:
IMG_0156.JPG
IMG_0156.JPG [ 112.24 KiB | Viewed 3204 times ]
Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Thu 02, 2017 4:49 pm 
Member

Joined: Sep Fri 02, 2016 10:07 pm
Posts: 40
should i take a photograph of my own record players amp? from what i understand at the moment do i only have to change the two black capacitors in that photo and the large electolytic capacitor?


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Thu 02, 2017 6:12 pm 
Member

Joined: Jan Wed 16, 2013 12:04 am
Posts: 1312
Location: 77001
Hi Tony,
RE:
Quote:
should i take a photograph of my own record players amp? from what i understand at the moment do i only have to change the two black capacitors in that photo and the large electolytic capacitor?


1. Yes, we must have a photo of your amplifier. The photo you have of someone else's amp
does not indicate all the tubular capacitors according to the schematic
Bill posted for you.

2. Also check the resistors in the circuit for values being within range. The large white/gray
one is a power resistor.

4. Buy some electrical cleaner/lubricant to spray in the control potentiometers
(for volume/bass/treble controls e.g.) since you'll have easy access.

5. If the amp has not been energized (turned on) for several days, the
large filter capacitors in the can may be drained of charge.
BUT, always check with a multimeter the voltage across the positive and
negative terminals of the filter capacitors to be sure the filter caps' voltage
is drained of charge.

Here's a nice capacitor tutorial from antique radios : https://antiqueradio.org/recap.htm#check
Hotwax


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Fri 03, 2017 12:43 am 
Member

Joined: Sep Fri 02, 2016 10:07 pm
Posts: 40
I use the record player everyday, i guess while I'm waiting for parts to come here I won't play it for a week, but if I open it up right now (played it an hour ago) should I be fine in taking the picture?


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Fri 03, 2017 7:20 am 
Member

Joined: Sep Fri 02, 2016 10:07 pm
Posts: 40
Here's my record player Amp, can someone please circle which ones I need to replace? So far I've figured out that there's 5 total? (Could be wrong)

Does anyone know what capacitors I should get to replace them?


Attachments:
IMG_0173.JPG
IMG_0173.JPG [ 148.08 KiB | Viewed 3156 times ]
Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Fri 03, 2017 4:55 pm 
Member

Joined: Nov Wed 27, 2013 5:59 am
Posts: 548
Location: Metzger Oregon
You want to replace the black "can" on the top of your chassis. From the bottom view, you will see a brown surface in the top right side with 3 large terminals coming through from the top. You can just read the values on the old part and purchase 3 new caps with the same value, or close to the same. The toughest part is removing the big resistors and other wires from these terminals and mounting them somewhere else. As others have suggested, you can install a terminal strip or replace the insides of your old cap. Hope this helps, we're always willing to answer more questions.


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Fri 03, 2017 6:36 pm 
Member

Joined: Sep Fri 02, 2016 10:07 pm
Posts: 40
okay am i replacing the other black capacitors underneath? or do i really just need to replace the large on that sits on top. also can i remove the cardboard while its still soldered together and just put the replacements inside the cardboard cover (as long as they all fit? or do i have to actually desolder the electrolytic capacitor all together


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Fri 03, 2017 7:15 pm 
Member

Joined: Sep Fri 02, 2016 10:07 pm
Posts: 40
also, im looking for at electrolytic capacitors for sale, and i just wanted to make sure, C1 is made up of 120, 80 and 20, at 150 volts, are the numbers "120, 80 and 20" measured in uF? If so, would it be fine for me to get 120uf 80uf and 20uf at 450 volts?


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Fri 03, 2017 8:02 pm 
Member

Joined: Feb Sat 06, 2016 1:47 am
Posts: 2171
Location: Santee Calif. 92071
Yes that is UF or MFD. If you are going to put all 3 new capacitors in the cardboard tube should stay with the 160 volt capacitors. The 450 are bigger and may not fit inside. Due note that all 3 new capacitors will have there negative ends tied together. The original filter can has an insulator to keep its negative can off the chassis. Connect the negative ends of all 3 capacitors to the wires that were connected to outside ring of old filter can. Nothing connects to chassis ground.


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Fri 03, 2017 8:16 pm 
Member

Joined: Jan Wed 16, 2013 12:04 am
Posts: 1312
Location: 77001
Quote:
okay am i replacing the other black capacitors underneath? or do i really just need to replace the large on that sits on top. also can i remove the cardboard while its still soldered together and just put the replacements inside the cardboard cover (as long as they all fit? or do i have to actually desolder the electrolytic capacitor all together


1. Yes, replace the 2 black Sprague caps. Clip off the lead (of one end only) near the
body of the capacitor. Then just bend the cap around to see the microfarads/voltage printed on
the body. Take photos as you go, so you have the original reference points where the
caps go in the circuit.

2. The filter capacitor can (C1) on the outside of the chassis may be
a metal body covered with cardboard. If the can is metal, then you have to saw off around
the cylinder and pull out the electrolytic "guts". Then you re-stuff the can with new caps.
You can search on ARF for tutorials/topics on that.

3. Yes, you can use a capacitor with a HIGHER voltage. To save space,
use the 160 Volt for your original 150 Volt caps.

4. Modern capacitors will not be available in exact values for your 80 and 20 uF
filter caps. You can sub a 100 uF for the 80, and a 22 uF for the 20.

There is a 120 uF electrolytic at this parts house:
You may as well buy the rest of your caps there, pretty good prices.
https://www.westfloridacomponents.com/J ... apxon.html


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Fri 03, 2017 11:32 pm 
Member

Joined: Sep Fri 02, 2016 10:07 pm
Posts: 40
Thanks for the help, are there any more caps I need to replace?, also can someone tell me which capacitor out of the 120, 80, and 20 go to which wire, is there like a sign that I'll see that can tell me?

And can I mix different voltage capacitors as long as they're all above 150v?


Top
 Profile  
 
 Post subject: Re: Magnavox Micromatic 1sc-237 Amplifier Restoration help
PostPosted: Feb Sat 04, 2017 12:46 am 
Member

Joined: Feb Sat 06, 2016 1:47 am
Posts: 2171
Location: Santee Calif. 92071
The values are on the cardboard tube and show a Symbol right after the values. Then look at the bottom of the filter can you will the same symbols right beside each lug on the filter can. That's how to know what's inside the can. And yes you can mix voltage as long as it's greater that original value. A tip is to hand draw the connections and values on paper when making up the new capacitors. Such as show diode and 100 ohm resistor connection to square terminal lug and value given. Won't make a mistake to easy then.


Top
 Profile  
 
Post New Topic Post Reply  [ 35 posts ]  Moderator: Alan Voorhees Go to page 1, 2  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 6 guests



Search for:
Jump to:  
























Privacy Policy :: Powered by phpBB