• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Inside the Minimus 7: repair and restore

J

jpdylon

non-active member...
I picked up some poor beat up minimus 7s today at a thrift for 14 bucks. They were calling to me. The cabinets were rusted and scratched and the grills were dented and smashed in places. One of the emblums was missing as well.

These were definitely used as outdoor speakers. The woofers were faded from black to almost white, and the surrounds were dry and stiff, and were developing cracks in places.

As you can see, these are fairly simple speakers. Why they sound so good is definitely a result of decent build quality and good parts.

Posted here will be pics of the restore progress as well as the demensions, x over specs, and any other information people might find useful

Cabinet demensions:
Exterrior
height = 7-1/16"
width = 4-7/16"
depth = 4-1/8"

Interrior
height = 6-7/8"
width = 4-1/4"
depth = 3-11/16"
 

Attachments

  • cabinet.JPG
    cabinet.JPG
    77.8 KB · Views: 1,761
  • min7 parts.JPG
    min7 parts.JPG
    72.6 KB · Views: 2,342
Last edited:
Register to hide this ad
Drivers and x-over

The drivers in the minimus 7s are very heafty and well built for their application. The woofer is a 4" and the tweeter is a 1" soft dome The crossover consists of a coil and a cap for the tweeter.

These are the pictures of the drivers when I got them . You can see the cone is very well sun faded.

Woofer: Radio shack no. 1218 (8 ohm)
Tweeter: Radio shack no SD-60 (8 ohm)

Crossover: 0.4mh coil for the woofer, 4.7@50 mf bi-polar cap for the tweeter.
 

Attachments

  • min7 woofer.JPG
    min7 woofer.JPG
    71.8 KB · Views: 1,257
  • min7 tweeter.JPG
    min7 tweeter.JPG
    70.9 KB · Views: 960
  • woofer mag.JPG
    woofer mag.JPG
    99.6 KB · Views: 1,128
  • tweeter mag.JPG
    tweeter mag.JPG
    103.2 KB · Views: 906
  • xover1.JPG
    xover1.JPG
    92.9 KB · Views: 1,410
  • xover2.JPG
    xover2.JPG
    98.5 KB · Views: 985
Cabinet refinish

because the cabinets were in such poor shape and rusted, I had to sand them down and repaint them. I used 120 grit sand paper down to bare metal. If you get the right paint that will adhere to existing paint, you can lightly sand your metal cabinets and re-paint them.

I masked off the terminal opening and the RS id tag on the rear. I then sprayed two coats of Krylon Acrylic all weather black gloss allowing an hour between coats. Its best to do this in a warm dry climate. cold and moisture is your enemy here.

I also did the same to the grills and the small brackets that hold the speakers to the wall. If you are going to repaint these, complete disassembly is the key to a good finish.

Here are some pics of the cabinets and parts in progress
 

Attachments

  • painted parts.JPG
    painted parts.JPG
    174 KB · Views: 1,217
  • painted.JPG
    painted.JPG
    148.2 KB · Views: 1,217
woofer repair

The surrounds on these were dried out and begining to show cracks in places. Rather than tossing them and trying to find the odd surrounds for these, I decided to repair what I had

I used some formula-2001 in the surrounds. This is similar to armaroll (sp?) but it is better suited for rubber parts. It actually does work well believe it or not. Spray a small cotton rag with it, rub gently on the surround a few times, let it sink in for 10 minutes, and repeat until they are no longer hard and dry. Wipe off any excess that is left behind.

Afterwards I used some clear rubber service cement specifically designed for speaker repair. Its called GC Service Cemet and can be found at most electronics supplies. Its also great for repairing tears and speaker cones. i applied a small amount in the cracks, wiped away the excess and let dry a minimum of 1 hr. Now the surrounds can flex as they did before without worries of breaking.

I also took some dark permenant ink and a very small brush, and gently applied it on the cones of the woofers in sections to bring back the dark color. It didn't turn out as even as I'd like, but it was much better than the patchy sun stained original look. You will see later on that it is un-noticable through the grills.
 

Attachments

  • surround repair.JPG
    surround repair.JPG
    71.4 KB · Views: 1,492
All finished.....

After all the paint dried, I re-assembeled everything and took some pictures. If you can only imagine the ratty looking, rusted out minimus 7s these once were, you can share in my joy of the finished product. Their only flaws are one of the emblums is missing and the rear ID tags are stil beat up looking.

I was glad I was able to rescue these. I don;t know what I'm going to do with them yet, but it was better than watching them get tossed.

Feel free to ask any questions if you need help fixing your 7s
 

Attachments

  • min7-nude.JPG
    min7-nude.JPG
    115.4 KB · Views: 1,749
  • min7-rear.JPG
    min7-rear.JPG
    86.8 KB · Views: 840
  • min7-right.JPG
    min7-right.JPG
    53.3 KB · Views: 816
  • min7-left.JPG
    min7-left.JPG
    65.3 KB · Views: 880
  • min7 front.JPG
    min7 front.JPG
    88.9 KB · Views: 974
  • min7-tag.JPG
    min7-tag.JPG
    64.7 KB · Views: 732
Gotta love those Minimus 7's. Any time I see a set at a decent price I pick them up.
You did an excellent job. :thmbsp:
 
NICE JOB...

I kept seeing post about minimus 7s and had no idea what they looked like... Now I do:)
 
Excellent job! That foam material on the baffle can be replaced with black "craft foam" which you can get at craft stores, and I think at Walmart.
 
OMI said:
NICE JOB...

I kept seeing post about minimus 7s and had no idea what they looked like... Now I do:)
Click to expand...
THere is also a more attractive version in a veneer cabinet. i think they used walnut.

BTW, thanks for the tip Paul. Nice to know that that can be replcaed easily.
 
I have one pair that have been beat up pretty good (before I got them) and I was thinking of just replacing the woofer with a full range 4" and disconnecting the tweeter. After seeing the work you did,especially with the woofer surrounds, I am now thinking that I'll give repair a shot. The pair I got had the grill smashed so that it was resting against the woofer surround and it kinda looks like that is what had happened to yours.

Thanks for the pictures and the work you did.
 
Here's some pics (though a bit out of focus) of the walnut version of the Minimus 7s, known as the W7s...
 

Attachments

  • m73245.JPG
    m73245.JPG
    121.6 KB · Views: 772
  • m73246.JPG
    m73246.JPG
    133.3 KB · Views: 1,555
OMI said:
NICE JOB...

I kept seeing post about minimus 7s and had no idea what they looked like... Now I do:)
Click to expand...


They came in white, too, under the Optimus label, and occasionally silver. I like the black, myself.

There was a larger version with 5 1/4" woofer, same tweeter, and much better bass. This was the Minimus 77, Optimus Pro-77, Optimus Pro-55AV (shielded woofer and poly cone). There was even a version (88?) with a horn looking tweeter.

A pair of 7's or 77's with a sub is a pretty good sounding system. And these are great for surround.
 
jpdylon said:
...Its called GC Service Cement and can be found at most electronics supplies. Its also great for repairing tears and speaker cones. i applied a small amount in the cracks, wiped away the excess and let dry a minimum of 1 hr. Now the surrounds can flex as they did before without worries of breaking.

I also took some dark permenant ink and a very small brush, and gently applied it on the cones of the woofers in sections to bring back the dark color. It didn't turn out as even as I'd like, but it was much better than the patchy sun stained original look. You will see later on that it is un-noticable through the grills.
Click to expand...

JP, do you think this would work well along a tear in foam? I've got some speakers with a split along the foam where the lip attaches to the driver cone- otherwise the foam is good.

and I second your idea on the re-dying of the cones- one could also carefully mask off the driver parts not to receive ink, and use an airbrush to apply the ink.
 
Nice job, Jordan! One thing that can happen on these speakers is the flexible wires that go to the voice coil can become intermittant or break. You can patch them or replace them with solder wick desoldering braid.
I have 2 sets of these speakers, one in white, one in black. You can pick these speakers up at garage sales for $10 or less. A super bargain! My inlaws have the Minimus 7Ws, I really like the look of those. Haven't seen those at a garage sale!
 
I have a pair of the Minimus 7W's. For a small speaker, the sound is quite good, don't expect earth shattering bass from a 4" speaker.
 
For those that don't know... the grills attach by pressing in. There are four little blobs of butyl rubber. This is uncured, a gray, sticky rubber material, almost like clay, but it holds together.

This would obviously be cleaned off for repainting.

Let me suggest using some blobs of E6000 glue to put the grills back on. If it is later necessary to remove the grills, they can be pried off. The best way is to stick a tiny precision screwdriver through a hole near an edge and pull gently. The clear rubbery E6000 will tear loose, you can peel off the old glue, and apply new when reinstalling the grill. This glue is also excellent for securing capacitors, coils, and other uses.
 
You must log in or register to reply here.
Back
Top Bottom