Fixing metal trim on face of radio!? (SANYO M-X920)

[ScottSpeed]

Greetings again wonderful people!! Hope you all are having a wonderful Saturday!

So on to the item in question. I have a Sanyo M-X920 that has the portion of trim in between the dial window and speaker where the metal trim reaches out to each side of the face of the radio. My trim seems to have came unglued and then it looks as if someone pressed on it to seat it again and it kinked it? Maybe I'm not sure the proper term.

Anyhow I'm included photos of the spot and I hope you all can see it well enough.

I'm going to make a little block of wood that's just big enough to sit on top of the trim and only the trim and then I'll clamp it after putting some glue? Using one of those long jaw clamps. Don't know the name but quick release C clamp? Haha?

Thank you good people!!

 

[floyd]

You could also try using a pencil eraser and use the eraser to push down on the metal where the high spots are to try and make it as flat as possible. This metal tends to stretch because it's so thin . it looks like someone tried to remove it.
I also advise to tape around any areas you are working on.

 

[BoomboxLover48]

Very careful when one work with any metal tool using force because the plastic dial glass can get easily damaged. Once the Al is somehow stretched there is practically no way to bring it back to normal.
Damage is already done!
Glueing might help to some extent and for that use a rigid and straight wooden piece of the same width wrapped in masking tape.
Hold it in position and pressed firmly in place till the glue hardens.

 

[Superduper]

That is a very common problem with boomboxes. The well renowned Toshiba RT-S90’s dial trim is kinked all over the place on every example. It’s because the plastic shell has shrunk over the years but the metal trim, being metal, doesn’t shrink. Frankly I don’t think you will be successful trying to pinch and glue it back if experience with the Toshibas are any indication but plastic shrinkage is the cause.

 

[BoomboxLover48]

I have a Crown CSC 850 with the same problem! If I try to warm the top panel with heat gun to soften the glue, then plastic might get deformed. If I try to pull the metal it will get wrinkled and stretched. Plastic deformation temperatures low on the types used in boombox construction at that period of time.
Dipping in water at 35C might soften the glue but I didn't try that without deforming the plastic.

I just left it alone!

 

[BoomboxLover48]

That is a very common problem with boomboxes. The well renowned Toshiba RT-S90’s dial trim is kinked all over the place on every example. It’s because the plastic shell has shrunk over the years but the metal trim, being metal, doesn’t shrink. Frankly I don’t think you will be successful trying to pinch and glue it back if experience with the Toshibas are any indication but plastic shrinkage is the cause.

Adhesive technology was not at its best when these boomboxes were made. I believe the adhesive was hardening and shrinking over a period of time and not the plastic. One can see the same phenomenon if you look at the dial plate of M90. The glue hardened and grabbed the adhesive applied spots under the dial plate. One can see that from the front glass of all M90s. The defect is telegraphed to the dial plate from the bottom.

 

[floyd]

Adhesive technology was not at its best when these boomboxes were made. I believe the adhesive was hardening and shrinking over a period of time and not the plastic. One can see the same phenomenon if you look at the dial plate of M90. The glue hardened and grabbed the adhesive applied spots under the dial plate. One can see that from the front glass of all M90s. The defect is telegraphed to the dial plate from the bottom.

I thought it was just me but I too noticed that wavy effect on the tuner scale of most m90's.
That would also explain why the top trims always pop up on these and you can almost never get them perfectly flat again.

 

[Superduper]

I agree about the adhesive not being the best. Or maybe the adhesive is fine but the boomboxes just way outlived their original product design. Regardless however, I am quite certain that the plastics have shrunk. Anyone who's had a gear or other part split will understand what has happened. A plastic gear that's wrapped around a steel shaft that shrinks will cause the plastic part to pinch ever tighter but since the metal shaft in the center is unforgiving, then the plastic will split because of shrinkage. Similarly, a thin aluminum sheet laminated over plastic underlayment, where the plastic (thicker) material shrinks means that the longitudinal dimensions between the 2 parts will no longer comport. The result is that the aluminum sheet will get pulled together by the shrinking plastic base hence the bulges. It is hard for the plastic to pull the metal in the wider areas, but the narrow areas is typically where the bulges will occur, and it's almost always along the tuner window where the metal trim is the narrowest. If you want a demonstration, just take a sheet of paper and push the two ends closer together to simulate the plastic shell shrinking ever so slightly. The extra paper material will have nowhere to go so it will bulge. The theory about the adhesive failing causing the owner to pull the metal causing the kink only holds water if it was actually done. That theory requires the presumption that the owner actually did something to cause this. However, I've had boomboxes that I've owned for decades and saw this happening over the years, with no attempt to do anything with the trim. Finally, if you look at the trim, you will notice that the raised areas are really bulges (extra material with nowhere to go) as opposed to kinks. I bet you'll also find that the trim, if measured flat actually will be longer than the areas they are supposed to be adhered to.

 

[BoomboxLover48]

I think the plastic shrinkage theory is less pronounced in many cases where metal plate is detached with defects. If by any chance the linear shrinkage of plastic was dominant, then the JVC M90 top metal trim would have bulged out. I haven't seen the top trim of M90 bulging out and the track in the plastic always fitted the very same panel all the time. The combined end clearance on both sides is less than 1.0 mm.

 

[Ghettoman]

i have had 2 RT S90s and it happened with both of them, always in the same place, in the centre under the tuner, i still have one of them with that problem, i was thinking of fixing it but in the end i just left it, the problem with it now though its developed a crackle in the right channel while playing a tape, and it isn't the switches as the crackle is uniform, not random.