Power switch
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If you look carefully at my switch, you will see the hoop has a small hole and I think the tip of the flat part inserts into that hole. On your photos of your switch, I can't tell if it's the same way because I don't see the tip of the flat blade protruding from the end of the hoop. Once again, depressing the tongue causes the top and bottom blades to flex at a different rate, and the bottom will compress and the hoop will deflect and push up the contact. The length of that assembly is critical. If the switch was modified or something, it will affect the operation. This is why I say not to mess with stuff unless you know for sure that there is an issue. Messing with parts that are obsolete if nothing is wrong will cause you huge headaches to resolve later. At this point, take a closer look at that switch. Make sure that it is "exactly" like the photos that I sent you. If the blade is depressing the hoop but not at that hole, then the length might be long enough to cause it to deflect. Things break, things get tweaked. This boombox is probably close to 50 years old now. Spending tons of brain cells trying to determine the cause of something that happened years or decades ago is not a good use of your time. Spend that time just correcting the issue. If the switch got tweaked and that blade tip is no longer in the hole of the hoop, carefully correct it and hopefully fix it. Otherwise, if you search for leaf switch or micro switch, you might be able to find something that you can rig up to perform the same function. Or maybe someone has a parts box that they're willing to offer parts from.
the blade tip is in the opening like it’s supposed to be. Is this an electro magnet or does it purely moves by spring bent metal?
I can do that and probably will in the morning but I already know contact is being made. When I push the leaf down with a pick it turns the motor off and when it springs back up it runs again.
Now if this has some magnet that’s supposed to pull the leaf down then it may be too dirty or something. I think it’s springing in the wrong direction.
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About 20 years ago, I messed with the power switch on an M70, which is similar to the deck switch. It wasn't working right and I tried to "re-curve" that middle leaf. All I know is it sprung apart, bits were flying and the switch became trashed. It's a lesson I learned the hard way, and which I'm sharing with you. Your luck might be different -- it's your boombox, you take the risk.
You have to understand how the switch works. No magnets are involved. It's purely mechanical and probably engineered to work with critically shaped pieces of metal. Alter something and it's just not going to work right anymore. If you look at my photo of the switch in the relaxed state, you'll see that the upper leaf has a curve to it. Yours is lacking that curve and is pretty much flat. Perhaps someone saw that and tried to "straighten it out" or perhaps it's from the play key being pushed down and left that way for decades in a garage. Who knows. If there is a leaf to be bent, it's not the middle spring, it might be the top leaf but honestly, there isn't much room to bend it without affecting other parts of the switch. It may seem counterintuitive, but you can use a pick and try to push up on the tip of the top leaf -- I'll bet you the middle leaf will suddenly straighten out and disengage.
BTW, back on post #26, I already advised you about your problem, with the switch. Instead you got distracted with wheels and solder joints close together and clicking, and melting obsolete plastic parts, and sanding switches.... all good for chasing your tail and wasting time going nowhere. But it's now post #46 and we're still talking about the switch which is something you need to fix first. As for the clicking, consider the following scenario: if the deck is running, without a tape in the chamber, the autostop sensor will notice that no tape is moving and probably trigger the stop-solenoid to turn the deck off. Except it can't turn off because IT'S CONSTANTLY POWERED ON by a malfunctioning switch so it continually tries to activate the autostop solenoid with each revolution. You know what a solenoid sounds like right? It's a CLICK. Ok, I'm not saying for sure this is the problem. But it's entirely plausible and until you fix your problem, you'll never know. Well, actually, if you install a tape in the chamber, and the click goes away, this pretty much confirms it. Also, you can power the solenoid yourself with a 9v battery (just a quick intermittent to avoid burning it out as it's not meant for continuous application). If the click sounds familiar, then you know the source of your clicking.
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hopey
Member (SA)
For what it's worth I think you have a simple voltage drop across the contacts. I fixed an M70 by cleaning the contacts, this restored the music search function which I think is the problem. All you need to do is cut a piece of fine grade sand paper 5cm x 5mm and fold in half lengthways so you have two abrasive surfaces. You gentle slide this in between the closed contacts and work back and forth carefully. The contacts are silver plated brass over time they will arc and pit reducing the contact area and creating a voltage drop which you don't want.
That sounds very plausible and I will carefully clean those contacts. I don’t think it will fix the tape switch but I’ll try anything atm.
thanks so much for hanging in there with me.
this is all great info. I won’t try to bend anything atm. Thanks for finding my switch is broken. I was trying to learn how The thing works before I try anything. When the middle leaf is pushed down the top one get the upward curve you described.
I will concentrate on fixing or replacing the switch first.
Tinman
Member (SA)
I'll chime in on the cracked plastic spring retainer.
I had an M70 and an M71 and both were cracked and loose.
Take it off, clean the shaft and the plastic retainer really well.
Put a drop of super glue (I'm partial to plain old Krazy Glue) on the shaft and push the retainer back on until it's flush with the shaft.
I put another drop around the tip of the shaft and tried to get some into the crack then let it dry really well.
I never had any problems after fixing them this way.
It retains the spring that puts pressure on the clutch below it.
There's a step adjustment that puts more or less pressure on the clutch depending which step the metal disc is set on.
I had an M70 and an M71 and both were cracked and loose.
Take it off, clean the shaft and the plastic retainer really well.
Put a drop of super glue (I'm partial to plain old Krazy Glue) on the shaft and push the retainer back on until it's flush with the shaft.
I put another drop around the tip of the shaft and tried to get some into the crack then let it dry really well.
I never had any problems after fixing them this way.
It retains the spring that puts pressure on the clutch below it.
There's a step adjustment that puts more or less pressure on the clutch depending which step the metal disc is set on.
I did just that, thank you.
It actually had popped off after I adjusted up to notch 4. I now have it back to 1st position and all is well.
And….. I bent it. After looking at all the pictures of my switch vs superduper’s working switch, I decided the U shaped copper piece is doing the pushing up and pulling down. I noticed the sharp break angle as it came out of the black plastic was less on mine. So I took it off, I warmed it up with a lighter and bent it back a little. It worked, it pushed the middle leaf down, but it was too much. It now wouldn’t make enough contact with the top leaf. A little push with the tooth pick and it ran.
So I went back and forth a few times trying to find the right angle and decided to add a piece of wood to support the upper leaf and all is well. I might go back in there and try and do it right but should probably leave it alone.
All the other problems, the clicking, the humming are gone.
The box is back together and so far so good.
one weird thing I noticed this morning was, with the power off and in radio mode, if I press down any tape player button, the radio plays.
not that worried about it, I consider it a magic trick.
So, this isn’t a victory lap because I’m sure other problems will arise, and this isn’t goodbye because old boomboxes keep showing up at the house.
I really want to thank you all for helping me out and for your patience. All the information you shared is golden, I’ll continue to re-read and make sense of it all as I learn along the way. I’ll post a vid of the box bumping soon. Max
So I went back and forth a few times trying to find the right angle and decided to add a piece of wood to support the upper leaf and all is well. I might go back in there and try and do it right but should probably leave it alone.
All the other problems, the clicking, the humming are gone.
The box is back together and so far so good.
one weird thing I noticed this morning was, with the power off and in radio mode, if I press down any tape player button, the radio plays.
not that worried about it, I consider it a magic trick.
So, this isn’t a victory lap because I’m sure other problems will arise, and this isn’t goodbye because old boomboxes keep showing up at the house.
I really want to thank you all for helping me out and for your patience. All the information you shared is golden, I’ll continue to re-read and make sense of it all as I learn along the way. I’ll post a vid of the box bumping soon. Max
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Tinman
Member (SA)
Some boxes work that way, the M70 might be one of them.
I have an Aiwa coming today and a Panasonic tomorrow.
I keep thinking "just one more", it's a terrible sickness.
It's not a magic trick. The switch that you tweaked is possibly now out of calibration. The tape deck has its own power switch that is completely separate from the main power switch. When you tweaked it, it is perhaps too sensitive now so it is now turning on with the slightest pressure (normally, the keys need to be depressed all the way down). This turns on the amp too (otherwise, there will never be any audio from the tape deck when it's playing without turning on the power).
In fact, this is also known as a sleep function feature whereas you can play a tape with the set in radio mode, and it will automatically shut off at the end of the tape, duration depending on the tape length. Normally the tape key would need to be depressed fully but yours could now be too sensitive which is why it’s turning in with just slight pressure although as long as it’s shutting off entirely with keys up, it should be fine.
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Good info. I did say press and not depress. I guess I meant depress. Pressed all the way down and engaged. But yea. Instead of tape it plays radio because I have radio selected and with the power off. I think I get it. If tape was selected tape would work. I put it back together last night so I haven’t had much time to run it. I should probably go easy on the volume at first ? ? This thing sat for a very long time.
pap
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pap
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