Tandberg 3001A Buttons Springs Oh my!

[CharleyP]

I took apart my 3001A to fix a stuck tuning system, which seems to have been successful.
(I pulled out the piece in the middle and sprayed various cleaners and oils while gently turning. It barely could move before and now moved in response to the tuning dial. Rewinding the string confused me a bit, but it got done. I just moved everything to the far left and got the string tight there, and then wound the other end by turning the black spool thing)
Problem is, I took off the front and back covers and had numerous buttons and springs fly out. The preset buttons don't seem to use springs. I put springs in the four buttons to the right and they seem to be working, but that was all the springs I found.
Now the power knob works only if I hold it in: it goes on when pushed, but comes out and the unit goes off when released. Did I lose a spring? How is the power button supposed to be configured?
I hope John will answer cause you seem like an absolute Tandberg tuner master!

 

[Riley Casey]

Post a picture of the switches in question. If they are Schadow switches then yes they have springs to return them to the released position.

 

[CharleyP]

I took apart my 3001A to fix a stuck tuning system, which seems to have been successful.
(I pulled out the piece in the middle and sprayed various cleaners and oils while gently turning. It barely could move before and now moved in response to the tuning dial. Rewinding the string confused me a bit, but it got done. I just moved everything to the far left and got the string tight there, and then wound the other end by turning the black spool thing)
Problem is, I took off the front and back covers and had numerous buttons and springs fly out. The preset buttons don't seem to use springs. I put springs in the four buttons to the right and they seem to be working, but that was all the springs I found.
Now the power knob works only if I hold it in: it goes on when pushed, but comes out and the unit goes off when released. Did I lose a spring? How is the power button supposed to be configured?
I hope John will answer cause you seem like an absolute Tandberg tuner master!

I just took off the front cover again. The power button seems to work fine inside: push in and it clicks and stays there, push in again and it clicks and comes out. I'm wondering why it would not stay in when I put the front face and the silver button on?

 

[CharleyP]

I just took off the front cover again. The power button seems to work fine inside: push in and it clicks and stays there, push in again and it clicks and comes out. I'm wondering why it would not stay in when I put the front face and the silver button on?

Here is me holding the exterior button. The interior button is right above.It seems to work fine.

 

[CharleyP]

Ah hah! That button on the left (the correct power button) is a little bit longer than the other four. It works now! Now, on to the next problem

 

[Riley Casey]

A not uncommon problem with thru panel switches like this is that the button can bind against the panel opening. Even a slight bit of friction can be enough to over come the return spring force. Check this on all of your switches before final tightening of the fasteners that hold the panel in place. Also if you even loosened the screws holding the power switch to the chassis panel that might have moved the switch enough to bind as well.

 

[jdurbin1]

None of these switches should ever have binding issues, sorry. The presets are all tact switches that do not pass through anything, they have the metal buttons shown above that also have small coil springs fitted between the larger diameter part of the button, and the face plate. Those coil springs provide ALL of the return force to make the buttons stay sticking out other than when you press one. There's also a small foam sheet in between the 8 preset buttons and the plastic plungers of the actual tact switches. That foam may have deteriorated with time, if so make a replacement from some light 1/8" foam sheeting - just cut it to the same size and use a solder tip you don't mind getting some melted foam on to poke the holes for the alignment pegs that pass through the foam sheet to locate it in place.

The button for the power switch is *very* slightly longer than the 8 for the presets, so make sure you get it in the right place. If you mix it with the presets the power button won't stick out as far as it's supposed to which may prevent you from getting it pushed in enough to toggle the power switch detent. Also, it may be too short to let you push it in far enough to toggle the on/off position which appears to be the case here. Take that button out and compare it to the other 8, you will find one is longer and that goes in the power position. Update: ah, I see the OP figured this part out - excellent. I skimmed past that the first time.

The power switch does have two positions but it's the coil spring between the button and the faceplace that keeps the button "in" when the power switch is on, not the actual plunger part which has it's own captive spring as seen in the picture - that one makes the detent mechanism work, but the metal button moves freely on its own controlled only by its own spring to the faceplate, and the depth that the power switch plunger allows it to have.

The coil springs should be be identical but there are nine of them so you will need to sort out some kind of replacement for any of those that you launched and can't find, if you want it to work properly.

Note: Please, NEVER spray or apply lube to the tuning mechanism. It is a dry-fit nylon part spinning in a cast metal frame, and anything you put in there will screw it up royally eventually if not very quickly. There is a breakage issue with the nylon part that causes the mechanism to get stiff or quasi-one directional with age, and lube will not fix it, in fact it makes it worse as some of them will make the cracked plastic part swell up and bind even worse. Contact me for specific repair direction if you run into one of these.

John

P.S. Riley, not to be an ass as I can see you're trying to be helpful but I seem to run into your off-target advice in these Tandberg threads more often than not - do you actually work on the pieces you comment on, or? In general I find if I don't have personal hands-on expertise with the subject, I try and not throw best guesses out there, or at least say so when I'm not more familiar with the subject. In this case, there is literally no way to have friction inhibit the metal buttons unless you've filled the hole with glue/grease/something sticky. It's the missing springs causing this problem.

 

[Derkk]

None of these switches should ever have binding issues, sorry. The presets are all tact switches that do not pass through anything, they have the metal buttons shown above that also have small coil springs fitted between the larger diameter part of the button, and the face plate. Those coil springs provide ALL of the return force to make the buttons stay sticking out other than when you press one. There's also a small foam sheet in between the 8 preset buttons and the plastic plungers of the actual tact switches. That foam may have deteriorated with time, if so make a replacement from some light 1/8" foam sheeting - just cut it to the same size and use a solder tip you don't mind getting some melted foam on to poke the holes for the alignment pegs that pass through the foam sheet to locate it in place.

The button for the power switch is *very* slightly longer than the 8 for the presets, so make sure you get it in the right place. If you mix it with the presets the power button won't stick out as far as it's supposed to which may prevent you from getting it pushed in enough to toggle the power switch detent. Also, it may be too short to let you push it in far enough to toggle the on/off position which appears to be the case here. Take that button out and compare it to the other 8, you will find one is longer and that goes in the power position. Update: ah, I see the OP figured this part out - excellent. I skimmed past that the first time.

The power switch does have two positions but it's the coil spring between the button and the faceplace that keeps the button "in" when the power switch is on, not the actual plunger part which has it's own captive spring as seen in the picture - that one makes the detent mechanism work, but the metal button moves freely on its own controlled only by its own spring to the faceplate, and the depth that the power switch plunger allows it to have.

The coil springs should be be identical but there are nine of them so you will need to sort out some kind of replacement for any of those that you launched and can't find, if you want it to work properly.

Note: Please, NEVER spray or apply lube to the tuning mechanism. It is a dry-fit nylon part spinning in a cast metal frame, and anything you put in there will screw it up royally eventually if not very quickly. There is a breakage issue with the nylon part that causes the mechanism to get stiff or quasi-one directional with age, and lube will not fix it, in fact it makes it worse as some of them will make the cracked plastic part swell up and bind even worse. Contact me for specific repair direction if you run into one of these.

John

P.S. Riley, not to be an ass as I can see you're trying to be helpful but I seem to run into your off-target advice in these Tandberg threads more often than not - do you actually work on the pieces you comment on, or? In general I find if I don't have personal hands-on expertise with the subject, I try and not throw best guesses out there, or at least say so when I'm not more familiar with the subject. In this case, there is literally no way to have friction inhibit the metal buttons unless you've filled the hole with glue/grease/something sticky. It's the missing springs causing this problem.

I was looking and I found the service manual for the 3001a on https://www.trading-247.com