M70 power and low volume issues, radio not working.

[lewdawg]

Hey guys, been a long time! I recently acquired an M70 off eBay with a functional tape deck. But basically everything else doesn’t work. FM and AM radio produce no sound (not even static) I was able to find a very low volume short wave signal but that was it. Also the tuner dial seems all out of whack, you have to spin it a lot before it starts moving in a different direction and it has severely reduced range across the spectrum (will not travel down past 96)

When plugged into AC power or running on batteries the power light is constantly on, volume while running the tape deck is much lower when switched to the ‘ON’ position and volume spikes up when switched to the OFF position. The volume jumps around intermittently while in the off position but that’s the only way I can get any kind of substantial volume out of the unit.It’s still severely underpowered though and sounds like crap with barely any bass.

Volume, Bass and Treble sliders all do have a noticeable effect. VU meters right and left do respond to music. But when switched to ‘TUNE BATT’ the level barely gets past 20% when it should be all the way up when plugged into AC power.

Pressing the dial light button or program button will basically mute the music.

Ive taken the back cover off and sprayed the sliders with deoxit, as well as all input/output jacks and repeatedly plugged and unplugged them with an RCA and headphone jack (large and small).

The internals seems a little daunting to me to dig further.

What have I gotten myself into??

 

[Radio raheem]

I would send it back if i'm honest, the dead tuner i doubt is repairable unless it is something simple like it's not plugged into the main board....good luck what ever you decide

 

[lewdawg]

I would send it back if i'm honest, the dead tuner i doubt is repairable unless it is something simple like it's not plugged into the main board....good luck what ever you decide

I took another crack at it. Noticed some heavy flicking of the power switch would kind of kickstart the volume if you will. Took the back off and saturated the switch with deoxit. She’s running beautifully now. Dial light works, radio works, even the MMS program thing works, well, it lights up but I don’t fully understand how to get it to work properly. The power switch still does nothing though. So everything is working minus the OFF button!

 

[Radio raheem]

I took another crack at it. Noticed some heavy flicking of the power switch would kind of kickstart the volume if you will. Took the back off and saturated the switch with deoxit. She’s running beautifully now. Dial light works, radio works, even the MMS program thing works, well, it lights up but I don’t fully understand how to get it to work properly. The power switch still does nothing though. So everything is working minus the OFF button!

Never mind the off button lol.. Sir the hole point is to blast them and use them, glad you have sorted her that easily as this normally isn't the case

 

[lewdawg]

Never mind the off button lol.. Sir the hole point is to blast them and use them, glad you have sorted her that easily as this normally isn't the case

I’d tend to agree but I would like to get a strap for it and carry it around this summer. Would like to be able to turn the thing off without having to pop the D batteries out haha. Also noticed I’m getting some static when I touch the metal panel below the tuner around the MMS program area. Bad ground?

 

[lewdawg]

I’d tend to agree but I would like to get a strap for it and carry it around this summer. Would like to be able to turn the thing off without having to pop the D batteries out haha. Also noticed I’m getting some static when I touch the metal panel below the tuner around the MMS program area. Bad ground?

Also just noticed it only buzzes if I touch that metal panel when it’s in TAPE mode. I’m assuming the last person to service it forgot to re attach the ground wire from the deck?

 

[hopey]

It the power / sleep switch is not broken? Then you can clean the contacts with fine grade sand paper. This can fix the sleep function which is also Radio off.

 

[hopey]

Also just noticed it only buzzes if I touch that metal panel when it’s in TAPE mode. I’m assuming the last person to service it forgot to re attach the ground wire from the deck?

There are a couple of ground points, one from the front casing though the chassis to the Main PCB. There is another on the back case, foil shield to the Main PCB.

 

[lewdawg]

It the power / sleep switch is not broken? Then you can clean the contacts with fine grade sand paper. This can fix the sleep function which is also Radio off.

Yeah I feel like the contacts are constantly touching which is why it’s powered on no matter what position the power switch is in. It’s not broken, I do see movement in the leaf spring when I move the switch. I’ll dig a little deeper.

 

[lewdawg]

Update! Removed the leaf switch for the power button, fiddled around a bit and now it’s working as it should. Can’t believe all those issues were attributed to one small switch! Box is loud and proud once more!