M70 good and bad!

[gregoryj16]

i had a m70 with the same problem, and I found it to be the contacts of the power switch, open the back and check the contacts when you switch the power on and off. I thought it was the amp, but it was the contacts of the power switch.. hope it does the trick.

 

[Northerner]

i had a m70 with the same problem, and I found it to be the contacts of the power switch, open the back and check the contacts when you switch the power on and off. I thought it was the amp, but it was the contacts of the power switch.. hope it does the trick.

Thanks Afraid I've cleaned every switch in it but no change. I'm taking it to a much more electronically skilled forum member on Saturday to see if he can sort it so keep your fingers crossed for me!!!!!

 

[blu_fuz]

i had a m70 with the same problem, and I found it to be the contacts of the power switch, open the back and check the contacts when you switch the power on and off. I thought it was the amp, but it was the contacts of the power switch.. hope it does the trick.

Greg, do I know you???? PM sent

 

[mrp32]

Just had thought on your M70 problem, have you checked the external speaker sockets, if these have poor connections they effect the internal speakers and the headphone output

 

[Northerner]

Thanks for the tip but I've literally just 10 minutes ago dropped it off with Docs to see if he can work his magic on it so I'm keeping my fingers crossed that he'll work out what's wrong with it

 

[BoomboxLover48]

Thanks for the tip but I've literally just 10 minutes ago dropped it off with Docs to see if he can work his magic on it so I'm keeping my fingers crossed that he'll work out what's wrong with it

I'm pretty sure Docs will bring it back to life!

 

[Northerner]

I really hope so as I love this machine!!!

 

[docs]

Looks to me like that slider is indeed the problem.
The resistance across either end (pin 1 and 3) is none existent. The slider is supposed to be a 50k ohms resistor, there is 22.3 from the middle pin (pin 4) and one side with zero resistance from the middle pin to the other side.
From the mid point to either side is supposed to be 25k ohms and from one end to the other 50k ohms.
With only one side working I conclude that one side of the slider is shot.
Trying to locate a metallic pen to increase the distance Northerner previously marked as there is no contact being made I don't think.

 

[Northerner]

...and the conclusion from this is....

that the owner doesn't have a clue what he's doing! I said I hadn't a clue how to use a multimeter and now you know I wasn't joking

I think I need some lessons or the Horowitz and Hill book

Thanks for the work you're putting into this Dave, it's REALLY appreciated

 

[docs]

Si what did you use in the first place ?
I have bought a metallic silver pen but I am not sure if it is conductive.

 

[Northerner]

Si what did you use in the first place ?
I have bought a metallic silver pen but I am not sure if it is conductive.

I got a tiny pot of silver conductive paint from maplins, it's actual silver in a suspension in a kind of varnish. It's says it's for repairing breaks in circuit boards etc. it was a tenner for a few ml but it'll go a long way. I read that you can get it in pen form too

 

[docs]

I just saw that too but after spending a fiver on pens I'm disappointed I can't fix it, close it and have it done with

 

[Northerner]

I'll reimburse you for whatever you've spent mate! I've got the silver paint at home so if I know where to apply it I could do it. Then if you tell me where I should've measured the resistance (I was clearly doing it wrong!) then I can make sure it's right. What do you reckon?

 

[docs]

I'll buy the stuff no problem, just wish you brought it with you
Now I have it all open and ready to do I'd prefer to fix that and make sure there isn't any other issue presents itself.

 

[Northerner]

Cheers Dave, you're a star Yeh, didn't think to bring it with me as I thought I'd eliminated the slider as the cause, d'oh!

 

[docs]

By the way Si, I think that there is a problem with one of the record level sliders too but to be sure I'll clean and treat all of them while I'm in that section. One at a time.

 

[Northerner]

Whoever invented sliders wants shooting! :grim:

 

[Fatdog]

Whoever invented sliders wants shooting! :grim:

Knobs are way better than sliders.

 

[docs]

All fixed.

The resistance is a little less than the other slider unfortunately so that channel is slightly louder than the other, but with sliders, you can normalise easily

This m70 booms again.

 

[Northerner]

OMG! Dave you are a blooming hero!!!!



Can I pick it up tomorrow then?...when are you in?

Thanks Dave!