Restoration One 465B

After power it up,  sweep trace and calibrate signal is good enough, this is a good sign. First several problem include some band switch sticky,  or it cloud not be locked properly. and several broken plastic knob.

The plastic friendly version of WD-40, the silicon lubricant is good enough spry to clean up the switch's plastic parts, and restore it's functionality. But while i finally reach the WD-40, I use pure alcohol wash everywhere  had suspicious contact problem.

Speak of broken knob, I use super glue sticky them together, of course i wash them use ultrasonic cleaner. I made a bad decition to ultrasonic clean the Div knob, the printed character on it is gone, because i use pure alcohol.

Now the tricky part of fixing was coming.  The several Div band is definitely wrong. the  0.5V, 1V, 2V attenuation position is lossing it's functionality every time in a while.  The wave forum on screen is much pretty much same as it's on 50mV. and the raising edge is a ramp not a step.

Obviously the 0.5V, 1V, 2V had  a common part, that's X10 thick film attenuation module.  While DIV on 50mV(X10 probe), there is no attenuation at all, then series with a X2 module get 0.1V range, then series with  X4 get 0.2V, while switch to 0.5V,  X10 module series in. on 1V series with X10 and X2.

Now the X10 is definitely the buggy one.

First thought it's should be some contact problem,  so i clean every module by the ultrasonic cleaner. then plug them back in the socket.  I pretty much believe i fixed them by then. but then, while the machine temperature arise, problem comes back again. 

So i did lots of touch and poke, try to sort out the problem. I found if the temperature arise more, i.e, i blow them by a air dryer,  it will became good.  and if i wiggle the attenuation board, it became good now and then.  If i take off the shield, most of time it's good.

Then I suspect there is some dry joint in the thick film module. checking them by DMM confirming it. refer following pictures, three of them had one dry joint. both them had a big blobs of tin there. the good soldering joint don't need that much tin, it's need good flux.

While fix the dry joint. This 465B is recovered.