Help with MKIII Repairs

[Guitar Adjuster]

My MKIII recently quit working. No power. I get power at the rear outlet, and at the fuse (which is good) and power at the 3-way ground lift switch on the left side but only on the middle terminal when the toggle is set to "B", there is power going to the cap on the power terminal but the main power switch gets no power. The green varisitor looks OK. No power at the fan outlet. I am thinking that the ground lift toggle has gone bad....

I posted some photo's here:

http://s43.photobucket.com/albums/e397/AllenJ7572/

Thanks for any help.

Allen

 

[Boogiebabies]

That's one early MK III. I wonder if you are getting any voltage to the plates through the standby switch/choke. In most case, when the secondary will not power up, there is a bad gound somewhere.

 

[Guitar Adjuster]

That's one early MK III. I wonder if you are getting any voltage to the plates through the standby switch/choke. In most case, when the secondary will not power up, there is a bad gound somewhere.

It is marked 1/85 with a + sign and MB by the power switch. It looks like some resistors were changed on the board as they are not all the small blue metal file ones? Anyway, if I bypass the ground switch and verisitor it will power up and all the tubes will light up, power indicator lights up, heaters work, etc. So I am thinking that the ground lift switch went bad? Anyone had this happen?

Allen

 

[Boogiebabies]

Sir, you have one of the very first MK III's ever made. It coincided with the IIC+ production, hence my belief of why you have a + above the power cord. Is there any chance you would divulge the serial number, or the first four digits?

I would blast the ground switch with contact cleaner to see if it's not all dusted and gummed up. I have never had one go bad.

 

[Guitar Adjuster]

Sir, you have one of the very first MK III's ever made. It coincided with the IIC+ production, hence my belief of why you have a + above the power cord. Is there any chance you would divulge the serial number, or the first four digits?

I would blast the ground switch with contact cleaner to see if it's not all dusted and gummed up. I have never had one go bad.

16234 is the serial #, will give the switch a good cleaning......

 

[Boogiebabies]

Those carbon film resistors are stock. They match late IIC+ production identically.

 

[Guitar Adjuster]

Well, I can't seem to figure out the problem so I called Boogie and got an RA #.