Millermatic 135 Control PCB Schematic

[hemi-1]

Found Q5 2N6388 Darlington pair transistor defective. Replaced. Motor speed now works but only with voltage control, not the WFS control. Will be looking at Zener diode D6 next out of circuit along with a few other discrete components as its likely Q5 degraded other components as well.

[hemi-1]

Well I got the service manual, with PCB schematic, but now there are no component values nor part numbers for any components. Unreal. Trying again...

[Aeronca41]

Super! Anxious to hear how it goes.

[hemi-1]

Thanks to all for your help. I received the schematic from an Ebay source thanks for this forum. Will let you know what I find on this control PCB when fixed.

[hemi-1]

Cruizer, I will tomorrow. Thanks, and thanks to all replies. Correct, working on surface mount technology is a far cry from basic semiconductors.

[cruizer]

email me: [email protected]

[ryanjones2150]

Ya man, sorry. If these guys here can't help you get this thing figured out, it probably can't be figured out. There's a lot of knowledge on this bunch, myself excluded. I bet somebody here knows where Jimmy Hoffa is.

[Aeronca41]

See you just never know what you might learn from all the brilliant minds here!

Meltedmetal, that was just great!

Sorry, hemi, we know you're trying to be serious here. Don't mind us.

[ryanjones2150]

Holy smokes! I never knew....

[Meltedmetal]

50+ years?!!<br />
<br />
...I didn't realize they had electricity back then...

They caught lightning bolts and kept them in a hair lined bag with a tiny,tiny hole so only a little got out at a time. That was later than the rubbing the cat thing. You've heard the saying "Letting the cat out of the bag." That's where it comes from.

[Aeronca41]

Yeah-you had to make it yourself by rubbing a cats back with some high-dielectric strength cloth-and the cat usually didn't like it. :-)

hemi-did you get any info on that manual? I'm thinking it will be what you need.

[ryanjones2150]

50+ years?!!<br />
<br />
...I didn't realize they had electricity back then...

[Aeronca41]

Aeronca41, you may be right. I overlooked this is not an Owner's manual but a Technical Manual. I will contact the seller to see if the control PCB schematic is included. Thanks!

Generally the Tech Manuals do have schematics; owners' Manuals, as you say, have rather useless block diagrams which aren't much help for component level repair. Hope this works out for you.

I hear you on fixes. I've been fixing things to the component level for 50+ years, up to and including mainframe computers, and find it very frustrating when I have to end up drawing my own schematics from the boards. That, of course, has become increasingly impossible with everything integrated into processor chips or gate arrays now, not to mention no longer having access to the necessary surface mount and hot air soldering equipment since retiring. Good luck.

[hemi-1]

Aeronca41, you may be right. I overlooked this is not an Owner's manual but a Technical Manual. I will contact the seller to see if the control PCB schematic is included. Thanks!

[hemi-1]

Thank you for your input. That Technical Manual contains a basic block diagram schematic, not the control circuit board schematic. I have this manual. I will not buy a circuit board as I will fix mine with/without the schematic. Have been repairing electronic PCB's over 25 years.