M-70 smoked cap

dd123

Active Member
I have read some posts about a known problem cap in the M-70 and I think I have first hand experience with the one I just got. The C607 cap on the control circuit board smoked and stunk up a storm. Picture shows the cracked shell.

Is 667-ECQ-U2A224KL still the preferred replacement part?
Is there any trick to getting the control circuit boards out of the chassis?
 

Attachments

  • blown cap on control circuit bd.jpg
    blown cap on control circuit bd.jpg
    51 KB · Views: 65
Is there any trick to getting the control circuit boards out of the chassis?
Yep. Heres my secret.Keep it under your hat! Read the manual..under disassembly..
 
:D Okay wiseguy, I had to laugh. :beerchug:
I read the service manual disassembly section before posting. Unless I missed something, it goes over removing top, bottom, and front panels, VR circuit board, meter circuit board, power circuit board, electrolytic cap circuit board, and power transistor replacement. But I didn't find anything on removing the control circuit board pair. Am I blind?
 
As your looking from above the top. 2 black plastic rivets hold the top bracket thats securing the boards(sheets) in place. Remove the rivets (rear side of the bracket), by pulling up on the center pin in the rivet. Once you get the pin about half way out the entire rivet will come loose.
Remove the bracket.Look at the base of the vert. panel next to the power transformer. There are two small screws- remove them.
Next look at the rear of the bottom circuit board . Remove the screw at the end closest to the side of the chassis. On the opposite side of the same board there is a white nylon standoff pin. Pinch this pin with a pair of needlenose pliers and slowly rock the board upwards off the standoff pin.You should now be able to roll the two-sheet assembly towards the side of the chassis for further disassembly thats pretty evident as to how to gain access to the solder side if required.
 
Last edited:
Great. Thanks. I hope to get to it tonight.

I notice in your "signature" that you have NS-1000's. Are they amazing?
 
Rolling the board pair out of the chassis works fine. Neat trick. I wouldn't have thought that would work with all the wires there.

Does the M-70 have other weird caps like C607 that should be replaced?

Also, I'm considering replacing all electrolytic caps on all boards. Is there a parts list anywhere that lists available replacement parts for doing that?
 
Back
Top Bottom