Hi,
I have taken on the challenge of recapping a Revox a77 mklll. After completing each stage and testing, I finally progressed to the basis board on which all controls and switches are mounted.
After completing the recap of this section, the machine does not switch on at all. Even with power bypass pins inserted and remote dummy plug in place.
I have tested the power switch and get 240v on the orange and black wires going into the switch, but no or very low voltage across the blue and white wires that supply the transformer.
Could something have become dislodged in the switch mechanism when the sliding rail was removed? Or has the switch simply failed due to age? Or, have I overlooked something?
I have taken on the challenge of recapping a Revox a77 mklll. After completing each stage and testing, I finally progressed to the basis board on which all controls and switches are mounted.
After completing the recap of this section, the machine does not switch on at all. Even with power bypass pins inserted and remote dummy plug in place.
I have tested the power switch and get 240v on the orange and black wires going into the switch, but no or very low voltage across the blue and white wires that supply the transformer.
Could something have become dislodged in the switch mechanism when the sliding rail was removed? Or has the switch simply failed due to age? Or, have I overlooked something?
Attachments
Fuses test good. 240v measured between orange and black wires. But intermittent low i.e 12-13v or no reading at blue and white, even when switch is rotated.
With a multimeter, analog or digital are the same, and the thing unpluged from mains, check continuity of the switch sections, primary of the transformer, fuses, etc. Depending on the transformer size, for 220 or 240ACV it must measure about 100 ohms. The switch contacts never more than 1 ohm.
Ok. Did some reading on this interesting topic and will attempt contact resistance tests with dvm dc power supply. Would 5v or 9v dc be adequate?
Hi,
I'm no expert, but pointing it out can't hurt - I'm looking at thre different service manuals (edition 3/7/10) and they all show the following wiring of the power switch:
I'm no expert, but pointing it out can't hurt - I'm looking at thre different service manuals (edition 3/7/10) and they all show the following wiring of the power switch:
Hi Borchee,
Yes, I am aware of the illustrations, but have found the manual can be deceiving. Some switches come with four pins (as per the manual, and others come with six pins I.e 3x 2 pairs.
Only when the switch is viewed vertically, can the rear lower pair be seen. Attached are pics of the switch in my a77 mklll.
Then there is the protective plastic like sheet surrounding the terminals….
I hope this will prevent any diyers from making the same mistake.
Thanks all for the time to follow up and respond to my request for assistance.
Yes, I am aware of the illustrations, but have found the manual can be deceiving. Some switches come with four pins (as per the manual, and others come with six pins I.e 3x 2 pairs.
Only when the switch is viewed vertically, can the rear lower pair be seen. Attached are pics of the switch in my a77 mklll.
Then there is the protective plastic like sheet surrounding the terminals….
I hope this will prevent any diyers from making the same mistake.
Thanks all for the time to follow up and respond to my request for assistance.
Attachments
Update!
Hi all - just to update this thread.
Since correcting the switch wiring, the power problem is solved. Heads were meticulously cleaned, then cleaned ... and cleaned again!
Sonic performance of my A77 Mklll is causing jaws to drop...and is still to be calibrated!
I have sourced a calibration kit, including the relevant calibration tapes for the job. 🙂
Now for the challenge!
Hi all - just to update this thread.
Since correcting the switch wiring, the power problem is solved. Heads were meticulously cleaned, then cleaned ... and cleaned again!
Sonic performance of my A77 Mklll is causing jaws to drop...and is still to be calibrated!
I have sourced a calibration kit, including the relevant calibration tapes for the job. 🙂
Now for the challenge!
