Dual 1229 : Strobe bulb is fine, something else is up

[davstev]

I recently picked up a nice Dual 1229. Upon plugging it in and testing, I noted that the strobe isn't working.

Believing that my original strobe bulb was shot, I ordered an LED replacement from dualfred in Germany. It arrived yesterday. Putting it in place of the original bulb, it exhibits exactly the same behaviour as the original bulb: when clicking the lever to 'start' and the motor engages, the strobe bulb turns on only for a fraction of a second, then goes dark (turns off) during the period when the turntable is spinning, when you'd actuall want to use the strobe to make speed adjustments.

Same at the end of the record: when it auto-clicks off, the bulb flashes on for a fraction of a second. Clearly, there's something going on electrically, a faulty switch or capacitor or something. If anyone has an idea of where to start to troubleshoot, I'd greatly appreciate it. I have downloaded the service manual.

THANKS!

 

[tonesteroc]

Not much to check, try Deoxing the start/stop switch and make sure the soldering is good to the strobe light

 

[davstev]

Just in case anyone has this issue, I've been in touch with a very reputable Dual tech, outside of AK. He said:

"With a multimeter set to the next highest voltage over 110 volts, check for 110 AC (may vary slightly) that goes into the circuit board (Fig 8 red and green circles) once the unit is on/platter turning. If power is OK, then move probe on green circle to blue and measure. Usually capacitor C1 / 68 nF calls it quits and needs replacing. If so, replace with the same value and ensure it is an "X2" safety capacitor.

Should the capacitor work then the only thing left is a defective diode (extremely rare) or a faulty solder joint on the board."

 

[Hajidub]

Just in case anyone has this issue, I've been in touch with a very reputable Dual tech, outside of AK. He said:

"With a multimeter set to the next highest voltage over 110 volts, check for 110 AC (may vary slightly) that goes into the circuit board (Fig 8 red and green circles) once the unit is on/platter turning. If power is OK, then move probe on green circle to blue and measure. Usually capacitor C1 / 68 nF calls it quits and needs replacing. If so, replace with the same value and ensure it is an "X2" safety capacitor.

Should the capacitor work then the only thing left is a defective diode (extremely rare) or a faulty solder joint on the board."

Just a heads-up Dav, no picture/diagram uploaded. I do it all the time.

 

[davstev]

Tha

Just a heads-up Dav, no picture/diagram uploaded. I do it all the time.

Thanks, I'll add the image later today.

 

[davstev]

Here's the image I forgot to attach, relevant to post #3: