• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Is your unobtainium power switch worth $5 and an hour or so of your time?

I was planning to mount it on the metal side, as a heatsink, close to the switch. That metal panel is still inside of the cosmetic cover. See the photo. Any problem with that?
20201130_185232.jpg
 
Make sure the to-220 tab is electrically isolated (assuming the part you're using has an exposed tab). That means a mica/silpad and and isolation bushing for the screw (so it cannot touch any part of the tab, but still clamp it down).
 
gpounce32768 said:
Make sure the to-220 tab is electrically isolated (assuming the part you're using has an exposed tab). That means a mica/silpad and and isolation bushing for the screw (so it cannot touch any part of the tab, but still clamp it down).
Click to expand...
Yep I know that, used to be a repair tech, just wondered if that would work as an adequate heatsink surface.
 
I think so... I mounted the triac via an existing screw thru an otherwise unoccupied corner of the rectifier board of the 100 watt Kenwood, so no good heat conduction. I put a heatsink on the triac- never got warm.
 
Hi guys,

I have both an SX-450 and SX-750 with the same symptoms. Perhaps this question is either moot or has been asked before. My machines are factory configured for 220 volts (Europe) and the power switches as well as the wiring are different. I am wondering if this triac solution is 110v only and what, if any, special arrangements I need to take for 220v.

Many thanks for your answers,

Bert
 
EastPoint said:
I just did this mod on a Scott 380R receiver, which uses a double-ended power switch to turn on both sides of the AC current for some reason. I used one triac per section and it turned out great.
Click to expand...
I am currently doing the double mod on a Scott 390R which is similar to the 380R. Does this look right to you ? Existing print :ice_screenshot_20210222-153506.png With mod: Image (49).jpg
 
gpounce32768 said:
Make sure the to-220 tab is electrically isolated (assuming the part you're using has an exposed tab). That means a mica/silpad and and isolation bushing for the screw (so it cannot touch any part of the tab, but still clamp it down).
Click to expand...
The triac K7 uses has insulated metal tab meaning that tab is not electrically connected to any of device's pins. So no need for mica.
 
This installed cleanly and worked flawlessly with my Kenwood KR-4010, which even after thorough cleaning of the power switch, was flickering constantly. It drove me crazy. I just double and triple checked that I was putting the right wires on the right lugs because I didn’t want to blow this unit up (I’m a hobbyist restorer and by no means an electronic engineer).

I found a nice spot on the chassis to mount the new circuitry, drilled a hole and tapped it with a machine screw, and added a dollop of heat sink compound, and it went in beautifully. This is a true game changer for these old flickering receivers, and it gave this one a new lease on life. Big thanks to the OP for this mod. It’s brilliant.

FB1402D9-010E-474D-A2EE-AE32B8464122.jpeg 373BEEC1-97DA-490D-9BEF-CED9D659BEA2.jpeg
 
Fitzer said:
This installed cleanly and worked flawlessly with my Kenwood KR-4010, which even after thorough cleaning of the power switch, was flickering constantly. It drove me crazy. I just double and triple checked that I was putting the right wires on the right lugs because I didn’t want to blow this unit up (I’m a hobbyist restorer and by no means an electronic engineer).

I found a nice spot on the chassis to mount the new circuitry, drilled a hole and tapped it with a machine screw, and added a dollop of heat sink compound, and it went in beautifully. This is a true game changer for these old flickering receivers, and it gave this one a new lease on life. Big thanks to the OP for this mod. It’s brilliant.

View attachment 2172009 View attachment 2172010
Click to expand...
upload_2021-3-23_16-22-50.gif Be careful around those Triac connections, you have full mains AC available there in a very open and accidentally touchable position upload_2021-3-23_16-22-58.gif!
I strongly suggest you put some heat shrink tubing over the leads on the triac and the resistor.
 
50 Green said:
The heat shrink is well advised. Also not a bad idea to flow a little more solder on those connections when you re-do them.
Click to expand...
They’re not taking solder well at all, and I’m concerned about cooking the thyristor, but I’ll try to get more on there. It looks worse in photos than in real life—the solder joints are quite solid and passed a good tug test.
 
Fitzer said:
They’re not taking solder well at all, and I’m concerned about cooking the thyristor, but I’ll try to get more on there. It looks worse in photos than in real life—the solder joints are quite solid and passed a good tug test.
Click to expand...
Are you using flux? What kind of iron? What heat?
 
Perhaps a little additional flux, applied prior to applying heat, might help the solder flow better.

Heat to the triac shouldn't be a concern, but you might try tinning the wires (especially the one with the light blue insulation) prior to attaching them, if you want to be extra cautious.
 
50 Green said:
Perhaps a little additional flux, applied prior to applying heat, might help the solder flow better.

Heat to the triac shouldn't be a concern, but you might try tinning the wires (especially the one with the light blue insulation) prior to attaching them, if you want to be extra cautious.
Click to expand...
All wires were tinned, those solder lugs on the triac are just very stubborn.
 
You must log in or register to reply here.
Back
Top Bottom