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

[UncleBingo]

Looks like I spoke too soon. My unit was functioning fine this afternoon as I tried it for short periods. Now tonight it doesn't totally turn off. The off position drops the amplitude to a much lower level, like before the relays kick in when turning it on. Not sure what happened. Pull the plug and of course it goes off, but comes right back on when plugged in. I was so elated this aft, and the unit sounds so good. I am kind of decimated. ~ Any thoughts? wired incorrectly, triac go out, relay or switch stuck?

The gate should be connected to the 100 ohm resistor.
The other end of the resistor goes to the power switch.
The other wire on the power switch (the switch output) goes back to M2 (MT2 on the Littelfuse Q4025L6 the OP used) and on to whatever it is/was connected to (fuse holder or switched outlets depending on the unit). Does that help? If you're using a different triac than the one I listed, the pinout may be different.

 

[UncleBingo]

Looks like I spoke too soon. My unit was functioning fine this afternoon as I tried it for short periods. Now tonight it doesn't totally turn off. The off position drops the amplitude to a much lower level, like before the relays kick in when turning it on. Not sure what happened. Pull the plug and of course it goes off, but comes right back on when plugged in. I was so elated this aft, and the unit sounds so good. I am kind of decimated. ~ Any thoughts? wired incorrectly, triac go out, relay or switch stuck?

You may have wired it to the "Hot" (Live side) of the switch. That would result in it being turned on all of the time.

 

[Pear52]

My triac says Q6025L6, the first 6 meaning it has a 600VAC rating I believe. That's what the vendor in China sent me. I have looked over my wiring and I think it is to spec. The gate is connected with the inline resistor to the switch on the side opposite the incoming yellow lead which I believe is hot. When it comes in, it goes right to the unswitched outlets and then to the switch.

Oddly, it was working fine this afternoon. On and off without an issue. I do recall tonight that when I turned it off one time, it made a pop sound in the headphones I was using. I thought that to be a little odd as I had not heard it before, so I turned it on again. I think that is when it stayed on.

 

[50 Green]

I personally would not want to have line voltage switched by a semiconductor from a Chinese ebay vendor.

Any (little) extra expense of buying from one of he major vendors is cheap peace of mind.

This mod is working fine for me, w/ an ST Micro Snubberless triac ordered from Mouser.

 

[Pear52]

Green, your point is well taken. My initial thought process was that since most of the semiconductors seem to come from China, I would be going just a little more direct. However, on second thought having worked with many Chinese companies, I should have been more cautious. The sourcing of these components is obviously uncontrolled. Might be seconds or God knows what. I will resource with a local vendor, and try it again. The fact that is was working fine for a while suggests that something failed, and the most likely candidate and really the only obvious addition besides the simple resistor, is the triac.

I just ordered a couple triacs from Mouser. Thanks

 

[UncleBingo]

Green, your point is well taken. My initial thought process was that since most of the semiconductors seem to come from China, I would be going just a little more direct. However, on second thought having worked with many Chinese companies, I should have been more cautious. The sourcing of these components is obviously uncontrolled. Might be seconds or God knows what. I will resource with a local vendor, and try it again. The fact that is was working fine for a while suggests that something failed, and the most likely candidate and really the only obvious addition besides the simple resistor, is the triac.

I just ordered a couple triacs from Mouser. Thanks

I just did this mod yesterday with a Q4025L6 from Mouser and it works perfectly. I'm 3 for 3 with this one. many thanks to the OP!

 

[50 Green]

I just ordered a couple triacs from Mouser. Thanks

You're welcome.

Of course be sure to mount the triac on a substantial piece of metal (such as the chassis) to serve as a heat sink... and either use an insulted-mount triac or insulate it when you mount it.

I mounted mine on the chassis w/ a small heat sink. Probably unnecessary, but it was cheap and can't hurt.

 

[Pear52]

I have a small heatsink made just for these units that I might add. We shall see how ambitious I feel when I redo the triac. I read some of the caveats about mounting and they caution about using a screw as it may feel a burr or raised surface and limit contact. Also suppose to use a washer under the screw head to help with all that. Not really worried about it too much.

Now I sit and wait for my Mouser supplied triacs to get here and I continue to read various posts to make sure I understand the wiring. I thought I did until I read some comment like using the M2 side of the switch or something like that and it leaves me hanging. So at the risk of appearing really stupid, versus the risk of blowing up a triac, I wanted to post my "schematic". Granted this is not is std schematic format, but the way I see it as I pulled it from the schematics and applied. If someone could take a look and make sure this is OK I would be grateful. Beats soldering in more triacs. I have noted the original yellow incoming wire which I believe is the hot as it used to come right in and tie off one side of the unswitched outlet before going to the alps switch, top terminal towards the inside. The red lead had been on the other side of the alps switch and is now going to the triac on the M1 position. Is it possible that I have this so the the switching occurs in quadrant 3 and is degrading the triac. See, I have learned only enough at this point to be dangerous.

As stated, it worked great for a while and then locked in "on" mode. Hopefully I am just a victim of some Chinese knockoffs, soon to be cured.

Thanks to anyone that can help.

 

[50 Green]

That is not the same as the schematic in the original post.
Per the original post, line in goes directly to the triac M1 (on the Littlefuse Alternistor in the OP.)
The switch is wired between M2 and Gate, via the 100 ohm resistor. Power connection to the amplifier (transformer) is from M2.

You'll find it helpful to get comfortable w/ a regular schematic, but for now here's a quick image that should illustrate how things connect in the diagram in the OP.
I used yellow and red per your drawing for line in and transformer connections, respectively, but you need to confirm that those are correct.

 

[Pear52]

Thanks ever so much Green. I feel only slightly stupid this morning seeing the error of my ways. Oddly enough I looked through my notes as I was figuring this out and I had this laid out that way at first. Then as I was actually doing it, I rethought the connections and my logic was very incorrect. I think it would have been helpful to have a better understanding of how a triac is triggered in the first place. It has been a long time since I had basic Electricity 101 in high school as well. I may actually pick up a basic circuit book one of these days if I decide to pursue any additional projects.

Is it true the leads to M1 and M2 could be switched around, but the lead (purple) from the switch has to remain on the neutral side?

At this point I am also wondering if I have ”let the smoke out” of the triac and is it worth resoldering correctly or just wait for my Mouser units to arrive. Any guesses?

Again, many thanks for taking the time to construct your answer. It is very helpful.

 

[50 Green]

Is it true the leads to M1 and M2 could be switched around, but the lead (purple) from the switch has to remain on the neutral side?

Someone with more knowledge than myself would have to answer that. However that is essentially how you show it in your diagram, so you may have already answered your own question.

At this point I am also wondering if I have ”let the smoke out” of the triac and is it worth resoldering correctly or just wait for my Mouser units to arrive. Any guesses?

As this is line voltage, IMO not the place to be guessing about anything.
An abundance of caution (and a modicum of patience) ought to serve you well (again IMO.)

 

[merlynski]

Is it true the leads to M1 and M2 could be switched around, but the lead (purple) from the switch has to remain on the neutral side?

The switch and resistor must be between MT2 and G. It does not matter from the electrons viewpoint if the triac is on the neutral or hot side as long as it is in series with the load. From an OCD/purist point of view I would put the triac on the hot side, but on a unit with a non-polarized plug, technically, there is no difference between hot and neutral.

 

[K7sparky]

An item that is, or is made from, something Unable to be Obtained. ( https://en.wikipedia.org/wiki/Unobtainium ) No longer available, etc . . . like a proprietary switch for a ≈40 year old piece of audio gear.

OUCH!
All this time and I didn't notice I misspelled it
So OK it's fixed

 

[50 Green]

OUCH!
All this time and I didn't notice I misspelled it
So OK it's fixed

Oh, no!!! Now I'll never be able to find it again!!
I've learned to search under the old spelling!

 

[K7sparky]

Looks like I spoke too soon. My unit was functioning fine this afternoon as I tried it for short periods. Now tonight it doesn't totally turn off. The off position drops the amplitude to a much lower level, like before the relays kick in when turning it on. Not sure what happened. Pull the plug and of course it goes off, but comes right back on when plugged in. I was so elated this aft, and the unit sounds so good. I am kind of decimated. ~ Any thoughts? wired incorrectly, triac go out, relay or switch stuck? When I turn the power knob from off to on, the relay clicks on inside the unit for full volume control.

Got my triac out of China on ebay. They sent me a 600 volt rated unit, but I judged that would be OK. Maybe that was not a good decision.

I have a LONG 9090 and it's litter mates / sibling repair / upgrade thread:
http://audiokarma.org/forums/index....setton-rs-660-series-repairs-upgrades.482152/. I cover the installation of the TRIAC in the 9090 in detail on that thread.

Also DO NOT sand the switch contacts. Also covered. Nice pretty contacts look great but looks don't count. Also see post107 on this thread

 

[K7sparky]

Guess my alert email link was not working. I haven’t been getting alerts of activity on this thread. Fixed that and the name.

Hint: At the top “Watch Thread” and in your “Profile” set up your “Preferences” to receive emails where you are interested.

General comments:

The voltage rating picked in a design using a solid state device is minimum. It makes a difference in $ to go higher voltage in manufacturing quantities. To usens here higher is not a problem.

Going substantially higher in current rating may or not make a difference. In this case it could because gate current is related to rated current rating.


Several comments:
post 181 “Retrovert”

The TRIAC specified is made for high inductive loads which was covered on page 1 post #7 in the thread. That’s why I picked the “Alternistor” The data sheet form Mouser is linked in the first post.
SEE post 160 for second source.

There is lots more information available to download from “Littlefuse” if you want in depth reading on the subject. See posts 96 & 97 for links

Slap in any olde TRIAC and you may well have the same olde problems from the dark ages. GREAT fun and merriment tuning snubbers.


post 191 sssboa

I expect your snubber is just fine and the bump is the .033MF cap enclosed in the assembly.

My SWAG for the dim glow you are getting is the snubber and that’s why it is not on the 220V grid models.

The Xc for 0.033MF is a bit over 80K. Sounds like a lot but with almost no load the power supplies are partially on.

 

[gpounce32768]

Just did this for my Kenwood KR-6030 - uses the alps switch. I used a TO-220 form ST T3050H (30a, 600v, gate current 50ma), and lacking a 100 ohm resistor I used a 120ohm 1 watt film. Happily the KR has an unoccupied corner of the power supply board w/ a screw there so the triac is easily mounted with heatsink (but incorporating a silpad and isolation collar). Parts are wired as directed in this thread, working great.

Thanks!

 

[K7sparky]

I used a TO-220 form ST T3050H (30a, 600v, gate current 50ma), and lacking a 100 ohm resistor I used a 120ohm 1 watt film.

Thanks!

Just looked at the data sheet. Good find. dV/dt of 1500V/us and 44 A/ms without snubber.

Nice to have another source

 

[Scott75s1974]

Littlefuse is now offering the QJ4025JH6TP. It seems the successor to the Q4025J6TP. But I don't understand such things well enough to be confident. Can someone advise? Will this work?

Here's the data sheet: QJ4025JH6TP Datasheet

 

[K7sparky]

Looking at the referenced data sheet:
You picked a 400V 25A pg8
J is the loop terminal isolated tab (TO218X) pg 7 & 8
H6 80ma sensitivity pg 8
P is for packed in a tube pg8 also

The original I picked was 400V 25A and had Igt (Gate current) as 80ma. Looks like the same beast to me.

I like your choice: Ring terminals and isolated tab. I'm lazy also!


note the torque spec for mounting in the clip is 8 in-lbs. Everyone (including me) over torques the mounting screw.
Use only a tiny (like in almost none) amount of silicon grease (or your favorite compound) between the tab and chassis. I keep harping on toooooo much. More is worse not better - you are filling the TINY air pockets between the 2 surfaces. If the compound holds the surfaces apart you are loosing not gaining from the compound.