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This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
I have two remote mains switches that have ceased to function. They will turn on and apply power to the outlet if the bypass button is pushed, but will not work in automatic mode.
Ive opened one up, and it appears that the main relay is used for both modes. That kind of eliminates it as the issue, though I thought that would be the culprit.
Anyone have experience repairing these? Any advice appreciated, thanks.
Jeff
I'm afraid I'm recovering from the BeoVirus.
I'm sorry I can't help you Jeff, but I would like to know more myself.
This is what you are referring to correct?
Beo4 'til I die!
That's it. The failure mode on both is that they stop switching the power outlet on in response to the trigger voltage from the receiver, etc. but work when you turn on the push button.
Live opened up one of mine, thinking it might be the main relay, but it appears that the on button doesn't switch the power directly bypassing the relay as I thought it might, but applies a switching signal to the same relay, so obviously the main relay is working.
Likely culprits seem to be either a single transistor in the switched path or this small rectangular black box that I haven't figured out what it is yet. I guess one of the caps could be bad, need to dig out my ESR meter and test them.
Sorry for yet again not being any help There is practically no info on these boxes anywhere on the net. I'm trying to workout whether or not I can integrate one of these guys.
What is the input voltage for the trigger?
It uses the Powerlink trigger voltage, but I can't remember what that is right now. Originally I think these were designed to operate off an older Beomaster, they use an adapter for Powerlink. A wire comes off the Powerlink plug and ends in a female small power plug such as you'd find on a wall wart power supply.
I have to assume most of these for sale on eBay and such are probably also broken despite what the sellers say about testing them, since they appear or work if you just try the on button.
Ive got mine apart, will take a picture and post it tonight.
Well, here's a picture of the guts,or would be if I could figure out how to post it.
Anyway, the small black box is an optoisolator, which appears to be an obsolete and unavailable part. So, it that's the issue, and I suspect it is, I appear to be SOL. Unless I can find something that would work. There's other possible issues, bad resistors, caps, transistor, but it will take a bit more testing to isolate (pun) the issue.
If it is the optoisolator I'm screwed.
Jeff:If it is the optoisolator I'm screwed.
No you're not. I'm sure some generic part would work, but it would help to know what the original part is...
--mika
It's an Isocom H24A2. All the listings for it seem to be zeroed out in the online catalogs. Not sure what would be a replacement, it was hard to tell from the listings but there has to be something I hope.
I found the datasheet here.
Of course they had to use some odd 4-pin component instead of something with an industry standard footprint. However, I can't find anything in the specs that would make this component somewhat special. I'm 97% sure a TIL 111 or whatever would work in it's place, but you'll need to wire it in as it is in a 6-pin case.
And remember it is there to isolate the live parts from the control side! What ever you construct in there will need to be electrically safe even if somebody throws the box around.
How did you arrive at the conclusion that the opto is dead?
The easiest way to attach a single photo is to click on the "options" tab while composing your post, the rest should be self-explanatory. I'd still like to see it
I have no real reason to think it's toast, it just seemed like the most likely component from looking at the others. I know the main relay is OK, because that's tripped for both the auto and manual on functions from the way it's wired.
This will undoubtedly take more digging. But, if I manage to fix it I'm sure it will be of interest to others in the future. These seem to be odd little boxes.
Close up, the optoisolator is the small black box on the right.
Oh, it's that simple - one could almost draw the schematic looking at your pictures
Very little to fail I think. SCR1 is a triac (or a thyristor) and might have failed as well, perhaps the diac or zener (no designation visible, but next to C3). Those brownish red Roederstein electrolytic caps fail quite often elsewhere, but I don't think just a tired cap would prevent this from working. Then there's the opto and that's practically it.
The five diodes on the left need to be checked as well; apparently this rectifies the mains voltage directly and uses the big 12K resistor to drop it something usable for the rest of the electronics. Don't kill yourself measuring around, most of the PCB is at lethal voltages!
Yeah, there's not much in the box, but I'm kind of surprised that it's as complex as it is for what it actually does. I suspect the purpose of the isolator is to shield the B&O receiver or Powerlink device from anything weird that happens with respect to the line voltage, keep it from killing the upstream trigger source, which would likely be pricey.
I was expecting a simpler relay setup though.
I'll have to do some measuring and playing around. I have an ESR meter as well as usual gear so I can check the cap. It's on my workbench waiting for me to get to it. I appreciate the help, it's been a while since I've done a lot of this, and I was never as knowledgeable as I'd have liked. I have worked on tube amps, so I definitely know about respecting the voltage. My little 6L6 SE tube amp has 300 volt B+, that'll light you up.
As for diodes, the last thing I messed with used a 5U4G as a twin diode! Not used to this solid state newfangled stuff.
Jeff: I suspect the purpose of the isolator is to shield the B&O receiver or Powerlink device from anything weird that happens with respect to the line voltage, keep it from killing the upstream trigger source, which would likely be pricey.
Indeed - and not to mention keeping it from killing the user.
From the pics, it seems that the Powerlink trigger voltage goes more or less directly to the LED of the optoisolator (through a current limiting resistor, and apparently a protection diode) and there's nothing more on the low voltage side.
If that is the case, I believe you could solder a 100 ohm resistor (value mostly out of a hat) across the secondary side of the opto. If the relay then pulls with nothing connected in the Powerlink socket, the opto has most probably failed; otherwise, there must be something else wrong (as well / or).
As you can trigger the switch manually,you can exonerate the entire "hot" side of the circuit.As other members have noted,the opto coupler is purely to isolate the trigger input from the power circuit.The output transistor of the opto coupler is in fact wired across the manual switch,so bypasses it.
These switches were designed originally to work with Beomasters and Beocentre's,that provided a 9volt output when powering up,to switch on auxillary kit such as tape decks.I wonder if the powerlink trigger is great enough ?
I remember that the original trigger lead was hardwired into the box,with a standard dc power plug on the other end?
try connecting a 9 volt (pp3 type) battery to the input .Polarity is crucial,positive to pin 8 of the opto,and negative to the cathode of D6 .
If it switches,then it means either your input from powerlink is too low,or praps reversed polarity?
Take great care working with power voltage equipment.
Regards,
Nick
Thanks for the additional info! Both of these were once working, one with an AV7000, one with a Beosound 9000. On the AV it switched a small Carver amp for the rear channels, on the BS it switched a Proton integrated that I used to run a couple of pair of speakers in the rest of the house. Both worked off the Powerlink for years, about a decade, before they failed, first one, then the other, a couple of years apart.
They came with a PL adapter, a short length of cable with a male PL on one end, a female PL on the other. Out of one of the PL connectors a two conductor wire issues forth, fitted with a small plug, female I think. The converter has a small wire with a male plug that fits into this.
We do get a lot of lightning here in Central Florida, but their failure wasn't accompanied by any other failures, but who knows. I did lose a couple of pieces once, one of which wasn't even plugged in! Had a huge strike about 15 feet from the house that vaporized about 50 feet of buried phone line and cable. Both devices lost their touch sensitive switches, nearest I could tell for the unit that wasn't even plugged in was that the static sensitive CMOS devices in the switches (this was back in the 80's when these were fairly rare) got EMP'd to death.
Imwill have some more time over the weekend to delve further. Thanks again!
Just realised,the input connection to the opto coupler should be pin 1 positive,pin2 negative(via R7 and D6).If it still does'nt function with a test battery input,it must only be the opto coupler.I Imagine a variety of modern devices would suffice as replacements.
Amazed to hear of your various power supply trauma's,you must glow in the dark after all that lightning?
Haven't had any lightning damage lately, knock on wood. But we get some increcible storms, supposedly we have more lightning than anywhere other than some place in central Africa. We get hot air that rises from the center of the state, but being as how the state is only about 170 or so miles across here, we get cooler, wetter air coming in from both coasts. They all meet in the middle and generate some very turbulent effects. I remember when I first moved here as a kid, sitting on the porch being fascinated by the huge storms that rolled in every late afternoon in the summer.
I went to a lightning seminar as part of my engineering tasks on a project long ago. The instructor had this large aluminum box that came from one of the toll roads here, the kind used to hold large copper buss bars and cable to connect the road lights/street lights. He stole it basically, because it demonstrated the power of lightning. It was big, about 2.5 feet high by about 1.5 feet wide or so, and almost the whole inside was plated with copper, and it was filled with these tiny copper spheres rolling around the bottom. All that was left of the wiring that was in the box, which was made up of cable over an inch in diameter.
I'll be getting to the remote switch this weekend, maybe tomorrow. I will probably need some advice on picking a replacement, so far what I've seen are surface mount devices which don't seem adaptable.
If you need an opto isolator Jeff,look at Atex 0pl11oa.This is a four wire(not pin!) device,designed to do just what you need?
Thanks for the part info! I've yet to have time to get to it this weekend but hopefully tonight. I've found a source for the H242 but the minimum order is $100 US and that's of the same part. What I'd do with a hundred bucks worth of them I have no clue.
OK, here's an update. At work browsing I found a substitution for the H24A2, and ordered a few (0.66 cents each). Before stuffing one in today I hooked a 9 v battery up to the thing, and lo and behold it works, the relay pulls in and the plug becomes active (I had a night light plugged in, you could hear the realy trip and see the light turn on).
Now, why did it stop working with the Powerlink when it used to? Is it possible the opto-isolator grows weaker with time, so that it takes 9 volts to turn it on? That's the only thing I can think of right now. I guess I can replace it in one of them and see what happens.
Any ideas other than aging of the opto? I need to get the two data sheets for the original and replacement opto-isolator side by side to make sure they are truly equivalent, as the new one is much smaller. It was listed as a substitution, but who knows for sure until I compare specs. But it was cheap enough it'll go in the spares bin if it's not.
Frustrating.
The red electrolytic capacitor is responsible for filtering the output of the power supply section... I guess that it could get marginal enough to drop the supply enough that the triac/thyristor won't trigger early enough (or at all) to energize the relay with the nominal output from the opto. The Powerlink trigger voltage is only 5 volts. Perhaps the opto could degrade as well, but I doubt it.
As I said earlier, I don't really think the type of the opto matters at all as long as the maximum ratings are at least the same as with the original - but I could't find a single type that would have the same footprint.
Well, this gets stranger. The relay triggers with 9vdc, and I tested it with 3vdc and it triggers perfectly. So, I figure it's a connector issue. I check both Powerlink ends of the adapter, both show continuity. So I check the other plug, it has continuity. So I check continuity from the Powerlink plug, thru the two conductor plug that connects the PL to the older Beocenter type plug, all the way back to the circuit traces inside the switch, all good.
So, I figure something is afoot at the PL on the Beosound, nope, I get 4.1 vdc across the pins.
So, right now I'm completely out of ideas. Everything says this should be working.
What do you have on the PL, or across the LED of the opto, when the switch is connected (no need to connect it to mains during this test)? Perhaps it is loading the PL trigger too much...
Now I'm completely flummoxed. Plugging it all in I measure no voltage across the opto, but then I measure no voltage across the PL adapter even when I unplug it from the switch. I pull the adapter, and measure directly across the PL cable from the BS, and I seem to sometimes get voltage and sometimes not, probably due to trying to hold the probes on the connectors (I need to rig up a PL test jig). When I measure continuity across the adapter it measures fine so I have no idea why I'm not measuring voltage when it's plugged in and the switch isn't.
This isn't turning out the way I thought it would to say the least! I definitely need a test harness before I can get to the bottom of this.
OK, so anyone know where to buy female Powerlink plug?
Edited to be more specific, I can find 8 pin DIN male plugs for the end of cables, and female panel mount jacks. What I need is a female plug for the end of a cable if such a thing exists.
something like this?
In Germany but probably the type MAK80SN helps (take care of MAK80S, it's in horseshoe-shape and doesn't fit!)
Gunther
That's what I need, thanks! I know what description to look for now.
I have about two weeks to get this sorted out, ideally. That's when my handyman is scheduled to finish wiring the rest of the house speakers, and I'd like to have them come on automatically with the Beosound.