Need help. I want to fix a Braun L810's crossover. 1 woofer doesn't get a signal.

Tony M

Well...I'm at a stage where where I'm ready to order parts and fix my one Braun L810 that hasn't had a woofer playing since I got them a VERY long time ago. The woofer works fine with a direct signal to it's terminals. The cross-over doesn't send a signal to it.

Maybe you've seen me posting some of my collection ( ) lately. I've tested a bunch to see if they still work. I found out my SDA2's have a wire or cross-over problem. I know my Polk Rti12's have a cross-over problem too since the tweeters don't play but the tweeters check out fine by themselves.

The RTi12's will probably be next. I think their problem is just a resistor being too fragile burning out on most all that were made.

I had guy who was going to help me but I'm getting impatient. He's elderly and I think he's hunkering down tight now.

This is a picture of it and I have no idea what these 2 yellow and 1 grey boxes are.

I put an ohm meter on the ceramic resistors and get a low reading.

I put the ohm meter on that first grey box and get nothing. I have stopped at this point thinking it might be the resistors and that grey box probably.

I've gotten tired of looking on the web because there's nothing I can find that talks about these yellow and grey boxes.

Any help teaching what these things are would be greatly appreciated!

Here is the one cross-over I took out years ago and am just getting to it.

mhardy6647

The yellow boxes are capacitors, as is the whitish object next to them.
The next two, tan-colored rectangular prisms are sand-cast power resistors.

The values on the caps all look to be clearly printed on them.
The resistors' values, likewise, are clearly marked.

In terms of a nonfunctional driver -- visually inspect the wiring (and the crossover component connections) for continuity. You can "wiggle" connections that might be intermittent while applying signal if you like.

Tony M

Thanks Doc.

I checked all the wires on the L810 years ago. That's why I clipped the wires and pulled this cross-over out.

What does **** / 10 /100 on those yellow caps mean? 10 to 100 watts? I don't think I've seen 3 values on anything before.

I see the % on reg caps. Is this ***/ 10% / 100 watts?

mhardy6647

I suspect it's the tolerance (10%) -- not 100% sure; I defer to a true expert, of which there are several/many here.

Tony M

Thanks.

This is hopefully my introduction / first day in class so to speak, to cross-over problem diagnoses. I can go to the web and see videos and write-ups BUT, I've yet to see anything on how to test Caps and resistors while they're on the boards.

I did see today the bulging caps tops can make a subwoofer hum. I have a NICE Mirage sub that hums. .. . Maybe I can learn on it too if the caps are bulging on it's amp plate.

Tony M

I'm now going out to hang some sun-shade panels my wife and I made. shouldn't take but an hour or so.

pitdogg2

10uf is the value 10 microfarads
10 is the tolerance. So 10%
100 is volts

So the next is 6.8 uf

That is the way I read it

Tony M

That's what I'm going to look into buying. I should do both speakers. I might be keeping these.

I wrote down at the time I cut out the cross-over board a schematic for myself where each wire went. I'm going to go get it now.

Tony M

Yup, I wrote down where most wires went to.

Tony M

Ok...

Are these yellow and grey caps polarized? These blocks have a bar on one side of the tops. Do those bars mean anything?

I'm looking at parts express. I'm going to search Polk Forum for the suggested brands.
I should know by now.

Mills resistors
? Caps...Clarity?

pitdogg2

I do not know for sure if they are polarized. Some caps like that are polypropylene not electrolytic.

Tony M

10-4.
Thanks.

mhardy6647

So -- @Tony M -- I would think/suggest that, before you spend a cent on components, you should determine that your "no signal" woofer is OK (or not).
There are two good ways to do this. The best way (IMO).

Being very careful to keep track of the wiring (and polarity of the woofer), disconnect the two wires from the XO to the questionable woofer. If there's no polarity marking on the woofer itself, mark at least one of the terminals so you know which wire went to which!

Get two pieces of wire and a low-voltage "battery" -- e.g., a 1.5 volt AA, C, or D cell.
Clip leads are ideal If you don't have any: 1) you should! and 2) PM me and I'll send you a couple.

connect one wire to the "minus" terminal (or either of the two terminals if you don't know which is which).

Connect the other wire to the other speaker terminal ("plus").

Hold the other end of the "minus" wire to the negative pole of the battery (that's the large, flat end -- usually the 'bottom').

Touch the other end of the other wire to the positive pole of the battery (the little button on the top).

You should hear a click or a brief static-like sound, and the woofer cone should move "out" (if polarity is correct). It'll move "in" if polarity's reversed.

If this happens, the woofer is (at least) functional.

You can, alternatively, use a DMM to test the DC resistance of the voice coil of the questionable woofer -- but the above test is safe (with a low voltage battery and a short duration test), easy, and requires nothing special to effect.

HTH.

Tony M

Years ago, I did check the woofer by touching the wires from my receiver directly to the woofer's terminals on it's frame with no other wires hooked up to it at a very low volume. The woofer is fine.

I also learned about the battery test from this forum many moons ago. That's a very cool and easy test to check for that polarity. I've used it a few times and always get a kick out it. It's so simple and easy.

I've replaced a couple of capacitors with new ones BUT, the capacitors were obviously bad. They had exploded. I looked on the wrapper shreds and got the values and went to Radio shack and got the same things, albeit the new ones were smaller. Those speakers came back to life or the lone speakers that didn't work, worked again.

Round things, capacitors. I can read clearly on their casings what they are.
I have no knowledge about "block capacitors'. I didn't even know they were capacitors. I thought relays came in that shape.

I have also replaced a ceramic resistor or two. But they're easy to identify also.

Here's where my skills end;
I don't know how to diagnose a bad component on a cross-over if there isn't a sign of a blown-up capacitor or a burnt-up ceramic/sand-cast (thanks Doc ) resistor. I know to look for loose or disconnected wires where-ever a wire meets something. My neighbor taught me about cold solder joints many years ago. I know what to look for in that case. That's the third thing I look for.

I received a method from a guy about testing the components on a cross-over. He told me to remove ALL the components except the choke(?) coils and then test each one. The same guy told me to JUST replace them all, caps and resistors with affordable Parts express replacements and I wouldn't even have to know what is bad.

That's all fine but I didn't know what these block things were up until yesterday. I still haven't seen on the web any electronic help site describing the block capacitors. I checked the Braun and ADS sites and got tired of searching them. I didn't post a question on those sites YET.

I figured I'd get my questions answered here pretty quickly.

Can I buy these block capacitors still or do I only have the option of buying cylindrical caps now?

mhardy6647

Don't worry about exact replacements for the blocky capacitors -- almost any component you buy now will be better anyway.

One area in which electronic components actually, really, truly are better today than in the good ol' daze is -- capacitors.

Plus, most loudspeakers then (and even now) tend to cheap out on capacitors any way to save $ (and maximize profit). Why use a $10 capacitor when a 10 cent one will measure exactly the same?

I am not a huge fan of the PartsExpress "Dayton" (Bennic) capacitors -- they're a bit tizzy sounding to my ears and taste -- but they're cost effective and not bad by any stretch of the imagination (FWIW).

Tony M

Thanks Doc.

I just had a couple of old friends over here looking at what I've done the past 2 months. They're glad I've been able to do sooo much. we spent about 3 hours listening to a bunch of speakers today.
The Polk SDA2's impressed the heck out of them! They know they weren't set up ideally and both of them could imagine how much better they would sound in an open room and spread out wider.

I told them I was trying to repair some cross-overs now.

Thomas said "yea, right!". He couldn't believe I'm now attempting to fix a few sets I've had for years. He believes I'm serious now.

Can I measure a resistor while it's on the board?

mhardy6647

Yes, as long as you connect the probes to the leads as close as possible to either side of the body of the resistor itself. That should isolate it from other components in the circuit. Note, though, that this is a pretty "Red Green" way to do it.

Tony M

Red Green looks like a show I'd like.

mhardy6647

I think I sort of live it out, many days.

L810

Tony M wrote: »

Well...I'm at a stage where where I'm ready to order parts and fix my one Braun L810 that hasn't had a woofer playing since I got them a VERY long time ago. The woofer works fine with a direct signal to it's terminals. The cross-over doesn't send a signal to it.

Maybe you've seen me posting some of my collection ( ) lately. I've tested a bunch to see if they still work. I found out my SDA2's have a wire or cross-over problem. I know my Polk Rti12's have a cross-over problem too since the tweeters don't play but the tweeters check out fine by themselves.

The RTi12's will probably be next. I think their problem is just a resistor being too fragile burning out on most all that were made.

I had guy who was going to help me but I'm getting impatient. He's elderly and I think he's hunkering down tight now.

This is a picture of it and I have no idea what these 2 yellow and 1 grey boxes are.

I put an ohm meter on the ceramic resistors and get a low reading.

I put the ohm meter on that first grey box and get nothing. I have stopped at this point thinking it might be the resistors and that grey box probably.

I've gotten tired of looking on the web because there's nothing I can find that talks about these yellow and grey boxes.

Any help teaching what these things are would be greatly appreciated!

Here is the one cross-over I took out years ago and am just getting to it.

L810

I know this is an old thread but if you haven't repaired these yet I highly recommend Richard So to repair them as he uses actual A/D/S parts " that are getting hard to come by " and knows what he's doing . I have a pair of one owner L810's in near showroom condition that I bought of an ADS salesman that bought them new in 1980 . These speakers sound good for a reason and using anything other than the actual product may hamper the quality of sound . I had the crossovers re-worked about 5 years ago .

I'm not sure if he's still offering the service as he's getting older but it doesn't hurt to try . He may lead you to someone else also but the A/D/S techs and the factory parts are getting old and hard to come by

..https://www.adsspeakersservice.com/