Crossover Help Needed With ANOTHER Pair of ALTECS

**zelgall** · January 13th, 2011, 11:46 PM

The only thing I can see 7 of are rivets. I'll go out on a limb and assume that there are circuit traces on the flip side of the board (that I've never seen) which will have the ground. The 19s are point to point wired with the attachments at actual lugs. There are pictures on this site of the 19 Xover.
The 470uF cap is for the protection circuit and is probably OK.

**voice of the theater** · January 14th, 2011, 02:15 AM

Originally Posted by zelgall

The only thing I can see 7 of are rivets. I'll go out on a limb and assume that there are circuit traces on the flip side of the board (that I've never seen) which will have the ground. The 19s are point to point wired with the attachments at actual lugs. There are pictures on this site of the 19 Xover.
The 470uF cap is for the protection circuit and is probably OK.

Yes the circuit traces are on the flip side of the board. As you mentioned, I'm sure they have the ground so I'll leave the rivets (lugs) alone in this crossover. Good--one less thing to solder!

**westend9** · January 14th, 2011, 03:44 PM

Originally Posted by voice of the theater

Still one last question I remembered before I do this upgrade....

In this photo I count what appear to be 7 (ground?) lugs--does anyone know if these should be connected with wire like people are doing with the Model 19's (or is it possible to tell from the photo or from Richard's schematic?)? Also, no one has chimed in about my earlier question regarding leaving the 470 uF capacitor alone instead of replacing it--any thoughts? Thanks again.......

An easy way to access the quality of the ground plane (lugs to plate) is to put a meter across varoius points and measure resistance. From the pictures, I think everything looks secure and no oxidation between metals. I have been known to give contact points like these a very quick squirt of Deoxit Gold or any other deoxidizing spray that is at my disposal.

I think you're being a little too apprehensive about desoldering the caps, it is very easy. There are lots of online soldering/desoldering tutorials but I could sum it up in a few words: Place soldering wick on soldered connection, place tip of iron on top of wick, watch solder flow onto wick. You might need to flow the solder a couple of times into the wick, I usually have a cutter on hand to trim the wick that contains the solder off of the roll. Lacking the courage to do this, and considering future replacement with the originals, you could cut the leads and twist together. It's your gear but if you want it done right, you should take the old caps off the boards and solder in the new ones. Maybe practice on a piece of something that has little value, even a piece of solder.

As I posted, my call would be to replace the 470uf electrolytic. There is no sense in keeping an aged cap in the circuit when I have an iron heated and the cost of a replacement is less than a dollar. I believe the cap is in the protection circuit so is not going to alter the sound, it is just a ticking time bomb.

**RonSSS** · January 14th, 2011, 05:10 PM

Personally, I would remove the protection circuitry....unless you have some sort of mondo power amp and kids who like to crank the volume all the way.

Ron

**voice of the theater** · January 14th, 2011, 05:41 PM

Originally Posted by westend9

An easy way to access the quality of the ground plane (lugs to plate) is to put a meter across varoius points and measure resistance. From the pictures, I think everything looks secure and no oxidation between metals. I have been known to give contact points like these a very quick squirt of Deoxit Gold or any other deoxidizing spray that is at my disposal.

I think you're being a little too apprehensive about desoldering the caps, it is very easy. There are lots of online soldering/desoldering tutorials but I could sum it up in a few words: Place soldering wick on soldered connection, place tip of iron on top of wick, watch solder flow onto wick. You might need to flow the solder a couple of times into the wick, I usually have a cutter on hand to trim the wick that contains the solder off of the roll. Lacking the courage to do this, and considering future replacement with the originals, you could cut the leads and twist together. It's your gear but if you want it done right, you should take the old caps off the boards and solder in the new ones. Maybe practice on a piece of something that has little value, even a piece of solder.

As I posted, my call would be to replace the 470uf electrolytic. There is no sense in keeping an aged cap in the circuit when I have an iron heated and the cost of a replacement is less than a dollar. I believe the cap is in the protection circuit so is not going to alter the sound, it is just a ticking time bomb.

I ordered all the parts for all 6 speakers today, locally. They told me to expect a phone call in about 5 days when the capacitors, etc. come in. It added up to about $160.00 for all 6 speakers but I figure that's only about $50 a pair so I'm happy. As soon as they call I'll pick up the caps and solder them into the first speaker for testing (A/B comparisons) the same day. I didn't even know that the 470 uF was an electrolytic cap. I'm glad you said something. I just called and had them add two 470 uF 100v electrolytic capacitors to my order. The ones in there now are 50 volt, I assume there's no problem switching to 100 volt is there? They are 470 uF, same value as the ones that are in there now....

So, the lugs/rivets are ground lugs/rivets? Should I solder a wire between all seven rivets just to be sure I've got a good common ground (similar to what I'll be doing with my Model 19's)? Or is this not necessary with these crossovers?

**westend9** · January 15th, 2011, 12:08 PM

Wise choice, replacing the electrolytic, you don't want a potential failure point in your recapped networks, correct?

If the rivets rare connected to the plate securely (and this appears to be the case), there should be no worries. The construction is different than the Model 19 and there isn't a picture of the mask side of the board, at present. This would show if the ground plane of the network board is grounded to the plate which is attached by rivet. As I mentioned, probing between ground points, measuring resistance, will turn up any abnormality's. To me, it is a non-issue.

Originally Posted by voice of the theater

I ordered all the parts for all 6 speakers today, locally. They told me to expect a phone call in about 5 days when the capacitors, etc. come in. It added up to about $160.00 for all 6 speakers but I figure that's only about $50 a pair so I'm happy. As soon as they call I'll pick up the caps and solder them into the first speaker for testing (A/B comparisons) the same day. I didn't even know that the 470 uF was an electrolytic cap. I'm glad you said something. I just called and had them add two 470 uF 100v electrolytic capacitors to my order. The ones in there now are 50 volt, I assume there's no problem switching to 100 volt is there? They are 470 uF, same value as the ones that are in there now....

So, the lugs/rivets are ground lugs/rivets? Should I solder a wire between all seven rivets just to be sure I've got a good common ground (similar to what I'll be doing with my Model 19's)? Or is this not necessary with these crossovers?

**rontec** · January 15th, 2011, 01:32 PM

I might be missing something here. I personally can't see any ground lugs in the photo. All of the common rivets are probably not current paths. Maybe a photo of the opposite side of the crossover board would help?

In the mod 19 there are four ground lugs. Each of the ground lugs is riveted to the board and has a wire soldered to it. (the current path is through the lugs) Connecting these four lugs together with a common wire eliminates any resistance due to oxidation between the ground lug and the board. You can also use deoxit as some have mentioned or you can physically tweak the lug to make a clean connection as long as it's not loosely connected to the board. Then measure for any resistance.

**voice of the theater** · January 16th, 2011, 09:35 PM

Originally Posted by rontec

I might be missing something here. I personally can't see any ground lugs in the photo. All of the common rivets are probably not current paths. Maybe a photo of the opposite side of the crossover board would help?

In the mod 19 there are four ground lugs. Each of the ground lugs is riveted to the board and has a wire soldered to it. (the current path is through the lugs) Connecting these four lugs together with a common wire eliminates any resistance due to oxidation between the ground lug and the board. You can also use deoxit as some have mentioned or you can physically tweak the lug to make a clean connection as long as it's not loosely connected to the board. Then measure for any resistance.

I have no idea if they are just common rivets or if they are ground connections. Here are two photos of the other side of the board and the original photo of the board for comparison. I can tell you that there is what appears to be a "circle of solder" (again, please excuse my excessively technical terminology!) on the green side of the board that corresponds EXACTLY with EVERY ONE of the seven rivets on the flip side of the board. Do these photos help to determine if the common rivets are part of the current path (ground) and whether or not it is therefore advisable to connect the rivets with wire? (CLICK ON IMAGE TO DOUBLE PHOTO SIZE)

**aditya** · January 17th, 2011, 12:28 AM

.............Do these photos help to determine if the common rivets are part of the current path (ground) and whether or not it is therefore advisable to connect the rivets with wire?.............

No it is not necessary. The lugs are not at all connected to the circuit path in any manner. You can see that the green area is actually the blank area of the circuit-board. The copper colour-ed areas are the real tracks (electrical). This style of connecting things are different from the 19's which was point-to-point wiring type, and hence will benefit from shorting all of them with common jumpers. No such thing is needed here, except changing ageing components may be.

Aditya

**voice of the theater** · January 17th, 2011, 12:42 AM

Originally Posted by aditya

.............Do these photos help to determine if the common rivets are part of the current path (ground) and whether or not it is therefore advisable to connect the rivets with wire?.............

No it is not necessary. The lugs are not at all connected to the circuit path in any manner. You can see that the green area is actually the blank area of the circuit-board. The copper colour-ed areas are the real tracks (electrical). This style of connecting things are different from the 19's which was point-to-point wiring type, and hence will benefit from shorting all of them with common jumpers. No such thing is needed here, except changing ageing components may be.

Aditya

Looks like I was way off in guessing that the green areas might be the ground.......