Strange tweeter issue after recap crossover for Monitor 7 series 2
xenonsky
Posts: 32
I recently recapped my Monitor 7 series 2 crossovers with Sonicap Gen 1 capacitors & mills resistors. On one of the speaker the tweeter sound goes out after a few hours.
I discovered if I take out the negative banana plug from the connector, and then touch the banana plug tip to the top edge of the negative speaker terminal post. Then carefully slide the banana plug back into the speaker terminal post (while maintaining banana plug contact with the top edge for as long as I can). The tweeter sound will come back as usual for a short while, but then the tweeter sound may go out again and I have to repeat the above action to bring the tweeter sound back. (While the time the 6.5" mid-range speaker sound never goes out)
I'm not sure if de-soldering and re-soldering the Sonicap may help, assuming I have a bad solder spot.
Does anyone know if this sounds like it could be a bad Sonicap capacitor and/or a bad mills resistor on the tweeter side of the crossover link?
Any suggestion on the best way to troubleshoot this? Or how best to check that the Sonicap is functioning properly with a multimeter?
Thanks.
I discovered if I take out the negative banana plug from the connector, and then touch the banana plug tip to the top edge of the negative speaker terminal post. Then carefully slide the banana plug back into the speaker terminal post (while maintaining banana plug contact with the top edge for as long as I can). The tweeter sound will come back as usual for a short while, but then the tweeter sound may go out again and I have to repeat the above action to bring the tweeter sound back. (While the time the 6.5" mid-range speaker sound never goes out)
I'm not sure if de-soldering and re-soldering the Sonicap may help, assuming I have a bad solder spot.
Does anyone know if this sounds like it could be a bad Sonicap capacitor and/or a bad mills resistor on the tweeter side of the crossover link?
Any suggestion on the best way to troubleshoot this? Or how best to check that the Sonicap is functioning properly with a multimeter?
Thanks.
Answers
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Pictures of the XO would help. Did you replace the poly switch in the tweeter circuit with a 1/2 ohm resistor or leave in the poly switch?
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Thanks I should have posted the crossover before and after picture per below.
I tried tracing the wires from cross over to tweeter and also check on the back of tweeter, there seems to have no poly switch in my Monitor 7 series 2. There seems also no poly switch on the other working one.
I have the SL-2500 tweeter so it seems to match the crossover diagram I found below without poly switch. (The earlier versions of Monitor 7 diagrams I found does have poly switch, but seems not for the series 2 diagram below)
These are the before pictures of the monitor 7 cross over and the diagram I found depict the components.
Below are the after pictures of the same cross over with 3 Sonic caps & a mills resistor.
And the green across below is where I have to try to touch a few times with tip of banana plug to get the tweeter sound to come back. (before I insert banana plug in slowly while touching that edge as much as possible)
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Those joints where the tweeter cap is paralleled to the resistor SCREAM cold solder joint to me.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Yeah I don't want to knock your work but the soldering is extremely poorly done- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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Echo, reflow soldier joints.
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Also, all of the components need to be secured and I would recommend isolating the resistor from the cap- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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Gardenstater wrote: »Those joints where the tweeter cap is paralleled to the resistor SCREAM cold solder joint to me.
BINGO!!!Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Thanks guys for the suggestions. This is my first soldering job, will try to clean up the likely cold solder join on the parallel cap & resistor to see if it solves the issue.
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Also, all of the components need to be secured and I would recommend isolating the resistor from the cap
I'll need to buy a hot glue gun to glue down the components down like the original cross overs does.
Or possibly zip tie can do the trick to secure components tightly to the cross over board?
How best to isolate the cap from the resistor? Will inserting a piece of foam in between the gap works? -
Zip ties work.
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I wouldn't put anything around the resistor, especially foam, because it needs air to breathe to stay cool. Keep it spaced away from the capacitor and the board by at least 1/8" I'd say.
When you reflow the solder joints make sure you apply some paste flux to the existing solder and leads. If it was more feasible, I'd suggest that you clean the solder and leads of oxidation with something like super fine steel wool or sandpaper. That is easy to do with plumbing. Not so easy to do here.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
A solder joint should look smooth and shiny. Even the ones under the board need to be reflowed.
What are you using for a solder pencil or gun? What are you using for solder?Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
A solder joint should look smooth and shiny. Even the ones under the board need to be reflowed.
What are you using for a solder pencil or gun? What are you using for solder?
I just have a basic solder iron.
For solder I was using cheap solder from local hardware store. I recently bought some Audio Note 6% silver solder, so I'll clean up the current cold solder join and replace with better solder then. (I didn't use flux initially and will add flux paste this time per suggestion above to reflow the join)
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That's good solder, it'll flow much quicker. Using that I see no reason to use flux.
You should use a solder sucker to remove the cheap solder.
Clean that tip. Heat it up then draw the tip across a wet sponge a few times. While you're soldering every now and then clean the tip. Of course, that will cool the tip, so wait a minute for it to come back up to temperature before you use it again.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
That's good solder, it'll flow much quicker. Using that I see no reason to use flux.
You should use a solder sucker to remove the cheap solder.
Clean that tip. Heat it up then draw the tip across a wet sponge a few times. While you're soldering every now and then clean the tip. Of course, that will cool the tip, so wait a minute for it to come back up to temperature before you use it again.
Thanks, will give it a try this week and report back my result. -
I like to use a tip tinner. Mine's from Radio Shack (LOL) which you aren't likely to find. Something like this:
https://www.amazon.com/Tinner-Soldering-Cleaning-Supplied-Wonderway/dp/B0DGPP78NY/ref=sr_1_2_sspa
I didn't read this whole thing but here's some advice on soldering
https://www.aaroncake.net/electronics/solder.htm
If you are going to try to remove the old solder I would still apply paste flux to it to get it to melt easier and flow out. It is very oxidized at this point.
If I was a beginning solderer I wouldn't attempt to do it without flux no matter what the marketing blurb for the solder says.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
For solder I was using cheap solder from local hardware store.
Man, I hope this wasn't acid core solder
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slow_polk7 wrote: »
Man, I hope this wasn't acid core solder
Not sure if it was acid core solder or not, but the cross over solder area metal don't seem to have any corrosion. -
More worried about acid based paste flux (for plumbing) vs Rosin based flux (for electronics)
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Hi all, I found the cause of problem after further check all the wiring and solder from top to bottom. It turned out to be the woofer inductor coil wire coming into the cross over had been very close and almost come in contact with one of the tweeter capacitor wire (which I didn't trim off and only bended it upward and away). After I pushed the inductor wire down and away from the capacitor wire the problem is now gone. Thanks everyone for the input and suggestions.
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Was the enamal on the inductor wire removed in that section?
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@xenonsky
Good job of tracking that down.
You may want to consider doing something in the way of securing those caps to the board. -
Was the enamal on the inductor wire removed in that section?
There were no enamel for the inductor wire coming up into the cross over board. It looks like that when I first took the cross over out for the first time. I have a pair of monitor 5jr+ and the crossover inductor wire there looks the same without enamel. -
slow_polk7 wrote: »@xenonsky
Good job of tracking that down.
You may want to consider doing something in the way of securing those caps to the board.
Will definately use some zip tie to sure them capacitors to the board. Thanks for the reminder. -
This is not correct.
The red coating is enamel, you have to scrape it off before connecting- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit. -
This is not correct.
The red coating is enamel, you have to scrape it off before connecting
Oh I thought the enamel was referring to the clear plastic. But the inductor wire coming up into crossover board feels like bare wire without any coating thou. -
you scrape off the red coating and you will see the color of copper- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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Here's where the red enamel is stripped off the copper wire to solder it.
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correct, that solder joint also looks suspect- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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Yes that enamal is why the wire doesn't create a short when touching other wire or soldered areas. SOO logically unless the enamal was removed I do not see how it was having an affect.
Unless you didn't remove the board to solder to the back side, then I can see maybe you burned off the coating with your iron.
