New Crossovers for old speakers (Pioneer Elite TZ7 |
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studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3863 |
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Posted: 30 November 2019 at 2:19pm |
For sure the cost. The electro would be less than half the price of any non-polarised cap the same value and voltage. When you have to make 10000 pairs that sh1t adds up.
There's a theory that if you connect a 1.5v battery across the electrolytic to maintain a polarising voltage, it sounds better. JBL do it in some of their expensive domestic models! Adding the battery holder is still probably cheaper than using the non-polar cap...
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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rchamlen
Registered User Joined: 26 November 2019 Location: minnesota Status: Offline Points: 21 |
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thanks. all connectors on the board itself are soldered - the connectors are only to attach to the speakers (I might keep those for ease of attachment/removal of the drivers). They did actually use several polypropylene caps on the original build, but have that one electrolytic you see, and two electrolytics on the midrange bandpass. Not sure why they would have used electrolytics when polypro were available? I am not a EE - so I do not know enough to know if there was a solid reason (other than cost...)
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rchamlen
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studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3863 |
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Right on! To put the good fix in, just get rid of the connectors and solder the wires direct to the board? And I would definitely recommend changing out that electrolytic cap for a good polyester or polypropylene type. Good luck!
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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rchamlen
Registered User Joined: 26 November 2019 Location: minnesota Status: Offline Points: 21 |
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Yeah - I know about the degradation of electrolytics ... which is why I ask the question. Sounds like you are voting in favor of replacing them while I have at least one of the speakers opened up? given the age, I dont think I will even bother with checking their values - just replace them with equivalents. The rest of the components I will leave just the way they are . Thank you all for your thoughts and insights!
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rchamlen
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Xoc1
Registered User Joined: 15 October 2012 Location: Devon UK Status: Offline Points: 397 |
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The electrolytics are usually the components that will go out of specification. Usually it makes sense to replace them with more electrolytics if the values are large. You could maybe look at higher voltage rated parts, or plastic caps if the values are small. Once this is done the speakers should be working properly if all the drivers are OK, and should stay that way for years. Most other component replacements would be to try to give the speakers a bit of an upgrade which would be down to you. |
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rchamlen
Registered User Joined: 26 November 2019 Location: minnesota Status: Offline Points: 21 |
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You know ... you might actually be pretty close on this one. This was bugging me this morning, because what I could see and measure of the circuits just did not make sense (in terms of the failure I was seeing). the two woofers are driven by entirely separate low pass filters, and only one of them has a capacitor. Now that I understood how the circuits are laid out better, I was able to take multiple measurements with my multimeter. Speakers checked out (you saw that before), the cap is not shorted, I do have continuity between the input jacks and the hot output to each of the woofers (you are right - the inductors measure about 1.4 ohms), and I have continuity between the neutral for the woofers and the neutral on the input jack on the back of the cabinet. Huh??? so I hooked the speakers up to a stereo, measured and got AC output at the wires leading to the woofers. Hooked up the woofers (one at a time, alternating front and back connections) .... AND THEY WORK. (I know from personal inspection that they did not previously) Grrr. The best I can figure (and here is where your "devils" come in ... is that the connectors from the crossover outputs to the speakers (the flat, slide on/off type) had corroded and lost continuity at the interface. Likely one went a while ago, and was not noticed. The speakers was thought to have "died" when the second woofer connector lost continuity. (duh .... I have seen this on so many other type of connectors - from ethernet to coax, to computer drive cables, etc). Not definitive, but that is my best guess). so, probably my best course right now is to go through all of the drivers, and re-seat all of those connectors. Question though: since I have the box opened, and I have (finally) traced the actual circuits .... I know those caps will eventually die (they are, what, at least 25 years old now??? should I go ahead replace all those caps on all the crossovers (four boards total .... maybe 4-6 caps per speaker) .... or should I just re seat the connectors and put the speakers back in to service. (since these will be with my son, there is no saying I will be in a position to service them after a year or two.....). What do you guys think? Thank you for your help in thinking this through - your comments did help guide me a lot!
Edited by rchamlen - 28 November 2019 at 4:54pm |
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rchamlen
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BJtheDJ
Young Croc Joined: 28 November 2012 Location: Bristol Status: Offline Points: 884 |
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Wrote something, posted it, changed my mind. You cannot delete posts to these forums, only edit them
Edited by BJtheDJ - 28 November 2019 at 4:25pm |
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If your vaccinations were mandatory and nobody in your class had measles,
then you know that you're not a Millenial kid.</f |
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studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3863 |
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Let's apply some problem solving logic here. Fixing the stock crossover is going to be a lot easier than designing a new one. You can upgrade the components later, if you want get some improvement.
So, you have no output from either woofer, but the mid and tweeter work. First thing to ensure is that the woofers are not blown. I think you've established this yes? They should have continuity, and a DC resistance of about 5-7 ohms when disconnected from the crossover. Next look at where the signal comes from for the woofers. It seems like the first thing it has to go through is the two inductors. So check that the inductors are still firmly soldered to the board and the input cable, and that they have continuity. You should probably be able to read an Ohm or so of resistance for inductors that size. Next possibility is that the cap for the front woofer has gone short. Lift one leg and check for continuity, it should read infinite impedance. If your meter has the function, check the capacitance value. It should be within 10% of what is printed on the cap. If all those components pass these checks, then your box contains devils. Call a priest. Good luck :) |
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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rchamlen
Registered User Joined: 26 November 2019 Location: minnesota Status: Offline Points: 21 |
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Oops??????
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rchamlen
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BJtheDJ
Young Croc Joined: 28 November 2012 Location: Bristol Status: Offline Points: 884 |
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Ooops
Edited by BJtheDJ - 27 November 2019 at 10:28pm |
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If your vaccinations were mandatory and nobody in your class had measles,
then you know that you're not a Millenial kid.</f |
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rchamlen
Registered User Joined: 26 November 2019 Location: minnesota Status: Offline Points: 21 |
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Yay .... now I get to browse to a file. Attached below. Looks like just a simple breadboarded affair. Not sure if there are any wires on the back side of the board. Will need to pull it to see for sure (hopefully I can get the thing to the outside of the cabinet with the wires intact - they had to solder the thing that way in the first place is my guess.....)
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rchamlen
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rchamlen
Registered User Joined: 26 November 2019 Location: minnesota Status: Offline Points: 21 |
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still no browse button ... lets try one more stupid post
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rchamlen
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