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Thread: need help with 4311's

  1. #1
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    need help with 4311's

    I inherited a pair of 4311's from an older man who passed recently. Hooked them up and neither speakers woofers work. Hooked the woofers to a sine wave disc and they move like they should. So Im assuming its not the voice coil. Its odd to me that both speakers are affected in the same way. The other components in the speaker work fine. May i assume that this is a crossover problem? I have had no experience or training in electronics. Any help would be greatly appreciated. thanks in advance guys. dave

  2. #2
    Administrator Mr. Widget's Avatar
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    I'm not sure if this is true of every version of the 4311, but most have no crossover on the woofer. The woofers play full range. Check the continuity between the speaker's terminals and the speaker wire for the woofers.


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    Thanks a bunch for your help. I'll give it a try this weekend. dave

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    Agree with Widget, if bot woofers were not working, there was a fault in the way they were wired either to the crossover board or directly to the input terminals, however JBL wired them. I would suggest rechecking all the wiring from input terminals to crossover to all drivers, something had to be off.

    also, make sure to check and correctly orient the solid color and black stripe color wires to the correct terminals, JBL has some odd wiring due to polarity differences in early consumer and pro models.

    here the link to the original 4311:

    http://www.jblproservice.com/pdf/Net...%20Network.pdf
    When faced with another JBL find, Good mech986 says , JBL Fan mech986 says

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    Again thanks for all your help guys. Mr Widget i checked the continuity of the crossover and thats good. I used Deoxit on the pots and the woofers came to life. The pots were pretty gnarly looking on the outside. The woofers do go thru the crossover on this set. Now i have non-functioning LE 25's and 1 LE 5-2 not working. So i will check the wiring (thanks Mech986 for the schematic) and the speakers for continuity. I truly appreciate all you guys. dave

  6. #6
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    Quote Originally Posted by mongomikey View Post
    Again thanks for all your help guys. Mr Widget i checked the continuity of the crossover and thats good. I used Deoxit on the pots and the woofers came to life. The pots were pretty gnarly looking on the outside. The woofers do go thru the crossover on this set. Now i have non-functioning LE 25's and 1 LE 5-2 not working. So i will check the wiring (thanks Mech986 for the schematic) and the speakers for continuity. I truly appreciate all you guys. dave
    ok, glad to help. But WAIT! You cleaned the pots and the woofers came to life? The woofers have no pots connections on their part of the crossover circuit - the pots should affect only the midrange or tweeter separately. This suggests the woofer is hooked up to the midrange circuit, and the mids and tweeters not working are either not hooked up, hooked up completely wrong, or are blown, possibly giving you the odd results you have now. Early 4311 had just color coding wiring, late 4311 may have have coded male female Faston connectors with corresponding connectors on the drivers. If you have a pic of the front baffle and serial numbers, we can semi-date them.

    As as you did with the woofer, test each mid and tweeter with appropriate band limited sound or music (mid for mid, High for high) to test function, check wiring again for all drivers, especially the woofer, and if still some drivers not working, then you have to look at. The crossover for bad connections or solder joints.

    was there any other gear from this person's estate?
    When faced with another JBL find, Good mech986 says , JBL Fan mech986 says

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    Mech986- I kind of wondered about the pots affecting the woofers. I am not "informed" when it comes to electronics but got to thinking about the wiring being crossed. The wiring to the woofers are both green with one having a black stripe. After i open the other speaker i saw where someone had wrapped masking tape around the port to hold the batting on. So I'm wondering if the wiring got crossed. I will get some pics for you hopefully tonight. (mother-in -law was admitted to hosp with heart attack/failure and other things so if i dont get back quickly thats why). As far as other equipment i ended up with quite a bit. Some good some i hadn't heard of (speakers mostly). In the stuff was a RCA lab 1200 turntable, Technics sl-d2, sansui g5700, technics m6 cass, onkyo turntable(cant remember the model), toshiba sa-420 reciever and the jbl 4311 and i'll have to get a list of the speakers. 4 or 5 sets total if i remember right. plus 3 to 400 albums. thanks for having patience with me. dave

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    Give this a whirl


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    JeffW- Thanks for the pic. It turns out that I can not get any reading with an ohm meter on the le 5-2 or the le 25's. Talked with a son( of the man who passed) and he said the grandkids were playing them "kinda" loud. So my next move is to repair or replace. Does anyone know of a reputable repair shop or if non-repairable an equivalent replacement? I was hoping it was something fairly simple...Thanks dave

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    Quote Originally Posted by mongomikey View Post
    I inherited a pair of 4311's from an older man who passed recently. Hooked them up and neither speakers woofers work. Hooked the woofers to a sine wave disc and they move like they should. So Im assuming its not the voice coil. Its odd to me that both speakers are affected in the same way. The other components in the speaker work fine. May i assume that this is a crossover problem? I have had no experience or training in electronics. Any help would be greatly appreciated. thanks in advance guys. dave
    Quote Originally Posted by mongomikey View Post
    JeffW- Thanks for the pic. It turns out that I can not get any reading with an ohm meter on the le 5-2 or the le 25's. Talked with a son( of the man who passed) and he said the grandkids were playing them "kinda" loud. So my next move is to repair or replace. Does anyone know of a reputable repair shop or if non-repairable an equivalent replacement? I was hoping it was something fairly simple...Thanks dave
    So I see these two posts as contradictory - your first post said "neither speakers woofers work" yet "the other components in the speaker work fine" - so did the midrange and tweeters play in both speakers at that time or not when you tested them. After you took the woofers out, you tested them independently with a sine wave tester (what frequency and how loud?) and the woofers moved and put out sound. Did you ohm those out?

    In the second post, I'm assuming you have taken all the drivers out of the cabinet and you are testing them with a known good digital multimeter, on ohm setting (usually 200 ohms) and when touching the two leads together, it reads less than 0.5 ohms, then you attach to both terminals of each of the LE5-2 mids and each of the LE25's and they all don't have a reading at all? And you touched or wiggled the leads to make sure you're getting contact (and they are not hooked up to the crossover for this testing)? Did you try to do any sine wave testing of the midrange or tweeter - how did you do it, and did you restrict the frequency to each respective band (mids = 500-4Khz, tweeter = 4K-15khz) at relatively low power?

    Was there any issue or fault with the power amplifier being used to drive these speakers or testing?
    When faced with another JBL find, Good mech986 says , JBL Fan mech986 says

  11. #11
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    If you're looking for true JBL sound quality from the 4311, if the drivers are truly blown, reading nothing on an ohm meter (indicates the voice coil wiring is open = has a break in it so current and voltage cannot flow), then you'll have to source replacement JBL drivers of the same number within reason. The LE5-2 and LE25 are both pretty common and show up on ebay all the time, although not always inexpensively. For the LE25, you can also sub in the LE25-2 or the LE26 without much difference.

    Do you have any pictures of the drivers, did you take out the crossovers, and is there any faults on the crossover boards wiring or solder connections?
    When faced with another JBL find, Good mech986 says , JBL Fan mech986 says

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    Mech986-I did contradict myself. What I did was hook up one speaker and the woofer didnít work and the mid on that speaker worked so I stupidly assumed both were working. I apologize for my assumption. Iíll start over and hopefully make sense. When i hooked the speaker up originally the woofer didnít work and the mid did work. So I assumed (having never done this before) both mid and tweeter were working. I hooked up the woofer to a sine wave disk I received when I refoamed another set of speakers. I turned it up enuf to make the woofer move. I then checked the crossover with an ohm meter(had continuity) and deoxitíd the pots. Hooked the speaker back to the receiver and woofer worked. (not thinking about wired backwards). So I tried the pots and noticed the LE 25 was not responding and the LE 5-2 was putting out the sound. Took the tweeter out (unhooked from the crossover) and there is zero continuity. Scratched, wiggled and nothing. Did get a reading on the mid. Did basically the same on the second speaker and both mid and tweeter are reading zero. The woofer is working so am assuming the woofer was wired backwards. Tried with several power sources and several other speakers and the power source was fine. Did test with the crossovers unhooked and all three are zero readings. The solder connections on the crossovers look good. Having trouble getting the pics uploaded but will work on that. I will start the search process for the ones you suggest. Thanks again. dave

  13. #13
    Administrator Mr. Widget's Avatar
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    Here are the schematics for 4 versions of 4311.


    http://www.jblproservice.com/pdf/Net...%20Network.pdf

    http://www.jblproservice.com/pdf/Net...20Networks.pdf

    http://www.jblproservice.com/pdf/Net...%20Network.pdf

    http://www.jblproservice.com/pdf/Net...%20Network.pdf

    Check and see which version you have. The network number is usually printed on the network itself.


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