7B crossover issue

gcstokes1
gcstokes1 Posts: 56
edited February 2010 in Troubleshooting
i replaced the capacitors today in the first speaker (Dayton 12 & 34). i now have no low end. Any clues?
G
Post edited by gcstokes1 on
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  • thsmith
    thsmith Posts: 6,082
    edited February 2010
    DOuble check your work and make sure you don't have a cold solder.
    Speakers: SDA-1C (most all the goodies)
    Preamp: Joule Electra LA-150 MKII SE
    Amp: Wright WPA 50-50 EAT KT88s
    Analog: Marantz TT-15S1 MBS Glider SL| Wright WPP100C Amperex BB 6er5 and 7316 & WPM-100 SUT
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    Thanks
    I have been through it twice now. Looking at the board, is the copper in each of the segments common to all of that segment? I am nervous about getting something too hot.
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  • Face
    Face Posts: 14,340
    edited February 2010
    Compare the connections to your other speaker's.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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  • george daniel
    george daniel Posts: 12,096
    edited February 2010
    IIRC the wires from the inductor are soldered directly to the board,,sounds like it's a solder joint/connection issue--good luck,keep us posted.
    JC approves....he told me so. (F-1 nut)
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    well, with your help, I have checked and re-checked all connections, re-soldered, checked the connection at the woofer, compared the location of my solder joints to the other speaker, checked visually all of the connections that I didn't make.....
    I must say that although my connections are not as pretty as the original, they seem to make contact as well as theirs.
    Is it possible that I fried something? It seems that I could lay the wire and solder any where on the copper in that particular section.
    trying, but lost....
    G
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  • thsmith
    thsmith Posts: 6,082
    edited February 2010
    Possible you got the new caps to hot ?

    COuld try putting the original caps back in.
    Speakers: SDA-1C (most all the goodies)
    Preamp: Joule Electra LA-150 MKII SE
    Amp: Wright WPA 50-50 EAT KT88s
    Analog: Marantz TT-15S1 MBS Glider SL| Wright WPP100C Amperex BB 6er5 and 7316 & WPM-100 SUT
    Digital: Mac mini 2.3GHz dual-core i5 8g RAM 1.5 TB HDD Music Server Amarra (memory play) - USB - W4S DAC 2
    Cables: Mits S3 IC and Spk cables| PS Audio PCs
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    thsmith wrote: »
    Possible you got the new caps to hot ?

    COuld try putting the original caps back in.

    The work I was doing was pretty far from the caps, needed all of the wire on the big 33mF just to get to the holes. The 33mF cap is the one connected to the part of the board where the woofer wires come in, might try just replacing that one first with the original. Make any sense?
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  • george daniel
    george daniel Posts: 12,096
    edited February 2010
    yep,,that makes sense,check those wires where they come in to the board,like you said--let us know what you find,and good luck.
    JC approves....he told me so. (F-1 nut)
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    Well, old caps are back in, one at a time, still no low end. What else could I have screwed up? It seems like all of the other original solder points are intact. the only one that is anywhere close to heat, is where the lg inductor comes in to the X over. It too seems intact.
    Anything else come to mind?
    G
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  • george daniel
    george daniel Posts: 12,096
    edited February 2010
    i had a similar issue,, it was a bad joint/connection on the board coming from the inductor,, the only way i found it was troubleshooting with the speaker connected--which should be done carefully--good luck--hope you find the problem
    JC approves....he told me so. (F-1 nut)
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    george daniel wrote: »
    i had a similar issue,, it was a bad joint/connection on the board coming from the inductor,, the only way i found it was troubleshooting with the speaker connected--which should be done carefully--good luck--hope you find the problem

    If I read correctly, I may have compromised the connection for the inductor. You are suggesting, with signal, to move/test/jiggle the connection to see it there is a problem there?
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    Holy $*&# Batman (Polk Man).
    Scratching my head, I changed the woofers out, good woofer now on bad (I thought) x over. the problem magically went to the other speaker.
    What could possibly happen to the driver to lose its low end???
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    What driver # does this model use, guess I am on the hunt.
    G
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  • F1nut
    F1nut Posts: 50,553
    edited February 2010
    The model number is printed in the back of the driver.
    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

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  • kcoc321
    kcoc321 Posts: 1,788
    edited February 2010
    Wow, that sucks...maybe she got bumped or was just hangin in there by a thread...
    should be MW6502
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    gcstokes1 wrote: »
    What driver # does this model use, guess I am on the hunt.
    G
    I found the #...DUH!
    These are marked MW6500. Dated 1983.
    Sure enough one driver is frozen.
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    kcoc321 wrote: »
    Wow, that sucks...maybe she got bumped or was just hangin in there by a thread...
    should be MW6502

    Out of curiosity, what happens that causes a driver to freeze up? I swear that I listened to these before I start the re-cap project, and they were just fine.
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  • kcoc321
    kcoc321 Posts: 1,788
    edited February 2010
    gcstokes1 wrote: »
    I found the #...DUH!
    These are marked MW6500. Dated 1983.
    Sure enough one driver is frozen.

    Interesting...you should check the driver in the other speaker, before you buy a new one. As far as I know, the MW6500 is from the Model/ Monitor 7A, not the 7B...but stranger things have happened. one of my Mon 7c's came, used, with a MW6501 driver. Not everyone is as specific when repairing them. That is why I always pull the drivers before I buy vintage speakers....Back to topic..
    Do your speakers have Peerless tweeters?
    gcstokes1 wrote: »
    Out of curiosity, what happens that causes a driver to freeze up? I swear that I listened to these before I start the re-cap project, and they were just fine.
    Over driving/ clipping/ OLD AGE/ phunz-****/ dropping them (happened to one of mine..not me though) The magnet shifts and the piston no longer can move.
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  • ben62670
    ben62670 Posts: 15,969
    edited February 2010
    gcstokes1 wrote: »
    I found the #...DUH!
    These are marked MW6500. Dated 1983.
    Sure enough one driver is frozen.

    I have a paper ring MW6500. Post a pic of the bad driver.
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    ben62670 wrote: »
    I have a paper ring MW6500. Post a pic of the bad driver.


    M7B driver pics
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    kcoc321 wrote: »
    Interesting...you should check the driver in the other speaker, before you buy a new one. As far as I know, the MW6500 is from the Model/ Monitor 7A, not the 7B...but stranger things have happened. one of my Mon 7c's came, used, with a MW6501 driver. Not everyone is as specific when repairing them. That is why I always pull the drivers before I buy vintage speakers....Back to topic..
    Do your speakers have Peerless tweeters?

    Pics posted above. both MW6500....
    phunz-****????
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  • kcoc321
    kcoc321 Posts: 1,788
    edited February 2010
    Nevermind...see you got it...well here they are bigger..
    It DOES look like you have the Early Mon 7b's, with Peerless tweeters & the Crossover designed for them. COOL.
    So you do need a MW6500. There were some MW6500's in the FS section

    DSC_0083.jpg

    DSC_0082.jpg

    DSC_0084.jpg

    DSC_0085.jpg


    "phunz-****" just made it up...LOL
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  • comfortablycurt
    comfortablycurt Posts: 6,745
    edited February 2010
    kcoc321 wrote: »
    Nevermind...see you got it...well here they are bigger..
    It DOES look like you have the Early Mon 7b's, with Peerless tweeters & the Crossover designed for them. COOL.
    So you do need a MW6500. There were some MW6500's in the FS section

    Just for the record, all of the 7B's used Peerless tweets. It wasn't until the 7C's came out that they started using the SL-2000's.

    Some of the earlier Model 7's also used the SL-1000's IIRC.

    The earlier 7B's also had the paper rings on the MW's and PR's like the 7A's had. They apparently did away with the paper rings part way through the 7B's production run, since most of the 7B's that you see don't have paper ring drivers.

    That can make things confusing, since both the Monitor 5B's and 10B's used SL-2000's.


    I'd guess that those are mid-late production 7B's.
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  • kcoc321
    kcoc321 Posts: 1,788
    edited February 2010
    Yep. I thought they are earlier or early-mid production because they have the MW6500 with the Peerless. I prefer to think of the Early, early Monitors as "Model 7a's" when they hae the paper rings.

    At some point it would be 'fun' to make a Monitor version 'timeline' like the SDA's have, just to track all the variations. Skrol made a pretty good start.

    AS an example, I have 7's that are labeled "7C" on the Xover, but they have the square '7B' cabinets and have the SL1000 tweeters. One of the tweeters even has a "Peerless" magnet, 5514#, no paper label....but with a Silver SL1000 faceplate.
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    Thanks to all for input and insight. New driver on the way from BigStereo. I will take all of the X over advice to the worktable when I install the caps for the SECOND time.
    thanks again
    G
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  • ben62670
    ben62670 Posts: 15,969
    edited February 2010
    gcstokes1 wrote: »
    M7B driver pics

    Sorry Bro I have nothing for you.
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben
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  • gcstokes1
    gcstokes1 Posts: 56
    edited February 2010
    ben62670 wrote: »
    Sorry Bro I have nothing for you.

    thanks for checking. found one.
    G
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