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Post subject: 1968 bassman 2x12 cab inop!!! TECH HELP
Posted: Sun Sep 26, 2010 8:45 pm
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I have a 1968 Bassman 2x12 cab that is cutting out... I took the back off to check the wiring and it all checks out. I laid it face down and stood it back up again it worked... GO FIGURE! So, I kept the back off and played it on and off for the rest of the day and placed the back on w/ out screws and it worked... I buttoned it back up took it to a gig and it did the same thing. :evil: I know the head works fine. The cab does have some out put - very faint - from one speaker. I also want to mention that when I got it I had to drill new mounting holes for the speaker because one of them wasn't attached. HELP


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Posted: Sun Sep 26, 2010 9:33 pm
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Possible intermittant contact within the cabinet wiring harness. If the wires are soldered to the speaker terminals, try re-heating with an iron until the solder once again turns molten. DO NOT BLOW ON IT OR OTHERWISE ATTEMPT TO ARTIFICIALLY COOL THE SOLDER.

Inspect all of the internal wiring and look for any kinked wires that might indicate an invisible open within the plastic or cloth insulation.

Also, check the continuity of the speaker cable between your amp and the cab.

Lastly, check the cab's input jack to see that the tip lug is sufficiently tensioned to engage the plug tip and that there is no corrosion anywhere.

Something is definitely wonky.

HTH

Arjay

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Posted: Sun Sep 26, 2010 10:08 pm
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My guess is a weak solder joint or dirty jack. You can do a continuity test on all of the joints and the jack while moving the wires. I'd also check the speaker cable between the amp and cab. Some contact cleaner on that speaker cable sure wouldn't hurt. Art

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Post subject: Ext cab not working
Posted: Mon Sep 27, 2010 9:06 am
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Going with the odds, it is the speaker or amp jack and/or speaker cable used to connect the cab (bad connection on end, unscrew cover and check). Try a different cable first. You did use speaker cable, not instrument cable, right? :idea:

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Posted: Mon Sep 27, 2010 11:37 am
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I will check for continuity in the cab. When i was testing the first time i took the head and the same cable and plugged it into a different cab and was spot on. So the cable and head are not the culprit. The cable is definitely a speaker and not an instrument cable.


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Posted: Mon Sep 27, 2010 12:40 pm
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pinhead88 wrote:
...When i was testing the first time i took the head and the same cable and plugged it into a different cab and was spot on. ..


From your first post, you indicated an intermittent problem. If you moved the cable to another speaker and it works, then you move it back it doesn't work, it could still be the cable. I would still try another cable to be sure. :)

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Posted: Fri Oct 01, 2010 1:35 am
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I've checked for continuity through the cab and with the speaker cable. At the time of testing the cabinet was working but just didn't have the zing that the amp usually pushes. So, I rewired the cab, tested to make sure I had 4 Ohms, and put the backing board on. Its working great !!!

While I was in the cab I decided to do a little research on the speakers since they were not the same. The speakers in the cab are a 12" Oxford, and "Fender Special Design" Utah AlNiCo-or what appears to be an AlNiCo-My question is: Did the Bassman cab (dated late 67) come with Alnico Utah's from the factory or neither are the original???


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Posted: Fri Oct 01, 2010 9:39 am
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pinhead88 wrote:
While I was in the cab I decided to do a little research on the speakers since they were not the same. The speakers in the cab are a 12" Oxford, and "Fender Special Design" Utah AlNiCo-or what appears to be an AlNiCo-My question is: Did the Bassman cab (dated late 67) come with Alnico Utah's from the factory or neither are the original???


Fender would never mix speaker brands within a single cab or combo amp -- that was verboten under company policy. But both Oxford and Utah were OEM Fender vendors during this era. It's possible that both speakers are legitimate but that one or the other (or both) were installed by a previous owner after the cabinet was built. The EIA codes on each speaker will reveal their vintage and pedigree -- "465-XXX" for the Oxford, "328-XXXX" for the Utah. Alnico Utah's would be extremely rare.

HTH

Arjay

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Posted: Fri Oct 01, 2010 12:03 pm
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I know that there wouldn't be speaker mixing in the cab from the factory. The cab has definitely been "molested".
Oxford number:
110296
465-837
12T6-11
This speaker has no fender markings on it, just a sticker with numbers on it. The only other number on it is F-8 39

Utah number:
030627
328708
This speaker has a small rectangle sticker that reads Fender Special Design Speaker etc... replace with part number 064121


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Posted: Fri Oct 01, 2010 12:34 pm
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pinhead88 wrote:
I know that there wouldn't be speaker mixing in the cab from the factory. The cab has definitely been "molested".
Oxford number:
110296
465-837
12T6-11
This speaker has no fender markings on it, just a sticker with numbers on it. The only other number on it is F-8 39

Utah number:
030627
328708
This speaker has a small rectangle sticker that reads Fender Special Design Speaker etc... replace with part number 064121


I suspect that they're both "genuine" Fender speakers despite the lack of a label on the Oxford. That speaker likely dates to '68 while the Utah was from early in the previous year. However, that T-series Oxford may have in fact been originally installed in a Twin Reverb. Bassmans, Bandmasters, and Pro Reverbs usually were fitted with "K" or "L" series drivers.

As long as they're correctly phased with one another I see no reason to worry.

Arjay

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