Home » VintageKustom.com » Repairing Kustom Amps » Kustom XII bi-amp (amp wires have been cut)
Re: Kustom XII bi-amp [message #23633 is a reply to message #23583] Sun, 16 August 2015 12:25 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Registered: June 2014
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Well it appears that someone did switch the output jacks on this thing......the low right is actually controlling the high end. With jumpers on the cut wires back to the left board, I am getting the same amount of sound out of the two boards. With volume turned all the way up, still getting maybe at best 30 to 40 watts........not blasting like the K-200 that I can only turn up to about 1 1/2. The horn signal is coming thru on that amp as well but would also expect it to be a lot louder.

How do I check out the filter caps........do the wires have to come off.......do you take voltage reading while the amp is on?
Re: Kustom XII bi-amp [message #23634 is a reply to message #23583] Sun, 16 August 2015 13:40 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
Senior Member
A couple of questions. What are you using to drive this amp? It is a power amp so it is probably looking for at least 1 volt of signal to get full power output.

Are you still hooked up to the light bulb limiter?

As for your meter, that should do fine, the ohms reads resistance, the uF (micro Farad) is capacitance, the mA (micro Amp) is current and the voltages are for volts.

To test capacitors, the amp must be off and the power supplies drained. Pulling the plug and leaving the amp sit for a while will probably be enough to drain the caps, but you should test for voltage at the two main filter caps to be sure.

Set your meter to read dc volts. Hold the black lead to the black wires that connect two filter caps together. Now take the red meter lead and touch it to the screw terminal where the red wires are connected. Make note of the DC voltage reading. If the amp has been off for a while there should be less than a few volts there. Then touch the red lead to the screw terminal on top of the second cap where the green wires connect. The voltage reading there will be negative, so your meter will have some sort of minus sign in front of the reading.

When you are sure that there is no voltage left on the filter caps, set you meter to read capacitance, the uF position. Now hold the black lead on the black wire terminal and the red lead to the red terminal and see what reading you get. Some meters will read into the 1000's of uF and some won't, so see if you get a good stable reading. Then test the second cap by putting the black meter lead to the green terminal and the red lead to the black terminal. You can also test any of the small caps on the boards in the same way.

As for testing the operating voltage, you will need to have the amp turned on to test this. If you don't feel safe in doing this, then don't. If you want to try it, you will need to do exactly what I described in testing the caps for residual voltage, but with the amp turned on. If you have clip leads, you can use them to connect the meter to the caps before you turn on the amp and then just turn the amp on to read the meter and then turn if off again.

Just remember that woring on any amp that is plugged in and turned on is dangerous and can cause you physical harm.
Re: Kustom XII bi-amp [message #23635 is a reply to message #23583] Sun, 16 August 2015 13:58 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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I work with 120/240 volts everyday so doesn't bother me working "live".

I'm using the external speaker jack on my lap top for the signal. Right now its plugged into my K-200 and has no problem rattling the windows......can't even come close to that right now with this amp.

Limiter is unhooked.

I'll check the filter caps like you said.

Re: Kustom XII bi-amp [message #23636 is a reply to message #23583] Sun, 16 August 2015 14:10 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Tested the filter caps just like you said.....left one says OL then goes to disc. The right cap just read Ol until I remove the probes then get a momentary reading of 23.2.....meter is set on uF.
Re: Kustom XII bi-amp [message #23637 is a reply to message #23583] Sun, 16 August 2015 22:41 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
Senior Member
It sounds to me like the caps still have a charge on them. OL (overload?) and then disc (discharge?). If the amp has been off for a while, try leaving the meter leads connected longer and see if you get a stable reading after the meter goes through the discharge cycle.
Re: Kustom XII bi-amp [message #23638 is a reply to message #23583] Mon, 17 August 2015 06:31 Go to previous messageGo to next message
stevem is currently offline  stevem
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Yes, that's all you should need ( that one meter ) along with some of our help maybe and the schematic, which brings me to the point that other then the volume / crossover board on the face of the you should be able to pretty much use the output stage schematic for a metal face K 250 and 150 amp to go over the 3 output sections since they are just powered in parallel off of a bigger version of the power supply in the K250 heads.

I have not seen a full chassis picture of it yet, but if it has a choke in the power supply like in the metal face K150 amps than the power supply is a bigger version of that one.
Re: Kustom XII bi-amp [message #23639 is a reply to message #23638] Mon, 17 August 2015 09:13 Go to previous messageGo to next message
C4ster
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Hi all, I have been following this post and I concur that a schematic is mandatory in this case, or any troubleshooting of amplifiers. But something just jumped out at me that I want to address. If you are comparing a K200 of any version, it has preamps that will take a low level signal, maybe 30mV or so and amplify it to the full output rating of an amp. Kustom amps have lots of preamp gain. If you then used that same signal without making any adjustments to it, and applying it to the Kustom XII, you WILL NOT get the same sound output as the K200. You are comparing apples to oranges. ChicagoBill is 100% correct about the levels necessary. Any power amp is designed to be driven from a mixer and subsequently, graphic equalizers, effects and other rack type equipment. These are line level sources, not instrument level sources that the K200 would be driven by. Sorry for the rant.
Conrad
Re: Kustom XII bi-amp [message #23640 is a reply to message #23583] Mon, 17 August 2015 10:22 Go to previous messageGo to next message
stevem is currently offline  stevem
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x2, the k200 only needs 100mv to drive it well into full output and clipping, these bi amps need ten times that or better!
If you feed the test signal into your k200 and then pull the feed for the bi amps input from the rca out of the k200 then that will get you in the ball park, and remember you do not need to have a speaker hooked up to the k200 to do this .
Re: Kustom XII bi-amp [message #23641 is a reply to message #23583] Mon, 17 August 2015 12:43 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Well the amp set unplugged all night.....readings from black to red on the filter showed -.017 same with the other cap as well.

Still can't figure out why the left amp wires were cut if the output volume from it is the same as the right amp?

Should I switch the output jacks so they are at least in the correct place? Assuming they have been moved for some reason?
Re: Kustom XII bi-amp [message #23642 is a reply to message #23583] Mon, 17 August 2015 12:44 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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I will hook up the K-200 and connect it like you said and see if there is any difference in the volume.
Re: Kustom XII bi-amp [message #23643 is a reply to message #23583] Mon, 17 August 2015 13:12 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Well now we are cooking! My K-200 RCA jack must have a short......all I heard was loud buzz. Hooked up the K-250, turned volume to second dot, started turning up the volume on the XII and could only get to about 6 before my ears started hurting. Horn is working perfect as well.

Looks like all I need to do is switch the horn jacks back or rather into their right spot and repair the cut wires, and rewire the switch back the right way.

So guessing even with the hatchet job that was done on this thing......the parts must be working okay.
Re: Kustom XII bi-amp [message #23644 is a reply to message #23583] Mon, 17 August 2015 13:38 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Someone give Conrad a big cigar......he hit it on the head. Pleat was right also about using this and the K-300 head......right now I have it hooked up to my 2 rebuilt 595 cabinets and my Altec horn......this thing is loud. Get my other two 595's rebuilt and add the other horn and this thing will rock. And right now, I am only using two of the XII amps and not all three. I can't even imagine what this will sound like with the additional K-200 and K-400 amps and four 3-15's cabinets. Damn this is awesome!
Re: Kustom XII bi-amp [message #23645 is a reply to message #23644] Mon, 17 August 2015 15:19 Go to previous messageGo to next message
pleat is currently offline  pleat
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Location: Belding, Mi
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Since so much has been rewired in your amp, I'd make sure that both low frequency amps speaker output jacks are correctly labeled on the back panel. Since it has two mono low frequency amps, it doesn't matter if low speakers jacks are in the left or the right low out. It's the horn amp that I'd be concerned with. You don't want to think your hooking up the horns and find out that your driving the horns with a low frequency power amp.

To check, I'd plug in a normal speaker cabinet to the horn amp speaker output jack, ( no chance of damaging a speaker with high frequencies ) Turn up the main volume control and then I'd turn up the horn amp volume control. If you don't hear a difference in gain with the horn amp control, then that indicates the horn amp speaker output jack is not in the proper location for the labels on the back of the amp.
pleat
Re: Kustom XII bi-amp [message #23646 is a reply to message #23645] Mon, 17 August 2015 15:34 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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I had already tried what you mentioned........there is a define difference between the horn and woofer inputs. For some unknown reason someone had put the horn output into the left low description.....same with plugging the amp molex plug into the wrong amp.

I have been running this thing for over 2 hours now without any problems and incredible sound. Pleat, the horn is working so much better now than it did with the crossover that I hooked up to it before. BIG thanks for steering me in the right direction on buying this amp.

Re: Kustom XII bi-amp [message #23647 is a reply to message #23583] Mon, 17 August 2015 15:41 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Have just removed the old crossover from this horn cabinet as well as the L-pad and since there are two holes in the input plate, added a fuse and wired a parallel speaker jack in the event I decide to add another 16 ohm horn with this one to get an 8 ohm load.........pretty cool.....I could have 4 of these horns running.
Re: Kustom XII bi-amp [message #23648 is a reply to message #23583] Mon, 17 August 2015 22:02 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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The amp is still running good after almost 6 hours. Only problem I'm having is trying to remove the output jacks and moving them to where they belong. They are so corroded all they do is turn in the hole. I'm now starting to wonder if these were ever switched around after all. Still after looking at the wiring, I don't see how any of the molex plugs could have been moved to a different amp in this thing. I may just have to mark the outputs with tape.
Re: Kustom XII bi-amp [message #23649 is a reply to message #23648] Mon, 17 August 2015 22:25 Go to previous messageGo to next message
pleat is currently offline  pleat
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Can you just unsolder the speaker wires and re-solder them to the right speaker jacks?
pleat
Re: Kustom XII bi-amp [message #23650 is a reply to message #23649] Tue, 18 August 2015 00:23 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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It would be easier to just cut the two wires.....black blue to the output jacks and just reconnect them to the right output. Its too tight where the jacks are to do a good solder job.
Re: Kustom XII bi-amp [message #23652 is a reply to message #23583] Tue, 18 August 2015 06:48 Go to previous messageGo to next message
stevem is currently offline  stevem
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Man!, Bill and myself do not even get some minor pat's on the back for helping out YET again! Lol!
Enjoy the SPL my friend!
Re: Kustom XII bi-amp [message #23653 is a reply to message #23652] Tue, 18 August 2015 08:16 Go to previous messageGo to next message
C4ster
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Registered: June 2001
Location: Mukwonago, WI (Milwaukee...
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Steve,
Sometimes its just better to wait the storm out. These long threads sometimes just get further from the answer than closer.
Conrad
Re: Kustom XII bi-amp [message #23654 is a reply to message #23653] Tue, 18 August 2015 11:46 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Hey Steve you KNOW I appreciate all the help you and Bill have provided.......the thing you don't know is that in the past two weeks Pleat has been helping me thru emails with this thing. He has spend an enormous amount of time with me on this as well as how to set up my PA system. Don't worry you'll get your share of fame when we start rebuilding the amps. All you guys are great in my book. Without all the priceless advice, this stuff would have been in the scrape heap long ago. You are the guys that keep it going. It's a team effort....what one guy doesn't think of, someone else does......that's what makes this website so great. You guys are not just names on a website, I consider you all my FRIENDS. Smile
Re: Kustom XII bi-amp [message #23655 is a reply to message #23583] Tue, 18 August 2015 11:54 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Add another 12 pack to what I already owe you.....that should help lol.

On another note.....are there an plans for another Kustom get to gather any time soon? I really would like to meet you guys.

[Updated on: Tue, 18 August 2015 11:56]

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Re: Kustom XII bi-amp [message #23662 is a reply to message #23655] Wed, 19 August 2015 02:39 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
Senior Member
Hey if you're supplying the beer, why don't we all meet up at your house.

Glad to hear you got the amp working.
Re: Kustom XII bi-amp [message #23667 is a reply to message #23662] Wed, 19 August 2015 12:00 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Hey come to Marshalltown Iowa any time.........door is always open and you can drink beer till you bust.....out here in the country we have lots of tree's.....pick your favorite. lol

It would be great if we could all get together some weekend if Kustom doesn't have any plans for another festival any time soon. Meet somewhere centrally so we could all get together and swap lies.
Re: Kustom XII bi-amp [message #23669 is a reply to message #23583] Wed, 19 August 2015 12:46 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
Senior Member
Gee, a guy living in Marshalltown and he plays Kustom amps. Go figure.
Re: Kustom XII bi-amp [message #23670 is a reply to message #23669] Wed, 19 August 2015 13:53 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Guess what Bill....we now have indoor plumbing, cable tv and the internet. Keeping shoes on sometimes is a problem but damn we is getting educated too. Smile
Re: Kustom XII bi-amp [message #23677 is a reply to message #23670] Wed, 19 August 2015 21:17 Go to previous messageGo to next message
pleat is currently offline  pleat
Messages: 1452
Registered: June 2004
Location: Belding, Mi
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We always have at least two problems. When and where to have a convention. There are about 20 core collectors I hang with daily. Everyone wants it in their backyard. We driven to Chanute in 09-10 and 2012. We did a regional gathering in Indy in 2011 and last summer we did one in VA. One collector in VA has over 380 pieces of kustom amps, speakers, organs, guitars. That one was a blast.

Consensus has been no more than a 6 or 7 hour drive. Kind of hard since we have collectors from CA to VA. The bulk of collectors could drive to Nashville, but where in Nashville would be a challenge. a couple of us tried three different times the beginning of 2015 to get something going and the emails go quiet. This is the 50 anniversary of Kustom.

pleat
Re: Kustom XII bi-amp [message #23686 is a reply to message #23677] Wed, 19 August 2015 23:02 Go to previous message
Iowa Boy is currently offline  Iowa Boy
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Registered: June 2014
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Oh man that is just so wrong. Is there even a Kustom museum anywhere?

Family reunions are hard as hell to organize so I can imagine how difficult something like this would be. Maybe Vegas.....everyone would make an effort to go there and there are always cheap airline packages and hotel deals to be found not to mention a great weekend get away.
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