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Kustom XII bi-amp [message #23583] Mon, 10 August 2015 20:54 Go to next message
Iowa Boy is currently offline  Iowa Boy
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Help.....just received a kustom XII bi-amp. The amp on the inside to the furthest left has the wires cut that are coming from the two filter caps into that amp. I have no clue as to why its been disconnected and am afraid to reconnect them for fear of something else blowing. Pleat has seen the pictures and says its the power and ground wires that have been cut. What do I need to do to test this amp out?

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Re: Kustom XII bi-amp [message #23584 is a reply to message #23583] Tue, 11 August 2015 06:44 Go to previous messageGo to next message
stevem is currently offline  stevem
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Reconnect the wires and install a fuse to replace the likely blown one with a fuse of 1/2 the needed amperage, then turn the amp on, if that fuse blows it's time to check the diode cup on the floor of the amp and start pulling the output transistors and checking them.

If the diode cup checks good I think you can unpower the high amp or the low amp one at a time by its Molex connector, if so then install another low amp fuse and power it up again and if the fuse holds you have pinned down the bad amp section.

It would be my guess that the thing has a bad amp section low amp section will be bad!

Oh wait, let's go back to square one here, the first thing to do is to unhook the power transformer from the diode cup, install that small fuse and then power up the amp to confirm that the PT is not shorted out, and then confirm that the diode cup is good.
Be sure to not let those wires you pulled off touch anything!

It's been a while since I have been in one of these, but if I recall right they have a thermal circuit breaker for each amp section, so both of those need to be checked for being open if the amp does not power up with a good fuse.

Is the crossover / control board in that biamp PC 5258?

[Updated on: Tue, 11 August 2015 06:52]

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Re: Kustom XII bi-amp [message #23588 is a reply to message #23583] Tue, 11 August 2015 13:19 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
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Let's not get ahead of ourselves here, let's have a bit more information. Does the part of the amp that is still hooked up work as it is? If it does, then the power supply is probably okay.

This thing has a large power amp for low freqs and a smaller power amp for highs and an electronic crossover to separate the signals. If the one power amp is still working, which one is it the lows or the highs?

The amp that was disconnected could be shorted, or it could have not been needed by some former owner and unhooked, or who knows why it was taken out of the circuit. In order to reconnect it, you will need to run a few tests to be sure that it in fact is not shorted.

The simplest test would be to use an ohm meter to check the two power supply line for shorts to ground.

Tell us more about the amp.

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Re: Kustom XII bi-amp [message #23589 is a reply to message #23588] Tue, 11 August 2015 13:52 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Okay here is what I have found....so far.

The amp that was unhooked is the far left amp. It is the one connected to the left low output. The red and green wires coming from the two filter caps were cut at the board. I also found that the three pronged Molex plugs at the bottom of the boards had been switched. The plug that had gone to the left amp had been put on the middle amp and no plug was connected at the bottom of the left amp. I reconnected the plugs to what I believe is the right amps. The middle plug will not reach the far left amp so I assumed it must go to the middle amp. I did notice that some work has been done on this unit. There are several new rectangular resistor...I guess.....white...have replaced some of the original ones. Also on the left amp there is something that I think is a diode.....three pronged fork with a black square in the middle with a hole in the center. Sorry for not knowing the actual tech jargon since its been 40 years since I took my electronic course.

I will take my meter and test for ground on the two wires cut at the board....I am assume the green wire is a ground and that should test closed. The red should not......

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Re: Kustom XII bi-amp [message #23591 is a reply to message #23589] Tue, 11 August 2015 14:08 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Okay....did a continuity test to ground on both the red and green wire coming out of the board. Open circuit on both.

Next?

[Updated on: Tue, 11 August 2015 14:11]

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Re: Kustom XII bi-amp [message #23592 is a reply to message #23583] Tue, 11 August 2015 14:19 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Retested the red wire....show a reading for just a split second and then goes to OL. Tried the ohms setting, goes to 4.7 and fluctuations some but holds. The green wire does the same thing but when you ohm it the reading steadily drops till it shows OL.

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Re: Kustom XII bi-amp [message #23593 is a reply to message #23583] Tue, 11 August 2015 14:45 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
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You never answered the basic question, does the amp work as it is?

The red wire is the positive voltage, the green wire is the negative voltage and the black is the ground.

What value or scale was the meter set for when you got the 4.7 reading? If it's 4.7 ohms, that would be a short circuit, if it was 4.7 megohms (million ohms), not so much.

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Re: Kustom XII bi-amp [message #23594 is a reply to message #23593] Tue, 11 August 2015 15:02 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Bill....I never plugged it in since I had seen wires cut and know now that the plugs have been moved.

The reading was in meg. Rechecking again...the longer I leave the probes on the wires, the values increase as well. Guessing that the battery in meter in supplying the increase.

Since I don't have a schematic to go by, I am also assuming that the Molex plugs are the output.

[Updated on: Tue, 11 August 2015 15:03]

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Re: Kustom XII bi-amp [message #23595 is a reply to message #23583] Tue, 11 August 2015 15:06 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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I can't believe someone would cut the wires just because they didn't need the one amp. Especially since they moved the Molex plug from the one amp to the other.

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Re: Kustom XII bi-amp [message #23596 is a reply to message #23583] Tue, 11 August 2015 15:17 Go to previous messageGo to next message
chicagobill
Messages: 2005
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I don't know how much test equipment you have, but if you have light bulb limiter, I'd suggest using it on this amp when you first plug it in.

People do dumb things. Who know why, all I can suggest is that you get it back to normal if you can. Have you looked for a schematic? That would help in putting everything back to normal.

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Re: Kustom XII bi-amp [message #23597 is a reply to message #23596] Tue, 11 August 2015 15:24 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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I have just the basic multi meter......

I went on line and can't find anything on this amp.

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Re: Kustom XII bi-amp [message #23598 is a reply to message #23583] Tue, 11 August 2015 15:40 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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I did find a schematic but will cost $20 to buy.

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Re: Kustom XII bi-amp [message #23599 is a reply to message #23583] Tue, 11 August 2015 16:15 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
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Well, can you see the pc board numbers? If you at least find the numbers on the power amp boards, that will be a big help. Exactly how many power amps are in this thing? Two 130 watt low freq amps, and two 60 watt high freq amps?

The limiter that I suggested, is nothing more than a standard incandescent light bulb that is connected to the ac line, wired in series with the test amp. If the test amp draws too much current, the light bulb turns on and shuts off the current going to the amp. This will prevent the amp's fuse and internal circuitry from blowing.

I'm sure that if you want to build one, you can find instructions out there. My first one was and old extension cord and a light socket.

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Re: Kustom XII bi-amp [message #23600 is a reply to message #23599] Tue, 11 August 2015 16:43 Go to previous messageGo to next message
pleat is currently offline  pleat
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The amp has three identical power amps housed with the electronic cross over. I think the boards may be PC5065 but I'm not sure. The XII BiAmp slave amp is the big brother to the VIII bi amp that uses one 130 watt amp for the lows an the smaller 75 watt amp for the horns.

I saw pictures and the he is describing a transistor with the 3 legs and the hole for mounting to a heat sink.

pleat

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Re: Kustom XII bi-amp [message #23601 is a reply to message #23600] Tue, 11 August 2015 17:31 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Just googled light bulb limiter.......easy enough to make. I'll build one tonight.

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Re: Kustom XII bi-amp [message #23602 is a reply to message #23583] Tue, 11 August 2015 17:59 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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I finally found a number on the board......kind of hard to make out the numbers since I had to use a mirror to get to them.......00 5065 009 I think. Pleat, your right as usual.

[Updated on: Tue, 11 August 2015 17:59]

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Re: Kustom XII bi-amp [message #23605 is a reply to message #23583] Wed, 12 August 2015 01:47 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Went to make my limiter tonight and didn't have a 250 watt bulb to use. I did accidently plug the amp in and even with the power switch in the off position the lights inside the switch came on. Is this normal for this amp? If so how would you know if the amp is on or off?

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Re: Kustom XII bi-amp [message #23606 is a reply to message #23583] Wed, 12 August 2015 06:10 Go to previous messageGo to next message
stevem is currently offline  stevem
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Sorry, I misread part of your first post.
The red and green wires where cut either to trouble shoot the amp, and or to un- power that amp section and be able to use the remaining 2 good amp sections.

In These Amps they stopped using the metal case TO5 type driver transistors that we are use to seing in the silver rectangular heat sink boxes, and switched to the plastic pack TO- 220 types, which if your amp is like mine ( the smaller bi- amp) these transistors are red cased and green.

Mine are RCA brand with one being a 65860, and the other being a 7701.
Neither of them have I been able to cross, but they are just standard audio driver types and not a issue to get a replacement for .

Let's go To back to square one like Bill posted, is the fuse good?

If any of the red wires on the output transistor sockets have a low resistance to ground( under 200 ohms ) then they are shorted.



The best way to get that reading and not have the meter try to charge those big main filter cans is to unhook the red and green wires from the cans first.

Like I posted yesterday, if you do power it up thru the limiter like you are making I would still derate the fuse you install by 50 to 75 %.

Let us know how it goes!

Oh, where did you find the schematic?

[Updated on: Wed, 12 August 2015 06:12]

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Re: Kustom XII bi-amp [message #23608 is a reply to message #23606] Wed, 12 August 2015 12:23 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Music Parts.com has this and tons of Kustom schematics.

Does you power switch light up when you plug it in.......this one does.

[Updated on: Wed, 12 August 2015 12:25]

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Re: Kustom XII bi-amp [message #23609 is a reply to message #23583] Wed, 12 August 2015 12:39 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
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I don't know for sure, but it sounds like the power switch has been wired wrong.

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Re: Kustom XII bi-amp [message #23611 is a reply to message #23609] Wed, 12 August 2015 14:48 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Guess I had better break down and order that schematic for this thing. Looks like some SOB did a hatchet job on this amp.

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Re: Kustom XII bi-amp [message #23612 is a reply to message #23583] Wed, 12 August 2015 14:50 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Steve....any way you could post a picture of the insides of your amp for me to go by?

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Re: Kustom XII bi-amp [message #23613 is a reply to message #23583] Wed, 12 August 2015 16:08 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
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A couple of things, have you taken photos of the inside of this amp?

For the limiter, you don't need a 250 watt lamp, a 100 or a 60 will be fine.

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Re: Kustom XII bi-amp [message #23614 is a reply to message #23613] Wed, 12 August 2015 18:42 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Well.....now I have a 300 watt bulb. The site I googled said to use the largest wattage you could find so that is what I did.

I have sent Pleat pictures of the inside. I don't know how to post on here yet. Send me a PM and I send them to you.

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Re: Kustom XII bi-amp [message #23616 is a reply to message #23583] Wed, 12 August 2015 20:27 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Well this thing is certainly a joke. Yes the switch was totally wired wrong.......so its on all the time.

Good news is that the limiter did not light up when I plugged it in. However, I connected two of my smaller PA cabinets into it and plugged my lap top into the input, tuned in a radio station, and the volume stinks. With it cranked all the way up I'll bet I'm getting less than 20 watts of power out of the two speakers. I even reconnected the molex plugs at the bottom of the middle board like it was when I opened it and no difference in sound what so ever. Any ideas?

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Re: Kustom XII bi-amp [message #23617 is a reply to message #23583] Wed, 12 August 2015 21:10 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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I reconnected the two wires that were cut on the left amp......this amp is the left low output.......but guess what.....the horn level controls the volume and its still just as low as the other low output.

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Re: Kustom XII bi-amp [message #23618 is a reply to message #23617] Wed, 12 August 2015 22:15 Go to previous messageGo to next message
pleat is currently offline  pleat
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A few things, have you traced from the speaker jack wires back to each amp? So you know what the center and the other amp is suppose to drive speaker or horns? Are the two remaining amps working?

You said the first amp or left side amp is a low frequency amp the one with the wires cut. The center amp I will assume drives the other low frequency speakers, and the remaining amp is driving the high frequency for the horns.

Since you are hooking up your computer to the input, the signal is going through the electronic crossover first, and the signal is then split or divided into the low power amps and the high frequency amp.
When you hooked up your speakers, did you hook one speaker to the low amp and one speaker to the horn amp? If you hooked both speakers to the horn amp, you won't get much volume as the crossover is only letting the higher frequencies pass on to the power amp. There are two volume controls, Main or master, which has to maxed to get the most volume and then the horn volume control. The horn volume tracks with the master volume control. Turning it down automatically turns down the signal going to the horn amp.

As to the switch always be on, Just tossing this out, the power switch is a rocker type with the center position being the off position. It functions as power and polarity in one switch.

pleat

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Re: Kustom XII bi-amp [message #23619 is a reply to message #23618] Wed, 12 August 2015 23:19 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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The left amp goes to the left low, middle is horn and right is low right. I tried the two cabinet into the left low first......very low and I mean low volume of sound about the same as the horn; tried just the right low amp with both speakers.......guessing about 20 watts output; tried just the horn......it squeaked out some sound but not much even when turned up all the way.

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Re: Kustom XII bi-amp [message #23620 is a reply to message #23583] Thu, 13 August 2015 01:40 Go to previous messageGo to next message
chicagobill
Messages: 2005
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It sounds like you are making progress. Do you still have the amp plugged into the limiter? If the bulb didn't light up brightly, then the amp is not drawing too much current and can be powered up directly without the limiter.

Using the limiter will reduce the power supply voltages and will lower the output power. Next step will be to test the power supply voltages with your volt meter. Take the readings at the two power supply caps. There should be plus and minus 40-45 volts at the terminals.

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Re: Kustom XII bi-amp [message #23621 is a reply to message #23583] Thu, 13 August 2015 06:19 Go to previous messageGo to next message
stevem is currently offline  stevem
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From what I see from the photos the left hand and the middle power amp board have both been worked on, I even see added top side jumper wires on one of them!
That middle board has had two of the 4 Emitter resistors replace, so that amp section had at least two shorted output transistors.
I think the best course of action is to pull each board one at a time and go thru it, all that you may need to replace semiconductor wise can still be had and if any circuit traces have been messed up due to the work done your gonna need to pull the boards anyway.

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Re: Kustom XII bi-amp [message #23622 is a reply to message #23621] Thu, 13 August 2015 20:16 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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Just gets better all the time......and this clown I bought it from said it worked just fine. Bill...sending you pictures also. Will take reading at filters.

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Re: Kustom XII bi-amp [message #23623 is a reply to message #23583] Fri, 14 August 2015 06:30 Go to previous messageGo to next message
stevem is currently offline  stevem
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Look on the brite side, even if you had to replace every darn transistor on one of the 130 watt power sections I don't think it would top 40 bucks!

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Re: Kustom XII bi-amp [message #23624 is a reply to message #23583] Fri, 14 August 2015 13:54 Go to previous messageGo to next message
chicagobill
Messages: 2005
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I've seen the photos now and agree that this has been hacked by someone that shouldn't have been in there.

The transistor that was added to the top of the one board has a different pin arrangement from the original one, so the jumper wire may have been added to connect up one of the pins.

I notice that the driver transistors are the old style TO-39H and not the later versions that used a TO-220 that Steve described.

I can't completely see how the switch is wired, but it looks like a replacement to me. All of the factory switches normally have the two cross connections for the polarity wiring made as part of the switch with flat brass strips. These are added on wires.

If you get a better photo showing how the wires are connected to the back of the switch, I can tell you how to rewire it so that it works correctly.

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Re: Kustom XII bi-amp [message #23625 is a reply to message #23624] Fri, 14 August 2015 19:33 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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This double throw switch doesn't make any sense. This amp has a ground plug on it........must have been added? The ground cap is still connected to the switch. Looks like a 2 year old soldered this thing. Problem seems to be with the way the lights inside the switch were wired. I'm going take all the wires off and start over.........since the soldering is so sloppy. One of the spades on each switch should go to ground to complete the circuit for the light inside the switch......correct?

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Re: Kustom XII bi-amp [message #23626 is a reply to message #23583] Sat, 15 August 2015 01:26 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
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In the early days of three prong ac cords, they still used a ground switch and cap, so the original switch would have been a three position center off one.

The light inside the switch is a neon bulb with a dropping resistor. It connects to the two sides of the power line hot and neutral. Nothing should be grounded except for the one end of the ground cap.

What you need to figure out is what terminals the neon light is connected to. My guess would be the two center ones. Is the ground cap connected to one of the center two terminals?

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Re: Kustom XII bi-amp [message #23627 is a reply to message #23583] Sat, 15 August 2015 06:44 Go to previous messageGo to next message
stevem is currently offline  stevem
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The problem with those TO-220 transistors as replacements is that the fatter leads will not pass thru the factory lead holes without being drilled out That makes for the need to wire it up with all jumper wires unless you tack solder one or more of the leads right to the top side of the other components it goes to.
This looks like a mess and a tack solder joint is iffy at best!

When I need to go this route I drill out the holes with a .060" bit and hope that the trace is wide enough that I do not have to use a jumper no less on the bottom side.

[Updated on: Sat, 15 August 2015 06:46]

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Re: Kustom XII bi-amp [message #23628 is a reply to message #23626] Sat, 15 August 2015 11:14 Go to previous messageGo to next message
Iowa Boy is currently offline  Iowa Boy
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No,.. it is attached to one of the bottom spades on the switch; then from each bottom spade they ran a jumper crisscross to the top spades, there is nothing attached to the middle spades on either of the switches.

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Re: Kustom XII bi-amp [message #23630 is a reply to message #23583] Sun, 16 August 2015 01:46 Go to previous messageGo to next message
chicagobill
Messages: 2005
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Okay, then the two wires from the transformer should connect to the outer connectors. The two wires from the ac line should connect to the two middle connectors.

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Re: Kustom XII bi-amp [message #23631 is a reply to message #23630] Sun, 16 August 2015 08:56 Go to previous messageGo to next message
pleat is currently offline  pleat
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You mentioned earlier in your post that one the Molex plugs, had been moved to a different power amp board. The wires to the Molex plugs are feeding the either the Low or High pass signals from the electronic crossover in the amp.

Since there are so many things that have been tampered with, in the amp, you can't be sure that the middle power amp is the horn amp. Someone may have shifted the molex connector to the middle power amp then and moved the actual speaker jacks from the middle power amp to the horn output labeled on the back panel.

I would think it's time to get a schematic. Trying to solve multiple problems (power amp, cut wires, power switch) all at the same time may be counter productive and confusing for people on this site. Until you get the power amps back up and running and making sure that the speaker jack labels go to the correct power amp, everything else is secondary. pleat

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Re: Kustom XII bi-amp [message #23632 is a reply to message #23631] Sun, 16 August 2015 11:39 Go to previous messageGo to previous message
Iowa Boy is currently offline  Iowa Boy
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I hadn't thought about the output jacks being changed but that's a good possibility. The way the Molex plugs are wired, the middle plug can't me moved to the far left amp so am pretty sure those are correct.....now.

Rechecked the output wiring.......don't see how they could have moved them since the length of the blue wires pretty much makes it impossible to reach the far left amp other than the way it currently is wired. There's also corrosion on the outputs jacks as well and no signs that any tampering has been done. Looks like that is okay for now also.

Tech question.......I have a multi meter.....read ohms, uF, uA and AC/DC voltage as well as continuity. Is this meter adequate enough to work on this equipment? If I need something else, I have no problem spending the money on getting it......I guess Sad

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