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new Kustom owner with a few problems [message #5349] Thu, 13 January 2005 13:28   Mister_Billion Messages: 4 Registered: January 2005 Junior Member Hi everyone. I was recently given a Kustom 200 head and a no-name 2x12 cab. This is my first non-combo amp, and I'm loving it so far. However, I have a few problems. First, the bright channel doesn't seem to be working. When a guitar is plugged in, you can very faintly hear some signal going when you crank the treble and bass knob, and moving the volume knob results in some loud scratches. Any ideas? Also, there is a fair amount of hum. I read about the grounding of them amp, and I think that would fix it. Does anyone have a diagram or detailed instructions how to do so? Also, in case there are various 200 models, this one has a bright and normal channel, with two inputs per channel. Both channels have volume, treble, and bass controls. Thanks a bunch! Report message to a moderator

Re: new Kustom owner with a few problems [message #5353 is a reply to message #5349] Thu, 13 January 2005 17:52   voided3 Messages: 200 Registered: July 2004 Senior Member Hello and welcome. If you are using this with normal guitar pickups, make sure you are plugged into the "low" input, the "high" input has a (i think) -10dB resistor on it, which would result in lowered volume, but the crackling means you'll either want to clean or replace your jack(s) or pot(s) most likely. I grounded my K200-A5, it's reletively easy. Just buy a 16-3 gauge grounded 15 foot (or whatever length you want) extension cord, open up the amp, disconnect the power cable where it's hooked up now, and remove the cord from the plastic retainer to remove the old cord. To install it, you'll want to use a small round file to enlarge the hole on the plastic retainer, then fish it through, install the black (-) and white (+) wires where they were before, then to install the all important ground, simply crimp on a loop connector of the end of the wire and bolt it on to the inside of the chassis with the the bolt that mounts the cord wrap. Pretty simple, but be careful with what you touch/cut. I'd also reccomend looking in past posts for more info or different methods before trying it. Good luck! Report message to a moderator

Re: new Kustom owner with a few problems [message #5354 is a reply to message #5349] Thu, 13 January 2005 20:17 rodak Messages: 511 Registered: October 2001 Location: Georgia Senior Member Actually, the "High" input has a capacitor in series, which acts as a high-pass filter, filtering out the low frequencies, and effectively reducing the volume. Anyone know what the intention for that was? My K150 had a similar, very odd problem - lots of loud scratchiness as you turned the volume up, some usable volume at about 8o-clock, then it dropped down to nearly nothing as you rotated it clockwise. On advice I got from a couple of friends (might have been here), I replaced the first two transistors in the preamp (i.e, the first two in circuit after the input jack), and that cleared the problem up entirely. Channel 2 was similar, but without all the loud scratchiness. I replaced only the first transistor in that one, and it cleared it up, too. I couldn't say if yours has the same problem, but if you're handy with a soldering iron it might be worth a shot. I bought a whole bunch of the correct transistors on eBay for about $12, so I have spares for future use. www.combo-organ.com Report message to a moderator

Re: new Kustom owner with a few problems [message #5355 is a reply to message #5354] Thu, 13 January 2005 21:18   Mister_Billion Messages: 4 Registered: January 2005 Junior Member Thanks for the replies so far guys. I think I have the soldering skills to do everything suggested so far, hopefully will get it figured out this weekend! As far as safety, do I drain the filter caps by alligator clipping the filter caps to the chassis, and flicking the switch a few times? Thats what I did for the fender. Report message to a moderator

Re: new Kustom owner with a few problems [message #5357 is a reply to message #5349] Fri, 14 January 2005 12:54   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member you should never drain any power supply cap by shorting it to ground, you can deform the plates by the rapid dicharge and ruin the cap.dicharge the cap thru a 10K resistor to ground.If you have never unsolderd transistors from a board before, and know how to figure out the correct way to put in a replacement transistor with a different lead configuration, then it may be best to leave the repair to a tech. Report message to a moderator

Re: new Kustom owner with a few problems [message #5359 is a reply to message #5355] Fri, 14 January 2005 12:58 chicagobill Messages: 2005 Registered: April 2003 Senior Member MB Welcome aboard! It would help if you had the model number of the amp, as there are three different versions of K200 amps, all of which had models with the controls that you describe. If the serial number plate/sticker is missing, then you can figure it out based upon the physical construction of the amp. Check out the catalog section and see if you can find a similar amp and then maybe you can get a copy of the schematic. Hum can be caused by many things like grounding problems, filter caps, bad transitors, etc. Is the hum low in frequency or more buzzy? Does the amount of hum or tone of the hum change with the controls? Try this first, in a quiet room, plug in the amp and speakers. Do not plug in an instrument and turn all the controls to zero. Turn on the amp. Try both sides of the polarity switch as one side may be quieter than the other. Listen to the amp. This is as quiet as the amp can be. Is there a low hum, a buzz, high frequency white noise or hiss? Try adjusting the controls. Does the hum change, get louder? From what you hear, you can track the problems down. Buzzes usually are ground problems, low freq hum is often filter caps, and hiss can be any number of things. As Rodak noted, bad input transistors can cause the scratchy volume control problem, but I think this will only apply to 200 A's and B's. A shorted coupling cap can also cause this problem. Rodak's also correct in that the high inputs have a series cap that filters out low freqs. Why? I guess to have another tone variation available. As for discharging the filter caps, unplug the amp and wait a few minutes. Then to be safe, discharge both plus and minus supplies to ground through a 200 ohm 1 watt resistor. There is approx + and - 36 volts DC available in the power supply, so discharging shouldn't take but a few seconds. Again, welcome aboard. Bill Report message to a moderator

Re: new Kustom owner with a few problems [message #5360 is a reply to message #5349] Fri, 14 January 2005 14:54   Mister_Billion Messages: 4 Registered: January 2005 Junior Member based on the knob and switch configuration, this looks like the 200 A, bass model. Its dead silent with everything turned down. Most of the noise seems to come from turning up the treble knob, and its more of a hiss than a hum or buzz. Turning the treble seems to add more hiss that any of the other controls. This is starting to look like a job for a tech, haha. Thanks for the advice and warm welcom everyone. Report message to a moderator

Re: new Kustom owner with a few problems [message #5366 is a reply to message #5349] Sun, 16 January 2005 12:08   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member The crakling you are hearing may just be dirty controls. If each channel you try can pass signal, but is some what intermitant as you bring up the volume then that may be the bulk of your problem.Also hiss in kustoms is normal to a certain extent as you open up the treable pot, even more so if the bright is on. The latter kustoms like yours have much more highs avalable than the preceeding frank heads or even a lot of other brands soild state heads of the same circa. Since 4 replacement preamp transistors are all of may be a buck .50 with out shipping, and the fact that new ones are less noisy plus sound better, why not? If you in there to dis-mount a preamp board for pot cleaning, your 70% there anyway! Report message to a moderator

Re: new Kustom owner with a few problems [message #5371 is a reply to message #5349] Mon, 17 January 2005 17:38   Mister_Billion Messages: 4 Registered: January 2005 Junior Member I think I will follow stevem's advice, since I am at least gonna clean the pots. If that doesn't correct things, it'll be off to the tech. Thanks again guys, I will keep you all posted! Report message to a moderator

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