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K200 thump [message #4736] Wed, 25 August 2004 21:59 Go to next message
voided3 is currently offline  voided3
Messages: 200
Registered: July 2004
Senior Member
Hello. I have a K200-A5 PA head, and I noticed that it acts differently than my K200-B6 head. It doesn't thump when I turn it on, just a quiet and breif (less than a second) oompf and some reverb clang. When I turn it off, the hissing only continues for half a second followed by a few small thumps. I also noticed that I have to turn up the volume half of the way to match the volume of my other head with the volume at 10 'o clock. Is this the same kind of thing that the person with the combo organ was talking about with the filter caps? If so, is it a fairly simple repair or should I leave it to an amp tech? Thanks!


P.S.- the amp still gets freakin' loud (and sounds awesome), i just have to turn it up a little more than my other amp through the same cabinet.

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Re: K200 thump [message #4738 is a reply to message #4736] Thu, 26 August 2004 07:47 Go to previous messageGo to next message
stevem is currently offline  stevem
Messages: 4733
Registered: June 2004
Location: NY
Senior Member
Do not be concered about this difference in amps gang!It all has to do with how well matched the transistors are in the driver and out put stage, it has no implication on the wellness of the amp, although if you carefully A/B ed both amps the amp that thumped the least would sound the best under a carefull listen.

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Re: K200 thump [message #4758 is a reply to message #4738] Mon, 30 August 2004 13:21 Go to previous messageGo to next message
Smoke1
Messages: 107
Registered: September 2003
Location: Southern Maryland Solomon...
Senior Member
My K200B 5 also only has a slight thump when turned on and off.
How sweet it is ????

Smoke1 Plays Kustom Amps & Old Tube Amps Loud in S. Maryland

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Re: K200 thump [message #4778 is a reply to message #4736] Sun, 05 September 2004 02:36 Go to previous messageGo to next message
voided3 is currently offline  voided3
Messages: 200
Registered: July 2004
Senior Member
Hello. My K200-A5 now has a new problem. Instead of doing the classic Kustom hiss while it's on, it buzzes. It always has a little, but it seems to be getting louder. Would going to a three prong help this? And if i do, where do I attach the ground wire? Thanks!

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icon2.gif  Re: K200 thump [message #4785 is a reply to message #4778] Tue, 07 September 2004 06:39 Go to previous messageGo to next message
Smoke1
Messages: 107
Registered: September 2003
Location: Southern Maryland Solomon...
Senior Member
Go to Repairing Kustom Amps webboard to page 12 to see instructions by C4ster and Kustom Blues on how to change your power Kord. I did this to my K200B 5 over a year ago. I bolted the wires on and did not solder and put the ground wire onto the metal chassis. Works Great. I wish I had know this 20 years ago. but all those electric shock treaments made my body build a better tolerance to electric shock. Yeah Right! It, however comma did solve the electric shock on the lips from the mike problem forever more and reduced the noise. You may still have a different problem. Steve will know what to do.

Smoke1 Plays Kustom Amps & Old Tube Amps Loud in S. Maryland

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Re: K200 thump [message #4789 is a reply to message #4736] Tue, 07 September 2004 18:58 Go to previous messageGo to next message
voided3 is currently offline  voided3
Messages: 200
Registered: July 2004
Senior Member
Hello. Any ideas what it the buzzing could be Steve?
(it is the same at any volume level, whether or not a guitar is plugged in and even though I just installed a three prong cord, it still persists). Thanks!

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Re: K200 thump [message #4791 is a reply to message #4789] Wed, 08 September 2004 10:24 Go to previous messageGo to next message
C4ster
Messages: 686
Registered: June 2001
Location: Mukwonago, WI (Milwaukee...
Senior Member
Judging from what you have said so far, I would suspect the power supply capacitors are shot. Because of the push-pull configuration of the power output stage, that tends to cancel the hum from dying filter caps. The only way to prove for sure is to scope the power supply. But instead, I think the hiss test and watching the light, should tell you if the caps are bad. A short hissing and the light going out quickly after turning the amp off, indicated that the filter caps can't hold a charge. I would replace them with a capacitor that is at least 10,000uF at 50 volts. The originals are 4500uF at 50 WVDC 75 volts surge. If you size them too large, there may be a problem blowing the input fuse. The only problem that I have encountered is that the new capacitors are taller and smaller in diameter. That requires a new mounting clamp and there may be a problem fitting them under the reverb pan, if you have one. There is no reason you couldn't lay them down and fasten them horizontally.
Good luck,
Conrad

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Re: K200 thump [message #4793 is a reply to message #4789] Wed, 08 September 2004 11:23 Go to previous messageGo to next message
KustomBlues
Messages: 490
Registered: June 2001
Location: Michigan
Senior Member
I would also check and clean up all the grounds in the amp, check for broken solders, etc.

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Re: K200 thump [message #4803 is a reply to message #4736] Wed, 08 September 2004 19:59 Go to previous messageGo to next message
voided3 is currently offline  voided3
Messages: 200
Registered: July 2004
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Hello. The light fades in when i turn it on and off, and yes, i have reverb on this head. Also, i saw on a post elsewhere on the site that running the amp for an hour without a load (speakers) can be advantageous, and gets rid of some buzz. Is that true/effective, and should I try it? Should I just have a tech look over the amp anyway since the thing looks like whoever owned the amp last used the inside of the amp as an ashtray? Thanks!

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Re: K200 thump [message #4804 is a reply to message #4736] Wed, 08 September 2004 20:01 Go to previous messageGo to next message
voided3 is currently offline  voided3
Messages: 200
Registered: July 2004
Senior Member
Oh yeah, also, when I turn the amp on and I have the reverb footswitch set to off, it makes a loud BUZZAP sound sometimes. What could cause that? And is my poor amp dying? Sad Thanks!

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Re: K200 thump [message #4805 is a reply to message #4791] Wed, 08 September 2004 20:38 Go to previous messageGo to next message
rodak
Messages: 511
Registered: October 2001
Location: Georgia
Senior Member
I have some 12,000uf, 63V caps that are both shorter and smaller in diameter - they're 2" high and 1-1/4" diameter. They're PCB mount, rather thanscrew-in connections, but if you like, I can make a PCBoard and solder them to that, and you can fasten screws and nuts to the board. I put them in my Kombo organ and they work great.

I'll sell the caps for $2 each, or two of them plus a PCboard for $10 - plus shipping (probably $4-$5).

Contact me at rodak@combo-organ.com if you're interested.

www.combo-organ.com

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Re: K200 thump [message #4812 is a reply to message #4804] Fri, 10 September 2004 00:18 Go to previous messageGo to next message
KustomBlues
Messages: 490
Registered: June 2001
Location: Michigan
Senior Member
I think I's have the old girl looked at, and cleaned. That way you won't smoke more stuff in it. Just based on it's age alone, it needs new caps and stuff, cuz after 20 years they aren't long for this world.

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Re: K200 thump [message #4813 is a reply to message #4736] Fri, 10 September 2004 00:39 Go to previous messageGo to next message
voided3 is currently offline  voided3
Messages: 200
Registered: July 2004
Senior Member
Hello. That would be a good idea, but oddly enough today i got bored so i fired it up and the buzzing was practically gone! I think the grounded cord might have something to do with it, but the buzzing was almost completely down to a quiet hiss. Oh well, i'll have it cleaned at least anyway (may I add, I didn't put the smoke in it haha; i'm 16). I noticed though, and the amp has always done this in the time i've owned it, the channel four seems to break up better than any other channels, which are very clean. The only difference is when you crank it (and i don't mean all the way, i never turn it up past half), it has more edge than the other channels, and i like it. It's not like a hard tube amp distortion, but like a tiny ammount of natural break-up. When you don't have a guitar plugged in, and you play with the volumes, only the channel 4 volume makes a hiss when you turn it up. I guess the wear has its advantages too, and I love it! I'm almost afraid to have it worked on for fear of losing that sound. If I use the amp with a 4x12 Orange, a Gibson SG and a Tubescreamer, it sounds like a raging Marshall, I kid you not. I can get that great sound on any of the channels, but the fourth seems to like overdrive more, and I like it too. I suppose amps can age gracefully too haha. Thanks!


P.S- does running the amp w/o a load for an hour have any positive effects, as someone stated in another post?

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Re: K200 thump [message #4836 is a reply to message #4813] Mon, 13 September 2004 10:14 Go to previous messageGo to next message
KustomBlues
Messages: 490
Registered: June 2001
Location: Michigan
Senior Member
Personally, I would NOT run it without a load.

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Re: K200 thump [message #4843 is a reply to message #4736] Mon, 13 September 2004 16:51 Go to previous messageGo to next message
voided3 is currently offline  voided3
Messages: 200
Registered: July 2004
Senior Member
Hello. Would my choice of footswitch have anything to do with sound quality? The amp doesn't buzz like it used too anymore, which is a huge plus, but just wondering. The footswitch I am using now is a home-made one, it's a regular house on/off light switch (rocker style) with the positive and negative wires attached to the two poles on the switch, housed in a metal gang box. I didn't want to spend $40 for something i could build myself. It works flawlessly, but once again, just curious. Thanks!

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Re: K200 thump [message #4844 is a reply to message #4843] Mon, 13 September 2004 18:42 Go to previous messageGo to next message
KustomBlues
Messages: 490
Registered: June 2001
Location: Michigan
Senior Member
Your lack of buzz, I believe came from putting on a 3 wire power cord... Without re-reading all these posts, I think that's what you said you did, right? That will make a huge difference in hum and buzz.

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Re: K200 thump [message #4845 is a reply to message #4736] Mon, 13 September 2004 19:53 Go to previous messageGo to next message
voided3 is currently offline  voided3
Messages: 200
Registered: July 2004
Senior Member
Hello. Yes, I did put on a three prong; it was a good call. Any comments on my bodge-tastic footswitch? Thanks!

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Re: K200 thump [message #4851 is a reply to message #4845] Mon, 13 September 2004 22:01 Go to previous messageGo to next message
KustomBlues
Messages: 490
Registered: June 2001
Location: Michigan
Senior Member
No, none other than I'm glad it works for you. I do know that the 3 wire cord kills most buzz. (Other than buzz from an unshielded strat with single coil pickups) That buzz comes from lights and other interference. Hum can also go away because of the cord change because it cures the polarity problem that is associated with a non-grounded power situation. You have a grounded amp now. That upgrade not only may have saved your life, but it always helps clean up the sound of the weird noises an amp can make. It's elementary Watson!! Cool

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Re: K200 thump [message #4853 is a reply to message #4736] Mon, 13 September 2004 23:42 Go to previous message
voided3 is currently offline  voided3
Messages: 200
Registered: July 2004
Senior Member
Well deducted, dear Sherlock Laughing Thanks!

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