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k250-4 hiss but no volume [message #9019] Fri, 23 November 2007 23:36   davohilts Messages: 40 Registered: August 2006 Location: Portland, OR Member Hi again, I'm the one with the 250-4 that has the hiss, my amp guy tried to fix it but couldn't and now i've got it back and the hiss is all it does. The hiss is not really too bad and can have the tone changed by using the effects but when I jack into it with a guitar I can not get any output. Is there something which might have become disconnected. I've checked all the power connections between the boards and they appear to be well connected. I'm really hoping to get this baby back into action someday. Dave Report message to a moderator

Re: k250-4 hiss but no volume [message #9021 is a reply to message #9019] Sun, 25 November 2007 15:34   BrianBartling Messages: 8 Registered: June 2006 Junior Member Hi, While I'm no expert I can tell you that I recently fixed a Kustom 200 by replacing the transistors on the preamp boards. When I bought it, 3 of the 4 channels were dead, and now they all work! If your amp "THUMPS" when you turn it on, and the hiss is there, then that pretty much means the output transistors are good and you may want to turn your attention to the PREAMP transistors. Hope that helps. Report message to a moderator

Re: k250-4 hiss but no volume [message #9038 is a reply to message #9021] Fri, 07 December 2007 00:08   davohilts Messages: 40 Registered: August 2006 Location: Portland, OR Member thanks for the help. i had an amp guy working on this for me and he was stumped because he couldn't get rid of the hiss so I got it back from him. I thought it a least worked but when I hooked it up all i get is hiss. he said he changed out all the transistors and couldn't get rid of the hiss. i'm currently looking for someone in the Portland, OR area who works on Kustom amps. I have a K250-2 which is really great and I'm dying to try out the fuzz on the 250-4 but i've just got to be patient. Report message to a moderator

Re: k250-4 hiss but no volume [message #9039 is a reply to message #9019] Fri, 07 December 2007 07:17   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member If all he did was change out some transistors, then is by far not much of a repair tech.He was just tring to shot gun the amp in the hopes of stumbling on the problem. This is the type of problem that you need to take time and use a o-scope to step thru the amps stages and view where the hiss id being introduced into the audio chain. This problem could very well be a bad tantalum type cap. As far as your now no sound problem, now the amp is worse than when you took it to him for reapir, so you should not have paid the jerk anything I hope. These are not hard amps to fix, it may just take some time and a tech who knows what the hell he`s doing! Report message to a moderator

Re: k250-4 hiss but no volume [message #9040 is a reply to message #9019] Fri, 07 December 2007 07:22   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member The only thing that is getting hard to get now are the IC opamps for each channel that have to be had from suplus electronic supply venders, but still they are under 5 bucks each. Report message to a moderator

Re: k250-4 hiss but no volume [message #9041 is a reply to message #9040] Fri, 07 December 2007 09:19   davohilts Messages: 40 Registered: August 2006 Location: Portland, OR Member my amp guy tried everything he could think of. he replaced a bunch of caps and transistors, put in a three wire power cord... here is the link from this list which will fill you in. http://www.vintagekustom.com/FUDforum2/index.php?t=msg&t h=1665&start=0&rid=0&S=02a9b71b02ce19b856975e815 e62a890 Report message to a moderator

Re: k250-4 hiss but no volume [message #9042 is a reply to message #9019] Fri, 07 December 2007 12:22   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member At this point after reading all the old post the guy needs a schematic of the amp, if he does not have one if he already has one, then like I siad you need a new guy. I can fax you one on monday if you supply me with a fax number. This amp is very easy to work in some reguards for signal testing with its plug in board interconnects. For example you can unplug the whole effects board install a jumper, and then unplug the male connector from the bottom channel and pump a audio signal right into the driver/output stage, heck you can even just touch that driver stages input point with your finger and get a buzz just like touching the end of your unpluged guitar cord but at a much lower volume, and that would prove out the driver/output stage. You could even pump in the output form a mp3 player if you keep its volume real low. If taking the effects board out of signal chain does not give you back sound, then the problem lies on the lower channels board. Report message to a moderator

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