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K150 Sound Problems [message #17934]

Thu, 20 December 2012 15:17

ReverbJoe
Messages: 37
Registered: October 2012

Member

So I bought a Kustom 150 Combo a few months ago and it was working perfectly, until about a week ago. When I first bought it, the guy told me that the left speaker needed some work and that it might need a re-soldering. It played fine all this time and all of a sudden it just sounded horrible. The left channel with the effects sounds like it has the tremelo on at all times even though it doesn't and if I raise the volume past the third spike, it sounds distorted and high pitched. The right channel sounds OK until you go past the second spike, then it does the same as the other channel. Has this happened to any of you? How can I repair it?

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Re: K150 Sound Problems [message #17937 is a reply to message #17934]

Fri, 21 December 2012 13:29

chicagobill
Messages: 2011
Registered: April 2003

Senior Member

I don't remember the details of your amp so let us know which model 150 combo you have.

The first test would be to try the amp with some different speakers. Unplug the internal speakers and try the head part with an external speaker cab. Still distorted?

If the amp part is distorting, you will need to check out the electronics. What sort of equipment do you have access to, multimeter, soldering iron, large hammer?

Seeing how it happened suddenly, either a part has actually failed or something has come loose. Turn on the amp and turn off the reverb and give the amp a good thump with your fist. Any difference? If something has come loose, sometimes a good whack will reconnect the part and will lead you to the problem.

If this doesn't work, you'll have to go inside the chassis to see what you can see. Unplug the amp and open up the head and visually inspect the interior parts to see if you notice anything loose or physically broken. Seeing as both channels are affected, the power amp and power supply sections would be the first things to look at. These are the boards away from the front panel.

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Re: K150 Sound Problems [message #17941 is a reply to message #17937]

Fri, 21 December 2012 23:17

ReverbJoe
Messages: 37
Registered: October 2012

Member

My amp is a K-150-8 combo, tuck and roll leather, and I think 2 12's. I have a soldering iron but I can go get whatever is essential for fixing it. I'll try to run the tests you gave me.

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Re: K150 Sound Problems [message #17945 is a reply to message #17934]

Sat, 22 December 2012 12:27

Kustom_Bart
Messages: 601
Registered: October 2010
Location: Greenville, MichiGUN

Senior Member

The K150-8 is a great sounding unit when it is operating correctly. I have one and it is great. It does have 2 x 12" speakers and once you get it going you will enjoy it for sure.

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Re: K150 Sound Problems [message #17947 is a reply to message #17945]

Sat, 22 December 2012 12:54

pleat
Messages: 1459
Registered: June 2004
Location: Belding, Mi

Senior Member

The Kustom K150-8 is either the 2x10" or 4x10" models. the K150-7 is the 2x12" model. Both models uses the same circuitry, but the pre amp board numbers are different. The only difference in board numbers is the control spacing. The dash 8 models the controls are closer together.
pleat

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Re: K150 Sound Problems [message #17948 is a reply to message #17934]

Sat, 22 December 2012 13:34

Kustom_Bart
Messages: 601
Registered: October 2010
Location: Greenville, MichiGUN

Senior Member

Correct you are Don, I always get the two mixed up. There are too many and I had to many K150's -6 -7 etc. lol! I am glad I have you to keep me stright Smile

Smile

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Re: K150 Sound Problems [message #17964 is a reply to message #17934]

Sat, 29 December 2012 23:36

ReverbJoe
Messages: 37
Registered: October 2012

Member

I opened it up and found this. Are they supposed to be different? The right one has the Kustom stamp on it but the left one doesn't.

http://i.imgur.com/7Ds7Dl.jpg?1

And this is the inside of the amp. Hope the pics help.

http://i.imgur.com/RlRfql.jpg

http://i.imgur.com/9dPBVl.jpg

http://i.imgur.com/in8Tzl.jpg

http://i.imgur.com/rS9gUl.jpg

http://i.imgur.com/LIc8sl.jpg

http://i.imgur.com/vrxB1l.jpg

http://i.imgur.com/3euf5l.jpg

[Updated on: Sun, 30 December 2012 00:23]

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Re: K150 Sound Problems [message #17965 is a reply to message #17964]

Sun, 30 December 2012 12:03

Kustom_Bart
Messages: 601
Registered: October 2010
Location: Greenville, MichiGUN

Senior Member

They should both be the same as the one with the Kustom stamp on it. I would double check each of them and make sure that the ohm rating is the same on both of them. Also, you can take a air nozzle and blow the dust out of the chassis or vacuum it out, just be careful not to bump or smack anything inside the amp. Other than the amp being dusty, it looks reasonably stock, other than the pic showing the fuse, it shows some items wrapped in black tape. That makes me wonder what is under it and why it is wrapped in black tape. I had one amp that had black tap holding a couple of wires together....inside the old black tape....the wires were not held together any more. I slid shrink wrap over them and soldiered them together and shrink wrapped them and it worked great and still does. Some times it is just stupid stuff. I have seen all kinds of dumb things done to them inside.....and just wondered WHY...lol!

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Re: K150 Sound Problems [message #17966 is a reply to message #17934]

Sun, 30 December 2012 12:53

ReverbJoe
Messages: 37
Registered: October 2012

Member

This is what I found under the black tape. Looks like they might have cut it on accident and just wrapped it back up.

http://i.imgur.com/KqMn9l.jpg

I also noticed that this is just hanging there. Should it be connected to something?

http://i.imgur.com/AYxNAl.jpg

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Re: K150 Sound Problems [message #17967 is a reply to message #17934]

Sun, 30 December 2012 13:48

chicagobill
Messages: 2011
Registered: April 2003

Senior Member

See the hole in the chassis. That's where the power original on/off/polarity switch was located.

The taped up wires used to be attached to the switch. How do you turn this amp on and off?

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Re: K150 Sound Problems [message #17968 is a reply to message #17934]

Sun, 30 December 2012 14:01

stevem
Messages: 4792
Registered: June 2004
Location: NY

Senior Member

Your amp has been worked on and I think I see a problem.
In your 7th photo on the right hand side you can see two black wires with slip on connectors that hook to a black round plastic object
The object is the amps thermal circuit breaker and the problem I see is behind it.
There is a small metal cased two wire lead diode in a clip, and the diode is mostly pushed out of the clip towards the front of the amp and looks like its shorting to the metal hold down clip of the termal circuit breaker. If this is the case push it back the other way towards the rear of the amp, but be carefull with the leads on the diode, support them and put a bend in them slightly to hold the diode and keep it centered in its clip.
It needs to be held firm in its clip, if thats not the case pull it out gentle and bend the clip in tighter as to grasp the diode better.
The amp is extremly dusty and dirty and the cut wires need to be checked out by a tech, and yes that left hand speaker is not original.
Keep us informed.

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Re: K150 Sound Problems [message #17969 is a reply to message #17968]

Sun, 30 December 2012 15:33

pleat
Messages: 1459
Registered: June 2004
Location: Belding, Mi

Senior Member

The taped up wires are because someone removed the on/off switch.
Are the two large transistors on the circuit board originals. The numbers look odd to me.
pleat

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Re: K150 Sound Problems [message #17970 is a reply to message #17967]

Sun, 30 December 2012 18:36

ReverbJoe
Messages: 37
Registered: October 2012

Member

chicagobill wrote on Sun, 30 December 2012 13:48

See the hole in the chassis. That's where the power original on/off/polarity switch was located.

The taped up wires used to be attached to the switch. How do you turn this amp on and off?

Here's the funny part, when I bought it, the guy told me that it was so old that it didn't have an on/off switch. That it just turned on when you plugged it in.

stevem wrote on Sun, 30 December 2012 14:01

Keep us informed.

Will do.

pleat wrote on Sun, 30 December 2012 15:33

Are the two large transistors on the circuit board originals.

I'm not sure. I don't have anything to compare it with.

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Re: K150 Sound Problems [message #17971 is a reply to message #17934]

Sun, 30 December 2012 21:35

chicagobill
Messages: 2011
Registered: April 2003

Senior Member

The two transistors on the board are not original, they should be the same as the RCA output transistors.

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Re: K150 Sound Problems [message #17973 is a reply to message #17934]

Mon, 31 December 2012 06:59

stevem
Messages: 4792
Registered: June 2004
Location: NY

Senior Member

Sorry, I ment to say that in regards to the clip in thermal diode, just make sure that when its tight in the clip that its leads will not short to the clip.

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Re: K150 Sound Problems [message #17977 is a reply to message #17934]

Mon, 31 December 2012 18:08

ReverbJoe
Messages: 37
Registered: October 2012

Member

Alright, so I adjusted the thermal diode and soldered the split wires(seeing as how I don't have an on/off switch at the the time) and that sort of helped, but its still pretty rough. As for the transistors, I don't know where to begin. And the speakers, I don't have any replacements for them. Are they worth replacing? Or would it be better to start looking for a new combo?

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Re: K150 Sound Problems [message #17979 is a reply to message #17934]

Mon, 31 December 2012 22:04

Kustom_Bart
Messages: 601
Registered: October 2010
Location: Greenville, MichiGUN

Senior Member

Everything is available, take it easy...lol!

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Re: K150 Sound Problems [message #17985 is a reply to message #17979]

Tue, 01 January 2013 18:29

pleat
Messages: 1459
Registered: June 2004
Location: Belding, Mi

Senior Member

It seems like we are trying to answer too many different questions. The speaker issue. Each speaker should be 16 ohms wired in parallel for an 8 ohm load. Since you have two different speakers, it looks like they are wired + to + and - to -. The thing you want to find out is, are the cones both moving in the same direction? A 9V battery qickly applied to the speaker plug will show you if both speaker cones are moving in the same direction. If not, then you will have to flip one of the speakers so both cones move the same direction.
Do you have another amp that you can try out the speakers in the kustom cabinet. Once you determine that the speakers are in good working order, then tackle the amp head issues.

Chicago Bill aggreed that the large transistors on the circuit board should be the same as the two large trasistors mounted under the heatsink. The original number is 36892. The large transistors PP3324 may be replacements, but might not work well with the other power two transistors. I'm not a tech but process of elimination is always a good start.
pleat

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Re: K150 Sound Problems [message #17987 is a reply to message #17934]

Wed, 02 January 2013 06:57

stevem
Messages: 4792
Registered: June 2004
Location: NY

Senior Member

I can not seem to cros over those pp3324 regaltor transistors, if you have have a radio shack near by most of them have stock of a 2n3055 transistor which is a good replacement.
Since they have been replaced the circuit board in that area would also be a good spot to look for bad solder connections.

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Re: K150 Sound Problems [message #17988 is a reply to message #17934]

Wed, 02 January 2013 12:18

chicagobill
Messages: 2011
Registered: April 2003

Senior Member

Those PP transistors are Perma Power branded parts. If they were working ok before, then leave then unless they test out to be bad. Changing parts now may add to the problems with the amp and may make it harder to fix the original problem.

Try to fix the problem at hand first and then go back and fix other possible problems. I'd start by replacing the missing power switch. Then try and find out why the amp is distorting.

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Re: K150 Sound Problems [message #18059 is a reply to message #17985]

Tue, 15 January 2013 21:21

ReverbJoe
Messages: 37
Registered: October 2012

Member

Sorry its taken so long to get back, work has been pretty hectic lately. I still don't have a power switch for it. Could one of you post a pic of the power switch and how its supposed to be wired in the amp?

pleat wrote on Tue, 01 January 2013 18:29

It seems like we are trying to answer too many different questions. The speaker issue. Each speaker should be 16 ohms wired in parallel for an 8 ohm load. Since you have two different speakers, it looks like they are wired + to + and - to -. The thing you want to find out is, are the cones both moving in the same direction?

I did the battery check, and the polarities are correctly matched with the wire. They are indeed + to +, - to -. Should they be wired differently?

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Re: K150 Sound Problems [message #18060 is a reply to message #18059]

Tue, 15 January 2013 21:47

pleat
Messages: 1459
Registered: June 2004
Location: Belding, Mi

Senior Member

If both speaker cones move in the same direction when voltage is applied, the speakers are in phase and correct wiring. You still have to determine if the speakers are good, using another amp you know is good connected to the speakers in question will tell you if both speakers are in good working order, or you may have one of the two speakers, or both that need to be replaced or repaired. Email me djt@chartermi.net and I can send you a photo of how the switch is wired.
pleat

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Re: K150 Sound Problems [message #18303 is a reply to message #17934]

Thu, 28 February 2013 23:13

ReverbJoe
Messages: 37
Registered: October 2012

Member

Hey guys. I'm back, and I've hit a giant road block. I bought some 2n3055 transistors like Stevem suggested and when I got to replacing them in the amp, I was stopped in my tracks. The bolts and nuts holding the transistors onto the board were soldered on. It looks like the nut might need to be soldered into the board, but they got solder on the bolt, making it impossible to remove. I have a soldering gun but it cant seem to remove the solder deep in the nut. I gave up on it, but since I'm out of options, I'm thinking about cutting the nut off. I know it sounds extreme but it's that or give up on the amp. Here are some pictures.

http://i.imgur.com/2vMqp4bl.jpg?1

http://i.imgur.com/iTUi3lMl.jpg?3

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Re: K150 Sound Problems [message #18304 is a reply to message #17934]

Fri, 01 March 2013 00:31

chicagobill
Messages: 2011
Registered: April 2003

Senior Member

There is no reason to solder those nuts to the board. I guess it was just some techs idea to make this better.

I wouldn't try to heat them off, it will probably cause damage to the board. I would try and drill or grind off the heads of the screws, unsolder and remove the transistor, and then heat up and remove the nuts and screw stubs from the board.

I guess that I should ask, are the transistors bad? Why are you replacing them?

[Updated on: Fri, 01 March 2013 00:32]

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Re: K150 Sound Problems [message #18310 is a reply to message #17934]

Fri, 01 March 2013 09:37

stevem
Messages: 4792
Registered: June 2004
Location: NY

Senior Member

You do not have to remove those transistors to check them, if need be cut thru two of the circuit board traces with a sharp small knife, or a cut off disc in a dremel tool and then test them,as with just two connections points open you can prove the transistors out, when done simple solder the board traces back togethere!
If they are bad and you need to remove the nuts than the use of a small size 1/4" drive socket or the right size nut driver and a well fitting philips head screw driver should let you bust the solder holding the nuts.

[Updated on: Fri, 01 March 2013 09:39]

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Re: K150 Sound Problems [message #18311 is a reply to message #18310]

Fri, 01 March 2013 10:27

Kustom_Bart
Messages: 601
Registered: October 2010
Location: Greenville, MichiGUN

Senior Member

Also, get yourself a good soldiering station that is adjustable and not a gun. The soldiering iron will allow you to remove them without issue.

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