| K200B-1 Bright switch kaput [message #25915] |
Tue, 14 February 2017 16:18  |
irish77060
Messages: 49
Registered: January 2017
Location: Atlanta, GA
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Hi Again,
Ok, have moved on to the 3rd amp. 1 and 2 repaired using this board. K100-5 and K200B-1 working great!
This is the 2nd K200B-1. Initially, I had the same problem as the first 200, meaning the bright side did not work. So I performed all the tasks that I did on the first one to resurrect it. It worked. Life.
But, when cleaning the bright switch on the bright side of the amp, I noticed that the 'stops' in the switch weren't doing their job! I can switch the switch knob a full 360 degrees as many times as I want. And no, the knob isn't loose--haha. There are maybe 8 dips in the switch, and the connection obviously works on only 2. The other side is fine, and by comparison the defective switch is OEM. I could leave it as is, but I know that it isn't right. I also tapped around with the plastic end of a small screwdriver on the circuit board of the Bright side, and got a mild cracking on all 4 pots. I will try this tomorrow when I am sure the cleaner is all dry, and see if it repeats.
Additionally, with still having the non-grounded cord on the amp, the electronic hum is very loud on the Normal side. On the other two heads I repaired, that diminished greatly when the cord was replaced. Maybe this one will as well.
Richard
Keep On Truckin'
[Updated on: Tue, 14 February 2017 16:48] Report message to a moderator |
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| Re: K200B-1 Bright switch kaput [message #25916 is a reply to message #25915] |
Tue, 14 February 2017 17:41  |
chicagobill
Messages: 2006
Registered: April 2003
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Senior Member |
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That switch is definitely custom made for Kustom. The stop mechanism is usually just behind the threaded mounting section. If you look at the back of the mounting plate, you might be able to see if the rotating limit mechanism is out of alignment with the end stop blocks.
As for the hum, a grounded cord is always safer than the two wire ones. All of the preamp boards are grounded by the pot mounting hardware, so sometimes just removing and reinstalling the boards cleans up the ground connections and fixes minor hum issues.
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| Re: K200B-1 Bright switch kaput [message #25923 is a reply to message #25916] |
Wed, 15 February 2017 13:39 |
irish77060
Messages: 49
Registered: January 2017
Location: Atlanta, GA
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Weirdness.
Ok, since I built the circuit limiter. I plug everything into that when I crack the case. I did so when I pulled the chassis out on this K200B-1 to look at the switch.
I carefully pulled the board and did a comparison with the other switch to see which part within sight could be in disarray. I saw it, but was not able to fix it. So I will have to see if there is a replacement switch or board cheap enough to salvage from another amp.
But, now here's the weirdness, when I turned it on just to check that all was still working, I connected a speaker and plugged in a bass. Normal side first. Both high and low worked like a champ. Bright switch good.
Then I plugged into the Bright side. Switch was in place to play (remembering it moves completely around) and guitar plugged in the low channel. Circuit light off. I hit a low note and the light came on! Muted the string--light off. Moved the jack to the high side and hit a string. No light. Back to the low side, had a light. Only when you play a note does the light come on, in the Bright Channel, low side.
Keep On Truckin'
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| Re: K200B-1 Bright switch kaput [message #25925 is a reply to message #25915] |
Wed, 15 February 2017 17:36 |
chicagobill
Messages: 2006
Registered: April 2003
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Senior Member |
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I will assume that you are talking about a PC203 preamp board with boost circuit. The bright switch is not just a simple add a capacitor type of circuit. This board has a small two transistor treble boost circuit that the bright switch bypasses or switches into the signal path.
Are you sure that the switch is on one of the two correct positions? It might be that the circuit is oscillating when it passes a signal causing the high current draw. How bright does the bulb glow?
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| Re: K200B-1 Bright switch kaput [message #25937 is a reply to message #25932] |
Thu, 16 February 2017 21:04 |
irish77060
Messages: 49
Registered: January 2017
Location: Atlanta, GA
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Ok. Bulb is 200W incandescent.
I once again removed the PC board again to insure nothing was in there, like solder Birthday s or other metallic trash that could be causing a problem. All clear. Then I cleaned the ground connections throughout (which reduced the very loud hum to a low noticeable hum). Plugged in guitar, cabinets, and turned it on.
High Jack, both sides, bright switch off. No light. Volume in middle, then cranked all the way.
------Same test, bright switch on, no light.
Low jack, both sides, bright switch off. Volume in middle, no light. Volume 3/4-full on, mid glow light. This is now on both sides. Bright and Normal channels. Low jack only. Bright switch on. No light.
High jack, both sides -- no light regardless of volume.
Keep On Truckin'
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| Re: K200B-1 Bright switch kaput [message #25938 is a reply to message #25937] |
Thu, 16 February 2017 21:12 |
irish77060
Messages: 49
Registered: January 2017
Location: Atlanta, GA
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BTW, I have now finished (assuming this light is acceptable) all 4 solid state amps! All are working where none were before. All repaired via your help, and through information gleaned from this board. Now I have to do the K400B, with both tube and solid state. Know anything about those? And one last question, do you, or anyone you know, have knowledge about Plush amplifiers? I have one that will be the last one I do in my collection.
Keep On Truckin'
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| Re: K200B-1 Bright switch kaput [message #25939 is a reply to message #25915] |
Thu, 16 February 2017 21:21 |
chicagobill
Messages: 2006
Registered: April 2003
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Senior Member |
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Is this with a speaker plugged in or a dummy load?
From what you have posted, that seems pretty normal to me.
Glad to hear that you have been able to fix up your collection. I'm not sure about the K400B is that one of the new made in China amps?
As for the Plush, they are basically Fender amps in a button tufted case. Which model do you have?
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| Re: K200B-1 Bright switch kaput [message #25940 is a reply to message #25939] |
Thu, 16 February 2017 23:00 |
irish77060
Messages: 49
Registered: January 2017
Location: Atlanta, GA
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The speaker is plugged in.
The other K200-B doesn't do this.
A little history from Wickopedia on the TRB400H (hybrid,switchable between tube and solid state)
Hanser Re-issues
Hanser Holdings, Inc. from Cincinnati, Ohio bought the bankrupted Kustom in the late 1980s. In 1994, Hanser produced some small solid-state amplifiers featuring tuck-n-roll covering under the Kustom brand. These amps were manufactured in China.
From 1999 to 2001 Hanser continued producing Kustom brand tuck-n-roll amplifiers including a full tube guitar amplifier, 100W and a 50W solid state reverb amps called TRT100 and TRT50, a 400W hybrid bass amplifier TRB400H, as well as 2x12", 4x12" and 2x15" speaker cabinets in original tuck-n-roll style. List prices were in 2000: $999.95 (TRT100), $899.95 (TRT50), $899.95 (TRB400H) $399.95 (2x12"), $599.95 (4x12"), $749.95 (2x15").
PLUSH:
I have heard that they are based on the Dual Showman. Mine is the P1000S. I needed the schematic to go through it, and possibly upgrade it. Additionally I wanted to get the original tube specs. Some are missing.
Keep On Truckin'
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| Re: K200B-1 Bright switch kaput [message #25941 is a reply to message #25915] |
Thu, 16 February 2017 23:57 |
chicagobill
Messages: 2006
Registered: April 2003
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Senior Member |
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That's pretty loud then isn't it? If the other amp doesn't do it, then this one might be pulling a little more current than the other one. It could be difference of transistors or a failing/leaky cap or a little too much idle bias. Do the output transistors get warm?
You can go through the power amp and read the voltages at different parts of the circuit and compare them to the values published on the schematic. Kustom amp test procedure is to test the voltages with no speaker load and no input signal.
I've not fixed many of the newer Kustoms, so I can only offer general suggestions to you. Steve owns one or did, so he may have a better handle on helping you out.
The Plush amps were a part for part copy of the Fender tube amps. You can pretty much just use a schematic for a Fender Showman or a Twin Reverb and figure out what's going on in there. The last time I had to fix one, the biggest problem was finding short bottle power tubes that would fit in the case comfortably.
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| Re: K200B-1 Bright switch kaput [message #25943 is a reply to message #25942] |
Sat, 18 February 2017 11:21 |
irish77060
Messages: 49
Registered: January 2017
Location: Atlanta, GA
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Bill,
Yessir, that's pretty loud. When I use these amps, I use an A/B box playing almost full tilt out of both K200B's and each with a cabinet of 3x15's. I will rearrange your innards. I haven't used them in years but my newest musical project will be playing some venues where I can get back to that amp group. I just don't wish it to spark a stage fire!
I will follow the schematic on the voltages and test the output transistors for warmth when I return to Atlanta Monday.
Thanks,
Richard
Keep On Truckin'
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| Re: K200B-1 Bright switch kaput [message #25944 is a reply to message #25942] |
Sat, 18 February 2017 11:37 |
irish77060
Messages: 49
Registered: January 2017
Location: Atlanta, GA
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Hey Steve!
I use the TRB400 currently playing out of two 4x12 cabs. Sparkly red. I get a lot of compliments on looks, but more importantly on sound. Amp has a sweet bottom.
As I play predominately out of the tube side, I've noticed the amp has developed what I refer to as the "R2D2" sound. It's usually after playing for a half hour or so. At first it was barely noticeable. Then a little louder. I moved the amp from one venue to another and the noise seems to have quieted. However, I did just lose a little power. Dropped about 20% and I don't know why. I haven't even had a chance to even crack it open to check tubes or anything. I will check them on Monday when I return home.
Thanks, and please do look at that PC board and let me know if I can afford it.
Richard
Keep On Truckin'
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| Re: K200B-1 Bright switch kaput [message #25950 is a reply to message #25946] |
Sun, 19 February 2017 23:29 |
irish77060
Messages: 49
Registered: January 2017
Location: Atlanta, GA
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Member |
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Thanks for that info Steve. Is there a reason you prefer the Eurotubes? Glue is a good rec. and did you find out about the pic board for the Bright channel on the 200?
Keep On Truckin'
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