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I have a old Kent 3 tube amp of witch I need info on when it was shipped to me the 3 tubes were removed now I don,t know where the tubes go. They all have the same pins and you can plug them into any of the three plugs/sockets so now I don,t know witch tube goes into witch plug/socket. I don,t know anything about tube amps but I want to fix this amp myself. It had a cap that was bad so I replaced it but I don,t want to take a chance on burning something up by placing the tubes in the wrong place.does anyone know about these little Kent amps? There is no schematics in the amp or model number , so I am not sure what amp it is ! here is the description first of all it is green/blue striped top and bottom it has solid green/blue on both sides. it is 13" inches tall 16" inches wide and 6"and 1/4th" inches thick. it has a volume knob and a tone/on/off knob. it has 3 input jacks. the knobs and jacks are on the top of the amp.it has three tubes one is a 12AV6 the tube has no brand name on it .It has 7 pins as do all 3 tubes.the next tube is a GE tube with 50C5usa in grey it also says in white Fl186-5 the third tube is also a GE with 35W4 in transparent grey letter/numbers and in white letters/numbersFJ 198-5 the tubes hang upside down under all the components . the speaker is a 5X9 it has a stamp in white letters/numbers on the paper of the speaker it says SP-CO-181 . if anyone knows what model this amp is or if they know what tube goes where or where I can find a schematic for this amp it would be GREATLY appreciated !!!! With the back off looking from back to front it has a orange paper tube like outfit with 3 wires coming out of it they are yellow /red /and green .the red wire goes to the first tube socket or closest socket to the orange tube like component.the yellow and green wire goes to the next or middle tube socket . there is a yellow wire from the on/off/tone pot to the first tube socket connected to the same pin as the red wire coming from the orange paper tube. sorry for such a long post ,but I want to be as clear as possible ! Thanks
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Easiest thing might be to just give us a picture of the guts. The tubes are preamp, power amp, and rectifier in that order. If you know a little about amps, you can guess which goes where without having a schematic. Please be advised, however, based on the tube selection, this amp is one of the transformerless types and is not considered safe without adding a transformer (search on isolation transformer).Originally posted by RitzRed View Post
Edit: Schematic heaven has a kent 2198 that is probably really close to what you have:
http://www.webphix.com/schematic%20h.../kent_2198.pdf
One last thought, that's probably 12aU6, not 12aV6? -
yea I don,t have a digital camera that works well I am waiting for the one I bought off ebay then I will post pic,s as far as the tube 12AV6 I have heard it is supposed to have a 12AU6 from a teck but it is for sure a 12AV6 tube I bought this amp used and not working the tubes they sent are 12AV6 , 50C5 , and 35W4Comment
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Please be carefull.
They call these amps 'The Widowmaker" for a reason.Comment
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I suppose it could be 12av6 int the circuit, although that sounds more "clock radio" than "guitar amp" to me. The 12av6 has a triode and some diodes which would be unused here. The 12au6 is pentode.Originally posted by RitzRed View Post
Anyhow, the scheme I linked to probably includes 2/3rds of what you want (rectifier and power tube). If you examine the guts of your amp (unplugged!) you should be able to trace the path of the power cord to the rectifier tube socket and filter caps and so forth and make a good guess which socket is the rectifier. Same for the output transformer on the other end, where do the primary leads go? To what pins? The tube data sheets above show you the pinouts. A good learning exercise would be to try and see if you can draw your own schematic for each tube and then connect them to make the complete circuit.
electron Tube Data sheets - 1Comment
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Still, a good guts photo and we can probably tell which of those two types it ought to be from the wiring.Education is what you're left with after you have forgotten what you have learned.Comment
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thanks guys I guess the thing to do is to get a 12AU6 to replace the 12AV6 they sent with the amp . I have another question, can I change the little transformer to a bigger better one this amp only has one transformer, So my next question is can I ad a output transformer to this little amp ? everything I have read says the type of output transformer you have helps the sound , I have to wonder how it even works if it does NOT have one? allot of questions, I will post pics as soon as possible.Then we can go from there thanks againComment
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Well, that was the point of taking photos, so we could determine if your tube needs to be the other type. Got a friend with a camera?
The one transformer you already have is an output transformer. what these dangerous type amps lack is a power transformer. The thing to do to use this amp is to put an "isolation transformer" in front of it.
A different output transformer might have som effect on tone, but there are a whole lot of other simple and cheaper things that will have large effect on the sound.Education is what you're left with after you have forgotten what you have learned.Comment
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I got some pics of the amp I want to identify but don,t know how to upload them to this sightComment
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how do I put the pics on this site?Comment
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When you go to reply, there is an insert image button at the top of the reply window...Comment
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ok cool here are the picsI hope they all got on here
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Before we get started, I hope you know how to identify the pins on the tubes? If I say pin #1, you can find it right? Okay. Also, I am seeing a lot of bare wires in this set-up. Do not mess with this plugged in unless you are sure of what you are doing. I would also add, looking at your picture is no substitute for you looking in person and trying to verify what I say below. besides, if you want to learn, you should try to proove it to yourself which tube goes where.
I can only see one picture (jpeg number 005), but I would vote for the tubes from top to bottom in this order: 35W4 - 50c5 - 12av6
My reasoning:
12series looks like it has a 4.7M and yellow cap hanging off pin 1 (grid) and pin2 (cathode) goes to chassis, so input cap, grid leak.
35W4 should have a lead from that big red multi-section cap (cardboard tube looking thing) to pin 7 (cathode), it looks like it might be that red wire, but it is hard to tell. That tube should also have a connection to the "line" from the wall plug. It may get there via a resistor, or via pin 6, but that line voltage should get to pin 5 (plate) of the rectifier tube. I see the line (white wire) going to a lug on the tag strip and then resistors (big ceramic) heading in that general direction, so check that out. Also, check if that big white rectangular resistor isn't a ballast resistor for the line voltage, maybe headed for pin 4 (heater) on the rectifier?
50C5 is likely the middle tube if my above is correct. Look for a lead from the output transformer straight to pin 7 (plate). It may touch some other compnents on the way there, but it should be electrically the same point. I would also be looking for a big one-watt resistor hanging off pin 1 (cathode)
I will be curious to see what others come up with. I would also encourage you to try and draw this schemo yourself, you will learn a lot if you do.Comment
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Dude, I realized why these tubes were all so familiar, but is was the fuzzy brown resistor that reminded me. Your amp is almost a dead ringer for a 45 rpm record player. Try this schemo on for size:Originally posted by RitzRed View Post
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I am trying to get some more pics to upload oh well. here is one more thanks for the info so far I will try to see if I can figure it out by what you have told me and yes I can find the right pin
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