bluefoxicy Posted April 12, 2008 Share Posted April 12, 2008 I turned on my amp that I just built and it spit sparks everywhere from the switch! Help me troubleshoot, I don't even know what you guys need to know to help ~_~ Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 12, 2008 Author Share Posted April 12, 2008 it's the switch, it's damaged. I reseated the spade jacks (they came out when I pulled) and it survived for a few seconds, then blew once and I unplugged it from the wall. PT isn't even hot, caps were holding a freaking HUGE charge that I discharged through my meter in like 2 minutes damn. Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 12, 2008 Author Share Posted April 12, 2008 might also not be a bad idea to plug a speaker into the output before turning it on. >_>; but there's no TUBES in the amp at all. Link to comment Share on other sites More sharing options...
layboomo Posted April 13, 2008 Share Posted April 13, 2008 You are Dangerous man! I've tried to suggest slowing down and understanding what you are doing before you wreck something or worse ...hurt yourself. If you slow down and do one mod at a time you'll know exactly whats wrong instead of trying to do 10 things at once and then yelling for help. The lightbulb current limiter costs about $5 to build and when used on power ups it will tell you right away if something is wrong....I think Gil also suggested you use one,but you obviously know better and don't need it. Work from a schematic...go one step at a time and post some pics if you have a problem and people will help......but if you want to just throw **** together without understanding what you are doing and then ask for help......you are waisting peoples time. If that sounds harsh....I'm sorry but I'd rather have you pissed off at me than DEAD! Link to comment Share on other sites More sharing options...
TWANG Posted April 13, 2008 Share Posted April 13, 2008 I need it. Is there a diagram explanation faq node schematic picture tatoo or a pancake in west virginia for the light bulb current limiter? I'm still spooked after frying my R10 into chunks. Never again! Link to comment Share on other sites More sharing options...
layboomo Posted April 13, 2008 Share Posted April 13, 2008 Limiter links... http://www.diyguitarist.com/GuitarAmps/FilterCapR.htm http://www.geofex.com/Article_Folders/SPO_Test.htm http://thenormster.com/DumbleLite/BuildersGuide/D-Lite%20Assembly%20Guide.htm Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 13, 2008 Author Share Posted April 13, 2008 It's (mostly) a TurretBoard marshall build, a couple things moved to get BitMo Trio stuff in there. That switch is damaged; I messed with it a little (wiggled wires, pushed spades in) and it seems to not shower sparks now, just pop one every few seconds. Rubber gloves and a fire extinguisher man. No tubes in there because they could explode if I did it wrong; I'll tube test it when it seems to work and I have it in a closed cabinet. I do need to get a fuse in that circuit somehow though. Link to comment Share on other sites More sharing options...
layboomo Posted April 13, 2008 Share Posted April 13, 2008 It's (mostly) a TurretBoard marshall build' date=' a couple things moved to get BitMo Trio stuff in there. That switch is damaged; I messed with it a little (wiggled wires, pushed spades in) and it seems to not shower sparks now, just pop one every few seconds. Rubber gloves and a fire extinguisher man. No tubes in there because they could explode if I did it wrong; I'll tube test it when it seems to work and I have it in a closed cabinet. I do need to get a fuse in that circuit somehow though.[/quote'] No MAINS FUSE??? WTF are you trying to do?? I just don't get it...maybe it's time for someone else to chime in cause I'm getting pretty frustrated......if you are going to ignore basic safety rules and practices...I'm all done trying to help you. Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 13, 2008 Author Share Posted April 13, 2008 There was no fuse on the turretboard, and I'm not sure what to get for a fuse. It's a 75W transformer, I guess I need a 115V .7A fuse or something. I'm pretty sure the next time I build an amp it's going to look a lot different; I've bought so many random parts in between to cover stuff I didn't think about. It's a learning experience; although you should probably point people at this in the FAQ of "**** not to do when messing with electricity." Link to comment Share on other sites More sharing options...
layboomo Posted April 13, 2008 Share Posted April 13, 2008 If you used the stock valve jr chassis with the power cord that came with it...then it is fused. The mains fuse is actually in the power cord connector on the chassis......you can pop it open with a little screw driver and check it. When you say you moved a couple things to get the bitmo mods in ....what and where? If you can post a picture that might help alot. Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 13, 2008 Author Share Posted April 13, 2008 I'm using a Hammond 270DAX transformer, 75VA (75 watt?), 260-0-260@90mA on the high-voltage secondary and 6.3V@3.5A on the filaments available. The stock tranny won't drive an EL34 at 25W bias. Running a Hammond 125ESE output transformer (which seems to be rated for 2kV) as well. In the marshallized turretboard, R6 doesn't exist. R7 connects directly to C1; I moved that end of R7 (and VR1, which connects to it) to the solder joint for R6 (which in this version is unused) and then connected the bitmo leads that parallel R6 to go in series from R7 to C1. EFFECTIVELY, the bitmo mods connect to R6 in parallel; R6 is removed (open) on mine. I also replaced C4; the bitmo trio mod has instructions to remove C4 and solder something in parallel with R8 (I think it's another cap there though, so I've still got a C4 in that spot). I specifically checked the board layout when I did this to make sure I got polarity right too. I ALSO ran pin 1 to pin 8 on the octal power tube (suppressor to cathode) as per Gil's recommendations; and tied R16 and R17 (filament resistors) to pin 8 as well rather than grounding them. I tied the input jack ground to the ground lead on the volume pot. Note there's no input, speaker, or tubes hooked up, so most of this is pretty much non-functional. Link to comment Share on other sites More sharing options...
layboomo Posted April 13, 2008 Share Posted April 13, 2008 I'm using a Hammond 270DAX transformer' date=' 75VA (75 watt?), 260-0-260@90mA on the high-voltage secondary and 6.3V@3.5A on the filaments available. The stock tranny won't drive an EL34 at 25W bias. Running a Hammond 125ESE output transformer (which seems to be rated for 2kV) as well. In the marshallized turretboard, R6 doesn't exist. R7 connects directly to C1; I moved that end of R7 (and VR1, which connects to it) to the solder joint for R6 (which in this version is unused) and then connected the bitmo leads that parallel R6 to go in series from R7 to C1. EFFECTIVELY, the bitmo mods connect to R6 in parallel; R6 is removed (open) on mine. I also replaced C4; the bitmo trio mod has instructions to remove C4 and solder something in parallel with R8 (I think it's another cap there though, so I've still got a C4 in that spot). I specifically checked the board layout when I did this to make sure I got polarity right too. I ALSO ran pin 1 to pin 8 on the octal power tube (suppressor to cathode) as per Gil's recommendations; and tied R16 and R17 (filament resistors) to pin 8 as well rather than grounding them. I tied the input jack ground to the ground lead on the volume pot. Note there's no input, speaker, or tubes hooked up, so most of this is pretty much non-functional.[/quote'] Well a couple of things don't sound right to me ...first on the marshallized boards R-6 is jumped(Closed not open) and some of the bitmo mods need an R-6 resistor to function correctly but I don't have the bitmo schematic for what you are doing. Second are you sure you don't have the terminals on the switch mixed up? You do know that you should never turn the amp on without a load(speaker) hooked up right? The r-16 & r-17 is just an elevated ground to further reduce noise if I'm reading you right. If you are working with Gil then you should be OK...I didn't know that part of it...but my advice to slow down is still the same. My first recommendation is to get the amp up and running and stable without the Bitmo stuff etc...and add that later once you have a working amp. I would still advise you to build a light bulb current limiter and follow this link http://thenormster.com/DumbleLite/BuildersGuide/D-Lite%20Assembly%20Guide.htm to power things up without and then with tubes once you know the trannies and filter caps etc...are installed and wired correctly. I really think you are trying to do way to much all at once for your experience level.....step back take it apart and crawl before you walk....that's how you learn SAFELY! Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 13, 2008 Author Share Posted April 13, 2008 ...first on the marshallized boards R-6 is jumped(Closed not open) and some of the bitmo mods need an R-6 resistor to function correctly but I don't have the bitmo schematic for what you are doing. That part of the circuit's non-functional anyway. No tubes. I have bitmo TRIO' date=' the duo knob (a tone knob...) goes across R6 with a cap + pot (resistor) in parallel, so effectively the pot becomes R6 in this layout. For a 1M pot (it's labeled as such...) with 1M R6, effectively I went from 0-500k R6 to 0-1M R6. Thanks, I hadn't thought of that :) Second are you sure you don't have the terminals on the switch mixed up? Both primaries are black. They don't have a specific order to go in, it affects the phase of the amp but if you swap them it still works. I have not moved the blue/brown cables (to mains power). Switch topology is correct. You do know that you should never turn the amp on without a load(speaker) hooked up right? No tubes, no power amp. B1 goes across the OT primary to OPEN so effectively the OT isn't hooked up. The r-16 & r-17 is just an elevated ground to further reduce noise if I'm reading you right. If you are working with Gil then you should be OK...I didn't know that part of it...but my advice to slow down is still the same. He made those recommendations, he hasn't been working over my shoulder. That would probably have lead to there being an actual fuse somewhere in my amp ;) My first recommendation is to get the amp up and running and stable without the Bitmo stuff etc...and add that later once you have a working amp. I would still advise you to build a light bulb current limiter and follow this link http://thenormster.com/DumbleLite/BuildersGuide/D-Lite%20Assembly%20Guide.htm to power things up without and then with tubes once you know the trannies and filter caps etc...are installed and wired correctly. Right now I have no tubes in, so I'm only testing the power supply. We did determine the switch has a fault through more troubleshooting here; I need to replace the switch. Any ideas on where to get one? I think it'll be fine with the bitmo stuff. I was going to add an NFB but decided to test the amp first; good call. The NFB will complicate matters a lot and I want to build that later when the amp works. What I'll do is fix the switch, turn on the amp and see if it works, and then take my meter to a few spots on the amp to verify voltages (I'm not happy about this). If the power supply works, I'll turn it on with tubes in a cabinet and see if the tubes explode; I'll put a mirror behind it so I can watch to see if the tubes red plate. If it works I'll play it for a few days, a week or two, then drop in an NFB. I really think you are trying to do way to much all at once for your experience level.....step back take it apart and crawl before you walk....that's how you learn SAFELY! Good advice. Link to comment Share on other sites More sharing options...
cGil Posted April 14, 2008 Share Posted April 14, 2008 Cheeze louise! I get distracted by life away from the bench for a day and I miss all the fireworks! Um, I hate to have to bring this up at such a late time, but I'm not sure I was aware you were using a Hammond PT. So I gotta ask... does that new Hammond power transformer have a high voltage center tap? And if so, did you ground it? And are you using the standard VJr full wave recitifier? If so, you may have another problem to resolve. With a center tap tranformer, you only need two diodes for full wave rectification! You might want to take a peek at this info. http://www.hammondmfg.com/pdf/5c007.pdf BTW, build the light bulb current limiter. Trust us on this one. BUILD ONE! Anyone who tweaks amps needs one. I've experienced enough disasters that now I won't fire up anything the first time after a simple mod or a fresh build without a current limiter in the AC line. Once I know things aren't gonna blow up, I'll check a few initial voltages. These measurements are usually a little off, but don't let that mess with your head. The amp is half starved for current! But if the amp shows proper signs of life, I shut it down and plug the amp to the wall normally. After that, I let the amp warm up for at least 15 minutes and let everything stabilize before I do any serious voltage measurements. Gil... Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 14, 2008 Author Share Posted April 14, 2008 Cheeze louise! I get distracted by life away from the bench for a day and I miss all the fireworks! Welcome back to the land of the dead? :P Um' date=' I hate to have to bring this up at such a late time, but I'm not sure I was aware you were using a Hammond PT. So I gotta ask... does that new Hammond power transformer have a high voltage center tap? And if so, did you ground it? And are you using the standard VJr full wave recitifier? [/quote'] It's doing 260-0-260, with both secondary red wires as my input power. I taped off the center tap. If so' date=' you may have another problem to resolve. With a center tap tranformer, you only need two diodes for full wave rectification! You might want to take a peek at this info. http://www.hammondmfg.com/pdf/5c007.pdf [/quote'] No, this application requires bridge rectification. According to that PDF, the secondary gives 260VAC (520VCT 260-0-260) and the full wave rectification peak is 260 x 1.41 when using a bridge rectifier (366V). The full wave rectification peak is 260 * 0.71 (184V). I need 340 at B1. Remember the original PT was 260-260 with no center tap. Pretty much someone knicked the insulation on the coil wire and soldered another wire coming off it; I taped that wire off so it doesn't exist anymore, now my Hammond is like the stock PT but it handles 1.5 times the current going through it. BTW' date=' build the light bulb current limiter. Trust us on this one. BUILD ONE! Anyone who tweaks amps needs one. I've experienced enough disasters that now I won't fire up anything the first time after a simple mod or a fresh build without a current limiter in the AC line.[/quote'] 75 watts. @_@ But yeah I hear you. I'll see what I can do. Link to comment Share on other sites More sharing options...
layboomo Posted April 14, 2008 Share Posted April 14, 2008 "It's doing 260-0-260, with both secondary red wires as my input power. I taped off the center tap." First,I'm glad your back Gil......second taping off the center tap is not the same as grounding it. I'm pretty sure this is a large part of your problem. From what I see you need to ground the center tap on that transformer for starters....I'm sure Gil will chime in soon. Link to comment Share on other sites More sharing options...
tunghaichuan Posted April 14, 2008 Share Posted April 14, 2008 No' date=' this application requires bridge rectification. According to that PDF, the secondary gives 260VAC (520VCT 260-0-260) and the full wave rectification peak is 260 x 1.41 when using a bridge rectifier (366V). The full wave rectification peak is 260 * 0.71 (184V). I need 340 at B1. [/quote'] I could be wrong, but it sounds like you have the Hammond PT wired for full wave *bridge* rectification. That Hammond is a 260-0-260 rated PT. That means if you run it into a full wave bridge, you are putting 520v into the circuit or *733v* after rectification. You cannot just drop that PT into the VJ circuit without modifying the rectifier circuit. Remember the original PT was 260-260 with no center tap. Pretty much someone knicked the insulation on the coil wire and soldered another wire coming off it; I taped that wire off so it doesn't exist anymore' date=' now my Hammond is like the stock PT but it handles 1.5 times the current going through it. [/quote'] Wrong. The original PT is 0-260. With the CT taped off on the Hammond you have 0-520. Look at it this way: if you measure the voltage across the secondary winding of the VJ, you get 260v. If you measure the Hammond the same way you get 520. That Hammond PT will only work in the VJ circuit if you use it as it was meant to be, full wave circuit, no bridge. Take a look at that Hammond sheet again. It's no wonder you had sparks in your amp. 700v is no joke. That will kill you dead quick if you aren't very careful. Not to be harsh, but you really should learn more about electronics before you injure or kill yourself. tung Link to comment Share on other sites More sharing options...
layboomo Posted April 14, 2008 Share Posted April 14, 2008 It's no wonder you had sparks in your amp. 700v is no joke. That will kill you dead quick if you aren't very careful. Not to be harsh, but you really should learn more about electronics before you injure or kill yourself. tung OK that's 3 warnings now from 3 guys who have helped alot of people mod valve jr's........see a pattern here? It's not a joke you are going to hurt yourself or worse if you continue the way you are doing things. I'm genuinely concerned about your safety and thats why I've continued posting here. Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 14, 2008 Author Share Posted April 14, 2008 It's the amps that kill. OK that's 3 warnings now from 3 guys who have helped alot of people mod valve jr's........see a pattern here? It's not a joke you are going to hurt yourself or worse if you continue the way you are doing things. I'm genuinely concerned about your safety and thats why I've continued posting here. Yeah, I know. Why do you think there's no tubes in the damn thing yet? I asked a bunch of EE's how to handle this and they said tape the center tap, but ok. I just asked someone else and they said ignore previous advice and use the center tap. Apr 12 00:40:09 <bluefoxicy> holyshit help Apr 12 00:40:22 <bluefoxicy> primaly blk-blk Apr 12 00:40:52 <bluefoxicy> secondary #1 red-redyel-red (520VCT@90ma) Apr 12 00:40:56 <bluefoxicy> okay, what the hell Apr 12 00:41:24 <bluefoxicy> how do I hook this up so I can get power out of it, and what the **** is 520VCT? It's supposed to be 260-0-260VAC@90mA Apr 12 00:41:39 <bluefoxicy> I need TWO AC LEADS why are there THREE LEADS on the secondary? Apr 12 00:41:51 <bluefoxicy> the wiring diagram does not explain this Apr 12 00:42:10 <inflex> erm, -center tap- Apr 12 00:42:52 <rue_mohr> 520vct is 520volts with a center tap Apr 12 00:43:05 <rue_mohr> 260V either side of the center tap Apr 12 00:43:13 <bluefoxicy> ah Apr 12 00:43:17 <rue_mohr> those big ones on the pole are 240VCT Apr 12 00:43:34 <rue_mohr> the center tap is neutral, wich is grounded Apr 12 00:43:43 <bluefoxicy> and the center tap is the stripe? Apr 12 00:43:50 <rue_mohr> its the one thats different Apr 12 00:44:01 <rue_mohr> usually in the middle of the other two, but not always Apr 12 00:44:08 <bluefoxicy> so how do I run this Apr 12 00:44:15 <rue_mohr> what do you want Apr 12 00:44:24 <bluefoxicy> circuit board gets AC1 and ground, or AC1 and AC2? Apr 12 00:44:37 <rue_mohr> uh no Apr 12 00:44:47 <bluefoxicy> rue_mohr: I want to drop 260VAC in the middle of a rectifier Apr 12 00:45:03 <rue_mohr> if you have 120V going in, you have "L1" and "L2" or "L" and "N" but not a line and ground Apr 12 00:45:06 <bluefoxicy> I guess AC1 and AC2, leading out to DC+ and ground/DC? Apr 12 00:45:19 <rue_mohr> what voltages you want to result in Apr 12 00:45:52 <bluefoxicy> 360VDC I think Apr 12 00:45:58 <rue_mohr> ok Apr 12 00:46:09 <rue_mohr> so tape off the center tap Apr 12 00:46:30 <bluefoxicy> tape? it doesn't get grounded? Apr 12 00:46:33 <rue_mohr> put the other two on the ac of a bridge rectifier, attach - to ground Apr 12 00:46:48 <rue_mohr> just tape it off and forget about it Apr 12 00:46:55 <bluefoxicy> explain plz. Apr 12 00:47:02 <rue_mohr> your not using it Apr 12 00:47:04 <rue_mohr> so dont .... :( <bluefoxicy> hey guys anyone know about transformers and rectifiers? <el1te> is there a crt/tv bar chart test cd/dvd or file i can get that will help me diagnose <bluefoxicy> I have a 260-0-260 transformer (center tapped) that I want to get 360V off, so I taped off the center tap and ran the +260 and -260 through a bridge rectifier with a capacitor bank; people are telling me this is getting me 700V, not 366 <koolatron> they're right. well, sort of. <bluefoxicy> k simpler question <koolatron> 260-0-260 is 520 VCT. <bluefoxicy> do I plug the center tap and one 260V into the bridge and tape off the other 260V? i.e. 0-260V? <koolatron> Yes. You'll get 260*sqrt(2) after smoothin thereabouts - you'll lose some in diode drops. <bluefoxicy> ok <koolatron> =~366V <bluefoxicy> rue_mohr: >:o <koolatron> if you tape off the center tap instead you'll end up with 700V+ I am not taking the whole blame for this! but... yeah, thanks guys. I really needed that. Link to comment Share on other sites More sharing options...
cGil Posted April 14, 2008 Share Posted April 14, 2008 Take a peek at the schematics on AX84.com. Plenty of examples of Hammond PT's in use there. Then take a peek at the answer to AX84 FAQ's question #3 "what is the First Law of Robotics? Um, I mean AX84?" Answer: "Don't Bozo The Layout!". Gil... Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 14, 2008 Author Share Posted April 14, 2008 You're right gil. My lack of information. Also my thing works now but I get 377-380 across B+1 B+2 and B+3. I turned the circuit off, discharged caps, and measured resistance from cap to cap positive lead (which goes across the resistors) and got the right R values (mostly ... that 220 R10 shows as 600), so the circuit looks correct. I have no tubes in there though, so like the whole circuit is missing. Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 14, 2008 Author Share Posted April 14, 2008 Okay! It sounds great, it plays great, the tubes don't red plate, I set the bias pot to 130 ohms. There's a small amount of smoke coming out. This isn't really a good thing. .... :/ ..... R10 needs to be like 5 watts. It's sliiiightly scorched. Link to comment Share on other sites More sharing options...
Eracer_Team Posted April 14, 2008 Share Posted April 14, 2008 smoke is bad... new heated resistor smell is one thing... smoke is bad anytime... that's too much current for the components you've got in there (yes I know some of it is a pre-built item you purchased). You’re going to have to go backwards and find out what you blew up with the initial 700+ volts you through into the unit before (with or without tubes). You’ll probably have to take out the resistors and check them out of the circuit; for you: you better do this 1 at a time… Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 14, 2008 Author Share Posted April 14, 2008 They're fine, I checked over the circuit visually and prodded around with a meter here and there (not very useful in circuit, I know). Plus without tubes B+ is open (+inf resistance) EXCEPT for the normal case where the cap banks charge at power on, so there's no current flow. The caps still work (tested in circuit, voltmeter, it takes FOREVER for those things to bleed). I got a 1k 5W flameproof cement brick thing for the B+1 resistor to replace the 1K 3W that WTA sent me. What I DO need to do is add a 1A slow-blow fuse to the primary! I want at most about .6-.7A across there, if I draw 1A something is wrong. Power-on surge might blow a fast-blow though. Link to comment Share on other sites More sharing options...
wpkg Posted April 15, 2008 Share Posted April 15, 2008 There was no fuse on the turretboard' date=' and I'm not sure what to get for a fuse. It's a 75W transformer, I guess I need a 115V .7A fuse or something.[/quote'] the next time you have a thought like this... F-ING STOP!!! Link to comment Share on other sites More sharing options...
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