ChewingAluminumFoil Posted March 4, 2006 Author Share Posted March 4, 2006 I just noticed Epiphone is now selling a head-only version of this amp that boasts a DC filament supply. Anyone tried that? http://www.musiciansfriend.com/product?sku=482069 CAF Link to comment Share on other sites More sharing options...
Broddi Posted March 4, 2006 Share Posted March 4, 2006 CAL, Now that's funny. I can picture the scene. 2 guys in the R&D dept. One guy says man what are we gonna do with all these valve junior chassis that no one is buying because they hum like a banshee? Other guy says well I saw this site where they fixed OUR design by converting the filiments to DC, and just unload them as a head only. Actually I bet it sounds great....might have to get one..... My home page http://www.klugemusic.com Link to comment Share on other sites More sharing options...
monkey-boy Posted March 4, 2006 Share Posted March 4, 2006 Need Help!! I ask anyone with the knowledge to chime in... I performed the mods listed by both Broddi and Foil... All we great for about 5 minutes, amp sounded great and NO hum. Then with no cause I can find it blew it's fuse, I check and everything was tight so I replaced the fuse. Same thing. At this point I have undone all of the mods and returned it to 'normal', but I still can't get it to stay on. FYI, when I turn on the power I hear a hum, then it dies. The hum is not from the speaker (I tried it w/o speaker hooked up.) I check and cannot find any shorts and am stumped. please help. Link to comment Share on other sites More sharing options...
Broddi Posted March 5, 2006 Share Posted March 5, 2006 Monkey Boy, Did you do the mods one at a time and test after each mod? If you did than the last mod you did would be the problem. If you ran the amp without a speaker hooked up accidentaly after performing a mod than that is most likely the problem. There is a good possibility the tranformer blew. You can not run a tube amp without a speaker connected. Even running the amp for a very short period without a load on the transformer can kill the transformer. My home page http://www.klugemusic.com Link to comment Share on other sites More sharing options...
monkey-boy Posted March 5, 2006 Share Posted March 5, 2006 Thanks for the response, Nope I did the mods all in one shot....none seemed hard... I did turn it on w/o speaker but only after it started blowing fuses. I tried a few combos of wiring, If I leave off T1 and T2 everything is ok , and I get the correct voltage off of my heater filaments. But as soon as I hook up T1 and T2, zap dead fuse. Even with T3 and T4 off (did that to remove the OT from the mix) Any advice on how to troubleshoot this? Link to comment Share on other sites More sharing options...
Broddi Posted March 5, 2006 Share Posted March 5, 2006 Hmmm... Let me think about this and look over the schematic. When I have an Idea I'll be back. My home page http://www.klugemusic.com Link to comment Share on other sites More sharing options...
monkey-boy Posted March 5, 2006 Share Posted March 5, 2006 much appriciated. If it helps I have gone over the pcb best as I can with a multimeter and all seems fine... I do fear something with one of the tranformers, but am not sure how to test...or how I caused it. I will say I had no hum...for the five minutes it worked... Link to comment Share on other sites More sharing options...
monkey-boy Posted March 5, 2006 Share Posted March 5, 2006 I tried it w/o any tubes and still blow the fuse..... Link to comment Share on other sites More sharing options...
Broddi Posted March 5, 2006 Share Posted March 5, 2006 I think its the transformer. If it is the tranny and the speaker was connected than I guess it's possible it just failed. Probably would cost as much for a new amp as it would for the tranny. If this happend to me I would probably just buy another Valve junior and use the one you have now for an extension cab or for parts. My home page http://www.klugemusic.com Link to comment Share on other sites More sharing options...
monkey-boy Posted March 5, 2006 Share Posted March 5, 2006 harsh. how would I test out the tranny? W/O a spare.... Link to comment Share on other sites More sharing options...
monkey-boy Posted March 5, 2006 Share Posted March 5, 2006 checked my board and I think the problem is the diodes but I need advice. When I check the filter caps for resistance I get and ever increasing number till I hit the limit of my meter, which I belive is correct. What should I get through my diodes? I am not sure what to expect but what is suspicious is that they are not all reporting the same thing... 3 report OverLimit when set to 2M and one is way lower at .46 at 20k..... Also of the 3 that go OL, 2 count up and get there in no time one takes a long time..... Any other thoughts on how to test the diodes? Link to comment Share on other sites More sharing options...
Broddi Posted March 5, 2006 Share Posted March 5, 2006 Hey, The way I would test a cap (after discharging it) is set the meter to ohms scale and test across the cap, then reverse your test leads and test again. Everytime you reverse the leads (polarity) you will see a small jump in the meter that settles back to infinity or open line. And you should get an "open" between any lead to the cap body (not shorted) As far as testing diodes I use an analog tester that has a 9 volt battery in it and I can get resistance one way and open the other way when set to a high ohm scale. Which diodes are you trying to test? Any component you test should be removed from the circuit so you know it is isolated. (crosses fingers) My home page http://www.klugemusic.com Link to comment Share on other sites More sharing options...
Broddi Posted March 5, 2006 Share Posted March 5, 2006 One other thought. Diodes and caps are cheap. You could just replace them and see what you get. My home page http://www.klugemusic.com Link to comment Share on other sites More sharing options...
monkey-boy Posted March 5, 2006 Share Posted March 5, 2006 FIXED. My one of the diodes was fried. I replaced it with 2 1N4005s in series (rat shack has no 1N4007s) and from what I have read I am better off with 2 1N4005s in series anyhow. Thanks for the help, now on to replace my mods. I did just do the input jack change a minute ago (could not figure out how that would hurt anything), and unless I am crazy the sound is brighter??? did you notice that. Link to comment Share on other sites More sharing options...
Broddi Posted March 5, 2006 Share Posted March 5, 2006 Wow good news! If you mean just the ground jumper mod I guess it could seem brighter due reduced low frequency hum. If you added the series/parallel resistors it will be brighter and louder too. Im glad it worked out for ya. I updated my web page with an easy install stand by switch FYI. My home page http://www.klugemusic.com Link to comment Share on other sites More sharing options...
monkey-boy Posted March 5, 2006 Share Posted March 5, 2006 Cool, I'll have to try the switch, maybe next weekend. I have the amp back together with the following mods complete: 1. nylon input jack 2. input jack ground jumper installed on back of board 3. DC heater filiments, FYI I checked the output coming off of the bridge rectifier and it was 6.33V, so not bad. I used a 1000uf/16V Cap and the 25Amp Bridge Rectifier from RS. 4. I added a 100uf/450V Cap in parallel with the first filter Cap. There is NO hum when the power is on and the Vol is down (before it was pretty loud) Also I decided to go with Foil's lightbulb mod but instead of putting it in the amp I made box that I put inline between the amp output and the speaker in. The box just has the lightbulb attached to the top and input/output jacks with the bulb inline. Didn't drop the vol. as much as I hoped but does cut it some and also adds some compression. Plus it looks cool to have little box on top of the amp with a light bulb on the top.... Link to comment Share on other sites More sharing options...
Broddi Posted March 6, 2006 Share Posted March 6, 2006 Monkey, That's great everything worked out. I might try the light bulb thing as well, maybe mount it on the inside behind the chassis with a lens. I had a THD hot plate that had a light bulb that lit up when you played. I think THD said it was "noise reduction" or something. I didnt notice anything different in the sound regardless of if it was enabled or not. My DC voltage was 6.0v That will probably vary depending on the voltage at the wall outlet. I have seen anywhere from 95vac to 125vac. Cheers! My home page http://www.klugemusic.com Link to comment Share on other sites More sharing options...
Junior 1 Posted March 6, 2006 Share Posted March 6, 2006 I have a Junior and recently got a Celestion Rocket 50, 8 ohm, 12 inch speaker. I'm building a cab and was wondering if it's worth installing an 8 ohm jack? Link to comment Share on other sites More sharing options...
Broddi Posted March 6, 2006 Share Posted March 6, 2006 Hello Junior 1, Yes I would say adding an 8 ohm jack would be worth while. One of the links at the bottom of my mods page talks about how to add a jack on a switch so you can switch between 4 and 8 ohm using the un-used 8 ohm tap available. My mods page While your at my page vote in the poll :-) My home page http://www.klugemusic.com Link to comment Share on other sites More sharing options...
Ricochet Posted March 7, 2006 Share Posted March 7, 2006 I've just picked up a bridge rectifier (way overkill, it's rated for 30A!), some 1000 uF 16V electrolytic caps, and a couple of 100 ohm resistors, to make a DC heater supply for my Valve Junior. I don't mind the hum when I'm playing, but it gets old when the amp's sitting idle. "A cheerful heart is good medicine." Link to comment Share on other sites More sharing options...
Junior 1 Posted March 7, 2006 Share Posted March 7, 2006 Same here, Ricochet. I don't mind it till I stop, and then it actually takes a while for me to notice it. Usually when I change guitars to my taco strat. The Valve Junior head is out and they make a point of telling the consumer that they have gone to DC filiments to quiet the beast. I e-mailed Gibson service to see if that could be a warranty fix!! Good luck. I figured, what the hell! Thanks for the info. Link to comment Share on other sites More sharing options...
Junior 1 Posted March 7, 2006 Share Posted March 7, 2006 Just got an e-mail from Gibson. Spec changes are not covered under warranty. Oh well! Link to comment Share on other sites More sharing options...
Broddi Posted March 7, 2006 Share Posted March 7, 2006 Ricochet, If your converting it to DC what are the 100 ohm resistors for? My home page http://www.klugemusic.com Link to comment Share on other sites More sharing options...
Ricochet Posted March 7, 2006 Share Posted March 7, 2006 Originally posted by Broddi: Ricochet, If your converting it to DC what are the 100 ohm resistors for? They're nonessential. But the rectified AC still has about 1V of ripple in it with this setup, and the 100 ohm resistors give you the option of tying it to ground (effectively halving the ripple relative to the cathode voltage) or tying them to a positive voltage derived from the power supply by a resistive divider network or from the power tube's cathode, to get rid of remaining hum. "A cheerful heart is good medicine." Link to comment Share on other sites More sharing options...
Broddi Posted March 7, 2006 Share Posted March 7, 2006 Thanks for clearing that up Ricochet. I was begining to think my amp was going to burst into flames. My home page http://www.klugemusic.com Link to comment Share on other sites More sharing options...
Broddi Posted March 10, 2006 Share Posted March 10, 2006 I updated my mods page with a tone cap mod and did some labeling on the front panel. Seriously considering a Chewing Aluminium Foil light bulb power attenuator. Probably mount it in the front through the cab under the Epiphone logo with a little sealed in glass lens or something to prevent low frequency cancelation. My mod page Cheers! My home page http://www.klugemusic.com Link to comment Share on other sites More sharing options...
Ricochet Posted March 10, 2006 Share Posted March 10, 2006 For a moment I was scratching my head wondering how a light bulb was going to cancel low frequencies. "A cheerful heart is good medicine." Link to comment Share on other sites More sharing options...
Kin Corn Karn Posted March 24, 2006 Share Posted March 24, 2006 Hi, I'm new here. I have a question for CAF, I linked in from his page -- For the light bulb attenuator, since it's just a light bulb in series with the output, would it work to put a bulb in an external box that you place between the amp and the speaker and wire it in series between two jacks? I just got a Valve Jr. head, and I'm not really up for cutting wires and drilling holes, especially when all the pics and guides on the net pertain to the combo. Thanks. Link to comment Share on other sites More sharing options...
miroslav Posted March 24, 2006 Share Posted March 24, 2006 I don't see why anyone really needs to attenuate this 5W Epi...? Yeah...its not "bedroom quiet" at higher volumes...but then, if you have to play real quietly...then why even bother with an amp...? For good playing/recording tones...this little Epi head needs to be at 1 o'clock or more...and IMO, sounds best when you get to 3 oclock and then up at full volume, it just rocks! I think if you are just practicing, and you need a very low volume...well, then...getting the best tone isn't really gonna happen anyway, not when the amp is "bedroom quite". When you attenuate that much...it kinda strangles the tone...IMO. Heck, for those very low bedroom levels...you might as well just use an amp modeler and some headphones. miroslav - miroslavmusic.com "Just because it happened to you, it doesn't mean it's important." Link to comment Share on other sites More sharing options...
Kin Corn Karn Posted March 24, 2006 Share Posted March 24, 2006 Originally posted by miroslav: I don't see why anyone really needs to attenuate this 5W Epi...? .... Heck, for those very low bedroom levels...you might as well just use an amp modeler and some headphones. Yup, I have an AD30VT that I use as my main practice amp. I just want to attenuate the Epi to see what it sounds like. Link to comment Share on other sites More sharing options...
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