AnalOg Posted October 22, 2005 Share Posted October 22, 2005 Turned on my system today, all of the sudden I started hearing a popping noise coming from my left speaker, looked down at the amp and saw sparks omitting out of the chassis, needless to say I quickly hit the off button on my system and shut it all down. I pulled the bottom cover off the ill fella and found a couple of resistors at the power tube fried one to a crisp.Is this the end result of a power tube going south? Are there any checks Icando or should I just replace the bad resistors and throw in a fresh batch of tubes. Tom Quote Link to comment Share on other sites More sharing options...
sfogg Posted October 22, 2005 Share Posted October 22, 2005 That don't look good. Do you have a tube tester? I'd check your tubes first to see if one of them died. Then replace the resistors and do some voltage tests in there. Is it just a weirdness in the picture or are those really bare wires running everywhere? If you are counting on just the varnish to insulate those wires you are just asking for serious trouble down the road. If so I'd swap that out for real insulated wire ASAP. Shawn Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted October 22, 2005 Share Posted October 22, 2005 MAN! I never saw so many bare wires in one place before! Maybe the picture is deceiving me, but it look like short circuits all over the place. I can't believe anybody would ever wire an amp with bare wires! There is just too many of them to be ground leads. Somebody tell me I'm seeing things wrong! Al K. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted October 22, 2005 Share Posted October 22, 2005 Well I thought that I would never agree with Shawn[] But what the heck are all those naked wires doing in there? That looks to be your 100 Ohm Triode resistor which is not a good sign. I bet you will find the tube has developed a inter element short. Replace the resistor and try the pair of tube out of the other amp before you order anything. Craig Quote Link to comment Share on other sites More sharing options...
NOSValves Posted October 22, 2005 Share Posted October 22, 2005 I know what that is its Magnet wire! I forgot old Tom is a wire freak and I bet he used it think it would create that special mist on the mid range[] Quote Link to comment Share on other sites More sharing options...
Marvel Posted October 22, 2005 Share Posted October 22, 2005 Kinda makes it hard to twist your heater wires together doesn't it? That scares me too. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted October 22, 2005 Share Posted October 22, 2005 GACK! Magnet wire is not intended for that kind of use. The insulation just isn't good enough. It's for winding inductors and solenoids. I would replace every bit of it with normal hook-up wire. I'll bet the burned resistor was casued by that wire shorting someplace. Al K. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted October 22, 2005 Share Posted October 22, 2005 I agree and besides the entire Mark III amplifier only has about 6" of wire 4 piece about 1 1/2" each that carries the music signal. The rest are all voltage source and ground wires no effect what so ever on the sound of the amp. Quote Link to comment Share on other sites More sharing options...
Speedball Posted October 22, 2005 Share Posted October 22, 2005 I'm not an electronics tech but bare wires and electricity don't mix...[li][li][li] Lol...lol..maybe the signal flows more freely without the friction of the insulation... Quote Link to comment Share on other sites More sharing options...
jheis Posted October 22, 2005 Share Posted October 22, 2005 Don't those fried resistors smell great? Love the smell of napalm in the morning. James Quote Link to comment Share on other sites More sharing options...
AnalOg Posted October 23, 2005 Author Share Posted October 23, 2005 OK, I hope everyone had a good laugh, yes that is magnet wire that was left over from the Bottlehead Foreplay, and Paramour projects. I figured if it was good enough for them it should be fine for the Dynaco's. I'll change out those resistors and try out some other tubes I have on hand. Thanks guys, glad I could put on smile on all your faces. Tom Quote Link to comment Share on other sites More sharing options...
AnalOg Posted October 23, 2005 Author Share Posted October 23, 2005 Changed out those resistors, put in some Russian 6550's in place of the Svetlana tubes. Back in business. Would it be ok to just order one tube to replace the bad one, since I hev bias adjustment pots for each tube? Thanks again, Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted October 23, 2005 Share Posted October 23, 2005 Tom, I hope I didn't offend you It was not my intention at all. Yes you can just order one but after as many hours as you may have on the tubes and one failing. I would just order a new quad to be on the safe side. I suggest you order either Valve Arts from AES or some Shuguangs from http://www.pentalaboratories.com/product.asp?dept%5Fid=5020&pf%5Fid=KT88SC+SHUGUANG+MPTrust me on this you won't be sorry! Craig Quote Link to comment Share on other sites More sharing options...
AnalOg Posted October 23, 2005 Author Share Posted October 23, 2005 Craig, You didn't offend me at all, it sort of felt like the teasings you get when your a kid, I'm use to it. In all honesty I regretted using that magnet wire during and after rebuilding the Marks. What a ***** it is to strip the varnish and work with it through the chassis being so stiff and all. After the rebuild, I had a situation of one of the wires shorting against the metal body of the chassis, at that point was the regret after rebuild. I'm really not looking forward to changing out all the wiring at this point, for two reasons, one is patience the other being I won't have tunes with my main system. The tubes I have in place of the Svetlana's which just read Russian 6550 are so sterile and uninvolving by comparison. They do everything right, just not with the warmth and tone that I enjoyed from the Svetlana's. Which of the to KT88 brands you refered would you edge to first place in way of what I want back in my system. Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted October 23, 2005 Share Posted October 23, 2005 Tom, The two I mentioned are made in the same exact factory and to me sound about the same but they are different. The one's from Penta Labs are pretty much a dead ringers for the NOS GEC KT88 I have a set of those I have put 6000 hours on without a sign of dying in anyway. I love the way either sounds but I think I would have to give a slight edge to the Penta shuguangs. My problem is in using them all the time for customers is a ease of ordering. I would have to tack on the extra cost of just ordering tubes from Penta labs while I get tons of stuff from AES. Craig Quote Link to comment Share on other sites More sharing options...
pauln Posted October 24, 2005 Share Posted October 24, 2005 There was a recent thread on this forum about the pros and cons of DIY vs Experts... Quote Link to comment Share on other sites More sharing options...
AnalOg Posted October 24, 2005 Author Share Posted October 24, 2005 The reason I decided to rebuild and mod these on my own was two fold, first being a chance to learn something new and the other being the pride of saying I did it myself and I didn't fry myself or burn down the house.[<)]LOL Although I did get zapped once, it was kind of refreshing![] Tom Quote Link to comment Share on other sites More sharing options...
AnalOg Posted October 24, 2005 Author Share Posted October 24, 2005 The reason I decided to rebuild and mod these on my own was two fold, first being a chance to learn something new and the other being the pride of saying I did it myself and I didn't fry myself or burn down the house.[<)]LOL Although I did get zapped once, it was kind of refreshing![] Tom Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted October 26, 2005 Share Posted October 26, 2005 Pauln: "There was a recent thread on this forum about the pros and cons of DIY vs Experts..." An 'expert' does not arrive at that ability level without first going through the sometimes awkward beginning 'newbie' stage. That someone makes a mistake is not a reason to stop. BTW: using a certain kind of magnet wire in the Bottlehead products is something that has been suggested to builder/owner/users by the company. If memory serves me right, it used to be referred to as an 'upgrade.' I hate messing with the stuff even when making power and output connections. I don't use it for point-to-point wiring, either -- just as Craig, Shawn, and others wouldn't recommend it. Lance Armstrong had training wheels on his first bike, too. Erik Quote Link to comment Share on other sites More sharing options...
AnalOg Posted October 26, 2005 Author Share Posted October 26, 2005 Eric said: "I hate messing with the stuff even when making power and output connections." Ya, try wiring a whole preamp & two Dynaco amps, you get really good at flowing solder after that. Tom Quote Link to comment Share on other sites More sharing options...
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