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#1
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I have a guitar amp that uses two EL84 in the power section. The two
EL84 tubes are mounted upside down and their sockets are PCB board mounted. If I use two 9 pin socket savers to extend the tubes a little bit away from the PCB do you think that their will be any advantage in reducing the heat flow to the PCB and extending the life of the amp? |
#2
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In article ,
kevin g wrote: I have a guitar amp that uses two EL84 in the power section. The two EL84 tubes are mounted upside down and their sockets are PCB board mounted. If I use two 9 pin socket savers to extend the tubes a little bit away from the PCB do you think that their will be any advantage in reducing the heat flow to the PCB and extending the life of the amp? The socket savers may help save your sockets, especially if they're starting to lose tension, but they won't necessarily protect your amp. In my experience, the real PCB killer isn't chronic exposure to normal operating heat, but localized acute damage due to a variety of failures including arcing between traces, overcurrent, and repeated replacement of components Piggybacking a socket saver just introduces yet another connection which can go intermittent from repeated jolts due to moving around as well as speaker vibration (and in the case of a power tube, you will usually hear it these wonky connections as crackles). Also, you'll lose the use of your tube retainer clips. These are pretty important, especially with EL84s. --Mike -------------------------------------------------------------------- Mike Schway | [Picture your favorite quote here] | -------------------------------------------------------------------- |
#3
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Mike Schway wrote:
In article , kevin g wrote: I have a guitar amp that uses two EL84 in the power section. The two EL84 tubes are mounted upside down and their sockets are PCB board mounted. If I use two 9 pin socket savers to extend the tubes a little bit away from the PCB do you think that their will be any advantage in reducing the heat flow to the PCB and extending the life of the amp? The socket savers may help save your sockets, especially if they're starting to lose tension, but they won't necessarily protect your amp. In my experience, the real PCB killer isn't chronic exposure to normal operating heat, but localized acute damage due to a variety of failures including arcing between traces, overcurrent, and repeated replacement of components Piggybacking a socket saver just introduces yet another connection which can go intermittent from repeated jolts due to moving around as well as speaker vibration (and in the case of a power tube, you will usually hear it these wonky connections as crackles). Also, you'll lose the use of your tube retainer clips. These are pretty important, especially with EL84s. --Mike -------------------------------------------------------------------- Mike Schway | [Picture your favorite quote here] | -------------------------------------------------------------------- Hi, If you really want to protect the amp, rather than that, I'd install small fan. You can run it off heater voltage. (if you rectify the AC, there are many choices of small DC fans such as ones used in PC cases) IMO, worst enemy of PCB is mechanical stress. Tony |
#4
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![]() Mike Schway wrote: In article , kevin g wrote: I have a guitar amp that uses two EL84 in the power section. The two EL84 tubes are mounted upside down and their sockets are PCB board mounted. If I use two 9 pin socket savers to extend the tubes a little bit away from the PCB do you think that their will be any advantage in reducing the heat flow to the PCB and extending the life of the amp? The socket savers may help save your sockets, especially if they're starting to lose tension, but they won't necessarily protect your amp. In my experience, the real PCB killer isn't chronic exposure to normal operating heat, but localized acute damage due to a variety of failures including arcing between traces, overcurrent, and repeated replacement of components Here I tend to agree. Sitting here and doing a mental review of all the PCB amps that have crossed my bench, the PCB's that were the most trouble free, were the ones designed long ago by people who were expert in the design of tube amps, and could give a rat's ass about Solid State characteristics and considerations. The trouble free PCB's were designed with the characteristics of the high voltage vacuum tube amplifier in mind. Never, did the two PCB environments get clouded in the mind of the designer. Which, is the case today. Anyone ever see a chronic PCB problem with any of the Ampegs out of the Linden New Jersey plant. Was there ever a thread to run here in AGA on the PCB problems of an Ampeg V-4 or SVT. There you go. It's the SAND CASTERS who can't properly design a PCB, for a tube amp. Two different animals, two different PCB design considerations. Take the SAND CASTERS out of the MIX, and you will have trouble free PCB's. Like the design of the rack mounted SVT with the kathode resistors on the mother board, and not the tube sockets to ground. Wait till I get the time to put the web page of that one on the web site. LOL,... then there are the amps where the use of the low voltage filament supply is used to power some SOLID STATE devices on the PCB,...... Never thinking what is going to happen when a case of fly back LIGHTNING hits that tube socket from plate to filament. What!!!!!!!!!!!!!!!!!!!!!!!!! What do you mean you don't have a MIDI board for my Marshall http://timeelect.com/mar30.htm What do you mean the parts fell off my PCB from high heat and/or current. That, should not happen. Should it? Hmmmmmmmmmmmmmmmm..........................!!!!!!! !!!!!!!!!!!!! When you get on the phone, and call "Customer Support",..... customer support Hello, customer support. Rich thinks Like it's some ****ing ISP or software company's "Customer Support" technician sitting in front of a freaking computer monitor with a data base of symptoms, causes, and fixes,....... customer support Can I have your account number please. Rich thinks So, everyone is a ****ing NUMBER now. Rich This is Rich from Time Electronics. customer support Can I have your account number please. Rich Yeah, Yeah,.... xxx-###-xxx-00-000 customer support OK, how can I help you. Rich I have a model _________ that came in the shop with the setup LED's locked "on", and are not functional with the adjustment. The unit had a shorted output tube. Also, the channel switching does not function at all. customer support Are you sure the LED's are locked on. Rich thinks Oh this is going to be one of those days. I can see it coming. Rich Yes, I'm sure they are locked on. customer support That's never happened before. Rich thinks Yeah, there's a new one for your freaking data base for ya. customer support and you said the channel switching isn't working either. Rich Yes, that's what I said. customer support That's strange. Rich thinks LOL, there's a new missing cross match for your data base now too!!!!! Boy, is that going to make your day for the white coats and suits in the company when they get this log entry. Rich Yeah, I guess so. customer support and,... you think the shorted tube had something to do with this. Rich Yes. I had replaced the bad tube, and the amp came up without blowing the fuse, and I can get full signal on the load. However, the LED's are locked up, and the channel switching is locked in the normal condition. Outside of that, the amp seems to work fine in the normal condition. customer support Really, are you sure. Rich thinks No, I'm making this whole thing up, because I have all this free time on my hands, and have nothing better to do with it, than to sit here on the phone getting no where. Rich Yes, I'm sure. I just played through it, and it sounds fine. If you could help me with the LED's and channel switching problem, I could get this unit off my bench, and the owner can play his gig tonight. I'm just hoping you guys can help me save some time trouble shooting this amp, thinking you may have had this problem before in your logs, and could point me in the right direction. After all, you guys designed and made this thing. customer support Let me see if I can transfer you to a technician. Rich thinks God, if I could only reach through this phone right now. customer support Hang On, I'm going to transfer you to _______, I'm sure he can help you out. Rich Thanks. Rich thinks I wonder if I should put my seat belt on for the ride. automated phone system plays shredder guitar music for a minute automated phone system Thank you for call _____ support, your call is important to us, and your call will be answered by ______ of customer support. automated phone system plays shredder guitar music 7 minutes Rich needs to hit the bathroom, and looks at his watch automated phone system Hi, this is _______, and I'm sorry I can't take you call right now. At the sound of the tone, please leave your name and phone number, and I'll get back to you as soon as possible. Or, you can press zero for the attendant. Beep!!!!!! Rich thinks Boy, I like to tell you where you can take your circus and shove it..... Rich Hi _______, this is Rich from Time Electronics, and I have a model _________ giving me a headache, and could use some help. I can be reached at,....... etc. Well, _______ was on vacation for a week, and I was never told at the time. It was almost 2 weeks before he returned my call. He, was the only expert on this model, and as it turned out, was no help on the matter. This problem never happened before with this unit. I found the channel switching problem, by passed the LED's, and did the setup adjustments old school. The amp worked great. thinking Now, if only the "service arm" of product manufacturing could have REMAINED old school,... life as a Service Tech in the field, would be a lot more stress free, with the consumer more confident in company integrity, because SERVICE after the sale, is NOT just a Web Site (without a phone number on most of them), and an AUTOMATED PHONE SYSTEM. Regards, Rich Koerner, Time Electronics. http://www.timeelect.com Specialists in Live Sound FOH Engineering, Music & Studio Production, Vintage Instruments, and Tube Amplifiers |
#5
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In article ,
Rich Koerner wrote: customer support Can I have your account number please. Rich thinks So, everyone is a ****ing NUMBER now. Rich This is Rich from Time Electronics. customer support Can I have your account number please. Rich Yeah, Yeah,.... xxx-###-xxx-00-000 customer support OK, how can I help you. Rich I have a model _________ that came in the shop with the setup LED's locked "on", and are not functional with the adjustment. The unit had a shorted output tube. Also, the channel switching does not function at all. customer support...[rest snipped] I can fill in that blank. Marshall 6100. That phone conversation, and the following dialog actually happened in my shop...nearly verbatum...seriously. First, you need an account number to speak with someone who knows NOTHING about amps, but knows the techs by their first names, then you get put in a call-return queue to talk to a real tech. Finally, 4 days later, you're told that since the amp is no longer being made (gee, I wonder WHY), the crucial part (in this case, the MIDI board) is unavailable...their remaining stock of replacement boards had been already doled out (again, I wonder WHY?? ;-) ) I had a 6100 on my to-do shelf for 3 months with regular calls to Korg/NY, their regional tech site in California, even an email exchange with Bletchley, UK. Eventually, I was able to get them to search their boneyard for a used MIDI board. Plugged it in and all is well...for now. All because the 5V digital supply was derived from the filament secondary...a pin 2-to-3 short took out the brains (WHAT, tube amp have BRAINS?) As bad a design as this amp was, the worst PCB design I've seen was the dreaded Ampeg VT60/120 family. Like you said, cathode resistors on the board with teeny, tiny traces. Seen several burn-throughs at this location. Roy Blankenship (IIRC) calls this amp the one voted most likely to start a fire. Combined with under-engineered switches for lo/hi power and triode/pentode mode, the amp is usually a time-bomb. But the absolute worst thing about this amp is the time it takes to get to the component side of the board. Even after having worked on a dozen of these, and the wire interconnect map permanently given a place of honor in my notebook, it still takes an average of an hour and a quarter to remove and reassemble....much to the customer's dismay. A shame, because this amp really doesn't sound half-bad when it's healthy. --Mike -------------------------------------------------------------------- Mike Schway | [Picture your favorite quote here] | -------------------------------------------------------------------- |
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