Usually static discharge caused problems in IC. Normally improper handling, while being installed, or inspected. Important to understand, it use to be a problem with brand new IC or pretty close.. The static discharge while building testing bagging and on and on.. Everytime it is handled improper the situation can arise...and raise it’s head LATER.
If static discharge were happening to logic boards INSIDE because of YOU touching them without discharging FIRST. Id say you could see a problem later on.. Usually it shortens the life of ICs.. Chips, bios, Eproms that type of chip is VERY susceptible. Caps, resistors, inductors, that lot, not that I’ve ever seen. The question is, does your stuff have chips or pure analog..
Did lightning strike.. did you hear and feel a discharge? from you to the tonearm, headshell, or something like that?
If not.. That POP just happened to be that components swan song..
You just happened to be there when it happened.. NEVER discount a transient pop for anything but trouble...TURN the volume down always...
Hope you find the issue, and it’s not to spendy.. 2 dollar fuse, two dollar resistor.. :-)
Two weeks before this, the same thing happened to a different phono preamp, a Trichord Dino. Pop, channel gone, R out out goes out.
I troubleshot it to a faulty DIP switch component on the board and swapped it out.
Coincidence? An unrelated swan song??
Oh wow.. That’s a bit of news... If you think discharge is an issue. Set up a discharge pad. Touch the pad, don’t shuffle your feet and do your work.. The only proper way to eliminate the problem.. I’ve done a LOT of board level repair.. Just 101 for infant mortality on IC..
I really think something else is going on.. same side? I normally repair one or two circuits before and after. I check, pretty darn close..
Dip switch failure? What the heck caused that.. what is the switch for? Cart load?
STOP... something else is wrong..Spidey senses are all fired up..Something else is going on...
Yeah, one setting of the dip switch would ground out the R output channel. No idea why or how.
Static electricity can cause the pop, but its the pop that blows the stage not the static charge per se. In other words the static charge itself doesn't reach the phono stage. Usually when stoic charges are powerful enough to notice gross pops like this they're messing up the signal pretty much all the time, just not in a way that's obvious until its gone.
Multiple different ways to reduce static charges- Zero Stat, Static Guard and other anti-static sprays (Static Guard is cheap and sold at many grocery stores as well as Amazon), ground wire to bearing/tone arm, grounding brush (a grounded carbon fiber brush that drags across just ahead of the tone arm), and various different mats. slaw I think has one that helps with this as well as being a sound quality improver.
All good things that will improve sound regardless whether or not it was static that blew out that channel. I spray Static Guard over everything on a pretty regular basis and every night when I get out my "special" recordings, for just that extra little something. My static is seldom bad enough to make obvious crackles but its often bad enough to hear improved clarity after spraying.
Should I contact Dynavector? What did I do wrong?
No, static won't do that until you get to the level of a lightening bolt. The pop was whatever blew in your phono amp.
It seems very unlikely that the exact same incident would happen to two different phono preamps, completely randomly.
Is there anything downstream/upstream that could cause this? Could I have a grounding issue in my house wiring?
Your phono pre-amp is solid state correct? If it has a FET or JFET input (discrete or op-amp) it is possible, though unlikely that static blew out the input of the phone-pre (it would not blow out the output, but the input). It will depend on what circuitry is right at the input (capacitance, etc.) to soften the ESD. Usually on analog circuits there is enough RC to soften spikes and/or ESD protection. You are not going to know unless you send it back and even then only if they do part level analysis of the failure.
It’s sort of weird the dip switch failure. Did you verify it was shorted after removal? I would have been more inclined to think it was a short on the PCB, and yes they can grow after manufacturing. Other issue with dip switches is if the wrong type are used for the manufacturing process and/or PCB cleaning process. That can result in internal corrosion which again may not reveal till much later.
Downstream/upstream issues? ... only thing that comes to mind would be possibly a large DC offset on a coupling capacitor discharging through sensitive equipment, but that is purely speculation of course.
The dip switches on the Trichord Dino are for gain and loading. I took a multimeter to see if there were any shorts, and the R output showed that both its signal path and ground path we’re going to ground. Different gain settings at the dip switch would make it so that ground short was no longer there, so it seemed like that has to be it for that device.
For the Dynavector P-75, I have no idea.
Electrostatic discharge (ESD) can absolutely damage electronics - this video (you can download a pdf of slides) by Texas Instruments (experts and reputable source) details the issue -
TI Precision Labs - Op Amps: Electrostatic Discharge (ESD) | TI.com Video
. BUT, a lot has to do with the individual design - how good were the components that were used, and how many times has the circuit been subjected to the ESD. Subject op-amps to repeated ESD events and eventually they can fail.
To the OP, using an anti-static brush incorrectly is an bad as not using it all. Assuming you are using the common Audioquest carbon brush, for that to really work you need to ground yourself (touch any metal that has an electrical ground) to discharge any static you and/or the record have to ground. You did not state - but is the tonearm grounded to the phono-amp? If you have a multi-meter, you can easily measure resistance between all components (metal casing) and the wall outlet ground (power source) to verify all are grounded.
Yes, the turntable is grounded to the phono preamp.
And I can’t as readily troubleshoot/repair the PCB on the Dynavector P-75 since it has surface mount components rather than through-hole.
Any other theories? I bought it used, should I send to Dynavector?
Yes static electricity can damage gear. Has happened to me and audio friends of mine. Dry, cold winters walking across a carpet and touching your stereo can indeed cause circuit board damage. I use a wooden knob on my preamp now!
Very sensitive digital can be effective by static especially in carpeting in the winter where the static is strongest and air is drier, also depending on grounding. I have found.
isprat static spray on the rug in front of the stereo in the winter
it is very effective .
Absolutely yes it can X 2
I always mute my preamp, and touch something metal nearby before changing records this time of year.
I thought that was the reason for proper grounding...that the chassis directs it back to earth before it ruins anything expensive
I live here in Nevada and have a constant problem with static discharge and I have thought of putting down a discharge mat in front of my equipment rack with the hope that I can discharge the static to ground before I touch any of my components. If anyone would care to chime in on this I think we all could gain something from this ongoing issue.
Speaking of which is a ESD (electrostatic discharge) compliant mat on Amazon that is about 2X3 feet that provides a path to ground for electrostatic charges for about $105.00, I might get one and let you know.
I ordered a grounding mat from Amazon yesterday. I’ll let you know if I destroy anymore expensive equipment with static while using it!
Typically, complete and ready consumer electronics devices should be immune from static if properly grounded. Only bare semiconductors & integrated circuits are very sensitive to this. You may have a grounding problem.
Check with a mains socket checker device.
ESD mats generally have two wire connections, one from the mat to earth ground such as the screw that holds a wall outlet plate, and the other is a conductive wrist strap that grounds you to the matt/ to the wall plate. If you put a matt down on the ground/carpet that is grounded (to the wall plate) and you are wearing shoes that are not conductive - its not going to work. Either you are barefoot, or your shoes have to be conductive to provide a ground path for you. You could instead use a touch pad such as the following -
Amazon.com: Anti-Static Touch Pad Touch Pad & Grounding Cord: Home & Kitchen
FWIW, I use an ESD pad for my table platter mat - but its not for grounding me (but if I touch my metal platter it will ground me), and if you are interested the details are here with discussion and links for reports/test on record static http://www.vpiforum.com/viewtopic.php?f=7&t=17186#p65882
Touching the AC metal case of any of your equipment will quickly discharge you. If you don't want a shock use a wrist band that adds a 1M resistor to limit current (same as the mat).
I checked the outlet with a socket checker device, and it indicated that the ground was good. It’s a device with three lights on it: two yellow and one red. When I plugged it into the socket my main power conditioner is normally plugged into, I got 2 yellows, no red.
Just realizing something...the Technics SL-1200 turntable outlet plug does not have a ground pin. Neither the Dynavector nor the Trichord phono preamps have a ground pin on their plugs either. Thus, if I am grounding the turntable to a device that also doesn't have a ground, I essentially have no path to ground for those devices. I always though the turntable should have its ground wire connected to the phono preamp, but is that just wrong? How do you guys ground your turntables/phono preamps?
Follow-up question: if I ground the turntable to a chassis screw on the amplifier, should I *also* ground my phono preamp to the chassis of the amp? Same screw, or different screw?
Try it and see. Those grounds are all the same. That is, the ground on the phono stage is chassis ground, whether its the ground screw used or any other screw that goes into the chassis. Same for the amp. These all go to ground.
Where you can run into problems is they all go to ground but not the same path. If everything were perfect, zero resistance across the board, then it wouldn't matter. Where there is even a small differential though, then some current goes one way, some another, and this is where the hum comes in. That is why the recommendation to have everything on one circuit. This ensures every path to ground is the same and so tends to be very quiet.
But people can often times get away with violating this rule and not notice problems. Better lucky than good, eh?
Phono stages are the highest gain and greatest EQ in all of audio. Orders of magnitude greater. The same exact imperfections that will never show up with other components can have you at the end of your wits with phono. To the point where even when you understand everything going on it still sometimes comes down to try it and see.
Yes for sure BEWARE STATIC!!!
But can the chassis of a component WITHOUT a ground pin on its plug actually act as a ground? I would expect that the chassis has continuity to the ground pin of the plug, which then plugs into the grounded socket, thus completing the path to the actual ground.
There is an article on the grounding of the Technics SL-1200 and you can find it here -
Internal Grounding » Technics 1200 Parts, Technics 1210 Parts, Technics Repair Turntable Repair, Mods Modifications, Pro Audio Parts, Accessories, and Repairs, Toronto, Ontario, Canada (technics1200s.com)
. It appears that the newer units are no longer internally grounded. Its not a safety issue, many electrical equipment such as plastic housing power drills are only 2-wire; from a ground safety - they are intrinsically safe and the reputable ones are UL approved. But even if the motor was grounded, unless the metal tonearm is somehow connected, grounding the motor is not going to help.
Current Theory: I believe the ground wire coming out of theTechnics 1200 is attached to the tonearm. When the ESD happened upon lifting the tonearm, it makes sense it would travel through that ground wire and arrive at the phono preamp where it was connected, as the next stop on its journey for ground.
Since the preamp does not have a 3rd prong (the ground prong), the electrostatic discharge didn't have a safe path to ground, so instead of bypassing the sensitive electronics, it pulsed through them, breaking something along the way.
I've attached my TT ground to a screw on the chassis of my fully earth-grounded amplifier, which will hopefully send any electrical discharges down a safe path to ground. As an added benefit, I have discovered an all-new blackness to my vinyl background I didn't even know possible.
Hopefully those who are more knowledgeable about electrical theory can confirm or deny the above hypothesis!
I think your analysis is quite possibly spot on! Well done. I didn't realize your pre-amp was ungrounded. You are correct, without that AC ground, the spark is going to find a new path to ground.
I'm currently in touch with Dynavector about this. I'll keep the thread updated with any new info as it comes!