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Re: [OT] Shocks in a large market. How to check ESD direction?
I think the problem comes from shopping carts with plastic tires instead of rubber. I had a small spark at a supermarket that had replaced their carts a few weeks earlier. The wheels have bright red polyurethane? tires. The problem will likely go away once the wheels get some dirt and scratches on them.
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?? Bruce Gentry, KA2IVY On 5/4/24 21:49, Dave Casey wrote:
I too have dealt with shocks from the cart at my grocery store. I |
Re: [OT] Shocks in a large market. How to check ESD direction?
i did think of a chain. or one of those grounding strips you can put on cars.
On Sun, May 5, 2024 at 3:49?AM Dave Casey via groups.io <polara413@...> wrote:
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Re: 7904A trigger problem
Thanks for the tip Mark I'll let you know how it turns out.
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Mark -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Mark Vincent Sent: Friday, May 3, 2024 8:05 PM To: [email protected] Subject: Re: [TekScopes] 7904A trigger problem Mark, Check the four zeners on the trigger board. I found mine to be open. I used BZX85B9V1. The low value tantalums were high ESR. They were replaced with film types. Mine did not trigger unless a signal was large enough before I replaced the parts. After the parts were replaced, it triggered as it should. It is possible the connections from the ICs to pads could also be dirty. Mark |
Re: Free to a Good Home - Dead Tek 485 scope
On 5 May 2024, at 6:35 am, n3ae2000 via groups.io <n3ae@...> wrote:
Too many scopes and not enough time. I have a 485 that will not power up. Last time that happened it was the vertical amp IC. Free to a good home for parts or a repair project. Local pickup in southern Maryland or at the upcoming Dayton Hamvention (17 or 18 May). |
Re: [OT] Shocks in a large market. How to check ESD direction?
I too have dealt with shocks from the cart at my grocery store. I
attributed it to the cart building up charge by rolling. A good test might be to hang a dragging chain from the cart, but I've never bothered. Dave Casey On Sat, May 4, 2024, 7:09 PM Dave Seiter via groups.io <d.seiter= [email protected]> wrote: Interesting; last week I was at one of the Costcos I visit frequently, |
Free to a Good Home - Dead Tek 485 scope
Too many scopes and not enough time. I have a 485 that will not power up. Last time that happened it was the vertical amp IC. Free to a good home for parts or a repair project. Local pickup in southern Maryland or at the upcoming Dayton Hamvention (17 or 18 May).
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Re: 6C10 Tube
You're welcome, Tom, but I can't claim knowledge here, I just looked it up in the manual. I am pretty good at that. ?
Dave Wise ________________________________ From: [email protected] <[email protected]> on behalf of Tom Lee <tomlee@...> Sent: Saturday, May 4, 2024 3:38 PM To: [email protected] <[email protected]> Subject: Re: [TekScopes] 6C10 Tube I love the knowledge of this group's denizens. Thank you, Dave. -- Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 420 Via Palou Mall Stanford University Stanford, CA 94305-4070 On 5/4/2024 3:36 PM, Dave Wise wrote: 6M11 triode-dual pentode, in V574, V774, and V1605. |
Re: [OT] Shocks in a large market. How to check ESD direction?
Interesting; last week I was at one of the Costcos I visit frequently, and I had the same experience (which has NEVER happened before, and I've been shopping there since the mid 80's).? The charge would build up very quickly (maybe 6-8 steps), then discharge between my hands/fingers and the plastic grip of the cart.? Most of the time it discharged while I was gripping it, not when I let go and re-grasped it.? It seemed like it was building up a charge until it could overcome cracks in the plastic or ???.? No discharges onto other metal surfaces.? Same old shoes/jeans etc.? Outside the store in the parking lot everything was normal.
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-Dave On Saturday, May 4, 2024 at 09:31:40 AM PDT, cheater cheater <cheater00social@...> wrote:
Hi all, I frequent a large grocery market nearby and inevitably every time I go there I get electrical shocks. I walk around with a cart and often if I touch a metal fixture (fridge, mesh rack) I get a painful shock. Sometimes I get a shock if I leave the cart for a few seconds and then touch its metal mesh. I was wondering what everyone thought. At first I thought it would be ESD, but why would it be so extreme? It happens every time. I live in a place that's pretty dry - RH goes under 20% regularly - and being on a plain it has a lot of wind, which could create triboelectric charging. But I'm not really sure about this. I don't know which way the ESD happens. Is my body discharging into the cart? Is the cart discharging into my body? Is my body discharging into the racks or vice versa? How can one check the directionality of ESD? One theory about ESD I have is that the fixtures get charged and my body gets the charge applied to it. This however isn't necessarily true to me because eg today I got a painful shock from touching the inside metal surface of a fridge, and that's supposed to be earthed. Another theory is that as I walk around in the store, as I move around with the cart, that charges my body. I wear rubber sandals and the cart has rubber wheels. That would mean I'm a conductor, attached to a large antenna (the cart's mesh frame), moving through dry air, insulated from the ground. The ground is made out of some sort of high impact ceramic-ish tile. But then why would my own cart shock me just mere seconds after letting go of it? I was unloading my groceries for the cashier. My third theory is that this whole facility has a lifted earth potential. There's an industrial area nearby and they may be dumping a lot of current into earth which would create a situation where walking on the ground charges you, and then touching something that's low-Z to neutral discharges your body (in this case this would be the earthed fridges etc). I was wondering how people would approach diagnosing this problem, and how you would fix it if you had the ability to change anything about the facility at hand - more as a thought exercise, but if I figure out what's going on I'm going to write to the company. Thanks |
Re: 6C10 Tube
I love the knowledge of this group's denizens. Thank you, Dave.
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-- Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 420 Via Palou Mall Stanford University Stanford, CA 94305-4070 On 5/4/2024 3:36 PM, Dave Wise wrote:
6M11 triode-dual pentode, in V574, V774, and V1605. |
Re: 6C10 Tube
6M11 triode-dual pentode, in V574, V774, and V1605.
6GF5 beam power tube, in V1300 and V1350. Dave Wise ________________________________ From: [email protected] <[email protected]> on behalf of Morris Odell <vilgotch1@...> Sent: Saturday, May 4, 2024 3:16 PM To: [email protected] <[email protected]> Subject: Re: [TekScopes] 6C10 Tube On Sun, May 5, 2024 at 05:24 AM, Tom Lee wrote: The 556 is the only one I've experience of but I can't remember which tube it uses. |
Re: Keithley anyone?
On Sat, May 4, 2024 at 11:13 AM, Bruce Atwood wrote:
More in the last resort category was finding a short and fusing it with a voltage low enough to not damage the semi when the short disappears.I've done this with a bunch of PNP Ge transistors that had developed internal shorts from tin whiskers. I used a AA battery to drive current thru the whisker and "fuse" it. To do this, you MUST apply the voltage so that it won't flow thru the PN junction once the whisker is gone. This works, but the whisker may grow back. I had about 20 Ge transistors to work with, and some of them had to be treated 2-3 times before the repair seemed to be "permanent," where "permanent" was about a week. In the end, I tried replacing all the PNP Ge transistors with 2N3906s, and that worked perfectly. This was in a bunch of Tek 3S76 plugins. OTOH, I'm not sure there were ever any FETs in those tin whisker prone cans. -- Jim Adney Madison, WI USA |
Re: [OT] Shocks in a large market. How to check ESD direction?
what would make an "accidental" ion generator?
On Sun, May 5, 2024 at 12:16?AM Jim Adney via groups.io <jadney@...> wrote:
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Re: [OT] Shocks in a large market. How to check ESD direction?
On Sat, May 4, 2024 at 11:31 AM, cheater cheater wrote:
I frequent a large grocery market nearby and inevitably every time I go there I get electrical shocks.My first recommendation was that you try different shoes. I'd still try this, but if this is happening to everyone, I'd suspect the floor tiles. Some materials are more likely to generate triboelectric charge exchange. We tend to think of "ground" as an absolute thing, but it's not, it's relative. This has me wondering if that store has some sort of ion generator, intended or accidental, that's pumping out ions into the air. If that were the case, you might charge up faster than your cart if the cart wheels were more conductive than the soles of your shoes, or vice-versa. -- Jim Adney Madison, WI USA |
Re: 6C10 Tube
Thank you, Dave. I’m wondering whether that 6C10 was used in a production instrument or an in-house fixture. I just checked the web and it commands crazy prices on eBay. Audiophiles have clearly fallen in love with its triple-triode sonic magic.
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Tom Sent from an iThing; please forgive the typos and brevity On May 4, 2024, at 12:58, Dave Wise <d44617665@...> wrote: |
Re: 6C10 Tube
I don't know which scope used compactrons. I do know a cal fixture sort of did.
From my notes: Tektronix 067-0502-01 Amplitude Calibrator. The voltage regulator originally used the 6GE8/7734 signal pentode/power triode, but later switched to the 6G11 signal pentode/beam power tube, triode-connected in a purpose-built adaptor. Besides the 12BU pinout (6AL11 and 6G11) the adaptor is made for, the 12EZ tubes (6AD10 6BF11 6BY11 6T10) can probably work, with a new adaptor. Dave Wise ________________________________ From: [email protected] <[email protected]> on behalf of Tom Lee <tomlee@...> Sent: Saturday, May 4, 2024 12:24 PM To: [email protected] <[email protected]> Subject: Re: [TekScopes] 6C10 Tube I’m curious: which Tek scope used compactrons? Cheers Tom Sent from an iThing; please forgive the typos and brevity On May 4, 2024, at 11:23, Bill Riches via groups.io <bill.riches@...> wrote: |
Re: 6C10 Tube
I’m curious: which Tek scope used compactrons?
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Cheers Tom Sent from an iThing; please forgive the typos and brevity On May 4, 2024, at 11:23, Bill Riches via groups.io <bill.riches@...> wrote: |
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