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Re: Leaking capacitors once again.
Glenn Little
The electrolyte is sulfuric acid.
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Use baking soda in water to neutralize it. The capacitor case should be pure silver. The end seal should be Teflon. Glenn
On 1/15/2018 12:19 PM, tmichaels@tower-sites.com wrote:
The capacitors in question are 50 uF, 25 V. --
----------------------------------------------------------------------- Glenn Little ARRL Technical Specialist QCWA LM 28417 Amateur Callsign: WB4UIV wb4uiv@arrl.net AMSAT LM 2178 QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license"
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Re: OT: Sunon SP100A 115V fan (0.26A) in a 240V unit
Ed Breya
The resistor is small (often zero), sometimes used for damping - most of the voltage drop is on the cap. I've also tried various capacitive dividers, where there's a shunt cap across the fan too, to neutralize some of the motor inductance. Ed
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Re: OT: Sunon SP100A 115V fan (0.26A) in a 240V unit
keantoken
Hmm. So you have to use a series resistor, but you can reduce the wasted power of that resistor by adding a series capacitor. On Monday, January 15, 2018, 12:05:38 PM CST, Ed Breya via Groups.Io <edbreya=yahoo.com@groups.io> wrote:
It depends very much on the specific fan brand/model/design. I have often added R/C networks to drop fan speed and noise. Some fans work just fine, while others don't. When you drop enough voltage to get a good speed range with a reactive network, the fan doesn't have enough starting torque to go reliably, and when you trim it back up to start well, it hardly drops any running speed. I always mark and set aside the relatively few good ones for low-speed applications. Ed
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Re: Source for long chassis mount BNC connector
No response. Ordered a couple from Qservice.
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Re: OT: Sunon SP100A 115V fan (0.26A) in a 240V unit
Ed Breya
It depends very much on the specific fan brand/model/design. I have often added R/C networks to drop fan speed and noise. Some fans work just fine, while others don't. When you drop enough voltage to get a good speed range with a reactive network, the fan doesn't have enough starting torque to go reliably, and when you trim it back up to start well, it hardly drops any running speed. I always mark and set aside the relatively few good ones for low-speed applications. Ed
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Re: Leaking capacitors once again.
Ed Breya
That should be easy enough - use 47uF 35V dry Ta caps, and you won't have to worry about what the actual supply voltages are in each spot. Ed
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Re: OT: Sunon SP100A 115V fan (0.26A) in a 240V unit
keantoken
I wanted to do the same thing to limit the power output of a transformer. The problem is for all the useful power limiting values of capacitance, transformer inductance resonates with it near the power frequency. This is due to the fact that both the inductance and capacitance were chosen to have an impedance margin with the load, and so will have similar reactance at the power frequency. As we know, when an inductor and capacitor have the same reactance, they become a resonator.
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Furthermore, assuming you could control the resonance, there is another problem. Nonlinear saturation of the magnetic core leads to a motorboating condition where the tranformer primary jumps to twice the mains voltage with a square wave! it buzzes like mad! Synchronous motors would probably have similar problems although it would be fun to try out. I don't know about other motor types like brushed AC motors. On Monday, January 15, 2018, 9:06:58 AM CST, David C. Partridge <david.partridge@perdrix.co.uk> wrote: I gave in and ordered the fan ...
-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Adrian Sent: 15 January 2018 13:46 To: TekScopes@groups.io Subject: Re: [TekScopes] OT: Sunon SP100A 115V fan (0.26A) in a 240V unit Hi David, Stupid question ...I'm assuming this is not a tapped transformer input so you just leave the fan across 1/2 the primary? Other than that I would go for the replacement fan, from the little I've done fans seem to present a strange (and to some extent dynamic) load and a capacitive voltage divider may not be quite straightforward? ...and fans wear out anyway..... Adrian
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Re: Leaking capacitors once again.
s92187
The capacitors in question are 50 uF, 25 V.
I also found that the elapsed time meter had corroded so I pulled it out.
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Re: Leaking capacitors once again.
Ed Breya
The 109Ds are wet-slug Ta caps. If they are just used for supply bypassing, you can replace them with similar-sized dry type solid Ta caps. But, watch the voltage rating versus the supply voltages - the wet ones were often used because of their much higher voltage capability and high CV density. It's hard to find larger sized dry Ta ones above 35V. At 35V rating, this limits reliable application to around 25V. You can replace them with suitably rated Al electrolytics, but you need about five to ten times the uF of the Ta types, to get comparable ESR. This means jamming rather large or multiple Al caps into confined space.
Ed
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Leaking capacitors once again.
s92187
Even though it was working properly at the time, back in 2011 I preemptively replaced all of the surface mounted electrolytic capacitors in my 1992 vintage 492BP. In doing so I found a few that had already leaked, and I recall there was one spot where I had to replace an etched through circuit trace with a piece of wire. After having not used it for awhile I powered it up last week and was greeted with frequency control function errors, so I took a look inside and quickly found more leaking capacitors, this time they are axial lead 109D tantalums. I plan on replacing all such caps in the entire unit, but an online search for replacement tantalums with the same ratings shows prices around $33.00 EACH! These caps appear to be power supply bypasses on various circuit boards although I haven't looked at all of the schematics to confirm if that is always the case. That would seem to be a relatively non critical circuit function, but does anyone know for sure if good quality electrolytics could be substituted?
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Re: OT: Sunon SP100A 115V fan (0.26A) in a 240V unit
I gave in and ordered the fan ...
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-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Adrian Sent: 15 January 2018 13:46 To: TekScopes@groups.io Subject: Re: [TekScopes] OT: Sunon SP100A 115V fan (0.26A) in a 240V unit Hi David, Stupid question ...I'm assuming this is not a tapped transformer input so you just leave the fan across 1/2 the primary? Other than that I would go for the replacement fan, from the little I've done fans seem to present a strange (and to some extent dynamic) load and a capacitive voltage divider may not be quite straightforward? ...and fans wear out anyway..... Adrian
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Re: OT: Sunon SP100A 115V fan (0.26A) in a 240V unit
No can do :(
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-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Robin Birch Sent: 15 January 2018 13:23 To: TekScopes@groups.io Subject: Re: [TekScopes] OT: Sunon SP100A 115V fan (0.26A) in a 240V unit Random thought, use the 120V mains winding on the transformer as an auto transformer just for the fan ? Robin Sent from my iPhone On 15 Jan 2018, at 13:19, David C. Partridge<david.partridge@perdrix.co.uk> wrote:
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Re: OT: Sunon SP100A 115V fan (0.26A) in a 240V unit
Adrian
Hi David,
Stupid question ...I'm assuming this is not a tapped transformer input so you just leave the fan across 1/2 the primary? Other than that I would go for the replacement fan, from the little I've done fans seem to present a strange (and to some extent dynamic) load and a capacitive voltage divider may not be quite straightforward? ...and fans wear out anyway..... Adrian
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Re: OT: Sunon SP100A 115V fan (0.26A) in a 240V unit
Random thought, use the 120V mains winding on the transformer as an auto transformer just for the fan ?
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Robin Sent from my iPhone
On 15 Jan 2018, at 13:19, David C. Partridge <david.partridge@perdrix.co.uk> wrote:
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OT: Sunon SP100A 115V fan (0.26A) in a 240V unit
Converting a 120V unit (it's OK with 50Hz) to 240V. Problem is that the fan
is a 115V unit (p/n 1123XBT). I initially thought of a resistor in series, but I'm thinking that would dissipate a LOT of power (470R resistor with 120V across it would dissipate 30W). I then considered maybe a capacitor in series but wasn't quite sure what value I'd need - initial thoughts suggested about 6.8uF - does that sound right and would it even work? Other than replacing it with a DP200A-2123XBT.GN (the 220/240V version) does anyone have any suggestions? Thanks Dave
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Re: Photos search function
Morning Dave:
I tried to find that earlier exchange (I thought had seen) but could not. While this interface is a BIG improvement on yahoo the photo search is surprising in it's absence. Photos are just another file - which are searchable. Just another storage area with a different name. But, it's probably more complicated than that. Here's hoping.
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Re: Photos search function
Rick
Moderator,
Not sure if it's already stated, but it would be good idea to state in the photo upload rules to always name your album folder starting with the device model number. Rick
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Re: OT: need special water line adapter or fittings
Ed Breya
Update. I'm up at the farm and have been digging through fittings and parts - finding things that haven't seen the light of day for years - but still can't find my "official" jars of compression fittings (but a number of loose ones are mixed in, so OK). Since there are apparently none of the "special" fittings I described available, it looks like the best option is a tight-radius pre-bent section of tubing, cut to fit. I even found a couple of pieces of old tubing already bent possibly about right. I've also got plenty of fresh tubing, my bending springs and sand, torch kit, and all kinds of various fittings, so I'm confident I can come up with a nice solution.
I tend to get carried away on projects like this during the searching phase. Even though I found enough stuff to get by fairly quickly, I took the opportunity to sort out and organize lots of things, and purge items that I realize/accept that I will never use. I got another hundred pounds or so of stuff out, destined for salvage, recycling, and trash. At the same time, I gathered and clarified stuff for some other ongoing projects. For example, out of the HVAC/refrigeration department, I've got most of the parts set aside to finally build my R-134a snorker (recycler/analyzer/recharger). It's only about ten years behind schedule. So thanks all, for the suggestions. I'll report on the results when it's done. BTW, when I was younger, it would have been no big deal to rip out some wall and/or crawl under the house and redo the plumbing, but as the saying goes, I'm gettin' too old for this %$^. I can still do that if absolutely necessary, but I'd rather not. Ed
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Re: Metrotek MG701
Mark Kahrs
Interesting box. It appears that Metrotek was involved in non-destructive
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ultrasonic testing. Also note that they were in Richland, WA, home of the (in)famous Hanford Works. Metrotek was bought and then bought again.
On Fri, Jan 12, 2018 at 7:38 PM, Joe Laffey <joe@thestable.tv> wrote:
On Fri, 12 Jan 2018, Lyle Bickley wrote:
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Re: Tek Blue Paint Color
Craig Sawyers <c.sawyers@...>
Did you get hold of the actual specification they determined?I'd have to go out the shed and check the original can. It is pitch dark and near freezing - so not just at the moment!
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