Date   

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


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.

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 <@perdrix> 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


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.


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


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?


Re: OT: Sunon SP100A 115V fan (0.26A) in a 240V unit

 

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


Re: OT: Sunon SP100A 115V fan (0.26A) in a 240V unit

 

No can do :(

-----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
<@perdrix> wrote:

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




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


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 ?

Robin

Sent from my iPhone

On 15 Jan 2018, at 13:19, David C. Partridge <@perdrix> wrote:

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




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


Re: Photos search function

John Brown
 

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.


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


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


Re: Metrotek MG701

Mark Kahrs
 

Interesting box. It appears that Metrotek was involved in non-destructive
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@...> wrote:

On Fri, 12 Jan 2018, Lyle Bickley wrote:

On Fri, 12 Jan 2018 18:13:24 -0600 (CST)
"Joe Laffey" <joe@...> wrote:

Anyone know anything about the Metrotek MG701 tm500 plugin?

Anyone interested in one? I saw four at a local store.
Here's a bit of information and pictures on what they are:
http://w140.com/tekwiki/wiki/Metrotek_MG701
Thanks. I had checked there. It has some pictures, but no description.

Let me know if anyone needs/wants one. Like I said, I saw four here
locally.

--
73
Joe Laffey




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!


Re: Tek Blue Paint Color

toby@...
 

On 2018-01-14 2:27 AM, Craig Sawyers wrote:
If you have similar things to us in the U.K. I d take a panel into an automotive paint supplier.
Most of
ours have an optical paint marcher that gives a match code that paint can be mixed with.

Robin
I've already done that for you! I obtained a can of Tek blue spray paint from Tektronix, spray painted
a swatch and sent it to https://www.paints4u.com/ . They did a match not only for colour but also
matt-ness.
Did you get hold of the actual specification they determined?

--Toby


So in the UK, just contact them. You can either buy spray cans, or a can of paint and thinners if you
want to use an airbrush or spray gun.

Craig






Re: Photos search function

ArtekManuals
 

The moderator acknowledged that the photo search function was broken and he was in contact with groups IO to see if it could be fixed. I think you will find they are in alphabetical order which helps some but the albums "466 tear down", "tek 466" and "my 466" wont be next to each other :-(

-DC

On 1/14/2018 10:26 AM, John Brown wrote:
Is there any possibility of a search function for Photos?


--
Dave
Manuals@...
www.ArtekManuals.com


Photos search function

John Brown
 

Is there any possibility of a search function for Photos?


Re: Tunnel diode 585a

 

Fred,
I received the images directly from you, thanks.

Raymond


Re: Tunnel diode 585a

Fred Schumacher
 

Raymond,
Here are some pictures I took of the 1N3848 made by RCA.
FRED




Sent from my iPad

On 13 jan. 2018, at 22:34, Raymond Domp Frank <@Raymond> wrote:

Fred,
I can't definitely find the case that the 1N3848 lives in. Is it the traditional in-line TD shape like the 1N3712, 1N3716 etc.? You may want to place a link here to a photograph. If it's that sort of shape, I can definitely help you. I have several 10 mA TD's NOS. If it's a Tek 152-0140-01, I may have an original but I'll have to have a look after the weekend.

Raymond