Re: OT: LED lamp bulbs at ridiculously low prices at (some) Costco stores
Of course, this is one of those subjects, like religion, sex, drugs, rock-and-roll and politics that I hesitate to respond to here as there are some fanatics about incandescent light bulbs in our ranks.? ?On the other hand, it's a topic near and dear to my heart as I have only a few incandescents left in my house.? ?I replaced all the PAR30 65 Watt flood lamps with CFLs at least 10 years ago, and started replacing them with LEDs starting 1/1/2014.? Out of 37 installed LEDs of all different types,? NONE have yet to fail.
A question I have that may be of relevance to others here is how does one measure the light output of an LED?? ?This is not at all trivial, and it wouldn't surprise me in the least if the stated output, in Lumens, on the box of many of the Chinese made LED bulbs is just a lie.? ?Lumens are not easy to determine because it's the light output of the bulb, multiplied by the response curve of the human eye (the so-called photopic response, for color daylight vision).? That means you need a sensor that is closely matched to the human eye, and then you have to integrate around the bulb.? ??
Most light meters have an extended response in the infra-red, which if properly filtered can give a better response, but they are often 10-20% off from the human eye's response.? ?You can't simply apply a correction factor because the spectral output of LEDs varies a lot and it's not a simple black-body light curve like an incandescent bulb.? You have to measure the spectrum, apply a curve to it, and then integrate around the bulb.? If I were ever so lucky as to have a 7J20 plug-in for my 7854 scope, this measurement is exactly what I would be doing with it!
Interestingly, I recently discovered a TI light sensor chip which has a very accurate photopic response.? It's the OPT3001.?? ?Even better, there are Chinese companies selling breakout boards (and probably knock-offs) of this chip for $5 and I have one on its way to me fro me-bay.? ?I'll just replace the chip with a free one sampled from TI....
So I am curious to play with this chip and see what kind of measurements I get from my LEDs.? ?Does anyone here have any direct experience with such light measurements of non-black body sources?
? Dan
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On Monday, June 25, 2018, 12:11:29 AM EDT, Ed Breya via Groups.Io <edbreya@...> wrote:
This is OT, but I just have to say I happened to stop by the Fremont Costco today, and stumbled upon some amazing deals on certain types of LED bulbs, like six-packs of PAR-xx/xxW equivalent spots for two dollars, and other stuff. They are mostly in the good warm-white 2700K/3000K range. PGE has some promotional subsidy pricing going on in some California markets, so anyone in the right areas can pick up some great deals. This is reminiscent of what they did in the CCFL era a decade or more ago. I've been an early adopter of LED illumination, and have all kinds of them collected over the years, so of course, I had to get a bunch of different ones to try out, and some more of ones that I paid five to ten times as much for only months ago. These are even cheaper than various questionable ones I've picked up at flea markets recently - and are brand new. Only certain ones (maybe slow-sellers) are priced in closeout ranges, like six-packs or two-packs for two or three bucks, depending on the particulars, but it may be worth a look. I don't know how long the deals and stock will last, but I'll be back looking for more. Usual disclaimer - no, I don't own a Costco store.
Ed
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Re: Novice question - 475, what mode is this?
Okay, but I did not think the posts about the Tek 475 had anything to do with Bob's computer, so I would have never guessed this.
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On 6/24/2018 4:35 PM, Jeff Urban wrote: On Fri, Jun 22, 2018 at 10:56 am, Mike Merigliano wrote:
The Tek 475 is analog, with a CRT screen, so the tools for LCD screens will
probably not work.
I meant Bob's computer monitor. If LCD which most are these days, some are not quite perfect. My 23" on my good old PC, I think it is an Acer has great viewing angle, about like a CRT. But my laptop which has an edge (bottom) lit LCD is not so good.
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Re: I have two Tek manuals I don't think I need
Hi Jeff,
Two separate members of this group requested one manual each.... I'm sure
they can see this note as they also saw my original post. I am trying my
best to pay the generosity I have received from this group forward. I
recently sent two mainframe plug-ins to California to a group member and
now am sending these manuals off to group members that can make good use of
them. In all cases, I've only asked that to be compensated for the
postage. I'll leave it up to the recipients of the manuals as to whether
they want to participate in that project.
Again, I want to express my gratitude to everyone that has offered
technical advice and also to Mike who gifted me one of his spare R7603s.
David
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On Sun, Jun 24, 2018 at 6:26 PM, Jeff Urban <JURB6006@...> wrote: There were people on here recently looking for donations for the cost of
scanning a bunch of manuals and making PDFs out if them. I would have
kicked in a few bucks but I do not have a credit card, so someone told me
to just spread the word about this site...OK.
Look back a couple of pages of posts and you'll probably find it, if not
maybe they'll find you. If you got something they don't, and are willing,
let them have it. In fact they probably only need to borrow it. Get them
back and actual paper manuals still have intrinsic value, and I have worked
with them and liked it. Sometimes I print sections and tape them together
into the bedsheet they resemble.
It's up to you, I would at least scan them or let others scan them. I have
a couple of old ones which don't seem to be on the net, once they get it
together I will send them what I have, either scans or the paper itself.
I will do everything in my power (which ain't much really) to keep good
technology out of the dumpster.
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You've got a dead 7603 with no lights. Definitely look at the low voltages first. Check the 0.15A (150mA) fuse, F855, just because its 'filament' is so delicate it can easily become disconnected from its end caps from heat and age. In my case this wasn't the 'magic bullet' to fixing my 7603, but losing the 130V line kills the HV system.
Getting the front panel power indicator to light would be the next challenge. The LV regulators are interconnected in a way that will prevent this lamp from lighting if one of them is bad. I can't remember how it all hangs together now, but there are a number of posts here that spell it out.
Sorry, about being too vague, but I'm writing this from memory. I think the LV rectifier board is going to be the key to this, and it's worth the time to pull it, give it a visual and check the condition of the electrolytic caps. And be sure to mark the ribbon cables as you disassemble things!
Good luck!
--Al
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Does it make a ticking sound - like 1/sec? You may need to put your ear
close to the cover to hear it. If so, it's something in the PSU - rectifier
board, LV board, inverter - likely a shorted tantalum cap.
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On Sun, Jun 24, 2018 at 10:18 PM, Jim Ford <james.ford@...> wrote: Hi, my name is Jim and I'm a Tek-aholic. ("Hi, Jim.") Long time lurker
(about a year and a half), first time poster. My latest Tek project is a
completely dead 7603 that I bought on the 'Bay. I did get a working 7S11
sampling plug-in and a 7A26 and a 7A18 in mostly working condition in the
deal. Anyway, the 7603, serial number B345179, shows no signs of life
whatsoever. No lights light, no sounds, no nothing when I pull the on/off
switch out. I checked the main fuse, the thermal cutout, and the on/off
switch. No issues there, 120 VAC gets through all of those. I'm wondering
if the main transformer is blown. Sounds expensive. I'm not retired, like
some of you are (God bless you!), so I unfortunately don't have a lot of
time on my hands. Got a working 7904 and a 5103N/D10 to help troubleshoot,
plus half a dozen odd multimeters in my garage lab. (Also, a fair number
of 7000 series plug-ins, a Tek TLA711 logic analyzer [I'll do a post on
that one someday], a good collection of HP microwave gear, and some other
manufacturers' stuff).
Yes, I have the service manual for the 7603, but I haven't been able to
decipher where the main xfmr secondary test points are located, if there
are any. Any guidance, folks? I'm continually in awe of the man-years
(and some woman-years, too) of collective experience concentrated in this
place called TekScopes!
Thanks! Jim
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If your main low voltage supplies are all there you should check for HV, and it is not like that
requires a
HV probe, there are places to measure where you can tell. The cathode voltage is only about 3KV, so
even if it goes overload on a DVM that can handle 2KV it shouldn't hurt it. if it has HV then go to
the
deflection plate voltages, just because it is easy. The ones on the top should be within a few volts
of
each other, same with the side ones. That diagnosis gives no information regarding the location of any HV fault. If the -3kV is not present, the fault could either be the HV transformer, something in the string of components associated with pin 8 of the transformer, or that the multiplier is dead and loading down the transformer. The HV multiplier (x4) is a known weak point. The good news is that you can rebuild it, if that is where the fault lies. Craig
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On Sun, Jun 24, 2018 at 05:46 pm, Harvey White wrote:
For the theory, the "standard" current limiting says that if the
supply is a 1 amp supply, it will try to deliver 1 amp into the load,
even if shorted. The pass transistor has to get rid of all the power
(say for an 18 volt bulk supply running at 1 amp, 18 watts).
Foldback current limiting triggers at the current limit (say for both
supplies, 1.5 amps), but effectively reduces the short circuit current
to, (say), 300 ma. Thus the pass transistor has to dump .3 * 1.8, or
5.4 watts into a dead short.
You probably meant .3 * 18, or 54 W? It's not entirely fair to think of 18 V in both cases since the voltage drop Vce will increase dramatically when the line is short circuited. In the 465 the foldback is very effective. A curve for +55 V is shown in the manual Fig. 3-12. It will be less pronounced for + 15 V (because of component values) but still I wouldn't be surprised if the dissipation is smaller when the output is shorted to ground. Anyway, my main remark is that a low bulk cap voltage is not a consequence of a shorted supply rail. Albert
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That model, if the graticule lights work you got juice to the Xfmr. Other lights are a different story. If you get absolutely nothing, turn it on and see if the blades of the power plug read infinity between. If so it is either the primary of the transformer or a thermal in it, or maybe something to do with the voltage selection. You DO have the voltage selector in properly right ?
It is rare for a primary of a power transformer to open up. But on any given Tuesday a connection could be defective and it didn't show up. If you get an open reading find the actual primary and measure it. Maybe stick 120 VAC in it through a 100 watt incandescent.
If your main low voltage supplies are all there you should check for HV, and it is not like that requires a HV probe, there are places to measure where you can tell. The cathode voltage is only about 3KV, so even if it goes overload on a DVM that can handle 2KV it shouldn't hurt it. if it has HV then go to the deflection plate voltages, just because it is easy. The ones on the top should be within a few volts of each other, same with the side ones.
After that you might need to go to the CRT grids.
Whatever, if it does absolutely noting that is usually a good omen. If it is just something stopping the 120 VAC from getting to the iron, that is easy. (unless you need the transformer, but sometimes it is a thermal cutout and that can be replaced. Usually.
Keep us posted.
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Hi, my name is Jim and I'm a Tek-aholic. ("Hi, Jim.") Long time lurker (about a year and a half), first time poster. My latest Tek project is a completely dead 7603 that I bought on the 'Bay. I did get a working 7S11 sampling plug-in and a 7A26 and a 7A18 in mostly working condition in the deal. Anyway, the 7603, serial number B345179, shows no signs of life whatsoever. No lights light, no sounds, no nothing when I pull the on/off switch out. I checked the main fuse, the thermal cutout, and the on/off switch. No issues there, 120 VAC gets through all of those. I'm wondering if the main transformer is blown. Sounds expensive. I'm not retired, like some of you are (God bless you!), so I unfortunately don't have a lot of time on my hands. Got a working 7904 and a 5103N/D10 to help troubleshoot, plus half a dozen odd multimeters in my garage lab. (Also, a fair number of 7000 series plug-ins, a Tek TLA711 logic analyzer [I'll do a post on that one someday], a good collection of HP microwave gear, and some other manufacturers' stuff).
Yes, I have the service manual for the 7603, but I haven't been able to decipher where the main xfmr secondary test points are located, if there are any. Any guidance, folks? I'm continually in awe of the man-years (and some woman-years, too) of collective experience concentrated in this place called TekScopes!
Thanks! Jim
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OT: LED lamp bulbs at ridiculously low prices at (some) Costco stores
This is OT, but I just have to say I happened to stop by the Fremont Costco today, and stumbled upon some amazing deals on certain types of LED bulbs, like six-packs of PAR-xx/xxW equivalent spots for two dollars, and other stuff. They are mostly in the good warm-white 2700K/3000K range. PGE has some promotional subsidy pricing going on in some California markets, so anyone in the right areas can pick up some great deals. This is reminiscent of what they did in the CCFL era a decade or more ago. I've been an early adopter of LED illumination, and have all kinds of them collected over the years, so of course, I had to get a bunch of different ones to try out, and some more of ones that I paid five to ten times as much for only months ago. These are even cheaper than various questionable ones I've picked up at flea markets recently - and are brand new. Only certain ones (maybe slow-sellers) are priced in closeout ranges, like six-packs or two-packs for two or three bucks, depending on the particulars, but it may be worth a look. I don't know how long the deals and stock will last, but I'll be back looking for more. Usual disclaimer - no, I don't own a Costco store.
Ed
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One thing that wasn't said on this thread ( unless I missed it) is that these scopes can be LETHAL !!! If you get "stung" by CRT high voltage (-1450) if it doesn't kill you, you'll be one hurtin buckaroo getting up off the floor over there in the corner of the room. That said, it sounds ( from reading ) you've got a low voltage failure for openers (15v most likely) and once that is corrected, things will probably come to life.
My main warning is that when one is around the filament of a CRT one must REMEMBER !!!
The filament low voltage AC ' is actual "riding" on Cathode (-1450) voltage SO extreme care is needed in any measurements in this area. ( high voltage probe).. perhaps the easiest and safest way to check CRT filament ( not glowing) is to simply remove the CRT connector ( after any high voltage has "bled off" and measure the resistance between pins 1 and 14 on the CRT neck....should be a very low ( <1ohm) resistance.
Anyway main purpose in writing here was to make sure you don't get electrocuted
Good Luck !
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----- Original Message ----- From: "Harvey White" <madyn@...> To: [email protected] Sent: Sunday, June 24, 2018 8:46:12 PM Subject: Re: [TekScopes] Tek 465 no display True, and I've made some of them. However, as I remember it, the voltage across the sense resistors should be the VBE drop of the trigger transistor. I'm also going on general theory without looking at the specific schematic as well. I prefer (if possible and reasonable) to talk about the theory, and let the owner apply it. Maybe a little more difficult, but once that's done, then the theory and practice are both in hand. For the theory, the "standard" current limiting says that if the supply is a 1 amp supply, it will try to deliver 1 amp into the load, even if shorted. The pass transistor has to get rid of all the power (say for an 18 volt bulk supply running at 1 amp, 18 watts). Foldback current limiting triggers at the current limit (say for both supplies, 1.5 amps), but effectively reduces the short circuit current to, (say), 300 ma. Thus the pass transistor has to dump .3 * 1.8, or 5.4 watts into a dead short. Harvey
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On Sun, 24 Jun 2018 11:43:29 -0700, you wrote: Hi Harvey,
I think you (and Dave before) forget here that the supplies are protected by foldback current limiting. In case of a nearly dead short the current will be much smaller than in normal circumstances, and I guess that also the power dissipation in the series pass transistor will be smaller (the reduced current "wins" from the increased Vce so to speak). The bulk cap voltage will be higher than normal. True, and I've made some of them. However, as I remember it, the voltage across the sense resistors should be the VBE drop of the trigger transistor. I'm also going on general theory without looking at the specific schematic as well. I prefer (if possible and reasonable) to talk about the theory, and let the owner apply it. Maybe a little more difficult, but once that's done, then the theory and practice are both in hand. For the theory, the "standard" current limiting says that if the supply is a 1 amp supply, it will try to deliver 1 amp into the load, even if shorted. The pass transistor has to get rid of all the power (say for an 18 volt bulk supply running at 1 amp, 18 watts). Foldback current limiting triggers at the current limit (say for both supplies, 1.5 amps), but effectively reduces the short circuit current to, (say), 300 ma. Thus the pass transistor has to dump .3 * 1.8, or 5.4 watts into a dead short. Harvey
Albert
On Sun, Jun 24, 2018 at 08:11 am, Harvey White wrote:
So, look for the bulk voltage, you'll find it to be a bit low. Now
look at the voltage drop on the pass transistor (that's the variable
resistor function). If there's a short on the output (I'd suspect
one), then the transistor drops the whole bulk supply voltage and
should be rather warm. There's a current sense resistor in there, say
0.1 to 2 ohms or so, generally with a transistor base/emitter junction
across it. Look for .5 to .7 volts across this resistor. If so, then
the supply is trying to current limit to protect itself.
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Re: Novice question - 475, what mode is this?
Hello Dimitri,
To you and all, first of all, apologies if my answer is maybe mission the
history (your previous messages) but I'm writing from my phone and couldn't
let this go.
Itseems no one mentioned or asked you about the following, and it may
explain (or not) this - so called -ghosting.
To which function the DM44 multimeter on the top is set.
If it's on function Time, or 1/time, the ghost you are seeing can be,
maybe, the alternate delay controlled the the DM's 44 delta time control.
To rule that out, just make sure the DM44 is set to function Volts, Ohms or
Temperature an tell us if the ghosting disappears.
Or else, keep the Time or 1/time selected and check if the ghosting changes
or moves, as you turn the delta time knob on the DM 44, while keeping
everything else constant.
If the ghosting moves, then what you're seeing maybe nothing more than the
DM44's differential delay time measurement, which when activated in
conjunction with the MIX function can turn the display quite confusing, as
they (the time and 1/time measurement functions) are meant to be used in
conjunction with the "A Intense" and the "B Delayed" horizontal modes.
In that case, I suggest you download and read the manual of the DM44 option
itself, and understand how this ingenious function is meant to work.
Brgrds,
Fabio
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On Sun, Jun 24, 2018, 19:47 Jeff Urban <JURB6006@...> wrote: On Sat, Jun 23, 2018 at 06:13 pm, Dmitri Shuev wrote:
I suppose that I will start by trying to clean both A and B Volts/Div
Attenuator Switch contacts...
Should help, but that jitter might be settings. If B sweep has an auto
trigger, turn it off. Also switch it to DC coupling and turn off any low or
high filters. Adjust the trigger level slowly and at some point it should
be stable. Hopefully. If not, it is probably some caps somewhere.
Nice scope, a coworker used to have one like it. He didn't use it all that
much, I used my old trusty 422 much more. In consumer electronics even on
the 20V/div scale you can tell 5V, 12V, -12V and all that. I let it freerun
and literally used it that way, then when I got to switchers and whatever
like the HOT, HVOT or LOPT then it is triggered. And the 422 has a good
enough trigger circuit to lock to almost anything. I don't know if yours
has tunnel diode triggering but as far as I have seen it is the best. A 422
will lock onto noise, I shit you not. Put music to it and you'll see things
you have never seen.
If switching to manual DC not auto trigger doesn't take care of it let us
know. I'll RTFM and see if I get any ideas.
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Re: Novice question - 475, what mode is this?
On Sat, Jun 23, 2018 at 06:13 pm, Dmitri Shuev wrote:
I suppose that I will start by trying to clean both A and B Volts/Div
Attenuator Switch contacts...
Should help, but that jitter might be settings. If B sweep has an auto trigger, turn it off. Also switch it to DC coupling and turn off any low or high filters. Adjust the trigger level slowly and at some point it should be stable. Hopefully. If not, it is probably some caps somewhere. Nice scope, a coworker used to have one like it. He didn't use it all that much, I used my old trusty 422 much more. In consumer electronics even on the 20V/div scale you can tell 5V, 12V, -12V and all that. I let it freerun and literally used it that way, then when I got to switchers and whatever like the HOT, HVOT or LOPT then it is triggered. And the 422 has a good enough trigger circuit to lock to almost anything. I don't know if yours has tunnel diode triggering but as far as I have seen it is the best. A 422 will lock onto noise, I shit you not. Put music to it and you'll see things you have never seen. If switching to manual DC not auto trigger doesn't take care of it let us know. I'll RTFM and see if I get any ideas.
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Re: Novice question - 475, what mode is this?
On Fri, Jun 22, 2018 at 10:56 am, Mike Merigliano wrote:
The Tek 475 is analog, with a CRT screen, so the tools for LCD screens will
probably not work.
I meant Bob's computer monitor. If LCD which most are these days, some are not quite perfect. My 23" on my good old PC, I think it is an Acer has great viewing angle, about like a CRT. But my laptop which has an edge (bottom) lit LCD is not so good.
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Re: I have two Tek manuals I don't think I need
There were people on here recently looking for donations for the cost of scanning a bunch of manuals and making PDFs out if them. I would have kicked in a few bucks but I do not have a credit card, so someone told me to just spread the word about this site...OK.
Look back a couple of pages of posts and you'll probably find it, if not maybe they'll find you. If you got something they don't, and are willing, let them have it. In fact they probably only need to borrow it. Get them back and actual paper manuals still have intrinsic value, and I have worked with them and liked it. Sometimes I print sections and tape them together into the bedsheet they resemble.
It's up to you, I would at least scan them or let others scan them. I have a couple of old ones which don't seem to be on the net, once they get it together I will send them what I have, either scans or the paper itself.
I will do everything in my power (which ain't much really) to keep good technology out of the dumpster.
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i find myself with a Duraprobe 123 100 mHz probe, which is very nice but doesn't say tektronix on it anywhere.
It has H and L adjustments which i assume are intended to get rid of the spikes using the self-compensation routine.? My other probes each have only a single adjustment.
How do you adjust this thing?? Is it really a Tek product?
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Hi Harvey,
I think you (and Dave before) forget here that the supplies are protected by foldback current limiting. In case of a nearly dead short the current will be much smaller than in normal circumstances, and I guess that also the power dissipation in the series pass transistor will be smaller (the reduced current "wins" from the increased Vce so to speak). The bulk cap voltage will be higher than normal.
Albert
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On Sun, Jun 24, 2018 at 08:11 am, Harvey White wrote:
So, look for the bulk voltage, you'll find it to be a bit low. Now
look at the voltage drop on the pass transistor (that's the variable
resistor function). If there's a short on the output (I'd suspect
one), then the transistor drops the whole bulk supply voltage and
should be rather warm. There's a current sense resistor in there, say
0.1 to 2 ohms or so, generally with a transistor base/emitter junction
across it. Look for .5 to .7 volts across this resistor. If so, then
the supply is trying to current limit to protect itself.
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Re: Agilent keysight HP group
Thanks everyone I just must have missed it or typed it in wrong
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On Sun, Jun 24, 2018, 9:12 AM Dmitri Shuev <dshuev@...> wrote: This one?
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Re: Agilent keysight HP group
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On 6/24/2018 8:58 AM, Pete Lancashire wrote: Does anybody know the fate of the Yahoo Agilent keysight HP group ?
I can't seem to find it anymore
--
Richard Knoppow
dickburk@...
WB6KBL
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Jeff Urban
Fabio Trevisan