"Stop ohming yokes" rant follow up. Ionizing radiation event research. 161% increase.

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"Stop ohming yokes" rant follow up. Ionizing radiation event research. 161% increase.

This is in follow up to the yoke mismatching concerns rant that I have posted sometime ago.

https://forums.arcade-museum.com/showthread.php?t=392981
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CPM_EVENTS.jpg


Chad Entringer
05-20-2017

Purpose: To observe and determine radiation event differences on a CRT when the flyback anode high voltage potential exceeds normal operating conditions.

Since literally almost all monitor boards that I see in the amusements industry have its flyback high voltage potential generation factored by the monitor deflection coil (yoke) this is to address the concern of mismatching monitor boards to deflection coils it was not designed around.

Potential causes for excessive high voltage:
Monitor yoke mismatching. Flyback pulsing capacitors. Excessive monitor chassis B+. Incorrect glass tube used.

Charted is ionizing radiation events emitted from a 20" CRT acquired with a MAZUR PRM-9000 Radiation Monitor. The radiation counter has been positioned 1" from the face of the tube in the same spot through all 3 test modifiers.
prm.jpg


The first 15 minute segment average CPM at the CRT turned off with 0kv anode voltage potential resulted in and average count of 87.6

This off state would include background radiation and tube elemental natural decay. I suspect there are possible radioactive phosphor isotopes contributing the higher than normal background readings of 29 CPM

The average background radiation activity level reading with the instrument set on an inert wooden counter was 29 CPM

The second 15 minute segment average CPM at the CRT turned on with a sustained 28.5kv anode voltage potential resulted in an average count of 87.933.

There is no detectable CPM difference detected between the CRT being off and turned on with a normal operation of tolerance of 28.5kv. However, I would expect a verified small increase if the same test was done over a long period such as 24 hours. Other instrumentation and methods would be able to demonstrate the subtle change better.

The third 15 minute segment average CPM at the CRT turned on with a sustained 32kv anode voltage potential resulted in an average count of 230.133

Conclusion: A 3.5kv difference anode voltage potential above a normal operating potential of 28.5kv resulted in a 161.7% increase in ionizing radiation event counts over a 15 minute period on the PRM-9000.

Considerations:

A scintillator would be a more interesting in order to calculate the energy levels (gamma spectroscopy) emitted and radiation types (weight) in order to calculate mR/hr. Future lab addition? Or perhaps good dosimeter that would pick up the energy ranges emitted.

An absorbed dose would be based on radiation weight, energy levels, surface area, what part(s) of the body it's zapping.

It is not possible to calculate the uSv/hr dose since my counter is calibrated in relation to a caesium-137 source.

The Food and Drug Administration strictly limits CRT emissions to .5 mR/hr.

No dose of radiation of safe.



[UPDATE 05-23]

Thanks for the all the supporters, challengers, contributors, the interest and the hunger for more knowledge. Question everything!

I will do more research as I mentioned and obtain accurate dose accumulations from CRT x-rays in normal to excessive HV. Whether extra x-rays are kicked off from excessive b+, a faulty flyback, incorrect PP drive pulsing capacitors, or the yoke by itself this is all fascinating and worthwhile to me.

It may very well end up that a couple cigarettes will deposit more of a radiation dose into tissue than a day or twos worth of an x-ray bath from a CRT. Or not. -->http://www.rmeswi.com/36.html (thanks to coinopper for the link on cig rads)

Thank you all.
 
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....what is the reading at the average stance distance.

What is the dispersion.

And would your source calibration not make a difference. I would think it would.

Since the warning is x-ray emissions... And not what im assuming is a unit calibrated for a radioactive isotope?

I am sure I am wrong in this. Please ELI5.
 
It's well established that higher voltage in a CRT causes more radiation... which is the reason for the X-Ray protection circuits.

Are you saying that your monitor chassis had a properly functioning protection circuit, but by installing an incorrectly matched yoke, it not only created the overvoltage, but also "tricked" the chassis into thinking there was no overvoltage condition?

DogP
 
Yeah but your average cellphone emits up to 3x more radiation than a crt so how much is unsafe? I'm not trying to heckle you just posing some opposition and questions.
 
You are not heckling. Glad you are curious we are supposed to question everything right? There is a difference between ionizing radiation and electromagnetic radiation to start with. Second the real dose from the emissions coming off the glass would have to be determined with gamma spectroscopy or possibly a really good dosimeter. Cellphone emissions will not trigger a dosimeter, a geiger counter nor a scintillator as its not an ejected electron, proton / neutron or a wave in the gamma spectrum

Yeah but your average cellphone emits up to 3x more radiation than a crt so how much is unsafe? I'm not trying to heckle you just posing some opposition and questions.
 
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Obligatory..... Gordon Ramsay almost was made sterile from standing in front of hot stoves most of his adult life...


I am not saying I doubt there are any bad effects...

What I am saying is it's like a bag of chips containing Olestra.... Untill you shit yourself.... It's hard to stop eating them...
 
It's well established that higher voltage in a CRT causes more radiation... which is the reason for the X-Ray protection circuits.

Are you saying that your monitor chassis had a properly functioning protection circuit, but by installing an incorrectly matched yoke, it not only created the overvoltage, but also "tricked" the chassis into thinking there was no overvoltage condition?

DogP

The x-ray protection circuits typically work by monitoring the chassis B+, and are designed with knowledge of the ratio of B+ into the HV circuitry to anode voltage out. Just as a completely arbitrary example, if your B+ is 180 and nominal anode is 18kV, you have a 100:1 ratio. So if your unsafe anode voltage is 22kV, you set the overvoltage to trigger at B+ of 220V.

If you modify the chassis in such a way that the B+ remains the same, but the ratio of B+ to anode voltage changes, the overvoltage protection obviously can't work as designed.
 
The x-ray protection circuits typically work by monitoring the chassis B+, and are designed with knowledge of the ratio of B+ into the HV circuitry to anode voltage out. Just as a completely arbitrary example, if your B+ is 180 and nominal anode is 18kV, you have a 100:1 ratio. So if your unsafe anode voltage is 22kV, you set the overvoltage to trigger at B+ of 220V.

If you modify the chassis in such a way that the B+ remains the same, but the ratio of B+ to anode voltage changes, the overvoltage protection obviously can't work as designed.




How are we modifying the chassis by swapping yokes?

Are you saying that by changing the yoke you are modifying the b+ circuitry?

How does that compare if you are using the original yoke?


Just say that not swapping yokes is going to make my penis smaller.

90% will stop completely.
 
Flyback high voltage potential generation is factored by the monitor deflection coil (yoke) used regardless of what the B+ is at. This can potentially increase or decrease the flyback anode voltage.

How are we modifying the chassis by swapping yokes?

Are you saying that by changing the yoke you are modifying the b+ circuitry?

How does that compare if you are using the original yoke?


Just say that not swapping yokes is going to make my penis smaller.

90% will stop completely.
 
This is in follow up to the yoke mismatching concerns rant that I have posted sometime ago.

https://forums.arcade-museum.com/showthread.php?t=392981
---------------------------------------------------------------------------------------
CPM_EVENTS.jpg


Chad Entringer
05-20-2017

Purpose: To observe and determine radiation event differences on a CRT when the flyback anode high voltage potential exceeds normal operating conditions.

Since literally almost all monitor boards that I see in the amusements industry have its flyback high voltage potential generation factored by the monitor deflection coil (yoke) this is to address the concern of mismatching monitor boards to deflection coils it was not designed around.

Potential causes for excessive high voltage:
Monitor yoke mismatching. Flyback pulsing capacitors. Excessive monitor chassis B+. Incorrect glass tube used.

Charted is ionizing radiation events emitted from a 20" CRT acquired with a MAZUR PRM-9000 Radiation Monitor. The radiation counter has been positioned 1" from the face of the tube in the same spot through all 3 test modifiers.
prm.jpg


The first 15 minute segment average CPM at the CRT turned off with 0kv anode voltage potential resulted in and average count of 87.6

This off state would include background radiation and tube elemental natural decay. I suspect there are possible radioactive phosphor isotopes contributing the higher than normal background readings of 29 CPM

The average background radiation activity level reading with the instrument set on an inert wooden counter was 29 CPM

The second 15 minute segment average CPM at the CRT turned on with a sustained 28.5kv anode voltage potential resulted in an average count of 87.933.

There is no detectable CPM difference detected between the CRT being off and turned on with a normal operation of tolerance of 28.5kv. However, I would expect a verified small increase if the same test was done over a long period such as 24 hours. Other instrumentation and methods would be able to demonstrate the subtle change better.

The third 15 minute segment average CPM at the CRT turned on with a sustained 32kv anode voltage potential resulted in an average count of 230.133

Conclusion: A 3.5kv difference anode voltage potential above a normal operating potential of 28.5kv resulted in a 161.7% increase in ionizing radiation event counts over a 15 minute period on the PRM-9000.

Considerations:

A scintillator would be a more interesting in order to calculate the energy levels (gamma spectroscopy) emitted and radiation types (weight) in order to calculate mR/hr. Future lab addition? Or perhaps good dosimeter that would pick up the energy ranges emitted.

An absorbed dose would be based on radiation weight, energy levels, surface area, what part(s) of the body it's zapping.

It is not possible to calculate the uSv/hr dose since my counter is calibrated in relation to a caesium-137 source.

The Food and Drug Administration strictly limits CRT emissions to .5 mR/hr.

No dose of radiation of safe.


You need to get laid/a life.
 
Flyback high voltage potential generation is factored by the monitor deflection coil (yoke) used regardless of what the B+ is at. This can potentially increase or decrease the flyback anode voltage.

Stupid question, Chad, but wouldn't you be able to measure the incorrectly high flyback anode voltage with an HV probe and see that it was wrong?
 
That is exactly what I did as you can see in the chart.
segment 1 0kv
segment 2 28.5kv
segment 3 32kv
all in a controlled environment. it was wrong because i introduced the excessive high voltage in order to conduct the research as written on first post.

Stupid question, Chad, but wouldn't you be able to measure the incorrectly high flyback anode voltage with an HV probe and see that it was wrong?
 
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Don't even encourage him with questions.
Just ignore him and this post will be forgotten.

sounds like you are the one who need to get laid, got some pent up frustration there pal??
 
I fine this post interesting and he is obviously passionate about what he does. Let's not discourage people from sharing knowledge on here it's the most valuable part of klov.
 
That is exactly what I did as you can see in the chart.
segment 1 0kv
segment 2 28.5kv
segment 3 32kv
all in a controlled environment. it was wrong because i introduced the excessive high voltage in order to conduct the research as written on first post.

So I guess my point is that if you swap yokes you should be able to tell if you're in a position where you're dosing yourself with radiation because the HV probe will show too high a voltage.

If you swap yokes and the HV probe doesn't show excessive voltage then you shouldn't have to worry about excessive radiation? And you should still be somewhat concerned about defeating the X-ray protection circuit by introducing a new yoke.

At least that's what I've gathered from this thread.
 
I've seen Chad test every chassis he fixes with an HV probe.

apparently there's a rhyme and a reason after all.

to djsolzs' point, I think the Kool Aid man should give it a rest now.
 
The x-ray protection circuits typically work by monitoring the chassis B+, and are designed with knowledge of the ratio of B+ into the HV circuitry to anode voltage out. Just as a completely arbitrary example, if your B+ is 180 and nominal anode is 18kV, you have a 100:1 ratio. So if your unsafe anode voltage is 22kV, you set the overvoltage to trigger at B+ of 220V.

If you modify the chassis in such a way that the B+ remains the same, but the ratio of B+ to anode voltage changes, the overvoltage protection obviously can't work as designed.
Yep... that's exactly my point. I don't see how changing the yoke can change the ratio of B+ to HV, which AFAIK is solely dependent on the ratio of transformer turns inside the flyback. If he can show that an incorrect yoke does significantly affect this, then it'd be interesting. By saying that 32kV in a tube increases X-Ray emissions over 25kV, I'd say "Duh" (the sticker on the back of the tube says that).

I personally think Chad is reaching with this one. He's making no meaningful connection between the yoke and HV/X-Rays in this post. IMO, if anything is going to create unsafe HV, and therefore increased X-Ray radiation, it'll be improperly manufactured flybacks, not a poorly matched yoke.

I do agree that by "ohming" a yoke, you don't get all the parameters, and aren't guaranteed a compatible part... but I disagree that it'll cause a hidden dangerous situation that can't be easily checked. AFAIK, the construction of a TV/arcade monitor yoke is generally similar, so if the wire gauge used on the yoke is the same and the DC resistance is the same, then the inductance/reactance will be similar.

More interesting "research" would be to measure the resistance and inductance of a bunch of yokes and see how much they track each other. If it could be shown that resistance and inductance aren't related, then you could make a case that "ohming" yokes doesn't work.

DogP
 
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