Dragon's Lair Fans - Arcade Lifestyle
General Chat => Technical Area => Topic started by: level42 on October 12, 2011, 05:42:54 PM
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I think you guys will like this video I made yesterday:
http://youtu.be/vQB7te6SunY
[EDIT] PLEASE NOTE: the small spots On the display that I mention in the video were only on the plexi protection above the actual display. Mike has upgraded these since so this shouldn't be a problem anymore. I have simply removed the plexi and it looks perfect, just have to be careful not to stick anything into the hole that could damage the display.
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LOL @ WE ARE IN THE BASEMENT ! ;D ;D ;D
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LOL @ WE ARE IN THE BASEMENT ! ;D ;D ;D
"well, actually, we are in my kitchen" :D i almost peed my pants!!!
anyway, thx for that great video, seems like this "machine" would be a nice thing to have ;)
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;D ;D ;D
Yup !
One thing I forgot to mention: Once you've got one of these: DISCHARGE THE CAPS FIRST !! Use a small resistor to do that (shorting them is not something caps like very much....)
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You should mention that in the videodiscription maybe..
not all people that see that video are reading this post aswell ;)
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Yeah, already thought about that...
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Very useful video, thanks a lot André! ;) :spaceace:
A short video would be also great from the discharging method.
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Thanks andre, i can got to sleep with something new learned ;)
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"Sometimes electronics is easy" ;D ;D
Thanks Dre!
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Hey guys....
A little more info....
I found the cap that I measured being bad looked a bit weird for a normal electrolytic (aluminum) cap. So I checked the schematics of Ms.Pac and found out that they indicate a Tantalum cap at C5 and C10.
When I hear Tantalum I immediately think of these kind of caps:
(http://www.acesuppliers.com/images/productpic/20071223850263182664.jpg)
BUT...the one's I measured wrong didn't look like those at all. Using the power of Google I quickly found out that there are also "wet" Tantalum caps, that look much more like regular electrolytic caps:
Compare, wet tantalum:
(http://img.diytrade.com/cdimg/1085232/11782886/0/1263992381/Wet_tantalum_capacitor.jpg)
and (old fashioned) aluminum electrolytic cap:
(http://img-europe.electrocomponents.com/images/R226692-01.jpg)
Since these kind of old fashioned "regular" electrolytic caps (GOD I would love everyone used the term Elco for it, like we do in Holland....) were all around the Ms.Pac board I didn't notice the difference...
HOWEVER, the ESR meter can still measure these just as well and so....they _are_ bad.
So I checked for some replacements and almost got a heart-attack:
http://nl.rs-online.com/web/c/?searchTerm=wet+tantalum&sort-by=default&sort-order=default&view-type=Grid
Note that these prices are EACH. I guess we're running out of Tantalum ? Should I sell mine to get the Tantalum out of them ?
My _real_ question is....what are the differences between a wet-tantalum (yes, this word sounds dirty) and a regular aluminum elco ?
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Mmmm, again Mr. Google seems to know the answer:
(You may jump to the conclusion right away if you want, last page of course)
http://ecadigitallibrary.com/pdf/CARTSASIA05/CARTSAsia0527_lpr.pdf
So....I should be OK using a regular cap....(elco)
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Sjeez, that prices does not make us happy :o
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Man those prices are crazy!! If i remember correctly i still have a few of those ::) Once bought the all the electronic components of a monitor repairman when i was 8 years old ::)
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....which means they might not be that good anymore.... elco's ("caps") tend to stay in better health when used regularly then on a shelf.
On the other hand....the story is not over....
I checked the schematics where cap C5 and C10 are used.
C5 is used across the input of the voltage regulator for the +5V. Instead of a more common 7805, a 78G is used, which can be regulated (contrary to a 7805 which is fixed output). However, the cap seems to perform the basic input filtering of the regulator. Usually you see something like 0,33 uF regular caps there. On data sheets for 7805 they are even indicated to be not necessary if the filter caps behind the rectifiers are physically close to the regulator....
SOooooo, IMHO it is VERY uncritical which type of cap is used here and I have no clue why they chose a wet tantalum ??
I'm sure I'll be fine with a regular elco with the same value there.
(I wonder what effect the high ESR would have had in this application...)
Now for C10:
That one is used in the reset circuit as far as I can see. Doesn't seem to critical either ? Any ideas, Robin, Andreas ?
I think it looks like it's safe enough to use a 10uF regular aluminum cap for both ?
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Received my early Xmas gift today. ;D
(https://lh3.googleusercontent.com/--BEc3tkd88M/TqmaLaXY6pI/AAAAAAAAE7Y/x7Vv-nIMVY8/s800/ESR%252520003.jpg)
Before you ask why did I bought this model, some answers:
-I like it's shape much more than the russian one ;D
-From 1945 to 1989 there were only russian products were available in Hungary, I bought more than enough from them for my whole life. ;D
-It has the auto discharge function
After a few tests it seems like a great product, the only disadvantage is that the crocs are too big for accessing smaller caps, André's equipment have sharp pins, I guess it's easier to handle it in these cases.
Anyway, I have a masterplan to fix this, simply attach some pins to the crocs. :D
I tried to make a video, but my camera didn't focus to the equipment, I will have to borrow a better one if you are curious it's live action.
Btw. that 10% capacity difference in this pic is acceptable, or it has to be replaced?
I guess the serial resistance is ok in this case.
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Mike already has a mod for his meter to include auto-discharge, but I can totally understand your position Béla :)
Caps (electrolytic one's) Usually have a a high tolerance (that is variation in stated value). Usually it's 20%.
Also usually manufacturers succeed in making the caps have a HIGHER value than specced, because that is often better than a value below specced.
This value is within -10%, if the cap is specced at 20% it is OK still. ESR is fine.
About the Russian meter, that's just one guy earning some cash with his hobby. Peak is more of a company.
Both have advantages and disadvantages. The auto-discharge is sure an advantage, but I didn't like the crocs, and especially the DIP socket to test new caps is ideal on the Russian one. Not to mention....it's about half as cheap...
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Thanks for the techical overwiev André, imho we both have great and very useful equipments and you are right about the price aslo. ;)
I really liked the ESR 70 since the first moment you posted it's pics here, I was too weak to change my mind and buy the other one. ;D
Those crocs totally dismatch with these kind of equipments, I totally don't understand why did the supply this cool machine with them
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Probably to have a very tight contact. I found out that the meter is pretty sensitive to that. You really need to use a little force when using the test leads. Remember, thee is a 100 kHz signal going through it, so measure tip to cap lead resistance is counting here...
If I were you I'd cut of the crocks and by some nice quality pens you can solder to the leads...
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If I were you I'd cut of the crocks and by some nice quality pens you can solder to the leads...
That is the plan exactly. ;D
One more noob question, does it have any difference if you measure the caps from the solder side of the pcb?
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Nope.
Do you have to calibrate the Peak ? Do check the manual, usually they do, and so does the Russian one.
It's very simple on the Russian: touch the leads together while powering up. After a sec or so it says calibrated.
This measures the "contact resistance" of the leads and the tips and it will take this into account when measuring caps.
It can have a pretty big impact on the measured results if you don't calibrate.
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Mine has the same calibration method, the manual advises to make it at least once a week to get true results.
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After a few tests it seems like a great product, the only disadvantage is that the crocs are too big for accessing smaller caps, André's equipment have sharp pins, I guess it's easier to handle it in these cases.
Anyway, I have a masterplan to fix this, simply attach some pins to the crocs. :D
I just had my hands on one of these Peak ESR meters this morning. Unless you have an older model without the feature, the crocodile clips are attached to the cable with 2mm banana plugs, you can just pull them off and replace them with any other type of probe, including small clips.
You can see where they clip together as the wire is wrapped in a thicker plastic element.
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Thanks Liquid, I didn't notice that and it is also not in the manual. :spaceace:
The manufacturer have some really expensive replacement parts, so I decided to use some single pens from a multimeter. ;D
(https://lh4.googleusercontent.com/-ZrT_dbvQTms/Trgk6T8mIjI/AAAAAAAAE9w/ZYDU1DF1R-U/s800/ESR%252520005.jpg)
(https://lh3.googleusercontent.com/-7jJCWRTfmD0/Trgk6jfUC_I/AAAAAAAAE90/RIGlARP3HFM/s800/ESR%252520004.jpg)
It works great. ;)
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I enjoyed the video much :) nice testing device. Does somebody know the trade off between model ESR 60 and 70
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If i remember correctly the difference is the "audible alerts", not being present in the ESR 60... In addition, i bought the ESR70 from RS online and surprisingly the it was cheaper than the 60 :? :lol:
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I enjoyed the video much :) nice testing device. Does somebody know the trade off between model ESR 60 and 70
"The Atlas ESR PLUS is even better
This new model introduces new features including “Audible Alerts” and enhanced measurement range. Every measurement of ESR will be shown on the display as usual of course, but the unit will also produce a variety of tones depending on the value of ESR. And the tones themselves are surprising pleasant, including “Bell-like” pings (a couple of different types for ESR that is below certain values), and also a “Beep-Barp” type tone for ESR that is likely to be too high. There is also a reassuring “Blip” when the measurement has started and completed.
The ESR measurement range has also been enhanced, now doubled, measuring from 0 to 40 ohms with a resolution as low as 0.01 ohms. This remarkably fine resolution is great for assessing large capacitors and even allows you to use the Atlas ESR+ for tracing short-circuits and finding the precise area of a PCB that has that invisible wisp of solder."
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thanks for the heads up.
The ESR 60 was at reichelt for 87 something. At RS Online 97 plus VAT. I`ll send the ESR 60 back. Or does somebody need a ESR60?
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Still double the price of the russian one, why not support a colleague 1 man hobby-business...
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Okay,
first repair action with an ESR Meter. Thanks to this friend I could focus on other parts besides capacitors.
http://bencao74.blogspot.com/2011/11/repair-log-sttng-star-trek-next.html
My ST:TNG DMD display works again.
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Super electro noob says: what's the correct resistor I need to discharge a PCB or monitor capacitor? (I guess it depends on the capacitor's value?)
I read that a light bulb with 2 wires would also do the trick.
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you can use a multimeter to check the charge of a cap, after that you can start to worry how to discharge it ;)
EDIT:
Maybe this helps a bit:
http://www.repairfaq.org/sam/captest.htm#ctsdc (http://www.repairfaq.org/sam/captest.htm#ctsdc)
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Does that means I should have a whole range of resistors handy... ???
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No i dont think so, i think if there is charge in a cap, and you connect a lamp like you said, then the most of the juice is out
to be very sure, put a insulated screwdriver between the terminals and short it.
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Will try, thanks for the tips!
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Will try, thanks for the tips!
Take care Chris, don't blow yourself up! :D
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http://www.youtube.com/watch?feature=endscreen&v=aQXy99SGuFg&NR=1
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Excellent way to destroy your caps......
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Yeah, it was to show that there can be a pretty big force in a cap with just 20 volts.
you can ofcourse just connect the multimeter and wait for it to reach zero.
you see in the vid that the voltage is dropping by just waiting with the meter connected.
i always just desolder them without shorting them
most of the caps are drained in circuit anyway
and i dont think that there is anybody that stupid to desolder it with the board connected and/or plugged in and/or in operation ;D
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That's the thing: I want to be able to measure them without desoldering them.
I contacted Mike, the guy who sells the Russian meter (thanks Dre for the address) and the auto discharge feature is not ready yet on his meter.
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Chris, as long as you havent powered up the PCB where the caps are on for a while (a day or so) you wont have any left charges, except for really big caps like the main filter cap on a monitor chassis PCB or like Atari's Big Blue and caps like that...
Caps do discharge over time and the smaller ones are discharge rather quickly....
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Good info, thanks!
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Chris, as long as you havent powered up the PCB where the caps are on for a while (a day or so) you wont have any left charges, except for really big caps like the main filter cap on a monitor chassis PCB or like Atari's Big Blue and caps like that...
Caps do discharge over time and the smaller ones are discharge rather quickly....
Confirmed, I tested hundreds of pcb and chassis caps with mine and never indicated that the discharge function is active.
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More fun with caps right here :D
http://www.youtube.com/watch?v=EoWMF3VkI6U&feature=context&context=G2642cb1RVAAAAAAAAAA (http://www.youtube.com/watch?v=EoWMF3VkI6U&feature=context&context=G2642cb1RVAAAAAAAAAA)