Re: oscilloscope probes
IMHO 200MHz is enough, maybe even a little more than enough.
When I worked for the military industrial complex we had a rule of thumb that any test equipment we built; I was an electrical design engineer, had to have 10X the resolution of the measurment tolerance. So, 200MHz may be about 10X the requirement. Now, in normal shops equipment which is 3 to 5X the requirement is OK. You're not trying to characterize circuits, just looking for a close match. Therefore, while 100 MHz probes may distort the waveform a little trying to buy 500MHz probes (you...
intp1000
Member
Last Activity: 02-22-2019, 09:00 AM
Joined: 11-19-2007
Location: Pennsylvania U.S.A.
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Cap chemistry/type for refurbing boat anchors?
After looking at digi-key and mouser I've decided I don't know what type cap I need in order to recap 1970-1985 era test equipment. Usually the power supplies and some bypass caps need replacement. They are usually of the tantalium type. It seems that unless a particular type is known the process of selecting a cap is just a crap shoot; esspically since there 100's of different chemistrys/manufactures/types/models. The caps needing replacement usually range from 1 to 4000 uF and 5 to 50 WVDC. So, for axial caps with high ripple capability, what brand/type/model would you suggest? -
Re: troubleshooting intermittent video from Gateway
Thanks stj,
Great minds think alike
,vis-a-vis a live disk. As to the gfx circuit, thanks for the tip. I may forgo the PS if it's the conscience that the described symptoms are not due to a PS.
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Re: Replacing caps in test equipment.
Thanks stj
So when replacing caps in the linear supply I'll have to go for replacements with the highest ripple rating. As to the lead spacing I'm replacing axial types with the modern radial type so that won't be a problem since their very different to begin with. As to the pcb hole diameter I hope I don't have to drill them out since the boards may, or not, be multilayer. Now that I think about it I think the boards are not multilayer. So thanks again for setting me straight about ESR.
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Replacing caps in test equipment.
I've seen a lot of posts on the yahoo HP group that suggest replacing the PS caps on newly acquired old test equipment. Question. If cap size is NOT an issue then should one try to match the ESR of the new with that of the old cap (can this even be determined)? Can one just use a good 105 degree C low ESR cap; or would too low of an ESR cause a problem? I seem to think that too low an ESR would cause too high a charging current in the caps and thus a higher than expected peak current in the, typically bridge, diodes thus leading the old diodes to an earlier failure than expected. What do you ... -
Re: troubleshooting intermittent video from Gateway
Actually I was thinking about using a live linux distro and booting into it. That way I hope to see if it's software or hardware. What do you think?
If the box still failes in 5 minutes I'll then take it apart and look at the mb for bad caps and R&R the PS. If the PS doesn't help then I'll concentrate on the mb. Does this seem like a correct methodology?Leave a comment:
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troubleshooting intermittent video from Gateway
I have a Gateway GT5458E that is intermittent. Started doing a black screen (no video) about once every three weeks. Has progressed to once every 5 minutes; after about 5 weeks.
How to troubleshoot? Doesn't seem like software to me but I don't know. Probably a bad component in PS or motherboard. I'll check the PS voltages once the box fails. Am thinking freeze spray might help locate the component. Might also be worn out heatsink paste?
Any thoughts as to how to eliminate the software? How to go about finding the component?
BTW, it's not the monitor. Checked by substituti... -
Re: Unknown Capacitor Brands
Anyone know who the mfg. of the cap pictured below? If not a well known brand then anyone know for what service the cap might be usefull for?...Leave a comment:
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Re: LCD display image shrunk proportionally
Thanks to both of you who replied.
I'll forward your suggestions to the client.
Sorry I hadn't heard/seen a display that would do what I described.
Sometimes, perhaps lots of times, practical experiance is worth more than 3 university degrees and 20 years of designing electronics.
Thanks again.
Sincerely, intp1000Leave a comment:
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Re: Dell Insperion 4100 LCD image shrinkage
Thanks equevarae;
I'll try your susgestion.
Forgot to mention.
When I connect the laptop to an external LCD monitor the [B]display is properly sized.[/B]Re: Dell Insperion 4100 LCD image shrinkage
Thanks equevarae;
I'll try your susgestion.
Forgot to mention.
When I connect the laptop to an external LCD monitor the [B]display is properly sized.[/B]Leave a comment:
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Dell Insperion 4100 LCD image shrinkage
Have a Dell 4100 whos display image has proportionally shrunk 70% toward the center of the LCD display. I've never seen this before and suspect a power supply problem. Anyone know how to troubleshoot this beast with no schematic and only a VTVM. Any way to troubleshoot with software? -
LCD display image shrunk proportionally
On a Dell Inspiron 4100 laptop the image on the LCD screen is about 70% of what it should be. Image is clear with no artifacts, just shrunk vertically and horizontally. Possibly the power supply? I've never seen this problem before so if anyone can point me in the correct direction to repair or just troubleshoot the beast I'd be pleased. -
Re: What do I need??
No voltage rating needed. The ohms and wattage will give you the max. V. V=(WR)½. Radio speakers were usually 3.2 to 6 ohms. Just supply the current needed (volumn) and the thing will work. Speakers are current driven devices. You could, in theory, supply 1KV, current limited of course, and the speaker would be find (except for flash over).Leave a comment:
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Re: Yet another victim of Antec! Q about cap replacement or RMA
Mr ANTECREP,
I thank you for your continued interest in this forum.
It's very nice to see mfg. reps. represented.
As an aside, PrintPlanet.com has always invited reps. to represent their viewpoints. Those reps. who do so have learned to not BS the fourms; for they will soon be found out by the "in the trenches" people who use their products everyday.
I would ask you, although I may have misunderstude which PSU you were talking about, there are a lot of people who...Leave a comment:
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