I just took delivery of an ESR Micro 3.1 and I'll have a full report in a few days. I got it from the maker in beautiful downtown Tver in the Russian Federation for sixty bucks shipped-it took 2 weeks to get here to central Iowa. He is making an improved model that can be used for testing axial capacitors on a fairly expedited basis but that wasn't something I needed.
So far it is very useful.
I checked some cardboard tube caps from an old Gibson amp and the sections on one of them measured 87 and 90 ohms respectively. The capacitance was so whacked that it couldn't even get a reading. I also checked soem of the capacitors from my brown Pro and one of the cathode capacitors was out to lunch.
Well,
I guess my take is if you have an amp with caps old enough to warrant testing, the performance of the power supply as well as the individual cathode bypassed stages would benefit greatly from new electrolytics throughout anyway.
If you're thinking of just replacing the ones that check bad, then IMHO you're not doing the amp justice or the customer any favors. Bad caps either by age or look (buldged, leaky, etc) are usually pretty obvious about their condition. Performance can also be an indicator of cap health (how much the power supply sags when pushed.
You also just get to know what amps need the cap-jobs from experience, too. We've just recently begun to realize that most of the Mesa Boogie amps (like the Mark series) from the early-mid 80's are beginning to need cap-jobs like all the old Fenders.
The difference in performance that the customer's indicate pre & post cap-job is always like night & day.
I was given one of the $200 ESR meters & frankly I've tried it a few times & come to the conclusion that when an amp is 20yrs-25yrs+ old...it probably just needs the electrolytic caps replaced.
Personally, I'd spend the dough on stocking the caps ;-] MPO, glen
I agree that there's no doubt on the old stuff. I just thought it would be a nice tool to have to check some unknowns. I also like the in-circuit ability to quickly check things first. One other thing that I found appealing was simply being able to get (supposedly) accurate resistance readings in the sub-ohm range. My meter doesn't really show me any differene between things under 1 ohm. With the typical SS power amp having a few of these types of resistors, I thought it would be nice to see just how close things like emitter resistors are to spec & to each other.
Enzo,
I had checked out the DIY meters (you thought I would post without googling first? ), but finally decided that a better use of my time might be just to purchase a meter or build something like the Blue kit, if it's any good. I like the digital display, if it's accurate. The analog meters don't look to have much definition under 1 ohm.
I worked in a shop where we had one of those Sencore cap analyzer, I forget the name, Z-meter maybe? It did everything, leakage tests up to 500v, ESR, capacitance. After the novelty wore off, we never used it. I found it most useful measuring inductors for speaker crossovers. I could buy a 3mH coil, and unwind it to get a 2.6mH coil.
As to resolution, I think I would be looking for an indication more than a particular number. Like all these look under 2 ohms, but this one says 50. At that point I don;t care if the group is 1.8 or 1.9 ohms, I know the 50 one is funny.
Education is what you're left with after you have forgotten what you have learned.
Oh, and as to googling first, after a few thousand posts here I have learned that many people actually don't, and I ought not assume. And you might not have been considering a kit.
I have a guy on another forum who is a constant source of amazement, and he was ranting and raving how he couldn;t find out who the "6th Jackson Brother" was. He was googling that exact phrase. No particular pat on my back, but I googled "Jacksons" and the first hit that came up was wikipedia on the Jackson 5, with a lits of all the names a couple inches down.
Education is what you're left with after you have forgotten what you have learned.
I've ...come to the conclusion that when an amp is 20yrs-25yrs+ old...it probably just needs the electrolytic caps replaced.
You probably want to be careful with that opinion.
I've held the same opinion for quite a while, and regularly advise people with mysterious problems in an amp or effect to simply replace all the electros if it's more than a couple of decades old. But then we got into -this-.
It seems that there is a dedicated corps of people who think that protectively and proactively replacing electros is not only wasteful, it borders on evil.
Last edited by R.G.; 11-08-2009, 03:41 AM.
Reason: ... can't spell...
Amazing!! Who would ever have guessed that someone who villified the evil rich people would begin happily accepting their millions in speaking fees!
I have a guy on another forum who is a constant source of amazement, and he was ranting and raving how he couldn;t find out who the "6th Jackson Brother" was.
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