capanalyzer 88 series 11

[clydey]

i was wondering if any of the techs are using these and if it is any good.
i understand there is equivalent devices on the market and that you can do cap checking by substitution but was really looking for opinions from techs who have bought this device. cheers

[jrfrond]

Purchased it a long time ago just for the heck of it. Returned it almost immediately. I found it utterly useless. My Wavetek LCR55 is way more useful in checking caps.

[ParthaD]

Works great for me!

Hi Clydey, I started messing around with old amps as a hobby 2-3 months ago, obviously am not a pro like others on the group. Got this item from ebay around the same time and have had amazing luck fixing amps with it, and a variac + ammeter, contrary to popular notion I wanted that more than the much revered light bulb limiter method - just catches my fancy to slowly ramp up volts with an eye on the current draw rather than blast the amps with full voltage and just trust a bulb to give out even though that works too. I have posted questions about only 2-3 amps here but have so far successfully fixed over a dozen amps - including tube amps (from not being able to read a schematic to that in less than 4 months is not bad right?!!.)

Let me give you just one example of how good this is. Got my hands on a 77 Deuce which somebody sold me as one with no sound but said that the tubes were all lighting fine. When I get it I see that the area surrounding the tubes is completely brown but he was right, the tubes were indeed lighting up. So I open it up and whatdya know, there is no fuse - I mean there's just a HOLE where the fuse assembly was, somebody has hardwired a bypass and the standard 400ohm power resistor in that is black and busted.

Had researched this amp on MEF (what an awesome site with some amazingly helpful people) and knew that resistor as a trouble point. The surface of some of the caps in there had tiny bubbles on the plastic, not the standard bubbling of a bad cap round the ends - looked like the SURFACE had been subjected to tremendous heat. So I shake my head and think I'll have to replace all these caps, especially since this is from 1977 - but just to be sure, I fire up the trusty 88A. Start checking each of the dozen or so caps and identify just TWO of the most unlikely caps (neither being the largest power caps in this amp) flagged as bad. The power caps were in the yellow zone but not bad.

A word here about the device itself, it can only handle caps from .47 to 2.2k mfd. Hence it will be useless for small value Orange Drop type caps or very large ones. If the cap has shorted out, this will catch it, also if it is borderline bad. It also comes with a forcep-type permanently attached probe so one needs to attach clip wires to test large sized caps. Also this is obvious but you use it with the amp powered off. You don't even have to discharge the larger caps, it does it automatically. And of course it works IN-CIRCUIT which is the best part!!!

So I install the missing fuse assembly, replace the resistor and the bad caps and then power it up with the variac plugged into a digital ammeter (a $20 "Kill a Watt" made in china item from ebay), and see that the power lamp comes on right around 70-80 volts but no sudden large amp draw. So I put in all the old tubes and repeat and find that the current starts ramping up pretty quick so I take them all out and try one tube at a time and quickly identify 2 tubes as bad. This amp works with only 2 out of 4 tubes in place too. By the way if you've never seen what happens when a power resistor is pushed to the limit (I mean everyone has seen them AFTER they fail, but happening right in front of your eyes is a sight, right around 80 volts when I was testing with all the tubes initially, it started drawing around 3.5 amps and the power resistor turned RED and actually became translucent (it is otherwise dark brown in color), a mesmerizing sight - of course I shut it down pretty quick - no permanent damage to that resistor surprisingly - even the white writing on it was still white!

Anyway that amp is now fully functional with no hum even!!! I will not bore you with other similar cases where it has helped me zero in on bad caps without even powering an amp on but to me it is worth the price of $160 that I paid for it.

Like some other respected folks on this forum, I too don't like the notion of replacing all the caps in a vintage amp just because it is old. But some will go bad obviously and this little tool will help you find them!

regards and good luck!

[Fragger]

Thanks ParthaD for that, I was was trying to figure a "cost effective" way to add an ammeter to my very old variac.

Sounds like a "kill-a-watt" might be the ticket.

[Steve Conner]

A Kill-A-Watt is a handy thing (I have one in the shop too) but be aware of the following:

1. If you put the Kill-A-Watt on the line side of the variac, it can't see the actual current drawn by the device under test. When the variac is turned down low, transformer action makes the line current much less than the current delivered to the DUT. This is also why you must fuse the brush on your variac: if you only fuse the line side, you can still burn out the brush when you turn the variac up on a shorted load.

2. If you put the Kill-A-Watt on the load side, well, it's powered from the same voltage that it measures. So it won't display anything until the variac is up to maybe 30, 40, 50 volts, by which time it could be too late.

[Prairie Dawg]

Thanks ParthaD for that, I was was trying to figure a "cost effective" way to add an ammeter to my very old variac.

Sounds like a "kill-a-watt" might be the ticket.

Mount a couple of binding posts and use a multimeter. I did that with my older than time Superior Adjust-a-volt.

[clydey]

thanks for all the replies
the fact that i am in the uk it is costing $219 and another $92.93 shipping by fedex i noticed a post by enzo where he had bought a sencore cap inductor analyzer which lay unused after the novelty wore off.i would rather purchase the right piece of equipment once so the jury is still out and the problem is the wife is looking for a new washing machine/ talk about loaves and fishes
cheers

[Gtr_tech]

I love my Sencore LC77 (I have 2). Checks caps for value, leakage, dielectric absorbtion, and ESR. True it does just sit there until its needed, but its nice to have it there. Useful for checking coils in wah pedals too. Those building pickups would find it handy for measuring the inductance and capacitance for blueprinting new builds to maintain consistancy.

75% of the test gear on my bench gets used once in a while. Most used? Fluke 79 meter, B&K 520b transistor checker, B&K 3025 function generator, and my trusty old B&K 1540 scope. Meat and potatos....

[Enzo]

You do want to monitor mains current coming out of your variac into the DUT. But you don;t need anything fancy. In fact, it doesn't even have to be very accuracte. A basic AC current panel meter. 0-10A, 0-20 amps, whatever. When I fire up some amp on the variac, and I see the current ramping up fast b y the time the mains is only at 20v or something, I really don;t care if the meter said 4.6 amps or 3.9. All I wanted to see was the trend. SO any dumb meter that can handle the current will be fine.

Somewhere around here I have a small box with a meter in it, and two binding posts. It was my original ammeter. You can make something semipermanent. Mount an ammeter in a box in series with an outlet. SCrew it to the bench. Trail a mains cord out the rear. You can plug that into the wall for simple monitoring, or you can plug it into the variac for that.