Oscope ?

[gtrplayr1976]

Also found this one which looks like it could use some work.

[olddawg]

Way too much for my pockets. I have also been told I can use a dimmer switch by an old Fender repairman ,but by the time I put that all together I can buy an inexpensive one. Just need to know what the output amperage should be rated ?

Like I said, this one is way over priced. I posted it for an example of a good bench unit. If you look around you can find one for less than that. The advantage is it is totally isolated, has a voltage and and amp meter, as well as the leakage test. Don't use a triac light dimmer as mentioned before. You can use a combination of an isolation transformer and a cheap variac. But seriously, a lot of mom and pop TV shops went under. There are a lot of these around. Its about the only piece of Sencore equipment i would deliberately own. If you get one for $100 it might be in the ballpark of jury rigging something from a pike of stuff and you have all of the functionality.

[Leo_Gnardo]

Also found this one which looks like it could use some work.

Squinting at that Lab-Volt, one outlet has full 120V at 10A, the other, 0-120V at 1 amp. A versatile unit with 12V AC and DC also BUT BUT BUT 1 amp output variable is too light duty for the amps you'll be working on. Pass...

The one in the funky box looks to be a bit bigger but not much. Maybe 3 Amp. Borderline. Can't run 100W amps off of 3A, they really should have 5A or more. Could run up to 50W safely I think. If it "needs work" pass it by too. Drat....

Have a link to the Chinese one? Never having used or seen a Chinese variac can't vouch for their quality. Might be OK but I'd hate to see you get stung if not.

The search goes on.

[gtrplayr1976]

Well, The Oscope I bought came pretty much destroyed. Now I get to fight with UPS ,and the seller. Oh joy. I did get two 300 watt resistors to use for load.

[olddawg]

Well, The Oscope I bought came pretty much destroyed. Now I get to fight with UPS ,and the seller. Oh joy. I did get two 300 watt resistors to use for load.

Take LOTS of pictures. Don't try to fix it or turn it on. If you used a credit card contact your credit card company, explain the situation, and stop payment if you spent a lot on it. One reason why these things are better done locally.

[gtrplayr1976]

I did take pictures. I did try to power it before I realized the extent of the damage. No worries though the power button won't pop out. With so little damage to the box ,I don't see how the unit was so damaged. It was bubble wrapped too. The stand was bent also. Seems it would have had to have been crushed to do that.

[gtrplayr1976]

So, A friend gave these to me this morning. I have no idea if they work yet. Are they work my time / money ?

[DrGonz78]

When friends GIVE you something it is a good sign that it might not be worth the effort... However, my friend has given me some pretty good test equipment that works rather well. Even one of the techtronics scopes has obvious leaking main filter caps, but still works as it should. Picture say a thousand words but not in this case. You are gonna have to test those on some piece of equipment and I would recommend the output of a throw it away 10-15 watt solid state amp. Test it at the output to see if you can scope the AC signal. Good luck and let us know what you uncover there...

P.S. I would try out that BK precision 1403A first...

[gtrplayr1976]

I have to find some probes that work with these first ,and I think the BK may be the best bet also. Not sure of the variac ,and how to wire it up yet.

[DrGonz78]

The idea that I have been toying with that involves a variac and ammeter is based on something like this...

http://archivedforum.beoworld.org/cf...F00_tester.jpg

I have a schematic for this somewhere but I can't find it at the moment... This thing would make a great testing tool! I will post more on this later... The ultimate light bulb meter!!

[Leo_Gnardo]

So, A friend gave these to me this morning. I have no idea if they work yet. Are they work my time / money ?

Variac = SCORE! good for you! Think of it as a huge potentiometer across the AC line. Looks like a good-size one too.

edit 1: 6A on the connector plate - 6 amps rated - enough to test 100W amps with room to spare - good! . . . end edit 1.

Squint at the brush - the movable contact - if it looks good then rig up a quick cable to the AC line, and another off the "moving terminal = wiper" with an outlet.

edit 2: for a quick n dirty test, AC line neutral and common to your outlet - "load" to terminal 2. AC line "hot" to terminal 4. Load "hot" to terminal 3, the wiper. This should be OK for an initial test with a light bulb, and ouput will be same as input voltage with knob set at maximum. This variac looks to be the type that COULD be set up for a voltage boost, but if wired as I suggest that won't be the case. And may need to derate a little, to 5A but no harm done there. Any variac experts see where I'm going wrong please speak up. Thanks! . . .end edit 2.

Measure the output with the AC scale on your voltmeter. Don't know yet if this is the 0 to 120V Variac or the type that lets you dial up MORE than line voltage (135-140V). What you read on the voltmeter will tell you what we need to know. Plug in an ordinary light bulb in a lamp. Run it up from zero and watch the lamp go from off to dim to brighter to full brightness. If everything goes smoothly then you have a good 'un. Now rattle up a box to mount it in, put in fuses for input & output, sturdy AC cable, an AC outlet, and you're on your way.

DO be aware that metal parts on the back of the variac are electrically LIVE when power is applied. Don't get shocked while testing it & do make sure there's plenty of clearance in the box you house it in.

Scopes - you'll have to scope 'em out. Hey, the price is right. Hope you can get sorted out on the one that arrived damaged. Darn shame that. Looked like a winner.

[gtrplayr1976]

The idea that I have been toying with that involves a variac and ammeter is based on something like this...

http://archivedforum.beoworld.org/cf...F00_tester.jpg

I have a schematic for this somewhere but I can't find it at the moment... This thing would make a great testing tool! I will post more on this later... The ultimate light bulb meter!!

Yeah that looks awesome. I made a bulb limiter awhile back ,and have used it regular. Thanks !

[gtrplayr1976]

Variac = SCORE! good for you! Think of it as a huge potentiometer across the AC line. Looks like a good-size one too. Squint at the brush - the movable contact - if it looks good then rig up a quick cable to the AC line, and another off the "moving terminal = wiper" with an outlet. Measure the output with the AC scale on your voltmeter. Don't know yet if this is the 0 to 120V Variac or the type that lets you dial up MORE than line voltage (135-140V). What you read on the voltmeter will tell you what we need to know. Plug in an ordinary light bulb in a lamp. Run it up from zero and watch the lamp go from off to dim to brighter to full brightness. If everything goes smoothly then you have a good 'un. Now rattle up a box to mount it in, put in fuses for input & output, sturdy AC cable, an AC outlet, and you're on your way.

DO be aware that metal parts on the back of the variac are electrically LIVE when power is applied. Don't get shocked while testing it & do make sure there's plenty of clearance in the box you house it in.

Scopes - you'll have to scope 'em out. Hey, the price is right. Hope you can get sorted out on the one that arrived damaged. Darn shame that. Looked like a winner.

Thanks Leo !...I think this one has 0-135 volt output according to the data sheet I found on it. They guy that sold me the oscope said he will work with me ,so that still may work out. I think the BK my friend gave me will be the best bet of those if I can figure out what type probe to get ,and if it works .

[gtrplayr1976]

The BK powers up. I guess that's a good sign .

[DrGonz78]

Here is the very simple layout to build the Lamp Limiter with the variac and meters. I like how it has the switch to take the bulb in and out of circuit for different test purposes. Also I am posting the source page to where I discovered this build, so we can read/credit the original post for his contribution. Look towards the bottom of this web page and his schematic is on the next page. I uploaded that image here so you can download it from MEF.

Beomaster 4000 (type 2408) Circuit Differences -

Edit: My one thought here is that it looks like the light bulb is not just in series with hot end of the plug. Does anyone think that the bulb should be wired up differently here?