Heathkit IO-12 oscilloscope

[electra225]

I bought this little scope at an auction. It didn't work at all when I got it. Dead as a hammer. I found the fuse blown, installed a new fuse, then it came to life. But that is about all it will do, the tubes light and I get a trace on the screen if I mess with it long enough. It has ten tubes plus the CRT. All the tubes are Mullard with the exception of the HV rectifier, a 1BC2 and a 6AG5 which are RCA. I don't think the probe I got with it is the right one. Looks identical to the one on my signal tracer. I have to tinker to get a trace on the screen. It is hard to get a straight line on the trace and it is almost impossible to get the trace to stand still, it wants to "twerk" as Shango likes to say. It waves back and forth on the screen. A TV doing that would be suspected of having leaky filter caps in the power supply. I am going thru all my test equipment to get a baseline of operation and to make up a parts list of things I need. I need to get the service literature on this probably first thing. All my test equipment is operational for the most part, but they all need service and maintenance. I believe this will be a nice little scope when I get it sorted. I bought it cheap, and it is in really nice condition.

[electra225]

I had the opportunity to pull a little maintenance on this scope today. One of the controls was frozen, so I freed it. While I was at it, I cleaned the rest of the controls. This seems to have stopped the "twerking" when there was no signal. I have a nice, steady trace. I have determined that the reason I don't get any activity on the screen is because the probe has seen better days. I was fiddling with it and the ground lead broke. Not worth messing with. New ones are available for not much money on ebay. I don't need the finest, nor am I going to use it a lot. I believe this little scope will do all I need it to do, it's small and easy to use. Win-win all around.

[TC Chris]

Was the probe a Heath kit item? I've got a Heath signal tracer and the do-it-yourself probe is a weak link.

Chris Campbell

[William]

I have a scope that was given to me by a friend, he had two and only needed one. I have no idea what to do with a scope, or how to use. What do you actually need a scope for?

Bill

[electra225]

All a scope really is would be a voltmeter with a visual display. More useful in TV work than in audio. I haven't used one much.

[hermitcrab]

if it has both X and Y functions, they can be used to align tape heads on a tape machine or you can troubleshoot stages in a amp or radio looking for distortion , as Greg said it is a visual volt meter

[electra225]

The probe is a Heathkit. I'm not impressed with it like Chris said.

[Firedome]

My little scope from my late uncle, also needing probes. I also don't really know what to do with it but it's cute, evidently the smallest Tek tube scope ever made and used by IBM field techs ("customer engineers"). Got all the manuals, so hopefully I can figure out how to use it sometime.

[electra225]

The trouble I have when I try to use a scope is to get a single trace to stand still. I have trouble getting one trace at a time, instead of having them go all across the screen. I'm sure I'm not saying this right.....

[Firedome]

This 310a does have a steady trace with no inputs, and works, I watched my uncle use it about 8-10 years ago to troubleshoot something, but I don't remember what that was. Tek and HP scopes are incredibly well built so often work well into old age.

[electra225]

I was digging thru a box of miscellaneous cables (I found enough audio cables with RCA jacks to last me and about ten of my closest friends three lifetimes )I found what I assume is the proper probe for this scope. The probe I got with the scope, I THINK, is for a signal tracer or some other device. This probe, the one I found today, is a Heathkit, but I can't read the model number. The ground cable has had "in field modification" but seems to work. I can get a trace, I can adjust it so it is stable. I tinkered with "looking" at the audio output on one channel of my tape deck. There must be something missing from the end of the probe I found, since it terminates with a banana plug. Probably had various ends one could use. I have some female banana plugs around here someplace, so perhaps I can kluge something that will work on the end of the probe. I haven't used a scope much (okay, not hardly at all....) and this will be fun to tinker with. At least I saved this little scope from the landfill and I found lots of cables I didn't know I had. I was "sortin' and tossin'" this afternoon.

[Conelrad]

My little scope from my late uncle, also needing probes. I also don't really know what to do with it but it's cute, evidently the smallest Tek tube scope ever made and used by IBM field techs ("customer engineers"). Got all the manuals, so hopefully I can figure out how to use it sometime.

I have that same scope! It is a great little unit, a real throwback to when tube test gear was built right.

I love how the screen glows a bit after the lights go out.

[William]

I have a Heath 4552 scope (it just says Heath on the front) given to me and have no idea how to use it. Just what would one use a scope for in our hobby? I guess I need to do some Googling.

Bill

[electra225]

What I want this one for is working on the TV in the Stereo Theater and for doing the alignment on my Hallicrafters SX-110 boat anchor. With a scope, one can peak the alignment on even a little AA5 better than with a VTVM connected to the voice coil. All a scope is would be a VTVM that lets you see the voltage you are measuring. You can also find distortion or clipping in an amplifier, providing you know what you are looking at, or looking for. A scope is probably overkill when working on a record player. Guys who use them all the time say a scope is indispensible. I think they are more important working with FM or TV than with audio.

[Conelrad]

Nothing else can measure AM modulation levels as well as a scope, providing you're not blind.

DG

[electra225]

I am either doing something wrong, or this thing isn't working right. If it was a TV set, I'd say the horizontal oscillator was not running at the right speed. I can't get the trace to "stand still". My thinking is the trace should be "solid", but the trace on this instrument seems to "flash" or just jiggles around. I know I'm not using the right terminology. They say to use as little sync as possible, but it seems like the sync control does nothing. The same with the phase control. I'm not even sure what it should do. If this was a TV chassis, I'd be changing caps and testing tubes in the horizontal circuits. It seems like the longer I tinker, the worse this thing gets. It may have a weak CRT. I need the intensity control fairly advanced to get a trace I can see with the shop lights on. The CRT needs to be turned because the line is not straight across the screen. This is a cute little scope and is not huge. I won't use it much, but I have a couple projects I really would like it to be available to use. I don't know what I'm doing, so there is that. Anybody have a suggestion on how to figure out what is going on?

[hermitcrab]

Greg, sounds like a ground problem if the trace is jumping around ...but what do I know

[electra225]

I found a manual for this scope online, downloaded it and may have found my trouble. Most if it was due to pure ignorance. The first thing I did was to confirm the probe I was using was right. IT was not. The probe I was using was for a VTVM or signal tracer. The OTHER one I had was the right one. The first thing I was doing wrong was not letting it warm up. It simply won't work right when it is first started. I let it run with the intensity control all the way down so as to not burn the screen. After that time, I was able to get a stable display, then I get an acceptable trace. It is hard to read the screen graduations on this thing. I have to turn the lights off in the shop, which works a lot better. I believe this thing will serve me well. I just have to remember to let it warm up, then adjust so I get a stable trace.