Heathkit ol-1 oscilloscope help. Can't get solid spot during setup procedure.

[JoeM]

So you can get a sweep, but it goes from upper left to lower right? Maybe the CRT has shifted. Some scopes have a trace rotation adjustment, but on this one maybe you just need to loosen the CRT clamp and physically rotate the CRT so the sweep is horizontal.

[jasonguitar]

So you can get a sweep, but it goes from upper left to lower right? Maybe the CRT has shifted. Some scopes have a trace rotation adjustment, but on this one maybe you just need to loosen the CRT clamp and physically rotate the CRT so the sweep is horizontal.

I think I am mistaken on the sweep. Dont have the unit in front of me. The setup for initial dot indication is adjust the trace with H and V positioning, H and V gains at 0, Hor select full clockwise and Sync amp at 0. This should produce a solid dot. I get the diagonal line shown in the pics above which has improved and shrunk somewhat with partial resistor replacments. Seems like I'm heading in the right direction. The H and V gains stretch the given trace straight across the respective hor and vert lines so the CRT seems to be in correct position and if I had a solid dot it would likely make a solid line horizontaly. Since I'm not getting the dot it simply stretches the given line across instead. The H and V positioning work correctly. The Intensity and focus work correctly. When I jump the 60cyc to vert input I get some action and am able to adjust the sweep. Seems like everything is pretty much functioning.

[Enzo]

Find the power supply caps, ideally use another scope to look at what they are doing. Otherwise, measure the DC voltage ion them and see if it seems reasonqable, but mainly measure them for AC voltage to see how much rippple there is. Caps are suspects, at 50 years old certainly the electrolytics, but also the film caps. When you recapped it, did you replace ALL the caps, or just e-caps?

have you tried different tubes?

Wait, you say you have all the documentation? Like including the schematic? Geez scan that and post it.

[jasonguitar]

I only replaced the electrolytics with fresh caps and brought the unit up slowly on the variac. Haven't touched the others. I will look at the power supply. If thats not a problem, once I have replaced all out of value resistors if there is still an issue I will have to look at the other caps. Hate to touch those cool old yellow spragues. Anyone restoring tweed or brown Fenders would go nuts for em!

I don't have the info on this computer but amazingly I found a link while scanning a forum somewhere with the full manual and schematic. Can't find it in a Google search. I will post them tomorrow. My workshop and studio are at my Dad's house just a couple miles away and that is where the gear and files are. As always thanks for your time. Hasta manana!

[Enzo]

I don't necessarily want you to replace them without question, but if they are leaking, that makes DC go where it is not wanted. And at 50 years, that is always a concern.

Drifted resistors are more likely to alter performance, rather than prevent it. The voltage scales might be off, or the linearity funny so the waveform distorts, or the sweep rates cockeyed, but unless the resistors are WAAAAAY off, if everything else is OK, then the thing should function. Just like a guitar amp.

The deflection is a pretty simple push-pull affair, but a dead tube stage can easily kill the signal.

And while this is a visual device, if you feed some audio signal into it, you can still use a signal tracer to see if it is passing through the scope stages.

If you google "Heathkit OL-1" you will find various references to it and the schematic, and several sources selling it. I wasn;t about to order the stuff myself.

[JoeM]

. Hate to touch those cool old yellow spragues. Anyone restoring tweed or brown Fenders would go nuts for em!...

Some of those old spragues can be leaky. On one of the scope groups, where do you these caps go after they're removed?

[added]

This may not be not be anything to do with your problem, but I picked up a scope a few years back, weird display that just didnt make any sense. I posted the problem to the Tekscopes group on Yahoo. A retired Tek engineer wrote back suggesting I clean the CRT socket - that fixed it. It's common for these guys when they get an old scope to wash them. Sounds weird, but at the Tek service centers, all scopes returned for service were first washed and then dried before any service or calibration.

[JHow]

...It's common for these guys when they get an old scope to wash them. Sounds weird, but at the Tek service centers, all scopes returned for service were first washed and then dried before any service or calibration.

Washed how? Can you elaborate?

[jasonguitar]

Wait, you say you have all the documentation? Like including the schematic? Geez scan that and post it.

Here's the OL-1 manual:

http://www.maintainband.com/AMP%20FILES/OL1_man.pdf

[JoeM]

Here's a good article on the cleaning process used by Tektronix

[JHow]

Thanks for posting this link. I like the old-style mica-cap color code chart included on the cover. I had a copy from a book I have, but this is much clearer.

[Enzo]

Ah, terrific, schematics.

Look lower right corner, the B+ supply. Get out your meter and check all those B+ nodes, A, B, C, D. especially A. Are all those B+ DC voltages reasonable? Now flip the meter to AC volts and remeasure. We are measuring ripple now. A little ripple might be expected on A, but the rest should be real smooth and clean. Zero VAC, that is.

[jasonguitar]

Got so busy today, didn't have time to check it. I will check tomorrow. Thanks!

[jasonguitar]

Ah, terrific, schematics.

Look lower right corner, the B+ supply. Get out your meter and check all those B+ nodes, A, B, C, D. especially A. Are all those B+ DC voltages reasonable? Now flip the meter to AC volts and remeasure. We are measuring ripple now. A little ripple might be expected on A, but the rest should be real smooth and clean. Zero VAC, that is.

Okay, here's what I got: A=412VDC, 2.4VAC B=262VDC, 0VAC C=189VDC, 0VAC D=261VDC, 0VAC

[JoeM]

On page 24 of the manual, there's a voltage chart. I'd go through these first and check. Be careful, some high voltages in that thing.

[jasonguitar]

On page 24 of the manual, there's a voltage chart. I'd go through these first and check. Be careful, some high voltages in that thing.

I checked all the pins on the 12au7s and the 12ax7. Most of the voltages are a slightly higher than the chart but are relatively consistant.