Heathkit IO-103 oscilloscope

[pchilson]

Hey,

Found this the other day on the local CL. Offered the guy $10 and he said sure. I went to pick it up and it wouldn't power on so the guy just gave it to me. There was no fuse installed... Anyway, there was no manual or probe with it.

Question, anyone have a manual in pdf or other format for one of these that could be shared?

Question, when looking for a probe anyone recommed one and a link to what you recommend?

Thanks

[tim]

There are lots of sites on the web that have manuals for heatkits...there is a heathkit collectors website that would probably have a manual for you...do a search on google.

Any old 10:1 probe will work for audio work.

[tim]

A quick Google search netted me this:

http://www.vintage-radio.info/heathkit/

There's a schematic in ZIP format on there for this scope...Google is a powerful and wonderful search engine...

[pchilson]

Thanks tim but I've had no problem finding the schematic. Its the manual I'm after...
Thanks about the probe info.

[pchilson]

Well apparently the fuse missing is only part of the story.

Upon inserting a new 1 amp slo-blo fuse it takes it out on powerup.
I inserted a 2 amp fast blo and the unit stays on giving me enough time to take some measurements.
The PT has 5 windings:
1 x 650 VAC
1 x 160 VAC
1 x 36 VAC
2 x 6.3 VAC
1 x 1 VAC

I get no reading on the 36 winding and the wrong reading on the 160 winding. I can't get at the 6.3 without major deconstruction of the chassis.

While on the CRT displays the "dot" in the center of the CRT. I can manipulate the "dot" in focus, intensity and brightness but cannot move it with the vertical or horizontal adjustments. After a few minutes of being powered up the PT starts to get hot and sounds like its cooking.
Sounds like the PT has lost a couple windings?
How and/or where would I source a suitable replacement?
Original part number on the transformer is "54-285"
Thanks for any help and suggestions.

[tim]

I had several of those o'scopes back in the 70-80's and they all cooked the PT. Not sure whether it was a poor design or not. I suspect it was. I now use Tek 465's..great scope, easy to find and fix and they are everywhere for great prices and perfect for anythig I do in here. The last one I bought was $100 and works great.

[pchilson]

Hmmm, sounds like I should scrap it then.

[pchilson]

Any help on how to find this type of PT?

[tim]

Unfortunately no ideas, unless you find another one with the power trafo OK. I doubt you'll find just a PT somewhere and it's certainly not worth having one made for it.

[pchilson]

Thanks tim, I'll just grab any useable parts and line the bottom of the dumpster with the rest.

[pchilson]

Thanks tim, I'll just grab any useable parts and line the bottom of the dumpster with the rest.

Well I'm going to resurrect this thread as I did not scrap this scope. I pulled it out from under the bench the other day and started futzing with it again.
I have access to the schematic but no other documentation containing parts lists.

The rectifier diodes are short.
The 1N4001 is just in the picture for size reference. The markings on the larger one is a "57" some space "27". No other markings. I don't know what to use.
Can anyone ID these and suggest some appropriate replacements for these?
TIA

[52 Bill]

The rectifier diodes are short.
The 1N4001 is just in the picture for size reference. The markings on the larger one is a "57" some space "27". No other markings. I don't know what to use.
Can anyone ID these and suggest some appropriate replacements for these?
TIA

The online cross reference sez that the 57-27 diode is a 1N2071 or a 1N4005, 1A 600V.

[pchilson]

The online cross reference sez that the 57-27 diode is a 1N2071 or a 1N4005, 1A 600V.

Thanks for that Bill. Where is this online reference?

[pchilson]

Never mind. I found the cross reference. Didn't know that existed.

Anyway. I have some UF4007s here. They sound like they could do the trick or no?

[52 Bill]

Never mind. I found the cross reference. Didn't know that existed.

Anyway. I have some UF4007s here. They sound like they could do the trick or no?

Yes, faster version of a 1N4007.