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gcwills 25th April 2012 12:22 PM

Schematic for a Heath IO-4540???
Hi - can anyone assist with a schematic for a Heath IO-4540 oscilloscope? This unit was also sold under the Bell and Howell brand as a 10D-4540.

The Heath construction manual is a #9570 for this CRO.

If anyone can help, I'd really appreciate it:)

Simon B 25th April 2012 02:42 PM

Nothing for Heath or Bell and Howell on BAMA, which is always worth checking, you might have some joy with this:

I've no experience of them, but possibly worth a shot?

PChi 25th April 2012 03:01 PM

You have probaly found this site already Heathkit Schematic Diagram Archive
The closest model number is IO-4550

gcwills 26th April 2012 04:19 AM

Thanks guys for your help - yes I have found the other Heath models, but am yet to find a schematic for the 4540. Have registered with - will see how that goes. Anyone else out there with the 4540 schematic??

Enzo 26th April 2012 07:18 AM

Have you downloaded the 4550 to compare to your unit? If they are very similar, it may be enough. Even if they are quite different, it may be that the section of the unit you are servicing may be similar or the same as some other model. Many product lines have "family resemblance" within the model range.

gcwills 26th April 2012 07:26 AM

Thanks for your suggestion Enzo - I have downloaded the Heath 4105, 4205 and 4550 schematics and they all differ substantially from the 4540 - still hoping someone will have the 4540 schematic;)

mrmodemhead 28th April 2012 04:32 PM

4 Attachment(s)
Good news and bad news. Good: I built that scope (Heathkit IO-4540 5MHz single-trace) as a teenager, and I still have both the scope and the manual, complete with schematic. Bad: I don't own a scanner, and even if I did, the schematic is a 31" x 20" single sheet. But I hung it on the wall and took a photo of each quadrant, and they're fairly readable at 100%. Hope it helps.

gcwills 29th April 2012 03:57 AM

Thanks! Really appreciate the time you took to post these photos - quite readable for service work and will work fine for me.

mrmodemhead 29th April 2012 12:30 PM

Glad you found it useful. If you need anything else from the manual, let me know. Post, PM, email, etc.

divadg 10th June 2012 12:17 AM

I copy the image as but it just a thumbnail. To you have the original jpg files I could download.


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