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 Post subject: Heathkit IO-4550
PostPosted: Jan Sat 06, 2007 9:21 am 
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Joined: Oct Tue 24, 2006 5:53 am
Posts: 51
Location: Manassas, Virginia, USA
Does anyone happen to have the operation and/or assembly manuals for the Heathkit IO-4550 Oscope? I've had one for a number of years, and now want to use it, but have no documentation!

On another note, is there a preferred probe(s) for this unit? That is also something that I did not get with the set.

Thanks!!

Bryan


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 Post subject:
PostPosted: Jan Thu 11, 2007 8:30 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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PM sent.


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 Post subject: Heathkit IO-4550
PostPosted: Jan Tue 20, 2009 1:06 am 
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Joined: Jan Mon 15, 2007 12:55 pm
Posts: 7
Location: Allamuchy NJ
I was given the above 'scope and was told "one channel is out". When I plugged it in, all I got was smoke out the back. Now the pilot lights lights, but I have nothing on the CRT. I was wondering if anyone has any suggestions and/or a user/assembly manual that I could use/borrow/scan so that I could start looking for the bad component(s).

Thanks,

Mike


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 Post subject:
PostPosted: Jan Tue 20, 2009 9:00 pm 
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Joined: Jun Sat 09, 2007 8:14 am
Posts: 4137
Location: Florida
I recently found one of these and also had smoke. Turned out to be shorted tantalum bypass caps. Not too hard to isolate, just follow the smell of burt resistors. After that and cal the scope was ok. Not a Tektronix to be sure, but an ok scope.

RRM


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 Post subject:
PostPosted: Jan Wed 21, 2009 1:12 am 
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Joined: Jan Mon 15, 2007 12:55 pm
Posts: 7
Location: Allamuchy NJ
Thank you very much for following up on my query. I have arranged to borrow a copy of the manual, so could you please point out for me the Heathkit part number of the offending cap? The unit has been sitting in my attic for a couple of years after it "smoked", so I cannot use the "sniff test" to find the bad piece.

Mike


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 Post subject:
PostPosted: Jan Wed 21, 2009 4:47 am 
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Joined: Jun Sat 09, 2007 8:14 am
Posts: 4137
Location: Florida
The bad caps in mine were tantalums on one or both of the 15 volt rails. I don't remember exactly which ones. I think they were the kind that look like jelly beans. Tantalums used to be famous for shorting out.

If you haven't worked on a scope before, be advised that there's about 1700 volts in this one for the CRT. If you get across it you will not be happy.

RRM


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 Post subject:
PostPosted: Jan Sun 25, 2009 1:55 pm 
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Joined: Feb Mon 04, 2008 3:20 am
Posts: 1171
Location: Coopersville, MI 49404-9643
Good suggestion at this point: Tantalum caps, especially old ones, are very prone to shorting out. Best approach ot this scope is to replace ALL the tantalum and electrolytic caps. I did that with all my Heath scopes. They were much happier as was I.

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 Post subject: IO-4550 manual/schematic
PostPosted: Mar Sat 21, 2009 9:07 pm 
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Joined: Mar Sat 21, 2009 8:57 pm
Posts: 5
Location: Wa
Howdy all,

I know this is a somewhat older thread....

I'm looking for a manual for one of these also. BAMA pulled all of their Heathkit manuals because the copyright owner (rightfully so) objected.

Are these manuals around?


Thanks and 73,

Rick
K7MYR


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 Post subject:
PostPosted: Mar Tue 24, 2009 12:16 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3550
Location: Harviell MO USA 63945 (12 miles S of Poplar Bluff)
Heathkit went the el cheapo route in their high voltage systems, often using voltage doublers and triplers on the 60Hz HV transformer to develop the few KV needed in the CRT circuit. I doubt that they ever used a CRT requiring a PDA accereration voltage. But those caps were typically 0.1µF 1KV tubular units, unknown dielectric and they tended to short out a lot. For one, I think they were a bit under the required voltage rating they really needed. Had an IO-104 that drove me nuts with those caps. I finally put in a set that worked long enough for me to get the thing sold.

Dean


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 Post subject:
PostPosted: Mar Wed 25, 2009 5:25 am 
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Joined: Jan Sun 06, 2008 5:49 am
Posts: 74
Location: Lansing Michigan
HI
If you need a part number or size, I can give you the info, or I have the complete manual for the Heathkit IO-4550 scope. It is excellent shape. If anyone is interested, I could put it on EBAY.
Max


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 Post subject:
PostPosted: Apr Mon 06, 2009 8:07 pm 
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Joined: Mar Sat 21, 2009 8:57 pm
Posts: 5
Location: Wa
Hi Max,

I need an IO-4550 manual.

If you want to sell it, I'd love to get it from you.

Just PM me with the info if you like,

Thanks,

Rick


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 Post subject:
PostPosted: Apr Sat 25, 2009 5:03 am 
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Joined: Apr Sat 25, 2009 4:06 am
Posts: 4
I just picked up a IO-4550 and also need a manual. MIne doesn't sweep at all. Anyone got a manual, or a PDF?


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 Post subject: Re: Heathkit IO-4550
PostPosted: Apr Fri 03, 2020 1:31 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 6891
Location: Sunbury, Ohio 43074
OLD THREAD I realize ... but I just "got" one of these and decided to ressurect it for a guy that's only doing audio. Besides I cannot throw anything marked "heathkit" away. I probably should have.

EDIT: Nevermind.... Update: I calibrated it the old fashioned way...fudged it. Thought I'd leave the post up anyway to remind me of my own folly.

Anyway, to make a longer-than-financially-sensible story shorter, it's working now. BUT in all the online manuals I've found, I cannot locate the "operations" section, which includes the detailed calibration/adjustments. While I could probably muddle through and fake it well enough for it's intended purpose, I'd like to return it to near specs if at all possible.

The end of the assy manual has you adjust the power supply and HV, and then refers you to Page 25 of the operation manual, which I do not have, for calibration.

FYI .... y'all know I am never in favor of shotgun replacing all capacitors. This scope was one exception. After it had been on for a few minutes it'd burn up a 10 ohm resistor. Tantalum was shorting after "warming up". I recapped it. No more issues.

Helpppp
Thanks
Barry

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 Post subject: Re: Heathkit IO-4550
PostPosted: Apr Fri 03, 2020 3:33 pm 
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Joined: Mar Thu 15, 2018 2:23 pm
Posts: 350
Barry H Bennett wrote:
The end of the assy manual has you adjust the power supply and HV, and then refers you to Page 25 of the operation manual, which I do not have, for calibration.

I'm pretty sure I have all the information you seek for this scope. I'll pm you a link once I locate it.


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 Post subject: Re: Heathkit IO-4550
PostPosted: Apr Fri 03, 2020 4:11 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 108
Location: Great Salt Lake Valley
Barry,

I have the calibration section for this scope pgs 25-34. I don't even know where I found them, but PM me and I can send them in PDF.

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-Dave


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 Post subject: Re: Heathkit IO-4550
PostPosted: Apr Fri 03, 2020 5:50 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 6891
Location: Sunbury, Ohio 43074
Thanks to both Mr Fabe and Pmeltech.... Fabe shot me the calibration manual this morning.

I think these scopes sell for around $15 at most, if they work. This one didn't. I've got about twice that in capacitors, and probably 3-4 hours into it so far. Last problem was no trigger on Channel 1. Figured out there's a DC zero adjust for each channel. Would have taken a lot less time with the (*&@#&^%(@# Calibration instructions lol. Had to actually remove the input/vert board to get at all the solder points for the new caps. Oh Joy.

Anyway I'll go through the calibration again, WITH the instructions this time, and hopefully once I pass it along, I'll never see it again. ;-)

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https://www.bbtvtestequipment.com


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 Post subject: Re: Heathkit IO-4550
PostPosted: Apr Fri 03, 2020 11:33 pm 
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Joined: Jun Sat 09, 2007 8:14 am
Posts: 4137
Location: Florida
Calibration of this scope comes up from time to time. How about one of you guys who have the data posting it or a link?

RRM


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 Post subject: Re: Heathkit IO-4550
PostPosted: Apr Sat 04, 2020 12:04 am 
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Joined: Mar Thu 15, 2018 2:23 pm
Posts: 350
Retired Radio Man wrote:
Calibration of this scope comes up from time to time. How about one of you guys who have the data posting it or a link?

RRM

You may want to read this regarding the Heathkit copyright issues...

viewtopic.php?t=105023

If you want the calibration information on the IO-4550, I can send you a link via PM. As far as posting the file publicly on the forum, you are welcome to do it yourself. I have no desire to deal with any legal BS whether the ownership rights are valid or not but have no problems with sharing information to a member or members in need.


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 Post subject: Re: Heathkit IO-4550
PostPosted: Apr Sat 04, 2020 12:50 am 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 6891
Location: Sunbury, Ohio 43074
I’ll post it up on my website. If one does not charge for people to read it, is there still a copyright issue? (assuming there’s really is)

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https://www.bbtvtestequipment.com


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 Post subject: Re: Heathkit IO-4550
PostPosted: Apr Sat 04, 2020 1:51 am 
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Joined: Mar Thu 15, 2018 2:23 pm
Posts: 350
Barry H Bennett wrote:
I’ll post it up on my website. If one does not charge for people to read it, is there still a copyright issue? (assuming there’s really is)

In the past, BAMA and Pestingers had hosted a bunch of Heathkit manuals/ schematics but no longer do so. Pestingers posted the information they received from the copyright "owner".

https://www.pestingers.net/pages-images ... anuals.htm

I wish you well in starting a hosting archive that will benefit many of us.


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