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#1
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Wanted - Manuals for Heathkit IO-4555 O-Scope
Hi, I have an IO-4555 Heathkit O-Scope that started spewing out smoke
15 seconds after turning it on. Would like to find someone that can shoot me a PDF of the assembly manual with schematics. The operations manual would be nice also. I've checked Google and Dogpile for variations and can only find a schematic for the dual trace version. (IO-4550) A few places are selling the manuals for a goofy amount of money. I may have some files, templates, webspace, etc. that I can offer for trade. Tim - WD8MQF http://www.frakkedmatch.com |
#2
Posted to rec.radio.swap,rec.radio.amateur.boatanchors,rec.radio.amateur.swap,rec.radio.amateur.equipment,rec.audio.tubes
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Wanted - Manuals for Heathkit IO-4555 O-Scope
wrote:
Hi, I have an IO-4555 Heathkit O-Scope that started spewing out smoke 15 seconds after turning it on. One of two things happened. Either an electrolytic cap failed, or the power transformer failed. The power transformers on these were very cheaply made, and the high voltage winding had a bad tendency to short to the case. If it made a loud snapping sound, it was probably the transformer. If it made a smell that was more sharp and chemical than ordinary burning, it was probably a cap. Would like to find someone that can shoot me a PDF of the assembly manual with schematics. The operations manual would be nice also. I've checked Google and Dogpile for variations and can only find a schematic for the dual trace version. (IO-4550) That'll probably be sufficient since the supply is more or less the same and it's a power supply problem you've encountered. You may also look on BAMA. You should not need the manual. Find the high voltage winding that generates the anode voltage for the CRT.... measure resistance to ground and you should see at least hundreds of ohms across the winding. Then look at the supply caps. You can also try powering it up with the case off and seeing what smokes. If the transformer is good, it's worth it to replace the caps. If the transformer has failed, scrap it for parts and get another scope. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#3
Posted to rec.radio.swap,rec.radio.amateur.boatanchors,rec.radio.amateur.swap,rec.radio.amateur.equipment,rec.audio.tubes
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Wanted - Manuals for Heathkit IO-4555 O-Scope
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#4
Posted to rec.radio.swap,rec.radio.amateur.boatanchors,rec.radio.amateur.swap,rec.radio.amateur.equipment,rec.audio.tubes
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Wanted - Manuals for Heathkit IO-4555 O-Scope
wrote:
Thanks for the trouble shooting tips. The smell and color reminded me more of frying resistors :-) I haven't opened her up yet to peek at the damage. Pull the case open and look inside! If you see some big resistors in the power supply gone open, check the capacitors downstream of them for a dead short. You'll never know until you open it! They are fun and easy to work on... everything is laid out very openly and the basic design you can figure out by looking for the most part. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#5
Posted to rec.radio.swap,rec.radio.amateur.boatanchors,rec.radio.amateur.equipment,rec.audio.tubes
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Wanted - Manuals for Heathkit IO-4555
On Apr 25, 7:37 am, (Scott Dorsey) wrote:
wrote: Hi, I have an IO-4555 Heathkit O-Scope that started spewing out smoke 15 seconds after turning it on. One of two things happened. Either an electrolytic cap failed, or the power transformer failed. The power transformers on these were very cheaply made, and the high voltage winding had a bad tendency to short to the case. If it made a loud snapping sound, it was probably the transformer. If it made a smell that was more sharp and chemical than ordinary burning, it was probably a cap. Would like to find someone that can shoot me a PDF of the assembly manual with schematics. The operations manual would be nice also. I've checked Google and Dogpile for variations and can only find a schematic for the dual trace version. (IO-4550) That'll probably be sufficient since the supply is more or less the same and it's a power supply problem you've encountered. You may also look on BAMA. You should not need the manual. Find the high voltage winding that generates the anode voltage for the CRT.... measure resistance to ground and you should see at least hundreds of ohms across the winding. Then look at the supply caps. You can also try powering it up with the case off and seeing what smokes. If the transformer is good, it's worth it to replace the caps. If the transformer has failed, scrap it for parts and get another scope. If you want a vintage scope get a Tek, since the toob models have excellent parts availability since no revenue users want them. The Heathkit trafo could be rewound if you really want an educational project, but most were not very good scopes except for X-Y use. In the SSTV days they were ham-popular since they used a commodity jug that could be had with a P7 phosphor. that also makes a great audio level indicator if you're too cheap to buy a Dorrough. |
#6
Posted to rec.radio.swap,rec.radio.amateur.boatanchors,rec.radio.amateur.equipment,rec.audio.tubes
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Wanted - Manuals for Heathkit IO-4555
On Apr 25, 7:37 am, (Scott Dorsey) wrote:
wrote: Hi, I have an IO-4555 Heathkit O-Scope that started spewing out smoke 15 seconds after turning it on. One of two things happened. Either an electrolytic cap failed, or the power transformer failed. The power transformers on these were very cheaply made, and the high voltage winding had a bad tendency to short to the case. If it made a loud snapping sound, it was probably the transformer. If it made a smell that was more sharp and chemical than ordinary burning, it was probably a cap. Would like to find someone that can shoot me a PDF of the assembly manual with schematics. The operations manual would be nice also. I've checked Google and Dogpile for variations and can only find a schematic for the dual trace version. (IO-4550) That'll probably be sufficient since the supply is more or less the same and it's a power supply problem you've encountered. You may also look on BAMA. You should not need the manual. Find the high voltage winding that generates the anode voltage for the CRT.... measure resistance to ground and you should see at least hundreds of ohms across the winding. Then look at the supply caps. You can also try powering it up with the case off and seeing what smokes. If the transformer is good, it's worth it to replace the caps. If the transformer has failed, scrap it for parts and get another scope. If you want a vintage scope get a Tek, since the toob models have excellent parts availability since no revenue users want them. The Heathkit trafo could be rewound if you really want an educational project, but most were not very good scopes except for X-Y use. In the SSTV days they were ham-popular since they used a commodity jug that could be had with a P7 phosphor. that also makes a great audio level indicator if you're too cheap to buy a Dorrough. This is mainly for my son to learn to work on audio amplifiers. He's a budding rock star that loves the sound of a tube amp. So I'm picking up some simple test equipment for him to work with. VOM, scope, freq counter, function generator (computer based), etc. I also have an old electronics course for him to learn. I hope that he's going to turn into a good repair tech for his equipment of choice. I do have another scope but I would rather he use the Heathkit. When I get the time I'll tear apart the heathkit and check out that power supply or make him do it. |
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