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Old 7th Jul 2017, 12:45 am   #1
Martin G7MRV
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Default Hitachi V-212 Oscilloscope in need of service advice

Hi All,

My Hitachi V-212 20MHz Dual Trace 'scope is showing its age and doing some very odd things, im looking for advice on what to check and fix/adjust to give it a bit of an overhaul,

I think probably the switches need a clean, and certainly the BNCs need tightening up!

But it also does odd things such as the size of the trace getting bigger or smaller in apparent amplitude as the vertical centre position is adjusted?

If anyone knows where I can obtain a service manual/alignment guide, i'd also be grateful,

Regards
Martin
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Old 7th Jul 2017, 1:30 am   #2
SiriusHardware
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Default Re: Hitachi V-212 Oscilloscope in need of service advice

Hello Martin, if no-one can point you to a PDF within a reasonable time scale I believe I have a paper copy of the manual which includes the circuit diagrams. I could pick it apart and copy it for you. We have about eight of these still in day-long use at work and I own one myself as well.

I've recently had to sideline one at work due to failure of the potted HT transformer, but I hung onto it and kept it complete as a potential donor for parts to keep the others going. If you find yourself needing anything (else) for yours, let me know.

Mostly a combination of switch cleaning and occasional power supply cap replacement has kept our little fleet going. You will also probably find circular cracks in the solder around the legs of any PCB mounted semis which get warm in normal use. I routinely resolder them if I have the PCBs out for any other reason.
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Old 7th Jul 2017, 1:41 am   #3
Martin G7MRV
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Default Re: Hitachi V-212 Oscilloscope in need of service advice

Cheers, well the HT seems to be one thing that is working! Never thought of dry joints but that makes sense.

Managed to find a service manual online, its a bit of a rough scan but mostly readable. The PCB layout diagrams are appalling but the schematics are not too bad!

I just hope I have better luck servicing this than im having trying to fix my Marconi 2955B!
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Old 7th Jul 2017, 8:05 am   #4
CambridgeWorks
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Default Re: Hitachi V-212 Oscilloscope in need of service advice

I had one that worked when it wanted. Turned out to be dryjoint on a pcb mount connector pin. Took a bit of waggling of plugs and harness to locate it.
I will look this morning to see if I have any manual copy.
Rob
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Old 7th Jul 2017, 9:06 am   #5
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Default Re: Hitachi V-212 Oscilloscope in need of service advice

Martin, you are in luck! I have 5x pdf of the manual. I copied and split into parts to email.
pm your email address and I will send them to you. Around 15Mb the 5 in total.
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Old 7th Jul 2017, 9:15 am   #6
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Default Re: Hitachi V-212 Oscilloscope in need of service advice

Hi Martin,

You can downlod your manual_ they has some another versions too...

Karl
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Old 7th Jul 2017, 9:18 am   #7
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Default Re: Hitachi V-212 Oscilloscope in need of service advice

mine has a Dicky on off switch I have to wobble it sometimes , one day I will replace it
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Old 9th Jul 2017, 5:20 am   #8
Martin G7MRV
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Default Re: Hitachi V-212 Oscilloscope in need of service advice

Cheers all,

Managed to get the service manual online,

so far only had time for a quick visual inspection and a squirt of switch cleaner on the open wafers of the timebase switch.

Most of the other rotary switches seem to be sealed/moulded, so not at all sure how to clean those!

When Im next free to work on it (annoyingly, gainfull employment keeps getting in the way!) I think i'll take the PCBs out and give the soldering a good going over.
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Old 12th Jul 2017, 2:37 pm   #9
Martin G7MRV
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Default Re: Hitachi V-212 Oscilloscope in need of service advice

Well, ive had it all apart, every switch and pot blasted with Servisol, any joints on the PCB that looked off resoldered, connectors tightened etc etc,

It seems to be happy now
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