Toppled over my analog oscilloscope. Now no display. (Hitachi V-1565)  - Page 1
Forum section: electronics / repair

author: AbsoluteCatalyst
author_rank: Newbie
timestamp: December 03, 2017, 02:41:19 am
content: I screwed up and left my oscilloscope standing upright while I was learning how to use it. Predictably a family member bumped into it and toppled it over. When I picked it up I found that the CRT display no longer functions at all, even after turning it on and off. I'm praying that this might just be an easy fix, maybe something just disconnected internally, but my outlook is grim.Ironically right before it fell, I finally got the hang of it.I've checked the fuses under the power socket and I found them to be seated properly. I've also opened up the scope itself, checked almost all the connectors and found none of themIn their sockets. I've also checked for continuity on the CRT's filament andbetween pins heater 1 and 2, so it seems to still be intact (this was suggested to me by someone on Reddit), and I'm assuming the power supply still functions correctly since the buttons and LED's for the front panel still work as normal.There was nothing loose or broken inside of the casing either, and the CRT glass is intact.If anyone can offer any advice or help on as to what to look for in a case such as this, or if anyone has gone through this before, I'd really appreciate your input!This oscilloscope was an awesome gift from my girlfriend's father (same as the multimeter), and I genuinely really liked this scope. I'mreallyhoping I can figure out what broke and if I can repair it instead of just replacing it with a digital scope.

author: xrunner
author_rank: Super Contributor
timestamp: December 03, 2017, 02:49:00 am
content: Do you see any signs that anything else is functioning, such as front panel lights or anything else?

author: AbsoluteCatalyst
author_rank: Newbie
timestamp: December 03, 2017, 03:00:23 am
content: Quote from: xrunner on December 03, 2017, 02:49:00 amYeah the small lights on the front panel still work. The buttons are also responsive (the TIME/DIV switch's "Auto" mode lights up when pressed, Selector lever still cycles through etc)

author: xrunner
author_rank: Super Contributor
timestamp: December 03, 2017, 03:16:10 am
content: Quote from: AbsoluteCatalyst on December 03, 2017, 03:00:23 amWell ... unless you can verify the high voltage is present, it's possible that the physical shock has damaged the interior components of the CRT. Let's see who else has ideas.

author: duak
author_rank: Super Contributor
timestamp: December 03, 2017, 04:49:42 pm
content: When you confirmed continuity between pins 1 & 2 of the CRT, was that with the CRT socket disconnected? ie., just the CRT heater by itself? Unfortunately, the electron gun assembly in a CRT is fragile and easy to damage especially with power applied because of the high temperature of the heater.With any luck, it might be a problem outside the CRT. If you can't find a schematic look for a pinout of the CRT. You'll have to find some safe way to measure high voltages. The cathode and control grids should be something like minus 1-2 KV relative to circuit common. The deflection plates should be around 100 V. The PDA (Post Deflection Acceleration, probably a separate lead to the bell of the CRT) could be 3 to 10 KV.Best o' luck,

author: alsetalokin4017
author_rank: Super Contributor
timestamp: December 03, 2017, 05:09:27 pm
content: ^ This.Confirm that the CRT heater is intact, preferably by actually observing the glow in the neck of the tube when powered on. Needless to say, don't kill yourself by inadvertently bridging some HV with your body parts. To use the resistance measurement you must first unplug the socket from the CRT and assure that you are measuring the correct pins on the CRT itself. Beware, again, because parts of the scope can still retain a high voltage charge even when the scope is off and unplugged.

author: Cyberdragon
author_rank: Super Contributor
timestamp: December 03, 2017, 07:55:44 pm
content: Check the CRT anode connector and see if it's loose. If it has one of those aweful pin type anodes the pin socket in the connector fatigues and pops off. It may or may not go back on, replace it if it doesn't.Other things to check from shock are board to board interconnects, they may have come loose or broken their solder joints. Also check for cracks on the traces, which may be microscopic and only detectable by testing. Poking around in it with something non-conductive while it's powered can help find these.

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: December 04, 2017, 09:52:11 am
content: This may seem like a silly comment, but have you checked all of the settings?I am not familiar with the Hitachi V1565, but banks of interlocking push buttons sometimes all 'jump out' when subjected to shocks. Position pots, especially vertical, can catch one outRegards, BT

author: Cyberdragon
author_rank: Super Contributor
timestamp: December 04, 2017, 08:06:47 pm
content: Quote from: BurningTantalum on December 04, 2017, 09:52:11 amThe pots maybe, but I don't know of any scope that just dies because all of the buttons are out, there should still be something on the CRT.

author: Bashstreet
author_rank: Frequent Contributor
timestamp: December 04, 2017, 08:56:28 pm
content: Right.Sorry for your bad luck with the scopeUnplug the scope from outletFirst i would check all the board inter connects leads front panel contacts PSU connectors etc etc.Those can get dislodged by shock quite commonly.Next check for any physical damage on the board (cracks chips etc) Twist boards carefully to reveal any hidden cracking (use care and not too much force)After that do careful physical study of the structure paying attention of stress points (Especially case screw areas where the shock will have transferred to internal components.)If all these steps show now damage you should progress to checking the voltages.Plug the device and turn it on (do not do this unless you are aware of the dangers of high voltage and are comfortable progressing. Use care be awareUse manual to find the voltage test points.Go through full voltage testing of all boardsIf all voltages are fine you should move to troubleshooting actual CRT what i believe is most likely culprit (do not skip the other steps as they will rule out other possible malfunctions)Unplug power (not just turn it off)Word of warning CRT's are dangerous best of times and study carefully what you can and cannot do with CRT'sAgain do not progress unless you are sure you know what you are doing.Make physical study of the CRT observe any outward physical damage do careful study with magnifying class or other suitable optical assist.Again pay particular attention to the stress points (where case makes contact with the CRT and ESPECIALLY the neck that is the weakest point in CRT.make sure neck board is attached well (again remember safety and checking the board is well seated can be done with plastic tool rather than touching it) use care!Now all these steps might show no issue but as the reason of the malfunction was caused by concussive force it is possible if not likely CRT is internally brokenTo verify this you will need some specialist equipment and a specialist.Do not fool around with CRT's with power on or fiddle with the nippleand i am not talking about the good kind.Good luck keep us posted how you progress

author: Cyberdragon
author_rank: Super Contributor
timestamp: December 04, 2017, 10:47:53 pm
content: I was under the impression CRTs implode if cracked. Also the filament would have gone pop too if it vented.

author: buck converter
author_rank: Regular Contributor
timestamp: December 04, 2017, 11:24:42 pm
content: You might be able to sell it on eBay as "not tested" for 100 USD

author: vk6zgo
author_rank: Super Contributor
timestamp: December 04, 2017, 11:57:20 pm
content: Quote from: Cyberdragon on December 04, 2017, 10:47:53 pmCRTs in analog 'scopes are much smaller than those in TVs, & hence, the air pressure on their surface is not near as great, also, the glass is proportionally thicker.A crack will normally just ruin the vacuum, with no dramatic effects.The very large RADAR CRTs which were commonly available surplus after WW2 were well known for implosions, as were some early TV CRTs, but small CRTs as used in ' scopes & TV CRTs made after the early 1960s are pretty much immune to such happenings, unless you work really hard to cause one.

author: rbm
author_rank: Regular Contributor
timestamp: December 05, 2017, 12:28:10 am
content: PM sent.Also, check outGrumpydoc's teardown of the sister scope, v-1065. It's a good reference thread.

author: james_s
author_rank: Super Contributor
timestamp: December 05, 2017, 12:29:23 am
content: Especially if it happens in the neck area, I've seen CRTs that had cracked necks but were otherwise intact, and the evacuation pip in the middle of the neck pins is easy to break. If it loses vacuum the filament will quickly burn out though, and if there's a visible getter in the neck it will change from silver to milky white.

author: Bashstreet
author_rank: Frequent Contributor
timestamp: December 05, 2017, 02:08:49 am
content: Quote from: james_s on December 05, 2017, 12:29:23 amYeah pretty much so.It is not always obvious when small CRT is broken

author: AbsoluteCatalyst
author_rank: Newbie
timestamp: December 07, 2017, 01:49:02 am
content: Thank all of you for your support and advice! Sorry I wasn't able to respond, finals week is coming along so I haven't had a chance to work on it as I would have liked, which kinda sucks.I'll try out some of your suggestions soon and keep this thread updated!Another thing I may have failed to mention was that despite receiving a resistance reading, I do not see the filament lighting up at all when on. (Or at least from what I could see with the metal shroud over it.)The only thing that worries me though is that I've never truly worked with high voltages, and not that i'm intimidated about injury or etc, but more so I'm not sure if I have the right equipment and the last thing I want to do is destroy my fluke multimeter as well. (Another gift)I've asked around acquaintances and even professors at my campus, no one knows how to deal with something like this. I'm completely out of luck with any outside help besides these forums, so thank you!

author: Cyberdragon
author_rank: Super Contributor
timestamp: December 07, 2017, 05:17:01 am
content: Did you check the filament with the tube unplugged? Otherwise you're just reading the transformer.

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: December 07, 2017, 12:24:58 pm
content: Sorry, Cyber Dragon - My post re the switches etc was not clear. In light of the assumption that the OP was fairly new to scopes, I thought that the trace could have been absent or 'hidden' due to switch positions.50 years of using scopes, and 30 years with my 'go-to' old CRT model and I switched it on yesterday and - no trace. I'm ashamed to say I faffed about for a good 60 seconds before I found a trace !!BT

author: rbm
author_rank: Regular Contributor
timestamp: December 07, 2017, 10:28:44 pm
content: The V-1565 has an on-screen display, so even if the trace was "missing", the OSD characters would be present. There's also a boot-up sequence that displays during power on that is independent of the dial settings.

author: AbsoluteCatalyst
author_rank: Newbie
timestamp: December 07, 2017, 11:44:39 pm
content: Quote from: BurningTantalum on December 04, 2017, 09:52:11 amThis was one of my first ideas, I also thought it might have just toggled or messed up a setting but sadly regardless of my settings nothing will display. I know when it reboots it goes through a "Calibration" self test which displays on screen, but this is completely absent now. On bootup, the buttons on the front panel still actually stay lit for a couple of seconds like as if it "thinks" it's still going through this test.Quote from: Cyberdragon on December 07, 2017, 05:17:01 amWas this the wrong way to read it?See the pins of the CRT tube on the bottom? That circuit board is normally plugged into it. Pins H1 and H2 are connected to my meter in this photo. (Note I took this off with my bare hands. Was I meant to get electrocuted at that point? Does that mean it no longer stores any charge in that case then?)Quote from: Cyberdragon on December 03, 2017, 07:55:44 pmThe anode seemed pretty well in place when I tugged on it. So did the board sockets themselves with the exception of the delay line which is a little loose on it's circuit board port but not enough to fall out on it's own, and still slides in fairly snugly.I have some free time tonight after class that I'll be able to inspect it more closely. Someone also suggested that the power rails for the CRT may have been damaged.

author: james_s
author_rank: Super Contributor
timestamp: December 08, 2017, 01:38:59 am
content: Without seeing the PCB I can't say how likely it is, but look closely around any heavy components like transformers, chokes or large capacitors, also look around the mounting points. It's not uncommon for equipment subjected to large G forces like this to get cracks in the PCB that can break traces and make it stop working.

author: Zucca
author_rank: Unknown
timestamp: December 08, 2017, 10:44:36 am
content: First, stick it on your Lab door:then move on with the repair.

author: Bashstreet
author_rank: Frequent Contributor
timestamp: December 08, 2017, 07:36:11 pm
content: Quote from: AbsoluteCatalyst on December 07, 2017, 11:44:39 pmDear OP i would suggest to follow the troubleshooting routine rather than randomly poking around.The changes you find the problem in such complex equipment without any thought are slim.

author: Cyberdragon
author_rank: Super Contributor
timestamp: December 08, 2017, 08:55:39 pm
content: I don't think this scope has a troubleshooting guide. I've looked at the manual for the 1065 which should be similar and all it says is refer servicing to a technician.I do have the 1065 schematics though, I'll try to find some voltages for the CRT circuit.

author: james_s
author_rank: Super Contributor
timestamp: December 08, 2017, 09:39:29 pm
content: Well you know the problem occurred when the thing was knocked over, so a good place to start is inspecting very closely for mechanical damage.

author: Bashstreet
author_rank: Frequent Contributor
timestamp: December 09, 2017, 01:38:52 am
content: Quote from: james_s on December 08, 2017, 09:39:29 pmThx as not one has suggest such thing in the topic before youQuote from: Cyberdragon on December 08, 2017, 08:55:39 pmI gave him troubleshooting guide and he ignored it much like you.nm im off to greener pastures!

author: TonyLangley
author_rank: Newbie
timestamp: March 31, 2018, 02:56:44 pm
content: Hello AbsoluteCatalyst:Did you ever resolve your problem? I have an Hitachi V-1060 with a shorted LOPT ( Fly-back transformer ) and need a replacement transformer. I believe it is the same part as in the V-1565.If you may be able to help, would be grateful for reply. Any other members who may be able to help, would be grateful.Thanks

author: Chris56000
author_rank: Frequent Contributor
timestamp: March 31, 2018, 09:22:28 pm
content: Hi!Michanical Parts & Circuits supplement for V695A/V1565A:-https://www.dropbox.com/s/x1ix2cls5nhv6l7/hitachi_v-1565_1560_695_mechanical_parts%5B1%5D.pdf?dl=0Service Manual V695/V1565:-https://www.dropbox.com/s/bztciml13nzlw6m/V-1065A-V1060-V665A-V660-Service%20Manual.pdf?dl=0Owner's Manual with slightly clearer schematics:-https://www.dropbox.com/s/7x3p55wihd6vzxd/hitachi_v-1585-65-60-v-695_om_sch%5B1%5D.pdf?dl=0Hope this helps! Please let us know how you get on - we're all here to help!Have you tried the "Beam Finder" or "Beam Locate" button? This places a partial bias/focus on the CRT and turns off the deflection, and proves the CRT and it's voltage-supplies are basically all present - you should see a fairly bright de-focussed "splodge" on the screen if this circuit and the CRT/voltage supplies are in order!If the beam Finder/Beam Locate does nothing, there is unfortunately, a risk you could have done serious damage!Chris Williams

author: AbsoluteCatalyst
author_rank: Newbie
timestamp: July 05, 2018, 08:04:20 am
content: Hey everyone!After staring at this broken oscilloscope in a cardboard box gathering dust for the past 4-5 months, I finally figured it all out. It's been the thing keeping me up at night.Nope. I still haven't gotten anywhere with it unfortunately. But here goes another shot at it again.Sorry about the late update, I haven't actually worked on it or attempted to repair it again until now.I've looked it over again and here's some notes:(Click my images to see bigger pictures)I removed some of the insulation wrap off the CRT neck to properly inspect it:Getter flash looks good.Shiny chrome/silver, no white at all. Inside components look good. No idea what this black insulation is, but I just quietly wrapped it back on.Then this happened to the yoke coil(Or maybe it was like this already and I didn't catch it.)Fantastic.I re-soldered the red wire back onto the small copper coil wire that was disconnected beneath the yellow insulation tape, but I had to slightly cut through the tape in order to get the wire out. Not sure what kind of tape this actually is. Trying to find some replacement tape.I pushed the wires back under different layers of the tape (as they were before) so they don't make contact to anything else, or each other. Hopefully this doesn't disturb the deflection of the CRT.After looking for cracks on the PCB's as some members have suggested, I found that after gently bending the high voltage/power supply PCB (PEF-999B in my case) that something was "creaking". One of the ground leads of the voltage multiplier (MUT1001) was loose. I re-soldered it, and it sits firmly again. I'm not entirely sure if this could have been a source of my problems, but hey why not? I'll keep checking for damaged traces/loose components.Before I turned it back on to check the voltage rail points, I found something interesting:The schematic for the HV board show a small PCB mount 400mA(?) fuse, F1001, on the +55V line that I didn't notice before.(Page 85 on the owner's manual. Thanks Chris56000!)After checking it's continuity, it seems to be flat out dead.Thing is, it's not an ordinary fuse but is a "Integrated circuit protector"(...So it's a fuse?)A bit of a bizarre fuse package I've never seen before.From what I've found so far, it's an ICP-F15 from ROHM Co. The schematics show a wrong "ICP-F18" for some reason, and it's datasheet shows it as a600mAfuse, not 400mA.The datasheet ishere.What's bizarre is that this fuse is rated for 50V but regardless was placed on the 55V line? Not sure if 5V makes such a difference on a fuse.I found replacement fuses on some sites I've never heard of. I'll try them out anyway.But i'm worried that not too many of these fuses still exist, and if there's more problems on the board, the fuses might blow again when I attempt to test it.Wondering what kind of an effect might occur if I temporarily run a cheaper, more easily available 500-600mA fuse with a higher internal resistance for testing?ICP-F15's seem to only have an internal resistance of 0.135 Ohms. Neat?Anyways, I have good hopes that the CRT tube itself should still be intact, and it leaves me to focus on searching for other problems on the PCBs. I might do something I keep seeing on this forum and recap the boards as well. Wouldn't hurt. I'll keep this updated when I can about my progress and whatever I find, for those interested. Any advice anyone shares is still always welcome!Edit: I just realized I actually haven't worked on it/replied to this thread for more than just "4-5 months". Woosh. How did time fly by so fast!? My bad if i'm necroing this thread. Wow.

author: Gyro
author_rank: Super Contributor
timestamp: July 05, 2018, 08:43:34 am
content: Don't worry too much about that "yoke coil", it is the trace rotation coil (controlled by the trace rotate pot). It operates at low voltage, low current,DCso the odd shorted, or lost, turn (within reason) wouldn't be a disaster. It won't affect deflection. The tape is polyester (transformer tape) but not critical there.Good news that the getter is still intact, I suppose there's still a small risk of bent deflection plates but that would be pessimistic. I think your current line of investigation will hopefully get you there.

author: TERRA Operative
author_rank: Super Contributor
timestamp: July 05, 2018, 10:12:20 am
content: If you are worried about that tape, some Kapton tape will be fine to use there.For the fuse, any PCB mount fuse will do, as long as it has the appropriate current rating and equal or greater voltage rating.

author: Chris56000
author_rank: Frequent Contributor
timestamp: July 05, 2018, 06:58:03 pm
content: Hi!How come the chaps that unfortunately drop these things are in the USA or some other countries where going to help personally is out of the question for me?!Pick up the oscilloscope and hold it VERY FIRMLY with both arms and hands, and move it from side to side and forwards and backwards, listening very carefully for any signs of rattling or anything moving about inside, in particular, any musical or metallic noises may point to physical damage to the CRT's electron gun!If you do this and can hear nothing, refer to the manual and try the "beam finder" button to see the d any illumination of any sort can be seen on or in the CRT itself – if there is none, remove the case of the scope and view it in a darkened room to make sure the heaters are glowing, if they are not, it could be physical/electrical damage to the CRT itself, or almost any part of the circuitry!I'm reluctant to give a detailed fault–finding guide as the OP may not be experienced enough to carry out investigation/repair in complete safety, and in my opinion, I feel the only way forward for the OP is, as other posters have said, put the damaged instrument to one side and obtain another one for testing/experimental purposes!I understand the sentimental value of this instrument to the OP, and in this case, storing it to one side carefully until the OP is adequately skilled to repair it, or get skilled assistance from another Member, is the best way forward from here on!Chris Williams

author: Relayer
author_rank: Contributor
timestamp: July 05, 2018, 11:04:46 pm
content: Hello AbsoluteCatalyst,If you have a variable DC power supply, you can check to see if the heater isopen circuit or not.You only need to de-solder one pin on the neck board either side of the heaterand connect your power supply and slowly feed it until it glows. But DON'T exceed4 volts. If it fails to glow, then the CRT is cactus.If the tube is unserviceable, you might be able to pick one up from eBay, wheresomeone is selling the same model cro, but is faulty for a different reason.Please let us know how you get on.Regards,Relayer

author: james_s
author_rank: Super Contributor
timestamp: July 06, 2018, 01:44:57 am
content: Seems easier to check the heater for continuity with a multimeter than to risk damage by trying to power it.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: July 06, 2018, 03:31:03 am
content: I'm guessing that the Beam Find button doesn't do anything.Therefore the CRT and/or the HV supply are shot.

author: Cyberdragon
author_rank: Super Contributor
timestamp: July 07, 2018, 04:06:19 am
content: He checked the filament along time ago and it seems to have continuity. He hasn't checked to see if it's actually getting power though.Does it make any noise when powered on? (If it does that's good, if not it's ambiguos)

author: AbsoluteCatalyst
author_rank: Newbie
timestamp: July 10, 2018, 02:02:30 am
content: Well.And the little Hitachi lived happily ever after.Wasn't really expecting to repair it so fast since I just started working on it again.All I've been doing since my last post on this thread was just waiting for the new fuse to arrive.Once it was here I soldered it right into place, and what do you know?It's alive. Perfect.The blown pcb fuse is still a mystery to me, maybe a sudden surge due to the impact knocking other heavier components around.Oh well.Thanks for all the help and advice guys!For anyone in the future that finds this thread and has a similar issue and has already done other things mentioned in this thread:Check if your (HIGH VOLTAGE BE WARNED) voltage multiplier's leads are loose if you have one, by flexing the board or gently tugging on it checking for "slack". Mine had a slightly loose lead, and I resoldered it just in case.Not entirely sure if this was the problem from the start, and it just caused my fuse to blow.Check if your fuse (F1001) on the top power supply PCB is still functional (Check for working resistance/continuity) if it isn't, replace it with a new ICP-F15 or similar.It runs on the 55V rail, which is why the buttons lit up, but the CRT didn't.

author: james_s
author_rank: Super Contributor
timestamp: July 10, 2018, 03:31:36 am
content: Did the fuse look blown? They can fail mechanically too, knocking it over could have just broken th element in the fuse.

author: james_s
author_rank: Super Contributor
timestamp: July 10, 2018, 03:40:42 pm
content: Break it open and find out, a blown fuse isn't useful anyway. I'd say it's pretty likely the element inside simply broke mechanically, fuses are normally just a thin wire inside an insulating housing.

author: Chris56000
author_rank: Frequent Contributor
timestamp: July 11, 2018, 10:53:57 am
content: Hi!Well done on getting it going and I'm glad the CRT has survived - Japanese instrument CRTs are very well made and fairly robust!ICP devices do tend to be both electrically and mechanically fragile, the F-type more so than the N-type, also overheating whilst soldering can make them go open-circuit.I'd order a few ICP N-type of the same rating (they look like plastic-case transistors but only two leadout wires) - they will solder into the PCB same as the original device did.Chris Williams

author: rbm
author_rank: Regular Contributor
timestamp: July 11, 2018, 06:24:32 pm
content: Quote from: AbsoluteCatalyst on July 10, 2018, 02:02:30 amThanks AC! I've saved the information in my archives. I have a Hitachi V695 which is very similar to the V1565.

author: padee
author_rank: Newbie
timestamp: August 01, 2020, 07:33:38 am
content: Thanks OP for taking the time to add this post to it's conclusion. I purchased a presumed good v1565 and was refunded when found to be not working. After reading this thread I tested that fuse and got very excited about replacing it! Sure enough I now have a working scope for the price of a fuse