Kikisui model 5650 service manual - Page 1
Forum section: electronics / testgear

author: GreyWoolfe
author_rank: Unknown
timestamp: December 03, 2013, 07:54:14 pm
content: Does anyone out there have a copy of the service manual? Does anyone know where I can find one? A friend asked me to look at her scope. The issue is, as the scope is on, after about 30 minutes, the display starts to fade. With the intensity adjusted all the way, the display will fade out. Unplugging it for a while will bring back the display but it will fade again. I said I would look at it but can't find any info on it.Tom, NW0LF

author: lowimpedance
author_rank: Super Contributor
timestamp: December 03, 2013, 11:15:32 pm
content: Maybe an email to ;http://www.kikusuiamerica.com/contact.phpand ask nicely for the schematics.I noticed they have manuals online but have removed the most useful parts.Any way if no luck I have an 6100a osc. which "may be" vaguely similar in the power supply and CRT ccts.I could upload jpgs of these sections here if you want.BTW when the trace fades is the CRT filament still on??. if not perhaps there is an iffy connection along those lines.

author: GreyWoolfe
author_rank: Unknown
timestamp: December 04, 2013, 12:28:57 am
content: I am not sure about the CRT filament. I think the CRT is still on but not a 100% sure. I turned it on, not taken it apart!. I will have to put a signal to it again and pay closer attention to details. I was waiting for my Fluke high voltage probe to come in and to see if I could find the schematic. I will try the email route.Tom, NW0LF

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: December 04, 2013, 12:48:33 am
content: Downlod the manual and test the voltages ,on page 75 (page 71 on manual)http://www.kikusui.co.jp/kiku_manuals/NUMERIC/5650E_E.PDF

author: GreyWoolfe
author_rank: Unknown
timestamp: December 04, 2013, 04:21:55 am
content: I just checked all of the supply voltages according to the manual. All voltages are well within spec. Since it is getting late and I'd rather not curl what is left of my hair on HV, I will give it rest until tomorrow. I will leave the scope on and when it starts to fade, I will go back and verify the voltages to see if anything drops or increases. I did notice, during an inspection, some corrosion on some filter caps after the bridge rectifiers. I will probably get them and replace them as a precaution. The person who belongs to this scope can't afford to put much money into it and neither can I as it is not mine, but the caps should be cheap and necessary before they blow out and let that lovely smell permeate the air.Tom, NW0LF

author: Marc M.
author_rank: Regular Contributor
timestamp: December 04, 2013, 06:12:02 am
content: Generally speaking, thermal intermittents are usually easy fixes. A can of freeze spray should allow you to narrow down the faulty component in a minimum amount of time. Conversely, if no freeze spray is available, careful application of hot air just after power up may locate it as well. I've found my hot air rework station is great for this because the small nozzle and relatively slow airflow helps to localize the heat. Regarding any sort of service information on Kikusui instruments, I've never had any luck finding it. I picked up 4 DOA PAL 35-10 power supplies off Fleabay a while back. I Googled and posted in forums for service info and came up empty. Unlike HP and Tek, they didn't seem to publish it or otherwise make it available. Their recommendation for faulty equipment was to send it to one of their service centers for repair.Best of luck,Marc - W9OM

author: lowimpedance
author_rank: Super Contributor
timestamp: December 04, 2013, 10:23:06 am
content: Quote from: Marc M. on December 04, 2013, 06:12:02 amThe manuals available online are the published manuals, (At least for the old gear I looked at!), how ever the schematics and PCB component overlays have been deliberately removed from the online version.I have a COS6100a with its manual which has all the schematics etc where as the online version is the same but without that crucial info. (similar vintage to the 5650)As you say the lack of info is to probably to force you to send the unit back for repair at a suitable cost.I had a quick flick through the 6100 manual to see what types of components were used (ie anything custom) and it mostly looks like 'obtainium' rather than 'un-obtainium', which would be promising for future repairs. I assume the 5650 would be similar.

author: GreyWoolfe
author_rank: Unknown
timestamp: December 05, 2013, 01:08:04 pm
content: You have to love simple fixes. Yesterday, I set the scope up with a signal on both channels and after about 15 min the display started to dim. I moved the scope to check the HV TP at the back of the unit and the display brightened and dimmed. I pulled power from the scope and reseated every connector I could find. I powered the scope back up and it sat for about 9 hours with a perfectly clear and undimmed display. Apparently, it was just some connector corrosion that was taken care of by reseating the connections. I will chat with the owner of the scope and see what she wants to do about the bad caps. Thanks for the help everyone.Tom, NW0LF