Advice on how to check voltages on tds210 psu towards ccfl transformer. - Page 1
Forum section: electronics / beginners

author: nic77
author_rank: Contributor
timestamp: January 28, 2022, 02:51:33 am
content: Hi to all ,as a beginner ,i really have never dealt with inverter circuits ,so my know how is extremely limited, i bought a old 210 ,and did change the lcd ,repaired a loose bnc connector ,and cleaned the underside of the PSU and also resoldered many connections ,finaly got it powered up and the only problem now is the ccfl is dim with a bit of flickering ,as there is no schematic availibile ,i dont know where and what to test ,if someone could be kind to help ,i would be very greatful,i have searched for about 10 days now but did not find anything ,greetings to all ,nic.

author: jpanhalt
author_rank: Super Contributor
timestamp: January 28, 2022, 11:03:42 am
content: I have the TDS210 service manual as pdf, but it lacks schematics: 071-0492-03It appears the relevant pages for checking out screen voltages are 6-40 thru 6-43 (pdf pages 98-101). If that will help, I can try to post. The whole manual may be on the Internet now too.Edit: Here's a link to the service manual.https://download.tek.com/manual/071049203.pdf

author: nic77
author_rank: Contributor
timestamp: January 28, 2022, 01:19:22 pm
content: Thank you for your answer Jpanhalt,as you can see there is no schematic, what i need to know is the how much voltage that goes to the small inverter tranformer that powers the small neon lamp, i know the voltage at the lamp as in the service manual it say's 1370vac but i have no way of testing that voltage ,if i know the input voltage to the transformer if it was correct i could deduce that the Tr. cuold be faulty ,thats why the neon is not at full brightness, ,at this point i would really like to get this scope fully working everything else on the scope works very well,,thankyou very much for your help,greetings ,nic

author: jpanhalt
author_rank: Super Contributor
timestamp: January 28, 2022, 02:13:27 pm
content: I suspect it would be easier to work out a way to measure the voltage than to get a schematic. Plenty of references for increasing the range of a multimeter. There are also probes. The 60 kHz may be a problem. Be sure to use resistors properly rated for that voltage.An alternative would be to get a replacement backlight (https://www.plazmo.com/products/ccfl-backlight-for-tektronix-tds210-tds220-tds224-digital-phosphor-oscilloscope-1) and use it to test the power supply. I didn't check but suspect the power supply will considerably more expensive, if available.I got my TDS210 about 20 years ago. It's a good little scope but doesn't get much use since I got a Rigol several years ago. I occasionally use it to look at glitches.

author: nic77
author_rank: Contributor
timestamp: January 28, 2022, 05:34:12 pm
content: Hi again ,yes i have already bought a new ccfl light backlight but only still dimm, i have also ordered a single lamp power board from china ,it has arrived 2 hours ago after 2 weeks of waiting ,so later on i will check both neons and see if i can find 10 or 15volts inside the scope to power the small board , as you say i can test the voltage on the secondary winding with my multimeter ,my meter is only rated at 700vac where in the service manual it says at startup voltage is about 1350vac on the secondary winding,i will also check if i can find some info on how to read this voltage ,thanks for now and 73s ,nic.

author: nic77
author_rank: Contributor
timestamp: January 31, 2022, 03:19:34 pm
content: Hi to all ,i have connected everything up ,and works well ,only thing now is to lodge the inverter board inside the scope and use an external power supply ,then that's done