(SOLVED)Power supply of tds 220 old ,caps 47uf or 68uf 450v?.

[nic77]

Greetings to all , and do have a problem with this PSU because i have read many posts that say the primary capacitor of the PSU is 68uf 450v ,so i opened the 220 and found that this has a 47uf 450v cap , now i don't know why ,maybe AULT Korea change this later to 68uf ,can someone give a helping hand as to this , as i am going to replace all caps and screen ,as you can see in the foto the old bag works ,as it was given to me by a friend that didn't want to spend any money on this scope ,which i think for me could be very useful , thank you to all here on EEVblog.nic.

[iJoseph2]

Photos and videos here to compare with ...

https://www.eevblog.com/forum/reviews/tektronix-tds-210-oscilloscope/

https://www.qservice.tv/vpasp/shopexd.asp?id=15290

https://www.qservice.tv/vpasp/shopexd.asp?id=15272

https://www.qservice.tv/vpasp/shopexd.asp?id=16535

https://www.ebay.com/itm/265521307468

[nic77]

Greetings Joseph ,thank you for the links , yes it seems that AULT Korea did make diverse power boards but you just dont find a schematic of one , another strange fact is this board comes with most SAMWHA  rx series capacitors where as a friend has has a board with nichon chemicon sxe series  and this is what i dont understand ,i will change all caps to nichon ky series as they are a good and reliable substitute ,greetings to all ,nik.

[Gyro]

Taking a quick look at the TDS200 series manual, It appears that they are universal 120-240V input and, in the case of the TDS220, only 20W power consumption. If you are going to be running it exclusively on 230V, 47uF is probably adequate. Maybe a bit of value engineering has happened.

Obviously you want the capacitor to last as long as possible though, so you have the option (rather than necesity) of going up to 68uF.

[nic77]

Thank you Gyro for your response ,so this evening i changed all caps new and will substitute the 47uf for 68uf as i have it already ,and see what happens ,greetings to all ,nik.

[nic77]

Hi to all ,now we have a big problem, there is no power any more and i am only a hobbiest , i changed all the caps and it did power up again ,as all the new caps are chemicon and same ratings as old , but did go dead , so now i am stuck on this power board and dont know where to start testing , can someone help to guide me will be very appreciated ,thank you to all ,nik.

[nic77]

Greetings to all ,happily i have found the fault ,it was diode D 8 and capacitor C 14 1000uf had very high esr and was only 649uf ,i hope this is useful to others in future trouble shooting of these scopes , have tested all voltages to mother board and are all in range of specs , thank you to all ,and may the Lord Jesus bless all , and pray for the end of war,nik