Requesting 2nd pair of eyes on a Sony/Tektronix AFG310 repair - component ID'ing - Page 1
Forum section: electronics / repair

author: neverendingstudent
author_rank: Regular Contributor
timestamp: June 28, 2025, 02:18:11 am
content: So, I won a pallet of T&M gear at auction a few months back and among the instruments were 4 Sony/Tektronix AFG310 function generators.Older, single channel 16MHz, but very nice none the less. Japanese made.I've fixed up and sold 1 of them to a customer and have been eyeing the remaining 3 to clean/service/test all the rest to get them lined up for sale, or rather to add 1 to my bench and sell the other 2 + the OWON function generator one of them will be replacing.Anyway, upon disassembly I found 1 to have a smoked and cratered component, though it still powers on and operates fine. After what research I could do I'm 95% sure it's a varistor / surge absorber that sacrificed itself saving the instrument. All markings burned away... but convienently I have 3 more identical units so I was able to pull markings.Blown component, labeled 'E220' on the power board has the a stylized 'M' inside a rounded-corner square on top, middle line of '7K470' and bottom line of '9D'. Cannnot find anything based on those markings on Google or Octopart. Fortunately the board DOES have one other very-similar-looking component with an 'E' prefix, 'E110' which has line one starting with the same 'M in box' symbol followed by 'ZNR' a middle line of '10K221U' and a bottom line of '??' symbol that looks kind of like 'backwards R followed by U' and then the numbers '01'.The second component DOES come up on search fortunately, link here:https://www.alldatasheet.com/view_datasheet.jsp?Searchword=ZNR-10K221Uand data sheet with helpful label-decoding lookup table here:https://www.alldatasheet.com/datasheet-pdf/view/1315009/PANASONIC/ZNR.htmlThe other part is a "ZNR Transient/Surge Absorbers (Type D)" - so some overload protection varistor-type component. Given the same 'E' component designation and same visual look, I logically conclude the other burned out component is the same type, just different value.Now, going by the decoder table from the data sheet, it SEEMS the mystery component is a 47 volt model - if that is correct then I can find an equivalent rated varistor or surge absorber and replace it... but I'm not sure about that 47 volts part since the data sheet is for a different 'ZNR' series component and the burned out component doesn't have that prefix.Looking for a second pair of eyes on this to give me their opinion. Also, if I'm correct about the 47 volts, anything specific I should be looking for in a replacement component other than that voltage rating? Is this 'Surge Absorber' a varistor or is it actually a different component type?Since I can only attach a few pics, going to upload more to imgur so people can get a more comprehensive view.https://imgur.com/a/uv3P6XWThanks everyone!

author: Dougmc
author_rank: Contributor
timestamp: June 28, 2025, 11:46:08 am
content: Nte crosshttps://www.sourceresearch.com/StoreWork/CrossList.cfmCrosses to

author: Dougmc
author_rank: Contributor
timestamp: June 28, 2025, 11:49:31 am
content: Nte2v030

author: neverendingstudent
author_rank: Regular Contributor
timestamp: June 29, 2025, 04:32:53 am
content: Quote from: Dougmc on June 28, 2025, 11:46:08 amThank you, I did not know about this search tool. That looks like another useful tool to have in the toolbox.Looks like it is referencing a different voltage rating component as a replacement though?I wish I could find a datasheet that unambiguously defines the specs of the 7K470.

author: factory
author_rank: Super Contributor
timestamp: June 29, 2025, 10:32:12 am
content: For the original parts, the first number(s) are the diameter in mm, the next three numbers are voltage, with multiplier as third number, the NTE part code makes no sense to me, also NTE datasheet link is dead due to NTE going EOL.David