Help ID Tektronix Scope Resistor-like Part - Page 1
Forum section: electronics / projects

author: fuzzoli
author_rank: Regular Contributor
timestamp: October 10, 2021, 11:57:39 pm
content: I'm beginning a repair of a Tektronix 475A scope and currently troubleshooting the power supply. Can anyone help identify the parts pointed to by the arrows?Are these by chance zero-ohm jumpers? A meter across them does seem to point that way. Would they by chance be the key points for isolating the various power supply voltages from the rest of the scope? If so, that would be just too wonderful.Thanks!

author: bostonman
author_rank: Super Contributor
timestamp: October 11, 2021, 01:16:30 am
content: I'm looking the 475 service manual and see the area that matches your picture, however, the components are not orientated the same.My guess would be a fuse, but I don't see any on the schematic.I think Tektronix scopes have different versions of the models which would explain the difference between your picture and my service manual schematic.In any case, just locate the service manual and that will give you the answer.

author: tooki
author_rank: Super Contributor
timestamp: October 11, 2021, 01:21:48 am
content: They’re almost certainly 0-ohm jumpers used to facilitate automatic assembly, since they can be inserted using the same heads as the actual resistors.Whether jumpers are needed for the layout, or if they’re there for troubleshooting purposes as you theorize, I couldn’t say.

author: fuzzoli
author_rank: Regular Contributor
timestamp: October 11, 2021, 01:52:23 am
content: Ugh...don't know where the 'A' went in my original post -- I put it there now. My question is regarding a 475A, not 475. Sorry about that.I do have the service manual. I don't see what these things could be, nor do I see anything on the schematic....the search continues. Thanks for the replies.

author: bostonman
author_rank: Super Contributor
timestamp: October 11, 2021, 02:15:01 am
content: I just downloaded the 475A manual and agree, I don't see those anywhere.I'd assume they are fuses or 0ohm resistors for whatever reason (I always think 0 ohm resistors are used as a fuse but guess they could be for measuring).It's odd they are not on the schematic, but, if they are zero ohms and working, I wouldn't worry about them.

author: WattsThat
author_rank: Frequent Contributor
timestamp: October 11, 2021, 03:07:34 am
content: They’re zero ohm jumpers with PTFE insulation. Classic Tek high end engineering.

author: bob91343
author_rank: Super Contributor
timestamp: October 11, 2021, 03:08:16 am
content: They are jumpers, nothing more.

author: fuzzoli
author_rank: Regular Contributor
timestamp: October 11, 2021, 04:08:35 am
content: Thanks folks for confirming they're just jumpers.The next question is were these jumpers strategically placed so that removing them will isolate the associated supply from the rest of the scope? Yes, I know I can trace out and follow the copper to confirm, but if anyone happens to know offhand, that will save a step.I put the question of the jumpers in this section of the forum as it's a more general question than specific to the repair. I plan for a full repair thread over in the Electronics->Repair forum...stay tuned!Thanks!

author: bob91343
author_rank: Super Contributor
timestamp: October 11, 2021, 06:45:46 am
content: The jumpers were not intended to be removed. They basically solve a layout problem where a trace needs to go somewhere but can't get there.

author: Ranayna
author_rank: Super Contributor
timestamp: October 11, 2021, 01:51:01 pm
content: Some of these are clearly not required to solve layout issues. All those marked, except for the far left one, look like they just as well could have been a trace.Them being testpoints or clip on points for probes also does not make sense, since there are actual tests points available, some obviously connected to the jumpers.Them giving the ability to separate circuits during troubleshooting makes sense, but i would assume the service manual would state such a use case