TEKTRONIX 2467B no trace - Page 1
Forum section: electronics / testgear

author: mj21
author_rank: Regular Contributor
timestamp: April 17, 2014, 04:37:05 pm
content: so few days ago i bought an tektronix 2467b 400Mhz scope from ebay. it was advertised as need screen replacement. as this was the second tek 2467 for sapre on the web,which i lost the first one to some guy by £5. i decided i try to see if i can fix this thing and i bid on it. lucky me i won this item delivered for £170.straight away i tear the boxand connected the scope to the mains and well nothing appeared. so i took the hodd off and to my surprise it was very very clean for its age, i mean not a single dust or anything. it was almost this was a brand new scope which just came of production line.anyways i pressed the beam finder and i could kinda see few dots on the screen. so first thing first i checked the voltages and all was OK. then i checked for ripple and again all was OK.so at this point i started to get a bit scared as i thought it might be one of hybrid which are paint to fix and obtain. looking at the A5 board i could see jumpers with label cal on and cal so i changed the jumpers round and to my surprise the scope screen came on, at this point i was overwhelmed by joy lol as it came to life. but my joy was short lived as there was an error 04 24 on the screen, goggling this and it came up with changing VRAM and all sort of other stuff.after few hours of bugging Google to give an answer i came a cross a forum in which some one had the same problem and they changed the A5 board and it all was OK after. so judging by this and other people mentioning the A5 board i decided that my problem should also be at this board.i downloaded the service manual and printed out the A5 schematic and parts location and parts list. also in the service manual was a waveform representation of four test point which was one of the most important thing that helped me fix my scope.using my rigol i checked the test point and to my surprise there was no waveform at test point 3, so i knew there was a problem there, also there is a dac chip which uses a 10v ref from the PSU board. now checking -Vref and +Vref of the dac i was not getting anything and this was also odd. so i decide to tackle the Vref problem first. using my fluke i started to trace the 10v ref from the psu to the dac and after few minutes i found the dam problem. a bloody resistor had gone bad and instead of having a value of few kilo ohms it was few hundreds of kilo ohms. changing this gave the dac its Vref and sorted all other issues.looking at the surrounding area i realized the the three caps at the top had ruptured and their electrolytes have been contaminating the pcb and few of the resistors and other caps, so i decided to change all of them as can be seen in the picture.fixing the scope took about a day but it was a day i never forget how i got a scope of this caliber for £170..nn

author: tautech
author_rank: Super Contributor
timestamp: April 17, 2014, 04:55:30 pm
content: Well done. I did this sort of thing for a few years, and it was great to get good old gear going again. But it can be very addictive, especially when you fix scopes EE's would wouldn't/couldn't.Often it is just a simple fix found by your bloodhound fault finding skills.Congrats.

author: mj21
author_rank: Regular Contributor
timestamp: April 17, 2014, 05:11:03 pm
content: thanks, lol i was well please with my self, this is the second tek scope i bought from ebay which i have managed to fix.

author: w2aew
author_rank: Super Contributor
timestamp: April 17, 2014, 07:05:29 pm
content: Quote from: mj21 on April 17, 2014, 05:11:03 pmAnd the fact that it is a 2467B with the MCP CRT - awesome. I remember purchasing two of these when the were NEW - about $12,000 US each, and that was in 1989 dollars - which would be equivalent to about double of that in today's dollar.

author: grumpydoc
author_rank: Super Contributor
timestamp: April 17, 2014, 07:09:41 pm
content: Rats!I was going to bid on that one and chickened out in the end because if the CRT had gone it would have been a £170 bag of bits - the MCP CRTs in those things are irreplaceable.Good fix though - well done!

author: David Hess
author_rank: Super Contributor
timestamp: April 20, 2014, 01:37:10 am
content: Nice job.The reputation for fragility of the MCP CRTs has always scared me away from considering a 7104 or 2467. The known electrolytic capacitor problems in the late 24xx series did similar for them.