Tektronix TDS3054 Random Power Cycling, Reboots - Page 1
Forum section: electronics / repair

author: jwet
author_rank: Frequent Contributor
timestamp: November 11, 2023, 01:54:22 am
content: I'm sorry if this topic has been covered previously, I did a search and didn't find anything. I could have missed it, kindly point me at a link and I'll go away.My trusty old TDS3054B is misbehaving. I've owned this since it was new (bargain auction- new in box at a startup). I have never had a minute's trouble, it really isn't that special anymore though with limited memory, a small screen and 9 bit ADC but 5 Ghz and 500 Mhz still aren't bad.The problem: All will be working fine for 10 minutes to 3 hours and it will just power cycle and reboot. It comes back where it was and will do it again some random time later forever. It seems that the longer its on, the less likely this is to happen. Once I got a warning that the input terminators were getting warm (non sense, no signals applied), I've seen this in Youtube videos when people operate them outside the case without airflow but mine is fully buttoned up, the fan is running, etc. I cleaned out all the dust with compressed air, etc and verified the fan is running and exhausting air. I ran a continuous self test and it doesn't show any errors (I'm going to do this overnight). Is this a known problem?. It sure smells like a power supply or temp related overheating issue related to big caps- just guessing. I haven't opened it yet, want to gather some knowledge and docs. Its usable as is and I don't want to really break it, "the enemy of good enough is better." Also, firmware is up to date, AC supply is coming in clean with no glitches. Does this with no signals applied and applying signals and other setting don't seem to affect.Any help appreciated.

author: Jwalling
author_rank: Unknown
timestamp: November 11, 2023, 09:42:05 am
content: Very likely that it's the power supply. I've seen that problem number of times.

author: sicco
author_rank: Regular Contributor
timestamp: November 11, 2023, 12:28:21 pm
content: Yes, the AC mains power supply. Bad caps. Best way to confirm: use another 15V, 3A power supply and see if the scope then behaves normally. It’s a six pin connector, black wires, 3 for +15, 3 for GND.Several alternative replacement power supplies are mentioned in this forum, search TDS3000b as keyword. E.g.https://www.eevblog.com/forum/testgear/tektronix-tds3xxx-replacing-backlight-power-supply-fan-etc-(photos)/msg5057032/#msg5057032Run without battery pack.

author: KE5FX
author_rank: Super Contributor
timestamp: November 13, 2023, 05:35:42 pm
content: Visual inspection of the caps would be a good first step, followed by shotgun-testing them with an ESR meter. The suggestion to use a separate power supply could be helpful but if you're dealing with a thermal issue on the motherboard that is triggered by heat from the power supply, maybe not so much.I'd try alternating between hitting various regions of the board with a heat gun or hair dryer, using freeze spray to cool individual parts back down once you trigger the failure. This can help localize the failing component very rapidly.

author: button.ch
author_rank: Contributor
timestamp: September 04, 2024, 10:27:42 am
content: I think this phenomenon is caused by the open soldering of the BNC terminal of a certain channel. Please check carefully!

author: CaptDon
author_rank: Super Contributor
timestamp: September 04, 2024, 01:27:57 pm
content: Usually power supply issues. That model is old enough to have issues with the capacitors in the power supply. I had an old TDS420 that was doing the same thing right up until the power supply blew up and wiped out the green unobtainium hybrid module!!! I donated the scope to a guy here on EEV and he did an in depth review as he made one good scope from two bad ones.