Tek 3054C repair - wont power on - Page 1
Forum section: electronics / repair

author: cncjerry
author_rank: Unknown
timestamp: January 03, 2024, 08:40:19 pm
content: Hi, I have the subject scope, worked fine last used about two years or so ago. tried to power it on today, the screen flashes, lights flash, then that's it. I've heard of power supply issues with these boxes.First question, how do you get it apart? I see two slots on the back that might be holding tabs. I just want to scan the insides quickly.ThanksJerryNever mind, found a video by Dave, of course. I'm going to leave this open for now as I expect to need some help.

author: cncjerry
author_rank: Unknown
timestamp: January 03, 2024, 09:17:41 pm
content: Well, I got it open. Nothing obvious, including no visible markings (so far) for voltage test points, etc. Looks like this is going to be a little more involved.Anyone have an similar symptoms? I get a quick flash of the screen followed by nothing.ThanksJerry

author: cncjerry
author_rank: Unknown
timestamp: January 03, 2024, 10:08:21 pm
content: just another data point, when I punch the power button on, it spins the fan, blinks the lights, flashes the monitor, shuts down. So I guess it is a power supply issue. I remember someone finding a supply that they swapped in, but I see it has a supply down on one of the boards too. I see +5V,-5V, 3.3v regulators on that board. I see where people had a resistor blow under one of the boards, I'm going to explore that, but I have so much broken stuff now, and with 13 scopes, though that was a favorite, I'm going to set it aside for a while. Unless someone has a pointer for a quick fix?thanks,Jerry

author: cncjerry
author_rank: Unknown
timestamp: January 06, 2024, 08:49:29 am
content: For those of you still following along at home, I brought the Tek 3054C back up, figured I should take another look at it. I thought if I left it in the lab on the top shelf for too long, I'd never fix it. Found the repair manual. Interesting that most if not all of the DC voltages are right behind the BNC connectors where the little pin on the probe gets power, if needed, or the scope reads the probe.I started checking the voltages, one after the other, and since the unit was powering off immediately, I had to keep hitting the power button. I noticed that each of the voltages came up and then dropped. I had to put my meter in manual range to catch them. They all looked fine from what brief view I could see, but they just wouldn't stay up to boot.Drum roll...After one of the quick power cycles, I noticed the voltage stayed up. Next thing I saw the splash screen and it's been working ever since. I mean, WTF?Not going to complain. It must of somehow scrambled its memory or calibration being turned off for so long, pre-covid I think now, because when it did come up, it seemed the like the measured voltages were all over the place. So I ran auto calibration, and all seems well.Now, if I could only get the back cover on right!That thing is a royal pain in the butt. I can get one side or the other, but it just seems like something isn't right. I played with it for 45 minutes before I started looking for the duct tape to hold it together. I'll have to go back and watch Dave's teardown video and see how he made out. I probably have some expensive, unobtainable part wedged against something hot and sharp.I've been using a Siglent 1104X-E that I had upgraded. It's a nice scope, I bought it primarily for the decoding and bode plotting. I wrote code for a couple of my signal generators that work with the bode plotting function and then bought their ARB unit, also upgraded. So the pair are pretty decent tools. This Tek scope is only 9bit, I think, but I grabbed it when I wanted to scope a mixer in my limping HP 3325b. I just wasn't getting the Siglent scope to trigger when the DC was at 3.6v with about 600mv of sine sitting on it. I played with the triggering levels, etc., tried everything, just couldn't get a stable picture. I needed it because the last problem on the 3325B is that the DC offset changes with the frequency. It's almost a log scale, so that 1K is fine, 10k is also, and like that up to around 1Mhz where you can see it going up, then 2Mhz is higher, 5Mhz it is about 3/4 of the sine amplitude above zero and at 20Mhz, the signal sits on the zero line instead of looking like AC. So yes, maybe the Siglent can trigger that level if I play with it more but I shouldn't need to do anything other than set the trigger level in the sine upper quadrant. But after you use this 3054, you can tell it was a good scope for its day. Picture is clear, lots of options loaded (all of them), separate knobs for acquisition, trigger, timebase and voltage so you don't have to go digging for acquisition changes. OK, so what was I working on before this scope broke?End of story, thanks for reading.Jerryp.s. I got the Sig triggering by hitting the noise button. Funny though as the signal is a sine wave and it looks like it is stair-stepped a little, not as smooth as the Tek though it could be because the Tek has lower resolution. Not trying to start a war, I love my Siglent scope. The Tek 3054C, though old, was still current up to 5yrs or so ago.

author: factory
author_rank: Super Contributor
timestamp: January 06, 2024, 02:46:33 pm
content: You probably need to edit the thread title (or ask a moderator if you can't) as it's not a HP and people will miss it if they don't know it's Tek from the model number.David

author: Vovk_Z
author_rank: Super Contributor
timestamp: January 07, 2024, 12:14:59 am
content: I've seen a digital scope with similar symptoms (I guess it was 15 years old Rigol). It was a faulty power suply. Yes, it could start after being powered for a some time. Using in-circuit ESR-meter I found two or three almost dead electrolytes really quick. Replaced them and it works now as new.I guess you don't have in-circuit ESR-meter. So, taking into account an age of your scope you may just replace all Low-ESR or just all electrolytes on the power supply board (including a large 450 VDC primary side one).

author: cncjerry
author_rank: Unknown
timestamp: January 07, 2024, 02:58:35 am
content: thanks, I do call it an HP for some reason, I guess 99% of my test gear is HP except for scopes.Also, I looked at the caps, they all look good. I don't have an in circuit meter though I have a number of ESR meters (HP again). I saw where the most common problem like this is a scrambled ROM chip. It comes up all the time now and the voltages are near perfect. No excessive ripple on any voltage. I thought about recapping it but usually the problems with these scopes are blown regulators and other chips related to the switching supply. I keep thinking I should do something before it blows the power supply as others have.ThanksJerry

author: sicco
author_rank: Regular Contributor
timestamp: January 07, 2024, 10:33:59 am
content: Still have a battery pack inside?