Tektronix DPO 70804 Power Failure - Page 1
Forum section: electronics / repair

author: wolfman2269
author_rank: Newbie
timestamp: January 22, 2025, 07:09:40 pm
content: Hi,I'm hoping for some repair advice and troubleshooting steps. In the middle of normal operation after years with no issues, in the middle of use there was a pop sound and the scope went dark. It does not power on. When unplugged from the wall and plugged back in, the initial time the power button is pressed it lights up and the screen flashes on briefly, but turns off immediately, and any subsequent tries there is no indication of power. I figure the power supply is dead. How would I test that? And what components should I test for possible replacement as opposed to buying a new power supply? (Which I don't even think is possible, they are no longer produced). Are there any other diagnosis for this problem other than the power supply?Thank you for the help, its an expensive piece of electronics and I just want to proceed more cautiously than usual.

author: Harry_22
author_rank: Frequent Contributor
timestamp: January 22, 2025, 11:11:32 pm
content: Hi!You have to find the popped component first.It would be good if you make a good quality photos of PCBs. So we can help you.

author: calibrationfixture
author_rank: Regular Contributor
timestamp: January 23, 2025, 06:45:55 am
content: Hi wolfman2269,Maybe you can join forces?https://www.eevblog.com/forum/repair/tektronix-dpodsa-70000-series-artesyn-afe-1200-power-supply-repair/msg5778867/#msg5778867You must be really sure that it is the Power Supply.Otherwise the Power Supply Modules are still for Sale (sometimes):https://www.ebay.com/itm/267132850364Allright bit pricey, you could also buy a not working DSA/DPO70000 which powers up. Their prices decline.Success,Calibrationfixture

author: mikehank
author_rank: Regular Contributor
timestamp: January 24, 2025, 01:10:10 pm
content: The company that builds these supplies does repair them. I forget the name of the company but as I recall it’s like $200 for the repair

author: calibrationfixture
author_rank: Regular Contributor
timestamp: January 24, 2025, 02:37:02 pm
content: Hi to All,Emerson and Artesyn are the Brand Names.Calibrationfixture

author: wolfman2269
author_rank: Newbie
timestamp: January 25, 2025, 11:29:58 pm
content: Hi all,thank you so much for the input. Especially on the repair, that is good to know. So I found the datasheet for the power supply online, its the afe1200 by artesyn, and I wanted to test the output pins to see if they are outputting the correct voltage. No combination of the outputs has 48V across it, (I had to test them all since the spec sheet doesn't label them), and there are three LEDs on it, 2 green and 1 red. While those also aren't labeled on the data sheet, the green ones indicate good AC and DC, while the red indicates power fail. When plugged in, only on green LED turns on and there is a faint clicking sound from the power supply itself. The cooling fans on the power supply do not turn on. My diagnosis is the green light indicates AC power but theres a problem on the DC end.Here's my silly question. There's a bunch of pin connectors on the power supply that connect to the motherboard. Is there any reason that power supply would need to be connected to the motherboard to operate? Or can I safely say that the power supply is faulty if it doesn't appear to operate normally by itself.Thanks!

author: benj38
author_rank: Frequent Contributor
timestamp: January 27, 2025, 04:26:21 pm
content: 1. Many switching power supplies require a minimal load in order to operate and regulate correctly. In other words, you maynotassume that you can test the power supply on its own without any load connected to it.2. If you hear a repetitive faint clicking sound from the power supply this usually indicates that it can not bootstrap itself. This is almost always caused by a dry electrolytic capacitor that starves the controller IC. Hence, I would start by looking at all the electrolytic capacitors, seeing if any have leaked, or are bulged. If you have an ESR meter, a quick and dirty check of the ESR of the electrolytic caps to see if any are obviously bad may prove to be a valuable shortcut.