I bought a tester from Zeusbtc two months ago, I can tell you that there is still no successful result regarding the repair of my miners, first the tester is of very poor quality, it can be seen that they looked to save on everything, asik 0 on almost all boards and cooperation with them grade 2
Yeah, the tester is only a small part of being able to repair hashboards. The output of the test is only sometimes useful, most of the time you need the fixture just to operate the board while you use an oscilloscope and/or voltmeter to measure signals at the test points.
Just FYI, with the COVID situation, Bitmain now offers an online repair course for $500. I haven't taken it so I'm not sure how useful it is, but once you complete it you get access to all of their official repair manuals and downloads, and you can order Bitmain's test fixture and spare parts direct from them. Previously it was $1000 and you had to travel to one of their sites to take the 1-week long course.
All of the testers of that type are built similarly ... I agree that it is not the best. Just kind of hacked together. I've ordered a different tester from here
https://tester.asic.repair/en. It was much more expensive and ships from Russia but looks like a much better product. Slow shipping from Russia to USA though ... ordered a month ago and the tracking estimated arrival is still 3 to 5 more weeks...