Re: Tektronix 2230


tekscopegroup@...
 

On Sun, Jun 28, 2020 at 06:19 PM, Saroj Pradhan wrote:
Hi Leo
I made myself a old style transformer type power supply to connect to the
inverter section. Here are my findings.
1. Un loaded external power supply out put voltage---44v
2. Loaded external power supply voltage--- 38.7v
3. Got the trace
.....snip


Sorry to barge in so late in this thread, and have not even read it all the way to the end, but it reminded me when back in 2004 got my first Tek scope, a 2213A with the typical tic-tic-tic sound and flashing power LED. It was from a customer that had several of these scopes and wanted me to try and repair it, but after I ended up putting a lot of time and effort into it he ended up stating to just keep it if I eventually managed to fix it. Back then I actually turned for the first time to Tekscopes for advice, and was lucky enough to get help from Denis Cobley that helped a lot and really went out of his way (same as he always did help everyone) with lots of quick back and forth messages over a period of several weeks at that time, if not longer, just like Satbeginner is doing here. I also used a linear power supply (actually putting two 24V supplies in series and adjusting one for a 43V combined output) to bypass the scope Prereg, which is what rocked my memory. But unfortunately for me that did not help much as I had problems in both in the Prereg and main inverter. But after replacing all the blown parts it would still not work, even after replacing every single even mildly suspect component that I had on hand (small Elco caps, power resistors, semis, etc), quite a few late nights, and many many diagnostic measurements and hand drawn schematics all over the place (only had the plain 2213 service manual, which in terms of power supply is somewhat different). Then after finally making some progress on the Prereg of course made the customary single brief but fatal mistake and almost every power semi I had replaced was once again shorted or plain blown up, and put me right back to square one. But I was really determined to fix this scope and started suspecting that the problem was a part for which I did not have a replacement for a test. In the end eventually it turned out that the problem was a shorted T948, most probably in the HV secondary, and after replacing it I was finally greeted by a steady light from the green power LED. I managed to get a replacement transformer when another kind member of Tekscopes (sorry his name escapes me now), and that I assume was also following the repair thread, Fedexed me for free a whole 2213A scrapped main board but that was still almost fully populated. And as they say, the rest is history, and the helpful experience was so positive that so far I never have once considered getting any other used ("it was working the last time I used it") scopes but from Tek. Anyhow, good luck with the repair and I think this is a nice and very educative thread for any future 22xx newcomers!

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