Tektronix 2215 oscilloscope restoration - Page 1
Forum section: electronics / repair

author: Paulo Peres
author_rank: Contributor
timestamp: November 07, 2023, 03:20:57 am
content: As I have few posts yet, I'm linking to an Linkedin article I published earlier this year about the restoration of this scope. I think somebody can find it useful.https://www.linkedin.com/pulse/tek-2215-bringing-analog-oscilloscope-back-from-death-peres%3FtrackingId=H26783CC1q3w1N%252BKw8PmaQ%253D%253D/?trackingId=H26783CC1q3w1N%2BKw8PmaQ%3D%3DFeel free to ask about...

author: p.larner
author_rank: Frequent Contributor
timestamp: November 07, 2023, 05:48:58 am
content: says page not found!.

author: Paulo Peres
author_rank: Contributor
timestamp: November 07, 2023, 11:35:19 am
content: Could be some some permission issue...Doesn't matter. I'll transcript the text (the pictures are at the end):Tek 2215 - bringing an analog oscilloscope back from the death (again)Paulo de Tarso PeresElectronics Engineer22 de março de 2023This is my ‘new’ Tektronix 2215 scope.I started to write this text two or tree times but something always interrupted me. So this history is about two years old.I bought this scope on an auction site. It had a nice external appearance and a bargain price. The former owner told the voltage multiplier was missing and he was unable to find a proper replacement. He was giving up and selling the equipment.So, cheap deal done, I bring the instrument to the lab and started to work. Here is what I found (and did):The main power supply was dead and the repair attempt I found was unintelligible. The time/div switch had a disastrous repair attempt made with glue (that actually isolated the affected section from circuit). Even the fuse holder cap was lost.Despite all those things, there was a chance of recovering. First of all, I needed to know if the CRT was still alive, and for that, I needed a working high voltage section.It was the original problem because it lacked this part (actually, I don’t even know the appearance of this component). Fortunately, it was not my first dead multiplier.Years ago, I discovered a manufacturer of some Tek voltage multipliers called Voltage Multipliers Inc. At that time, I was unable to obtain an original multiplier for a Tek 7834 I was restoring (the part was obsolete). Fortunately, their Design Guideline (www.voltagemultipliers.com/wp-content/uploads/2018/08/Multiplier-Design-Guideline.pdf), the Tek 7834 service manual and the ‘autopsy’ of the old multiplier gave me some interesting directions. Long history short, I was able to build a suitable replacement.Building a voltage multiplier is basically Electronics 101. The main constraints (and the ‘secret sauce’) are the voltage withstanding values of the components and the isolation between them. Since I only needed to test the CRT, I used some spare high voltage components from the 7834 to make a quick & dirt multiplier. Well, was dirtier than quick, but it worked (see the big green dot in CRT in the pics). Now I knew the tube was alive! And, most importantly: a restoration was technically feasible!First point, I properly fixed the main power supply. A new electrolytic capacitor, some rebuilt PCB tracks and a new power MOSFET bring the supply circuit back. I also applied a pending service bulletin on the flyback transformer.My next step was try to rebuild the time / div switch. But I had no success here. The last repair attempt made to much damage. Now I was hunting for a Tek switch 260-2023-00.I was not inclined to make a Frankenstein switch (I confess the idea had an appeal… but no). So I managed to find a used one in an instruments repair shop in Sao Paulo. It costed little more than the amount I paid for the scope actually, but was a functional part. They also had the fuse holder cap.Parts bought, I still needed to build a proper voltage multiplier (no Quick&Dirty this time) and find replacements for missing screws. From what I learned in the past and in the service manual, I designed a PCB for a new one and ordered it from JLCPCB.I bought the proper HV parts (ok, I over engineered all of then, just in case). The red coating in the picture is a voltage insulator that I was willing to test. The label said 6500 volts per mm coated. Fair enough.Thing built, scope assembled and turned on…… and it’s alive!A beautiful and bright trace, in all timescales, including delay!And woosh! The filter cap at mains input smoked while I calibrated the equipment.As with old HP equipment, this old Tek celebrates this 30+ years with a smoking cap.Well… there’s no reason for panic. Just another replacement and voila: my Tek 2215 returned to its old glory!Não foi fornecido texto alternativo para esta imagemThe beauty of analog... same signal and same scale in both scopesI love these old analog Tek designs.

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 07, 2023, 01:29:38 pm
content: Nice work!