Hello Roger - thanks once again! Went into a dark room and spotted the spark straight away. It's coming from the top right corner of the CRT. I can see the spark lighting through a very tiny opening

I've considered making custom covers from laser-cut birch ply. That should be trivial given the ability to generate finger joints, e.g. https://en.makercase.com/#/basicbox (no recommendation, simply

A crackling sound from the front of the CRT is not good. If you take the scope into a dark room with the cover off you may see some flashes from the region where the high voltage lead attaches near

This https://www.rc-cam.com/forum/index.php?/topic/4165-tektronix-2245a-oscilloscope-smps-repair-re-cap/ may be of some interest. On a side note to everyone; is there a cannonical design or schematic

Here's an interesting one - custom-made from clear acrylic. IMO it's a bit expensive ($85), about what you'd pay for an original Tektronix front

By now I have removed almost all the electrolytic capacitors and have observed that they all have much higher capacitance than stated, for example 1000uF have 1400uf, 470uf go for 600-700uF. How

Very few of us use veteran analog 'scopes because they are better suited to the job. That's only true in some situations, if compared with fast-refreshing digital 'scopes. Raymond

Hi, just want to continue with my lessons learned on the same subject. The device was operative, suplly voltages were adjustable to their nominal values, but no output. 1. No output a) open R251 and

I will blaspheme here for a little if I will be indulged. Don't get me wrong I do love the 7904A but for the VERY slow and the very fast above 1Ghz I will take the screen of a digital scope. Seeing

That's been my excuse for having two or, better even, three copies of all models for a few years now. But we're treading on very different ground here... Raymond

Hello Roger, I am back with some measurements. ** Vertical Switching ** Both measurements taken in ALT mode, no probe attached, and lowest TIME/DIV setting. TP364 (-2V and -0.102V) TP374 (-2V and

Not having an MCP CRT hardly ever is (or rather: was) a problem. It's not like "You don't have a good 'analog 'scope unless it has an MCP CRT"... Raymond

I think that's generally true, though it shouldn't be exaggerated. Acceptable brightness levels are fine and the 'scope does have some protections. OTOH, some people like to see how bright the image

The lack of an MCP is why I went with the 7904 as apposed to the 7104. Due to the difficulty of being able to source a tube if I needed one.

What is the DTM mechanical max CCW reading ? It should be 0.20 http://www.hakanh.com/dl/docs/hardtofind/dtmsettings.pdf /Håkan

That's correct or you wouldn't experience the writing rate being as "limited" as with all the other regular models. Raymond

Just wanted to chime in and let people know that they're also available at a slightly lower cost on www.n0dy.com<http://www.n0dy.com>. The cost there is lower because Ebay doesn't take a cut as a

AFAIK, the 7904A does *not* use and MCP CRT. The 7104 and 2467 do use MCP CRTs. DaveD

Hi guys, I need your help again, I am trying to do horizontal calibration on my 465 but I cannot set step one of calibration, "Check/Adjust Sweep Start and A Sweep Calibration", With Sweep start

The two most common faults causing the P/S to go into burst mode I've seen on the 224x supplies have been one or more shorted rectifier diodes on the secondary or a bad HV multiplier. Another not so