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Thanks for the advice guys: I do normally run stuff up on a variac, and I will check those fuses are in place. Fortunately I have a supply of many of the valves used (and a valve-tester): fingers

Replacing the fuse with an ammeter I read 120mA.

Hi John: Before you fire your 575 up check that there are fuses in series with pins 14 and 16 (two fuses). I had a short in C244 which did not draw enough current to pop F601. The short overheated

Thank you, You deserve a medal!

I am sorry, I was not aware that editing a message caused this. I will refrain from doing so in the future.

Perfect Keith. This clearly shows that Q1416 is always in saturation and that CR1416 never conducts (is even reverse biased). Hence I think the fault is not in the regulator circuits. You might

Even with as out of spec as the PSU is I have been getting intermittent traces on the screen and one of the two traces was pretty clean. The last time I turned it on I heard a pop and shut it off

I have parts for extender kits on hand (for TM500 / TM5000). I have been emailing people that are on my wait list, but if you haven't heard from me and would like a kit please contact me off list.

Thank you Albert. I put the scope in dc coupling and centered it. Needed to adjust the scope to .5V/div in order to keep the same gain for comparison. Here are the waveforms:

Hi Keith, A waveform is not complete without an indication of DC levels. When Q1416 is all the time in saturation, then the 3 waveforms will look identical, but the base waveform will be at about

Ho John, Congratulations on getting the 575 400V version (575 Mod 122C). You should search through the archives for advice on bringing up older vacuum tube instruments carefully to allow the

Hi Rick, The brilliant designers of the 7000 series made sure all of the slots were "generic". In other words the slot doesn't care whether you put a horizontal or vertical type plugin in it. There is

Lot of old ICs here…some should be relevant to 70s & 80s Tek gear. https://www.ebay.com/itm/302763294559 Pardon the intrusion.

The 49x and 27xx use the same extender kits ...line for line... The 27xx series was basically just updated 49x's some of the boards are even common -DC manuals@... -- Dave

I have been switching to aluminum poly caps which cost more but it their specs look so much better. Lower ESR, Longer life, Higher temp. handling. <mustang_gt_y2k@...> wrote:

I spent some time going over the circuit around Q1416, and made a photo with the various components labeled here: /g/TekScopes/photo/49286/6?p=Name,,,20,1,0,0 in case someone sees

I picked up this 500 MHz SA for cheap, because the CRT display is very dim, although it appears to work otherwise. I was hoping that some internal adjustments would fix it right up, but no. The unit

I believe you are asking for this: /g/TekScopes/files/Caps%20list%20updated%20March%202018.xlsx I did not verify the series information but all are high temp, long life and most are

I use one of John's extenders. Great buy. What I did was buy a plugin I needed as parts. Spent $20 on a 7a26,fixed my broken 7a26 and used the frame for the extender.

I've just bought (but not yet collected) a 575, I think the 400V option. I suspect it's been stored several years unused. This will be my first piece of Tek valve kit (apart from a 130). Is there an