My memory certainly hasn't improved with age.Not much else seems to have, either...But, the beeswax thing I'd be willing to put money on - fwiw. Incidentally, I still have not installed the 2nd wax xf

Hi Chuck;Assumed scatter because of the larger size of Schell rewinds.It has been a looong time, but I think I'd remember if he'd said anything about epoxy...B

Talked to Bill Schell a couple of decades ago about taking over and buying his setup from him.Instead, I ended up contributing what I had learned to Chuck Harris' efforts.My recollection is that Bill

https://w140.com/tekwiki/wiki/Tunnel_diodes https://en.wikipedia.org/wiki/Tunnel_diode In the 540 series the 547 (1964) was the first scope designed with TDs.Retrofits were made to the 585/A (time bas

Have 561A/Bs and 565 in service and consider them a favorite for general bench work.Had one bad 565 (bad filament winding - my 1st Tek scope) but now own two that work.GREAT scopes, very reliable. The

Look at 2B67; hor in without tunnel diode triggering and often available for nothing.The 3B4 is much more rare and my personal favorite, but may be overkill for your application.

That could be problematic; the hor input isn't cal'd and it probably won't match the vertical plugin's impedance or gain. For symmetrical x/y displays of equal bw you will likely need 2 identical vert

why not use another vertical plug-in for external hor input?

Thank you - I expect to find exactly the same condition, here.

Looking for A4 board/#38 switch assembly!!My 'new' 475 is suffering from stuck vertical mode switches. CH1 and CH2 buttons are depressed and will not de-latch.ALT, ADD, CHOP buttons are out and will n

Nothing is forever, and, I used to enjoy this group more in the past, myself.Though I am no fan of Facebook, I do enjoy our "Old Tekscopes" group, there.The visual interface is a nice alternative and

If it aint broke don't fix it!!!Running several 561As & 565 in original condition with NO issues.That is the norm for 500 series gear.Bernie Schroder

Its been a few years since I worked on a 555 so my memory is spotty. The -150 rail is the one all others reference - it must be spot-on and NOT sag under full load with low line voltage; see service m

Finding a used one would be the best shot. NOS is probably a pipe dream. Be sure you know the HV oscillators are happy before you go there. What are you seeing? Bernd Schroder

They are not, but they will get 'used up' with many hours of use. If you have to increase intensity much past 12 o'clock you're crt may be getting tired. Next symptom is 'double peaking'. You can find

Thx.

Matt; Have found a standard 'short' interconnect. No part numbers so I need to verify this is for 555, not 551. Possible Tek only built one cable for both...just not sure. Let me know if I should dig

I may have a cable - not thrilled at parting with it but do not want to see a 555 butchered... Will have to go dig. The connectors are worth crazy money and I have not found a better HV interconnect.

I may be able to help

Shame when that happens; a full complement of tubes is not cheap to source and full calibration will be necessary. Also, the 565 can be prone to crt heater isolation breakdown and HV transformer issue