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What is the normal operating frequency of that transformer? 1000 Hz test frequency seems to be on the rather low side. What is the frequency of the ringing that you're seeing? That's probably the

Hi, You could try a lower frequency, like 10Hz or so, with a longer 'On' time, to allow the ringing to dampen by itself. Now it could be stopped by the short 'on' time of the 1% of the 1kHz. Did you

Good catch Ozan. I've uploaded a revised photo. /g/TekScopes/photo/263498/3223503?p=Created,,,20,2,0,0

The ring test with a 10 volt 1000 Hz square wave with a duty cycle of 1% shows ringing on the primary winding of T460 - so that looks good! No ringing though, on the feedback winding on pins 3 and 6

(Again continued, wish I had a reset knob for myself.) I didn't trust my C420 measurement and repeated things. The new results were different. I won't report these or other results before I found out

Mac, While I agree with you that the original Tek construction note doesn't show a connection for the BNC shell, it seems clear to me that while "normal" practice would be to ground the shell of the

Thanks for the replies so far. Kim, what type of storage board do you have? The type is indicated with 2 letters at the bottom right and likely reads something as 'PB' or 'PC'. And in addition, if it

Hi René, I measured C420 voltage. To my surprise it was +9.0 V. So I was very wrong with that +13.5 V. The mistake is I thought that +9 V would be present at the inputs of U430. I also did waveform

Hi Dave, Have you asked Marc Christian at Telford Electronics? marc@... I have had good manuals from him on many occasions and only a few failures. He is one of the good

Hi all, A DC resistance check does not give a valuable result. E.G. a primary winding only has so many windings, and in a HV transformer could have a quite thick gauge, meaning a low resistance. If

Sadly the 7A12 parts Dennis mentioned are not the same. Very sad as I had found a source for them new here: https://www.smcelectronics.com/tekpart.htm. 1. The buttons on the 7A12 parts are latching

Bernie, I have a T922 and a T935, both working; nice little basic scopes. I checked my parts mule T460 using a FLUKE Meter and a 4 wire test. The resistances are very low. 3-6 = .033 Ohms 4-5 =

Hi René, It seems that Q440 never supplies a reference current to U460/2. C420 should sit at about +13.5 V anyway. Between centre and CW your U400/1 will be steady High since U470/7 is negative. For

My 549 has a lot of background noise in the stored display so I'm going to tweak it up some.Haven't found the time, so far.Not sure how this helps, except to say mine is open, at the moment...Bernd

I just used a DC coupled TTL level pulse generator, capable of driving 50 Ohm. Triggered the scope externally on that pulse, and used a probe to look at the pulse on the primary winding to see the

Leo and. Mike Thank you both for the quick responses. The Tek 922 is such a nice instrument, I hate to part it out. Not exactly sure how to inject a square wave pulse into the primary winding —

Hi, I advise to do a "ringing test" to test the transformer. It's basically a fast rise, slow repetition square wave connected to a primary winding. (Can be done in circuit) Use a working scope to

I have a T922 with a good T460, let me check it to confirm the values that I see.. -- Michael Lynch Dardanelle, AR

HI John! I can't help with the issues, but I do have a 549 carcass that has a storage board still in it, if that would be any help. Let me know. Kim Herron

I have the PDFs but I find the paper versions nicer to use. I am looking for the 2225 service manual with the fold out schematics in reasonable condition (original NOT photocopy please). Please