Tektronix 7834 power supply defective.

[stfjohn]

Hello everyone.
Does anyone know how you can replace the condenser "C1237", apparently inaccessible?
Thanks.

[bd139]

Doesn’t the power supply just pull out as per https://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_7000_series_mainframe/rep-und-kal/7844_reparatur_engl.html ?

[nsrmagazin]

Can you post a few pictures?

[perdrix]

C1237 is the tank capacitor, which is inside a metal box beneath the oscillator transistors.

To get at it you pretty much have to completely disassemble the PSU.  Refer to the Service Manual if needed.  You need to remove the LV Regulator board, then the Cap Rectifier Board, then unsolder the leads to the transformer and the tank circuit and remove the inverter board (you'll need to unsolder the mains input leads too.   Then you can remove the metal box containing L1237 and C1237 and open it up to get a the capacitor.

How do I  know - I just did all that with a 7854 supply.

Good luck finding a replacement for that part - the original is 600Vrms (900Vdc), 0.03uf +/- 5%, 3.3A at 25kHz!   I removed one from a 7904 supply which I'd kept for spares.

PS If you are not already aware there are the Tekscopes and Tekscopes2 mailing lists on groups.io

Cheers
Dave Partridge

[stfjohn]

Thank you all for your help.
Best regards.