Re: Recapping Tektronix 2465


Not having received any recommendations for my last post, I had to fend for myself.
I finished replacing the components on A2, A3, A5, A9. Having no way to build the load for the power supply due to lack of suitable components, I just double-checked the job over and over again, then held my breath and pressed ON.
After a moment of suspense, the oscilloscope started up regularly and with satisfaction I saw that the screen and readout are much more defined and clear than before.

For information, here is a table with the ESR values ​​that I measured with an "AVR Component tester" of both the old and the new capacitors. Despite the possible limitations of the instrument used, I was surprised to find significantly higher ESR values ​​in the new 10uF 160v and 3.3uF 350v capacitors compared to the old ones removed from the instrument.

Furthermore, I found that the old capacitors removed have a capacity equal to or greater than the imprinted value, while the new ones on average almost always have a capacity lower than the rated value (data not shown in the table).
Orig.Value OLDValue ESRold ESRnew New Cap Mouser Part# Note
.056 uF 250v 58nF 12,00 12,23 594-2222-372-41563 Film capacitor .056uF 10% 250VDC Vishay sp10
.068 uF 250v broken broken 10,33 594-222233810683 Safety capacitors .068uF 20% 440VAC Vishay X1 17.5x8.5x15sp15
1 uF 50v 1uF 3,50 0,76 505-MKS2C041001FJC00 Film capacitors 63V 1uF 5% Wima 7x5x10sp5
10 uF 100v 15uF 0,60 3,50 647-ULD2C100MPD1TD Aluminum Electrolytic Capacitors - Radial 160V 10uF 20%
10 uF 160v 11uF 0,63 3,50 647-ULD2C100MPD1TD Aluminum Electrolytic Capacitors - Radial 160V 10uF 20%
10 uF 25v To do ---- 0,52 647-UPW1V100MDD Aluminum-radial electrolytic capacitor 35volt 10uF AEC-Q200
100 uF 25v 102uF 0,45 0,12 647-UHE1E101MED1TA Aluminum-radial electrolytic capacitor 25volt 100uF 6.3x11sp2.5 20%
180 uF 40v broken broken 0,07 647-UHE1H331MPD1TD Aluminum-radial electrolytic capacitor 330uF 50volts 10x25sp5
22 uF 10v To do ---- 0,28 647-UHE1H220MDD1TD Aluminum-radial electrolytic capacitor 50volts 22uF 5x11sp2 20%
220 uF 16v To do ---- 0,30 647-ULD1C221MPD1TD Aluminum Electrolytic Capacitors - Radial 16V 220UF 20%
250 uF 20v 300uF 0,15 0,07 647-UHE1H331MPD1TD Aluminum-radial electrolytic capacitor 330uF 50volts 10x25sp5
290 uF 200v 290uF 0,13 0,19 647-UPW2E331MRD Aluminum Electrolytic Capacitors - Radial 250volts 330uF AEC-Q200 22x50sp10
3.3 uF 350v 3,8uF 2,97 4,20 647-UPW2V3R3MPD Aluminum-radial electrolytic capacitor 350volt 3.3uF AEC-Q200
4.7 uF 10v 4,7uF 1,30 0,21 505-MKS2B044701KJC00 film capacitors - Wima 4.7uF 50 Volts 5%
4.7 uF 35v 4,7uF 2,00 0,72 647-UPW1H4R7MDD Aluminum Electrolytic Capacitors - Radial 50volts 4.7uF AEC-Q200 5x11sp2
47 uF 25v 45uF 0,45 0,36 647-UHE1E470MDD1TD Aluminum Electrolytic Capacitors - Radial 47uf 25V 105c 25V PET

Now I still have a bag of capacitors for the A1 board and am very undecided whether to replace them or leave the old ones that show no obvious signs of swelling or electrolyte leakage. In addition to the complexity of removing the A1 card, I am concerned about the possibility of static currents damaging it while I do the job. What precautions should I take to avoid the worst?


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