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Those Rifa caps in the line filter are safety caps. I was told this is generally a failure mode of safety caps. Short voltage spikes on the power line damage the caps. Safety caps are self healing.

In the groups interested in resurrection of old(er) radios, this is a common problem. One solution is to, carefuly, open the capacitor base crimp and remove the innards. Replace with suitable leaded

Hello, I have two 7904A scope frames. The first is now functioning after some power supply repairs, but the second is very sick. Eventually I have determined the trouble is that one of the 950uF 200V

The bad C95 sockets I mentioned are easily recognized by the unique profile on the short end as shown on the center picture at the bottom of the Wiki page. If you have those in your scope or TM500

By "buzzing out" I mean using a meter with either a buzzer /continuity or set to ohms to find what wire goes where. The intensity pot wiper - white/yellow stripe wire I think - goes from the front of

Mike this is exactly what I just said. <mjdrum1958@...> wrote:

New Rifa caps have the same failure mode as old Rifa caps??? I sure hope that's not true! Does anyone know for sure. Hard to imagine manufacturing steps have not been taken to eliminate that. Mike

I had to purchase this value (.1uF + 22ohm) recently for a Tek 7912AD repair, and if it helps anyone, the part number to order at Mouser is 80-PMR209MC6100M022. (Assuming you're ok with the risk of

Thanks Mark. Will contact my friend to see if he has the appropriate adapter. Gordon

Thanks Andy, but a bit puzzled by your procedure. My DMM doesn't have a continuity beeper so not sure what you mean by "buzzing out" from the intensity pot. Are we trying to determine if the

According to a later manual the change was made at B040000: 0.1uF + 22 ohm 250VAC Albert

Bruce your on 240 or 120V mains? THe 240V blows them often! 120V no so. Jon

My advise is this: Look up the RIFA parts you are replacing and then use parametric search to find another vendor. RIFAs problem isn't wear out from heating & cooling or "dry out". I left a fresh

Bruce, If you want .047mfd: https://www.mouser.com/c/passive-components/capacitors/safety-capacitors/?capacitance=0.047%20uF&safety%20rating=X1&voltage%20rating%20ac=440%20VAC&instock=y If you want

They are usually 47nF+47R or 100nF+100R or 47nF+100R. I use all three indiscriminately according to availability. I can’t see that it matters much.

All, Well, it finally happened - POP! - sizzle, sizzle. My fine 7104 blew its RIFA capacitor in a loud manner, and I know, I should have replaced it sooner. I found what's left of the RIFA in the

Hakan, After knowing about the socket problem, is it best as PM to do a sweep of the sockets in the scopes and plugins? Is there a point where the sockets were better so replacing would not be needed?

While you are at it check if they are the bad TI C95 sockets. They are trouble waiting to happen. Some spray might help but probably only for a short time.

That worked, thx. After cold start (with J156 removed), self cal and ext cal the scope returned with 0 Fail messages.

Finally solved! I replaced the battery, that did not clear all the Fail messages but then I forced a cold start (after J156 removed). Then a 'self cal' and an 'ext cal' (the latter needed to apply