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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 order of them
in their original packaging in a box in a climate controlled closet
(away from UV light) for a few years and when I opened it the
encapsulation had cracked. I believe the resin mix used is going
through an overly aggressive cure to keep the production line running
fast or something.


On Sun, May 25, 2025 at 6:54?PM bandrsn via groups.io
<bandrsn@...> wrote:

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 shielded power supply, but there's not enough of it left to get info from its case.
The downloaded service manual and schematics don't exactly match the B053423 S/N. The A23 Inverter Board shows two ceramic 0.02UF, 1400VDCAC capacitors in parallel (C1205 and C1206), both in series with a 27 Ohm resistor, R1205. My A23 board has (had) a single RIFA where R1205 was and what appears to be a jumper across one of the places for the capacitors.
My question is, what should the replacement RIFA be? Since the exploded one is in bits and pieces I can't get enough info from it to know.
The schematic shows the RIFA directly across the hot and neutral lines after the power switch.

Any brand/device values, etc. recommendations for a commonly available 115VAC replacement that, hopefully, will not explode again?

Also, the power supply construction makes it difficult to gain access to the back side of the Inverter Board. I was able to carefully snip away the bits of the RIFA plastic and foil, etc. so there are about 1/4" or slightly more of the tinned leads sticking out on the component side. I was planning to cut, bend and quickly solder to these exposed leads, being careful not to melt the solder too much on the other side and cause a short.

Does anyone foresee a problem with this if care is also taken to avoid any shorts, etc. on the component side too?

Thanks,
Bruce
AB6BA

Bruce,

If you want .047mfd:
If you want .068mfd:

The value is not critical. The latter is common in the 2000 series as mains filters. What I sent is X1 type that is higher voltage rating than X2. You can use a resistor where the original was which is in series with the filter.

Getting to the underside of the bottom board is not that difficult. There are four small phillips screws that hold the bracket for the two main screw cans. Two are on the rectifier/regulator board and four are on the side panel with the vent holes. Remove the two filter cans making sure to get polarity right when reinstalling. You can put in an additional NTC off the mains while you are in the cavity. A CL-70 is an option.

If you have not already done so, clean out the odor and any deposits left by the exploding condenser.

Mark

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 shielded power supply, but there's not enough of it left to get info from its case.
The downloaded service manual and schematics don't exactly match the B053423 S/N. The A23 Inverter Board shows two ceramic 0.02UF, 1400VDCAC capacitors in parallel (C1205 and C1206), both in series with a 27 Ohm resistor, R1205. My A23 board has (had) a single RIFA where R1205 was and what appears to be a jumper across one of the places for the capacitors.
My question is, what should the replacement RIFA be? Since the exploded one is in bits and pieces I can't get enough info from it to know.
The schematic shows the RIFA directly across the hot and neutral lines after the power switch.

Any brand/device values, etc. recommendations for a commonly available 115VAC replacement that, hopefully, will not explode again?

Also, the power supply construction makes it difficult to gain access to the back side of the Inverter Board. I was able to carefully snip away the bits of the RIFA plastic and foil, etc. so there are about 1/4" or slightly more of the tinned leads sticking out on the component side. I was planning to cut, bend and quickly solder to these exposed leads, being careful not to melt the solder too much on the other side and cause a short.

Does anyone foresee a problem with this if care is also taken to avoid any shorts, etc. on the component side too?

Thanks,
Bruce
AB6BA

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? If so, what year? There are 8 and 16 pin sockets that will have this problem. I have seen some of the sockets have contacts that make contact on the sides of the IC pins. These will have small holes where the pins go in. Some dual wipe sockets that are taller to give more contact surface area work well. The MilMax machined types are better by being machined. Is the machined type the preferred type to use?

Mark

On Thu, May 22, 2025 at 11:12 PM, Rogerio O wrote:

Also, I intend to reseat (with some Deoxit) all the IC's and connectors of the readout board.

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.

/H?kan

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 some voltages to the 2 inputs and a fast rising signal), and all Fail messages were finally cleared.
Thx to you all for giving me the direction to get this solved. I love my 2343A scope and I would hate to miss it.

On May 22, 2025, at 14:12 , Rogerio O via groups.io <rodd414@...> wrote:

I was thinkin to start with the easiest issue (2) which would require spraying a little of Deoxit Fader on the pot's wiper but, to my surprise, it seems impossible to get there
see (/g/TekScopes/album?id=302608).

I'd try taking the knobs off and spraying Faderlube down the shaft before disassembling it, and I'd also try that from the exterior and see if it'll wick through any gaps.

For garbage and missing values in readout, don't forget your vertical and horizontal plugins. I've had more problems with those causing missing/wrong readout due to dirty/damaged cam switch contacts. YMMV.

Adam

Roger,

You may have to, unsolder the leads from the diodes from the rear wafer, loosen the nuts on the rear of the switch enough to keep them on, loosen the nut for the pot, move the pot back enough to get access to the tabs holding the metal case on, pry the tabs back enough to get a gap where you can spray cleaner inside then reverse to get back to original. It is possible you will have to remove enough to get the pot out to clean it. I know it is a lot of work. Drilling a hole will get metal shavings inside the pot. I had two pots that were open in a Bogen DB130 I had to replace the guts. That had a similar thing as you have, a wafer and wires that needed to be removed. This has concentric controls. It took a few hours in my case. No other way was possible.

Mark

Thank you very much for having time to check and post this reply, Barry
Roger

Hello and need help for this part.
I’m looking for the vfd display used in the counter timer of the 2236.
Part number is 670-7423-01 for the small board and 150-1110-00 for just the display tube. The display tube also known as a
Noritake Itron p/n FG94C1.

dear all,
I dropped my 7904 from its cart last week.
Up to the moment the identified losses are:

1- broken 7B85 time/div pot and cal/uncal knob and rod
2- Very noisy redout pot
3- Garbage number showing on the top rows of readout
4 - No information shown in redout bottom lines.

Probably issues 2 to 4 were already there, since I had almost no time to play with this instrument since I bought it some weeks ago.

I was thinkin to start with the easiest issue (2) which would require spraying a little of Deoxit Fader on the pot's wiper but, to my surprise, it seems impossible to get there
see (/g/TekScopes/album?id=302608).

So I would like to know if there are known practices of what to do in situations like this one.
I have read somewhere that one possible solution is to drill a 1/8" hole on the case to allow sprying the cleaner than later closing the hole with some inert putty.
Is this an "approved solution"?

Also, I intend to reseat (with some Deoxit) all the IC's and connectors of the redout board.
Any other recommendations concerning the random readout characters?
Is there a known fault that would cause the entire bottom readout line (all four fields) to be missing?

Thank you very much,
Roger

Looking at that pot from the back, on mine the center pot has the left tab grounded, the center tab has a wire with white insulation and a violet stripe, and the right tab has a wire with red insulation and a wire with red insulation and a brown(?) stripe.

HTH,
Barry - N4BUQ

Hi to everybody.
I bought a 067-0587-01 on Epay and, for the moment, I have two issues:

1- One red wire going to the amplitude Pot is "floating" as shown in photo (/g/TekScopes/album?id=302607).
I tried to figure out where it should be going following the schematics but I couldn't find any pot terminal having two connections.
Each terminal seems to be connected to ground (local terminal), +15V or -15V.
Can anyone be kind enough to open its unit and tell me where this wire is going to?

2- One of the clear plastic press "button" from the REP RATE switch is broken and it flies like a rocket when it goes from "pressed" to "non pressed" .
I was lucky enough to find two times but Murphy is always around...
Is there a way to disassemble it to try to glue it in place? Any other suggestion?

Thanks to all,
Roger

Rogerio O <rodd414@...> added the photo album 067-0587-01 ( /g/TekScopes/album?id=302607 ) : one wire connection is broken

On Thu, May 22, 2025 at 06:38 AM, n4buq wrote:

I had opened an older version of the schematic which doesn't have that relay.
I see it now on the later versions. Apologies for the interruption.

Looking again: the offending relay was K490, which is the bandpass limiting relay; I misread the numbers on the board since I wasn't using a flashlight. From the description and schematic, K480 bandpass-limits the trigger, and I believe that was added in later revisions as you pointed out. I was pretty sure it was the lower rear relay (490), not the middle one (480), so thanks for making me take a second look! I'm only documenting this for the next poor slob who runs into it, which might well be me.

thanks,
Adam

I had opened an older version of the schematic which doesn't have that relay. I see it now on the later versions. Apologies for the interruption.

Barry - N4BUQ

On May 22, 2025, at 05:52 , n4buq via groups.io <n4buq@...> wrote:

Hi Adam,

Was that, perhaps, K48 or K490? I don't see a K480 but I might be looking at a different version of the manual.

I'm looking at the manual on Tekwiki for B200000 up, and K480 is at the very back center of the output amplifier board on the labeled component photo. I need to find it on the schematic and see if this makes sense.

Glad you found/fixed it. Those relays are definitely a pain.

I should have taken before-and-after photos of the trace, but I'll probably have another opportunity, the way these relays are.

thanks,
Adam

Hi,
my 2784 Spec lost all the data, because Li- Battery has not been changed last fifteen years. Now, when I power the Spectrum Analyzer the display shows me a 2782 .
How can I fix this problem? I can only tune up to 33 Ghz instead of 40 Ghz. I didn't found anything in the manuals.

Juergen