On Thu, Aug 16, 2018 at 03:43 PM, tom jobe wrote:

Hi Leo,
Thanks for the progress report, It's good to see that your 2215A repairs
so far have gone well!
In studying your photos, it looks like you have one of those dreaded
"Schaffner" brand AC inlet filters (where the AC cord plugs into the
back of the scope).
If that is what you have, they have a poor reliability record when used
on 240 AC line voltage, if you also have that too.
I'm in a 120 volt AC part of the world and I started changing them after
having just one scary "Schaffner" failure.
The Tekscopes message archive should have some "Schaffner" discussions
from the past, and a Google search on the term 'Schaffner filter
failure' will get you more information too.
You might also consider changing the few X and Y caps in the 2215A,
especially C904 which is under the AC inlet filter and behind the main
power switch.
C904 is much easier to change while you have the AC inlet filter removed.
The original X and Y capacitors have difficulty with 240 volt mains, so
you might want to get the highest rated replacements you can find.
tom jobe...

On 8/16/2018 4:19 AM, satbeginner wrote:

Hi all,

just a final message: it's all done!

Today I received the 12V 60mm brushless fan that was a perfect fit.
I used the half wave rectifier circuit I was able to place the components

for on the board, the fan is running nicely without real noise on 9V.

I mean, you can hear it, but only just.
There are plenty perforations all around the casing to let cool air in, so I

choose to have it blowing out, so it is sucking the warm air from the inside
of the scope and remove it from the scope.

(Like in my 2465's)

One extra thing I found: When I put all the covers back and ran the scope

for a while, I found that the one screw on the right hand side is actually
quite important.

This creates a thermal connection between where the internal heatsink is and

the outside blue cabinet, so that way the scope's casing helps in cooling the
scope too.

Again, pictures are here:

https://groups.io/g/TekScopes/album?id=64919&p=pcreated,,,20,1,0,0

Un saludo,

Leo

Hi Tom,

As it turns out, it is not yet solved... ;-)

Yes, I opened the scope again, and yes, it's a Schaffner line-filter.
I put a picture of it in the album: https://groups.io/g/TekScopes/album?id=64919

Is this one of the "explosive" types?? If so, I'll will replace it.
Although this scope spend his whole life in The Netherlands,, so maybe it OK?

Further down the line there is this black, plastic box that contains another line-filter.
In there are two 2n2 RIFA capacitors (similar as in the 2465 PS), they already look "cracked", so I will replace them too.

To be continued,

Leo

Hi Tom,

Thanks for the documents, I added them to my 2215A paperwork and checked my scope for these mod's.

I am in Spain, but based on the SN (204xxx) my 2215A was manufactured in the UK, so it's probably always been in a 220V environment.
I got the impression these mod's were based on the early US build SN's, depending on scope model. (01xxxx - ), and not for the (later?) manufactured UK (2xxxxx) and Dutch (7xxxxx) SN's?
I checked my scope for these mod's, and some were already standard in the schematic of the 2215A, but funny enough there seem to be many iterations around of the PS design, some mod's are to be done only to 2235's, and some only to 2215 but not to 2215A, etc.

What I did do was:

Replaced the Schaffner line filter to be on the safe side;
Replaced the two (already micro cracked) 2n2 RIFA capacitors in the extra line EMI filter build to the back of the scope;
Kept the capacitor C900, it looks as if that one was replaced before;
Kept the power supply mod's as they are now.

Pictures of the removed components are here: https://groups.io/g/TekScopes/album?id=64919&p=pcreated,,,20,1,0,0

Thanks again for the input,

Leo

On Aug 17, 2018, at 18:56, garp66 <hrgerson@...> wrote:

Could someone please post the model # for a replacement of the Schaffner line filter unit for a standard 120V North American powered Tek 2215a scope ?

I don’t know what is in the Tek scopes, but if it is a FN323-1/01 as was mentioned earlier, you want a Schaffner FN9222-1-06 (and probably some isolated quick-connect connectors and a crimper so you don’t have to solder them in again).
You *don’t* want NOS, because even unused ones of the old style are likely to have exactly the same problem (moisture intake to a metal/paper capacitor the plastic shell of which has crazed).

I put these replacements into all my HP 3457a DVMs after one of the original ones exploded (the DVM had been stored and then shipped, and that probably exacerbated the moisture problem).

I strongly advise anyone who has an FN323-1/01 or similar to replace these *before* connecting line power, and, if there is absolutely no way to avoid connecting the unit to line power before the replacement, make sure there is something like a steel plate in the passageway the molten/vaporized tar will shoot out into from the back of the unit. And have a flashlight in your pocket so you can find the breaker box after the fireworks.

Oh, and replace the other metal/paper RIFA (or WIMA) capacitors from the 1980s, too, if they see high-energy voltages — in particular if you already can see the crazing. But this is not quite as critical as these are much less of a bomb setup than the capacitors tar-sealed into Schaffner line filters.

Grüße, Carsten