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So, is the 4 AAA == 6 Volts and the divide by ten == .6 Volts a level that tests the TDs well? It's just below a normal .7V diode drop, so it tests their "tunneling" ability?

Another point - download both service manuals and take a look at what's involved in fixing each of them. The 46x series tends to develop bad filter caps and rectifiers. It is possible to replace them

While the comments are valid for 454, the 454A (as listed in the subject) does have a larger screen and FET input circuitry.? So, if Frank truly has a 454A available its more of a level playing field

Update: I soldered an IC socket in U174 thinking that I would connect leads to it externally to diagnose the Ch1 issue and now the trace has completely disappeared! The beam finder works, but when I

640 ohms ought to be enough for anyone.

I recently obtained a batch of old and diverse probes. Many are junk but a few are rather interesting. Out of a number of old 1x Tek probes I should be able to put together 2 nice ones (as soon as a

My manual, for SN B250000 and up, does in fact say "check the collector of Q984", so you're right. Raymond

Hi, In an original paper high S/N 475 manual (B250000 and up) it only says Q984 on page 4-16 in step 2. There is no mention of a Q3984. tom jobe...

Stand the scope on it's rear and dribble small amounts of De-Oxit down the shaft. Let it sit for an hour, then try turning the pots. 73, Dick, W1KSZ

Neither of my 475 manuals have a page 4-16. I did not find the section of the manual you are referring to. <javier.alberola.perales@...> wrote:

Hi, I'm trying to repair a 475 following the procedure in the manual. In the page 4-16, paragraph "sweep and logic", step 2, the manual says to "check the collector of (3984". Is this an errata, and

I would try to put a little thin oil down the shaft. Take the knobs off and just apply a drop or two to the shaft and allow it to soak in for a while. It may take a few applications to break it free.

For the 465, it's almost a bucket list sort of thing. This scope was the goto guy during the adolescence of computer history and I'm sure many of us could fill up this list with war stories where the

Hi, First posting on this group, hope someone can help.... I have a T935A scope which has developed a problem and I'd like to try and fix it as its a very useful portable scope. Basically two of the

I also own both a 465 and a 454. The 454 has a smaller screen and 50% greater BW. However in tests I very recently made, both scopes would display and (barely) trigger on a 200mhz signal from a GDO.

That is great news. Sometimes direct observation can point directly to the area of the circuit where the problem is. I always install sockets if possible. I hate having to desolder a part more than

You need two oscilloscopes so you can use one to fix the other and if they are different types so you can cover more applications, then hen you need a parts mule for each so that is four. My mistake

The 454 and 465 series both use tunnel diodes which seem to be the most common point of failure and the most difficult parts to find replacements for. The 465 series was built for a long time so spare

Dave - Where did you get that little bearing you used to repair the motor? Dick

There is a special place in hell for the guy that throws all the logic analyzer pods and leadsets away when the gear is sold, along with all the scope probes and scope covers. somewhere out there is a