Re: Type 284 Pulse Generator performance check and quick fix


toby@...
 

On 2021-02-23 9:43 p.m., Rick wrote:
Hi All,

It bought a Type 284 Pulse Gen off Ebay a few weeks ago. I had planned to get it up and running so I could tune up my 5S14N sampler, which will help me fix a TG506's 1ns issue; when all of a sudden my 5440 dies. I decided to look for 5440 that has a readout. Again on Ebay I found a 5440 with readout. Turns out to be pristine, like new 5440 with what looks like new out of the box 5A42 & 5B48's, all for dirt cheap. At only 61, I'm not old enough to have ever seen, let alone own, any new Tek equip. What a treat. Turns out in the new scope my sampler passed it's performance check with minor adj. So on to the 284.

All looked pretty good except for the pulse trigger level. Timing was good but terribly low level at 15mV. It should be around 150mV. This unit has a ton of carbon resistors. I measured the carbon comps around the trigger's two transistors. There were four 5% resistors there and all where sitting at 10%-15% over. The trigger level came back up all the way. Sort of surprised me since most of the time I don't really know what I'm doing. It seems like every Tek repair is so completely different than the previous.
Congratulations! I'm a learning repairer so I like these success
stories, they give me hope.

--Toby


I know the electrolytic caps should be changed. When I lifted the resistors legs the solder had different smell. I pulled the solder fan in, but thought, could this be from the cadmium solder era. It looks like a lot of gold plating inside this thing. Definitely a through back.

Rick





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