[time-nuts] Strange E3610A PSU - Old revision

[cfo]

On Thu, 14 Jun 2012 16:58:41 +0200, Adrian wrote:

> There appears to be some massive contamination on the board, apparently
> not only from a leaked electrolytic cap. It looks much like some unknown
> liquid flooded a large area of the board and dried.
> 
> I do not see any reworked solder joints on the board, so the 'unusual'
> components have to be original to the unit. Do not attempt to change the
> circuit (replace components with values from a schematic that does not
> match the given circuit exactly), otherwise you'll end up in a mess. You
> may perform the service note changes though, given you check carefully
> if they work for your unit. Especially the voltage overshoot issue
> should be easy to check in advance.
> 
> The 12/91 date code on the transformer (unfortunately, the serial number
> is still undisclosed) indicates a very early example of the E3610A that
> was actually introduced in the 1992 catalog.
> 
> As by the 1992 catalog, there is a 10-turn voltage pot and a 1-turn
> current pot. More recent versions have 10-turn current pots as does mine
> from 1998. Also, it has U2 = LM340T (!), U4 = LF442CN, U5 = LM393N, U1 =
> LF411CN, U3 = LM336.
> 
> Hope that helps.
> 
> Adrian
> 
Hi Adrian 

Thanx for the ansver.
I have come to the same result ....
That the parts are "original" mounted , and it's an early model.

I have already been recommended a 2'nd cleanup of the PCB , 
and after a 2'nd washdown with IPA , and a top-side resolder of all the 
resistors in the PSU-Meter voltage divider section. The PSU volt meter is 
actually stable , and is following the PSU-Output , quite nicely. I 
verified by having my 34401A on the PSU-Output.

Now i'll wait for the new CAPS to arrive , and then calibrate it 
according to the manual. First Current , and then voltage.

I don't have the Current cal. resistors specified in the manual , but i 
just got an Agilent 6632B. Witch should be able to work as a variable 
0..5 Amp load. Providing i can get it to do that (manual reading).

I actually think i have gotten the PSU to behave now.

Thanx for all the hints. 

Ps: Current Calibration hints are welcome ...


CFO