Re: Tek 2215
On Tue, 26 Jan 2016 00:42:40 -0600 (CST), you wrote:
On Mon, 25 Jan 2016, David @DWH [TekScopes] wrote:There is probably no reason to preemptively replace them if closeThe replacements were physically smaller than the original parts. II believe I found them. They are actually the same Vishay/Dale CCF series
inspection shows no damage. On the one I repaired, the resistors were
visibly discolored but the cracks could not be seen with the CRT in
place until they were removed.
The symptom of attenuated and nonlinear vertical deflection pointed
directly at the collector load resistors and ohms measurement from the
bottom of the printed circuit board conclusively showed they were bad.
They were the first thing I checked because it was easy to do and
visual inspection showed that the printed circuit board itself was
discolored from high temperature in the area under and around them.
The value for the 51 ohm series resistors is not critical but I wonder
how hot they run and about higher parasitic inductance of spiral cut
film resistors. Why did Tektronix use carbon composition resistors