Re: Tek 465 Sweep
|
Hugo,
toggle quoted message
Show quoted text
Do you mean the "A7 Timing board" with the A/B sweep cam switch on it, or the "A8 Trigger Generator & Sweep Logic Board"? The A8 board has a 15uF, 20v electrolytic cap, C897 which could be a source of a pwr/gnd short. I'm not seeing a power decoupling cap on the A7 board that would so neatly explain the short. I have found a number of shorted electrolytic and Tantalum decoupling caps now on several pieces. So that's my first suspicion. Could still be something else, U640 for example. What serial number? Though, I'm seeing the same C897 on 070-1330-00 (pre SN B250000) and 070-1861-00 (SN B250000 & UP). But what else might be different? Knowing which is important. Also, what jumper are you referring to? Dave On Monday, November 22, 2021, 05:34:31 PM PST, <la4wka@...> wrote:
Hello group. I have on my desk a Tek 465 scope (not M) with low serial number, given to me as dead from navy surplus. Well it its not dead anymore, but I have a fault I can't trace and figure out. Also have a "donor" scope that actually works fine, sadly cant say it looks fine. So parts awailable at least to try if its IC''s or something. On the -8V rail there is a short to gnd somewhere. The other voltages are fine. However, when I lift the "jumper" that isolates the timing board the -8 is stable even with small load and no ripple, so I dont think the psu is faulty. Screen shows both channels in voltage, but the sweep is missing. Can move around the dots and focus is fine. Tube seems to be fine. Have measured just about every transistor and cap on there, but the short to ground still exist. Does anyone in here have experience in this and? could point a finger in the right direction? I'm stuck....... Rgds Hugo / LA4WKA |
Dave Peterson