Re: TEK465 Horizontal trace
|
I found a set of 4 on eBay that are supposed to be NOS and tested good:
toggle quoted message
Show quoted text
These match what's called out in the SN<250K service manual: 152-0125-00, 4.7mA, 15pF. Not that I have much of a clue what I'm talking about. However, per something I found, that I'm going to have to find again, probably the horizontal debug manual I've referred to before, you can test for basic function in-situ. And the A-sweep fire diode tested open - high voltage. So I suspect that one is dead. The other three seemed to be ok. If it's just the "A-fire" diode dead, then I have 7 to pick 4 from. I'm hoping I can use our hacked curve tracer to match two pairs. It certainly allowed me to see the variation in the 151-0212-00 vert amp xtors. I also have sets of plug-in sockets coming in this Mouser order. I'm going to re-build the tunnel diodes on this scope to be plug-in instead of soldered in. That'll give me more opportunity to fix and tune this aspect. I.e. I may well be buying more diodes soon. A little knowledge, a little guesswork, a little luck. In other words, typical repair procedures. Thanks for the info. I'll let you know what comes of it. Dave On Thursday, March 25, 2021, 10:31:28 AM PDT, Jeff Dutky <jeff.dutky@...> wrote:
Dave, I've had a search through the CDPC (Common Design Parts Catalog) for the tunnel diodes (Tek PN 151-0386-00) in the 465. The service manual says that they are selected from 1N3718, but the Tek part number is not listed as a selected part (as with transistors, whose part number appears to change from 151- to 156- when selected by Tek internal processes, it looks like diodes change part number from 152- to 153- after selection, but I'm just inferring this from what's listed in the Matched or Selected diodes table on page 12-6 of the CDPC). The CDPC also indicates a different vendor part number, STD927 rather than 1N3718, so I don't know what's up with that. The specs given for STD927 are a 10 mA part with 25 pF capacitance, which appear (based on the Russian Tunnel Diodes list on TekWiki, ) to be matches to 3I306M, 3I306N, 3I306S, 1I305A, 1I305B, 1I308V, 1I308G, 1I308J, 1I308K, 1I308I, 1I308E, or 1I308D (where the rated current meets or exceeds 10 mA and the capacitance is around or less than 25 pF). Most of those are available on eBay. I also looked for the Tek PN on eBay and Amazon with no success. -- Jeff Dutky |
Dave Peterson