Path: ...!feeds.phibee-telecom.net!weretis.net!feeder8.news.weretis.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: legg Newsgroups: sci.electronics.repair Subject: Switch-mode microwave HT boost in Paderno MW Date: Sun, 05 May 2024 12:32:50 -0400 Organization: A noiseless patient Spider Lines: 21 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Injection-Date: Sun, 05 May 2024 18:31:11 +0200 (CEST) Injection-Info: dont-email.me; posting-host="fa048d507a455bfeefb38b436db369ec"; logging-data="2062732"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19MndSdMJuuGHR5ZV+QPTsj" Cancel-Lock: sha1:iWqoby14ZMZXrqxL+NtFStwmGpU= X-Newsreader: Forte Agent 4.2/32.1118 Bytes: 1728 Came across a switch-mode boost converter in a microwave HT supply today.~ normal magnetron. Output of the high frequency transformer looks to be a voltage doubler with 32x12mm film caps doing the job of the old 120Hz can. Paderno Mwo021 seems to have had a pretty flakey reliability. The controller in this one gives the magnetron supply three chances to produce a feedback amplitude, they quits. The HT supply into the magnetron shows 'some' output during these attempts but is visibly falling before each cut-off. I found a dry solder joint where the HT winding returns to the ref ground. I assumed this would have just arced over without much interference in basic function. Anyways behavior unchanged when restored. Film caps and diodes next? RL