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"J.B. Wood" <arl_123234@hotmail.com>: Apr 02 12:43PM -0400 Hello, all and I'd welcome any input on subject quality relative to equivalents available from Duracell or Energizer. The Maxell SR626SW (Eveready 377) Silver Oxide and CR2016 Lithium cells are standard usage in electronic watches, and I'd like to focus on these. Thanks for your time and comment. Sincerely,   -- J. B. Wood e-mail: arl_123234@hotmail.com

John Keiser <johnkeiser@juno.com>: Apr 01 01:10PM -1000 This is a 30 year old dual channel 35 Mhz scope I was given. It is simply a challenging retirement project. I am a hobbyist, not a technician. From old TV days, I am aware of the hazards of HV.   The unit is very clean inside and outside but R437 [4.7 K] in the early stages of the power supply fried immediately when I powered on. Replacement did the same. No other burnt components are observed. Here's the schematic: https://imgur.com/E6WV4yD   I have an ESR and all caps seem OK. All the diodes I tested seem OK as well. I removed and tested the Q423, the diode/limiter D 444 and optocoupler which are connected to R437. All appear good.   The 560V winding of the transformer is not grounded but I assume measurements stated on the schematic are to ground.   R 437 reads -270V [to ground] but the schematic says should be 1.8V [hard to read.]. [I would have thought such a large variance easy to spot.] The 15, 40 and 150 [schematic says 130 but board says 150] volt rails seem accurate and steady.   Before I abandon the project, does anyone have experience with A Leader scope this old? Does the schematic provide any clues that I am unable to see?   Thanks for any comments.   John Keiser           --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

M Philbrook <jamie_ka1lpa@charter.net>: Apr 01 07:38PM -0400 In article <8sydnUgLQ6B0-1zHnZ2dnUU7-YHNnZ2d@powerusenet.com>, johnkeiser@juno.com says...   > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus   I can't read your schematic, very low res...   but anyways, I would say it could be one or two things since you obvioulsy have checked the caps and diodes..   The Tranformer may shorted to a HV wouding...   The heater in the CRT may have shorted to the cathod, unplug the CRT and see what happens with the voltages.   If the heater did short, install a small transformer just for the heater and let it float..   if you can provide a better schematic to look at maybe you would get better help!

tabbypurr@gmail.com: Apr 01 04:37PM -0700 On Monday, 2 April 2018 00:10:42 UTC+1, John Keiser wrote: > to see?   > Thanks for any comments.   > John Keiser   circuit diagram unintelligible.     NT

tabbypurr@gmail.com: Apr 01 04:39PM -0700 On Monday, 2 April 2018 00:37:30 UTC+1, tabby wrote:   > > Thanks for any comments.   > > John Keiser   > circuit diagram unintelligible.   Until we get a readable schematic, as a general principle one can always disconnect as many loads as poss to find out which one is sucking the thing to death.     NT

John Keiser <johnkeiser@juno.com>: Apr 01 03:18PM -1000 On 4/1/2018 1:10 PM, John Keiser wrote:   I have disconnected all loads, including the CRT. Still radically wrong voltage appearing at R437. Here's a better [but much bigger file] version of the schematic. Thank you for reviewing and comments. https://imgur.com/a/QURla     --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

jurb6006@gmail.com: Apr 01 11:06PM -0700 A decent print for the 520 but not A is at   https://elektrotanya.com/leader_lbo-520_2x5mv,30mhz_delay_line_5inch_oscilloscope_1977_sm.pdf/download.html   Scroll down and get to where it says "processing". Watch that until it says "Get manual" and click there to download. I guess that rigamaroll is to keep the bots out.   Anyway, R 437 feeds Q 423 which appears to be a simple pass regulator. It is in the return for a 560 volt winding that is doubled for negative voltage, which would only be used for the cathode circuit of the CRT. This regulates that.   Disconnect C 424 or 425 and see if the resistor is still stressed. If not look for a short around D 412 through 415. If there is no short try it connected but without the CRT socket on. Look for arcing in the socket. If none, disconnect the filament winding from the power transformer at pins 5 and 4 and see if the resistor is comfortable then. If so, suspect the power transformer for internal leakage to ground via that winding. That is actually among the most likely suspects.   If it proves to be the transformer it is no doubt unobtainium, but there is a way. You need an isolated transformer to feed the filament, a 6 volt AC wall wart would work. Or a regular hipot transformer will work. If you use a wall wart make sure it puts out AC, not DC.   If it is not the transformer, it is not likely to be the CRT, so that leaves he circuitry associated with that doubler for the negative source. Any shorted cap for example. When they are in series like that, one shorting will impose excessive voltage on the rest.   If all that is good then move on to the circuitry associated with Q 420.   The problem has to be around there somewhere. If the picture you supplied is your only print, get the manual for the 520 as it seems to conform to what you said. It should be close enough. I checked the 522, 510, whatever and none of them are close, there is no R 437 anywhere nearby in any of them.   The voltage at the junction of D 417 and 418 would be telling once you start disconnecting. Right now with the short it will be high. Once the short is gone by disconnecting things it will be low because due to the lack of output voltage the feedback will force Q 423 into full conduction. That is when you found it.

jurb6006@gmail.com: Apr 01 11:11PM -0700 Reading fast I missed the part where you disconnected the CRT, so forget that part.

N_Cook <diverse@tcp.co.uk>: Apr 02 09:09AM +0100 On 02/04/2018 00:10, John Keiser wrote:   > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus   As it will be a linear ps presumably, before frying anything else, run on a variac at 50% or a step-down site transformer and ratio the voltages.

peter wieck <peterwieck9@gmail.com>: Apr 01 11:55AM -0700 With the new relay in place, the unit is now operating properly and reliably. What I took out, once the elephant snot was removed, was a 12V sub-miniature US-made relay on a 24V system. That it lasted 10 years is remarkable. I Looked it up. No longer made and the company no longer listed.   Peter Wieck Melrose Park, PA

Joerg Lorenz <hugybear@gmx.ch>: Apr 01 07:16PM +0200 Am 01.04.18 um 16:32 schrieb Colonel Edmund J. Burke: >>> part of the Path is different.   >> The injection point is: news.highwinds-media.com, a typical troll-server.   > I don't use highwinds media, dumbo.   Certainly you do, Private Burke ...

Joerg Lorenz <hugybear@gmx.ch>: Apr 01 07:18PM +0200 Am 01.04.18 um 16:32 schrieb Private Edmund J. Burke: > I don't use highwinds media, dumbo.   news.highwinds-media.com!post01.iad!fx44.iad.POSTED!not-for-mail

Joerg Lorenz <hugybear@gmx.ch>: Apr 01 07:22PM +0200 Am 01.04.18 um 16:30 schrieb Private Edmund J. Burke: >> Certainly. That is exactly the header of your posting. Typical Troll-path.   > That's your own header, dumb bunny. > LOL   That shows all users, that you have no clue: I'm using the Albasani-server and everybody can see it.   Private Burke, you are fired and as of now in my killfile!

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