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Re: 7B50 - No Trace
Hi Ozan, I'm not sure but I think I may have found problem with the LEVEL/SLOPE control. I checked the base voltage of Q224/Q234 with the SLOPE in + and - mid-positions. In both cases, Q224's base is
By n4buq · #188104 ·
Re: TEK 475: Powersupplies repaired, HV CRT circuits fixed (INTENSITY, FOCUS, ASTIGMATISM working) but horizontal Sweep NOT working any more :- (
@ Ozan, Correction: the shorted tantalum was C961 (2.2. uF 20V), fed by a serial resistor of 10 Ohm on the +15V power line.. This shows that such a 10 Ohm series resistor does not protect the tantalum
By Redguuz · #188103 ·
7 photos uploaded #photo-notice
The following photos have been uploaded to the TEK475 Shorted +15V rail (Intermittent shortcut C961 PLUS intermittent interruption in GND rail. ( /g/TekScopes/album?id=270063 ) album
By [email protected] Notification <noreply@...> · #188102 ·
Re: 453 trigger issues
well,my scope scrubup didnt last long,now neither channels trigger!,it looks shiny tho!
By quadzillatech@... · #188101 ·
Re: 7k plugins fault finding outside scope?
John Griessen's flexible extender kit does what you want. I have used them to check out the caps on a 7A26 applying just +/-15V and watching the current consumption.
By Richard Steedman · #188100 ·
Re: 7B50 - No Trace
Hi Barry, My comments are below: There is a subtle reason. If you are interested (otherwise skipping is fine): We want to turn off the current to CR262 to see if it goes to low voltage state. With
By Ozan · #188099 ·
Re: TEK 475: Powersupplies repaired, HV CRT circuits fixed (INTENSITY, FOCUS, ASTIGMATISM working) but horizontal Sweep NOT working any more :- (
Everybody: Thanks for your help and suggestions. Dear Ozan, You definitely mentioned C1387 as a potential culprit and helped me locating it (some errors in the manual , hence I could not find it
By Redguuz · #188098 ·
Re: 7B50 - No Trace
Comments interleaved with readings in brackets below. I presume you want "-" slope so as to disconnect the CQ connection point from the rest of the circuits. TP262's voltage is 11.1V which, if R261 is
By n4buq · #188097 ·
Re: TEK 475: Powersupplies repaired, HV CRT circuits fixed (INTENSITY, FOCUS, ASTIGMATISM working) but horizontal Sweep NOT working any more :- (
Congratulations for the fix Martin. I was guessing in the same area but I don't know if I got it right in my message /g/TekScopes/message/187822 Mystery solved! Ozan
By Ozan · #188096 ·
Re: TEK 475: Powersupplies repaired, HV CRT circuits fixed (INTENSITY, FOCUS, ASTIGMATISM working) but horizontal Sweep NOT working any more :- (
Good find Martin! Not important: In my 475 pdf C1387 is shown correctly I think in location 7D. But despite my new glasses I can't find C1387 in diagram <12>. Albert
By Albert Otten · #188095 ·
Re: Horizontal preamplifier #chat-notice
Did you check the connections to the plates, as Raymond suggested? Sent from my iThing, so please forgive typos and brevity.
By Tom Lee · #188094 ·
Re: TEK 475: Powersupplies repaired, HV CRT circuits fixed (INTENSITY, FOCUS, ASTIGMATISM working) but horizontal Sweep NOT working any more :- (
Goed gedaan, Martin! (Well done, Martin!) Raymond
By Raymond Domp Frank · #188093 ·
Re: TEK 475: Powersupplies repaired, HV CRT circuits fixed (INTENSITY, FOCUS, ASTIGMATISM working) but horizontal Sweep NOT working any more :- (
Hi, I managed to repair the CRT circuit of my TEK 475. The screen intensity control and focus, is currently working as I should. I now can create nice, sharp horizontal and vertical lines in the XY
By Redguuz · #188092 ·
Re: 453 trigger issues
Thank you Mike! I will bookmark those articles. By the way, the individual files of Service Scope and TekScope are hosted at Kurt Rosenfeld¡¯s excellent TekWiki site, w140.com . Dave Wise Information
By Dave Wise · #188091 ·
Re: 453 trigger issues
Hello, The first one in Charles Phillips' series was in February 1969. This is the volume when Service Scope was renamed "TEKscope", which in turn includes Service Scope. The look changed somewhat as
By Mike Merigliano · #188090 ·
Re: 7B50 - No Trace
I don't know the answer to that, perhaps someone with more experience with 7000 series knows. Reading the interface notes it sounds like MF inhibit is only used in Alternate and delayed B sweep modes.
By Ozan · #188089 ·
Re: Tektronix 576 CRT replacement
That's interesting, my 576 had black soot all inside the HV cage and its components, along the wiring all the way up to the CRT yoke. Do you mean everywhere, or confined to that area? The soot
By @gmilliorn · #188088 ·
Re: 453 trigger issues
From my 453 repair journal: ++++++++++++++++++++ Then I noticed that B trigger wasn't working. The culprit was tunnel diode D675 (TD3, 4.7mA). Luckily I had a spare. Later I lost B trigger again.
By Dave Wise · #188087 ·
Re: 453 trigger issues
Hey Mike, I have Service Scope and TekScope in individual files. Can you tell us the Month/Year or Volume/Number? Thanks, Dave Wise Sent: Wednesday, November 17, 2021 8:02 AM To: [email protected]
By Dave Wise · #188086 ·
Re: Removing the Adhesive From Hell
Found the spray bottle version on Amazon (of course). There¡¯s apparently a ¡°heavy duty¡± version as well but I have not tried that. With the ¡°regular¡± version, I think some who complain that
By stevenhorii · #188085 ·