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Free to a good home: partially working Tek 7623A CRT
I would like to find a home for a used Tek CRT, p/n 154-0723-00. It comes in an original Tek box, complete with shock absorbing foam. I am located in southern Ontario, Canada. The CRT works well in
By Dan G · #188114 ·
Re: 172 programmable test fixture plastic latch modelling effort for 3D print replacement (105-0286-00)
As an update for those interested, I was able to create an accurate 3D model thanks to Hakan's measurements (thanks again!) that now can be found at https://w140.com/tekwiki/wiki/105-0286-00 For those
By Gregor Lasser · #188113 ·
Re: 453 trigger issues
In my 453, I replaced many of the carbons with 1% types. There are ones that are too small in wattage. If yours has the dark brown body type resistors, these are usually out tolerance enough to
By Mark Vincent · #188112 ·
More goodies on the Stuff page, plus sale on scopes and power supplies
Just in time for Christmas, we have put all kinds of goodies on the Stuff Season page, especially under the Surprises Category (including 20 pounds of DC Fans!), Scopes and Power supplies sections.
By walter shawlee <walter2@...> · #188111 ·
Re: 7B50 - No Trace
Hi Ozan, After repairing the connection to S260, I gathered another set of readings. The setup was the same as before (e.g. NORM, EXT, TIMEBASE, LEVEL midway on the negative slope): Base of Q224 :
By n4buq · #188110 ·
Re: 7B50 - No Trace
I took the assembly out and tested it and it worked. I put it back in and it doesn't work. I then noticed the solder joint that should have been holding the wire that connects to one of the switch
By n4buq · #188109 ·
Re: 7B50 - No Trace
Now I see the description in the manual. Very interesting design, makes sense for PP-Auto mode but probably makes life complicated in non PP-Auto mode. Ozan
By Ozan · #188108 ·
Re: 7B50 - No Trace
Comments below. The LEVEL knob does vary that voltage but issues with S260 (see below) may need to be corrected before going further.
By n4buq · #188107 ·
Re: 7B50 - No Trace
We expect base voltages of Q234 to change with LEVEL knob (pot) but SLOPE control shouldn't make any difference. Q224 base will be at about trigger input voltage + 0.78V and Q234 base should be
By Ozan · #188106 ·
Re: 7B50 - No Trace
Regarding S260, I see now on the schematic that the connector numbers for P260 are shown (3 and 6) so I can follow those and check the switch. Thanks, Barry - N4BUQ
By n4buq · #188105 ·
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 ·