[TechAssist] Re: Tektronix 485 Oscilloscope - Power Supply Cycling ON/OFF - FIXED

Perry..
Same here.
But everyone approaches repairs to what they know.
As Wayne mentioned...I don't use it to full advantage.



-Ed-


Ed Gaidies
Tel-Tek Electronics
Est-1969
Ontario/Canada

teltek@xxxxxxxxxx









> From: Electric Medic <info@xxxxxxxxxxxxxxxxx>
> Reply-To: <techassist@xxxxxxxxxxxxx>
> Date: Sat, 26 Feb 2005 23:23:26 -0500
> To: <techassist@xxxxxxxxxxxxx>
> Subject: [TechAssist] Re: Tektronix 485 Oscilloscope - Power Supply Cycling
> ON/OFF - FIXED
> 
> I'm Sorry, but I don't have time to hook up a scope everytime I change a
> H.O.T. I only use our scopes for audio problems, and that is rare when a
> scope is needed. I could drag out a service manual and all sorts of test
> equipment, scopes, volt meters, display color bars, etc but if I can fix the
> unit without all of that, I will. Now if some field rep, or especially the
> newspaper comes by then I can hook the TV up to more equipment and really
> make it look good, but not the norm. Pretty much if you change the cap in
> the driver circuit especially on Sanyo's and solder up the driver
> transformers you fix about 85% of blown H.O.t's. Except on the RCA's, CTC195
> and CTC197's where you usually have a bad flyback. On the 203's you usually
> have a bad solder conn. on the drive coil. I have never used a scope on
> those and have fixed I think every blown H.O.T on every brand set I have
> come across. As far as the Sony's if you check all VDR's and especially the
> 6. something ohm resistor and do a good solder up of the horizontal circuit,
> q601 and q602 hold up just fine unless you had a surge of some kind, then
> you might need the scope. We have three scopes in the shop and I use ours
> mainly just with audio problems, never had too in low or high voltage power
> supplies. So, I guess we all do have many different ways of troubleshooting.
> 
> Perry Bower
> Electric Medic
> "It's Cheaper to Keep Her"
> http://www.electricmedic.com
> 3850 Washington Road  Suite 4C
> Martinez, Georgia 30907
> Phone: 706-8MEDIC4  (863-3424)
> Phone: 706-863-3474
> Fax: 706-863-2316
> mailto:info@xxxxxxxxxxxxxxxxx
> 
> 
> 
> -----Original Message-----
> From: techassist-bounce@xxxxxxxxxxxxx
> [mailto:techassist-bounce@xxxxxxxxxxxxx]On Behalf Of Gary McCartney
> Sent: Saturday, February 26, 2005 9:55 AM
> To: techassist@xxxxxxxxxxxxx
> Subject: [TechAssist] Re: Tektronix 485 Oscilliscope - Power Supply
> Cycling ON/OFF - FIXED
> 
> 
> Every time I change a HOT or a flyback, I connect my scope to the HOT
> collector and view the waveform as the set fires up. If I see something
> abnormal, it gets unplugged in a hurry. I don't understand how anyone
> can go on without using a scope. What about the Sony power supplies with
> the shorted Q601- Q602, don't you check if the square waves are
> symetrical at low AC before you fire up the set at 120V? Ripple in power
> supplies?  Proper horizontal drive? etc. etc. etc.
> 
> 
> 
> 
> Gary McCartney
> 
> McCartney Electronics
> Guelph Ontario Canada
> Est. 1984
> email: gary (at) number63.ca
> 
> 
> 
> 
> 
> 
> 
> Kevin wrote:
>> How would you test for shorted transistors, IC's and diodes?  How would
>> you test resistors that have changed value?  I use my scope about once
>> every two years.  It is interesting how we all repair things in
>> different ways.  I guess it all comes down to what tools we feel
>> comfortable using.
>> 
>> Kevin Wilks
>> Kevin's TV & Video Repair
>> Penticton BC Canada
>> kevintv@xxxxxxx
>> 
>> 
>> -----Original Message-----
>> From: techassist-bounce@xxxxxxxxxxxxx
>> [mailto:techassist-bounce@xxxxxxxxxxxxx] On Behalf Of Al Gutz
>> Sent: Friday, February 25, 2005 8:23 PM
>> To: techassist@xxxxxxxxxxxxx
>> Subject: [TechAssist] Re: Tektronix 485 Oscilliscope - Power Supply
>> Cycling ON/OFF - FIXED
>> 
>> 
>> My Tektronic is my main peice of test equippment.
>> If I had to give up either scope or DDM, for me it would be DDM. I can
>> measure voltage if needed with scope, cannot look at a waveform on a
>> meter.
>> 
>> Al G
>> 
>> 
>> Ed Gaidies wrote:
>> 
>>> Al;
>>> Sorry to say...these days, providing you know what your scope should
>>> show...and actually getting a Manual for scope traces..mine has
>> 
>> gathered
>> 
>>> dust.
>>> 
>>> 
>>> 
>>> -Ed-
>>> 
>>> teltek413@xxxxxxxxxxxx
>>> 
>>> 
>>> 
>>> 
>>>> From: Al Gutz <alg@xxxxxxxxxxx>
>>>> Reply-To: <techassist@xxxxxxxxxxxxx>
>>>> Date: Thu, 24 Feb 2005 22:11:16 -0500
>>>> To: <techassist@xxxxxxxxxxxxx>
>>>> Subject: [TechAssist] Re: Tektronix 485 Oscilliscope - Power Supply
>> 
>> Cycling
>> 
>>>> ON/OFF - FIXED
>>>> 
>>>> A new Tektronix TDS224  100 meg 4 channel  with accessories runs about
>>>> $5000, why not repair.
>>>> Al G
>>>> 
>>>> Electric Medic wrote:
>>>> 
>>>> 
>>>>> I wish I could get my 2216 repaired. I bought it new in 1996 and it
>> 
>> died
>> 
>>>>> last year, no power. It is just sitting on a shelf collecting dust, I
>>>>> thought it was a lost cause. You mean you all actually repair these?
>>>>> 
>>>>> Perry Bower
>>>>> Electric Medic
>>>>> "It's Cheaper to Keep Her"
>>>>> http://www.electricmedic.com
>>>>> Check out the Electronic Repair Screensaver We created. More Images
>> 
>> to come!
>> 
>>>>> To download these Collections you must first install the Eyetide
>> 
>> Viewer:
>> 
>>>>> http://www.eyetide.com/download/?s=O3OfmSLHXygGHCv1W6Gz3Bgjtq3DNNMNdc
>> 
>> KsYSVGC
>> 
>>>>> "We're Number One Where it Really Counts, With our Customers"
>>>>> 3850 Washington Road  Suite 5b
>>>>> Martinez, Georgia 30907
>>>>> Phone: 706-8MEDIC4  (863-3424)
>>>>> Phone: 706-863-3474
>>>>> Fax: 706-863-2316
>>>>> mailto:info@xxxxxxxxxxxxxxxxx
>>>>> "WE REPAIR WITH CARE"
>>>>> 
>>>>> 
>>>>> -----Original Message-----
>>>>> From: techassist-bounce@xxxxxxxxxxxxx
>>>>> [mailto:techassist-bounce@xxxxxxxxxxxxx]On Behalf Of David Lessard
>>>>> Sent: Wednesday, February 23, 2005 10:18 PM
>>>>> To: techassist@xxxxxxxxxxxxx
>>>>> Subject: [TechAssist] Re: Tektronix 485 Oscilliscope - Power Supply
>>>>> Cycling ON/OFF - FIXED
>>>>> 
>>>>> 
>>>>> They sure are, I couldn't have traced this short without one. The (-
>> 
>> 5V)
>> 
>>>>> power distributes everywhere. This was a great experience for me, now
>> 
>> I'll
>> 
>>>>> be able to service this thing forever...oh yeah...most of the parts
>> 
>> are
>> 
>>>>> obsolete now...forgot this thing is 30+ years old. You couldn't tell
>> 
>> by the
>> 
>>>>> way it works.
>>>>> 
>>>>> David Lessard
>>>>> Alexandria, Ontario, Canada
>>>>> mr_fixit@xxxxxxxxxxxx
>>>>> 
>>>>> ----- Original Message -----
>>>>> From: <majorthom@xxxxxxxxxxxxx>
>>>>> To: <techassist@xxxxxxxxxxxxx>
>>>>> Sent: Wednesday, February 23, 2005 10:05 PM
>>>>> Subject: [TechAssist] Re: Tektronix 485 Oscilliscope - Power Supply
>> 
>> Cycling
>> 
>>>>> ON/OFF - FIXED
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>>> Aren't schematics great
>>>>>> Pete
>>>>>> David Lessard <mr_fixit@xxxxxxxxxxxx> wrote:
>>>>>> FIXED
>>>>>> 
>>>>>> These things are built like brick sh*! houses. After acquiring a
>> 
>> schematic
>> 
>>>>> I
>>>>> 
>>>>> 
>>>>> 
>>>>>> discovered a shorted C852 (.47uf) on the attenuator board - PS
>> 
>> decoupling
>> 
>>>>>> capacitor shorting (-5V) to ground. All power supply current is
>> 
>> monitored,
>> 
>>>>>> shorts or excessive loads cause the power supply to shutdown. In
>> 
>> this case
>> 
>>>>>> the power supply was restarting, over and over again, about 3 times
>> 
>> a
>> 
>>>>>> second. While I had it opened I cleaned all the switches and
>>>>>> potientiometers. Signals look better then ever.
>>>>>> 
>>>>>> David Lessard
>>>>>> Alexandria, Ontario, Canada
>>>>>> mr_fixit@xxxxxxxxxxxx
>>>>>> 
>>>>>> ----- Original Message -----
>>>>>> From:
>>>>>> To:
>>>>>> Sent: Tuesday, February 22, 2005 1:23 AM
>>>>>> Subject: [TechAssist] Re: Tektronix 485 Oscilliscope - Power Supply
>>>>> 
>>>>> Cycling
>>>>> 
>>>>> 
>>>>> 
>>>>>> ON/OFF
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>>> I love these old TEK's
>>>>>>> On and on
>>>>>>> I'm replying because I have the complete S/M [1" thick]Maybe I send
>> 
>> you
>> 
>>>>> a
>>>>> 
>>>>> 
>>>>> 
>>>>>> schema of a cktif you like
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>>> Regards,
>>>>>>> Pete I mennt the 475A:they are very similar,Pete
>>>>>>> Wally Heise wrote:
>>>>>>> David,
>>>>>>> 
>>>>>>> I don't know if the 485 is similar to the 465 scope, but my 465
>> 
>> died
>> 
>>>>> last
>>>>> 
>>>>> 
>>>>> 
>>>>>>> year. I traced the problem to the sealed high voltage module which
>> 
>> is no
>> 
>>>>>>> longer available from Tektronix. My scope would power up when I
>> 
>> removed
>> 
>>>>>>> this module, except no high voltage of course. I still have service
>>>>> 
>>>>> manual
>>>>> 
>>>>> 
>>>>> 
>>>>>>> but gave the scope to a friend. Hope that helps in troubleshooting
>> 
>> it.
>> 
>>>>>>> Wally Heise
>>>>>>> South Isle Repair
>>>>>>> Isle, Mn.
>>>>>>> sirepair@xxxxxxxxxx
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> ----- Original Message -----
>>>>>>> From: "David Lessard"
>>>>>>> To:
>>>>>>> Sent: February 21, 2005 7:31 PM
>>>>>>> Subject: [TechAssist] Tektronix 485 Oscilliscope - Power Supply
>> 
>> Cycling
>> 
>>>>>>> ON/OFF
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>>> Hello All, My week just got tougher, my scope failed today. I may
>> 
>> need
>> 
>>>>> a
>>>>> 
>>>>> 
>>>>> 
>>>>>>> scope to fix my scope. When powered "ON" I can hear the power
>> 
>> supply
>> 
>>>>>>> cycling - on/off/on, etc. The rear fan starts to spin and panel
>> 
>> lights
>> 
>>>>>> start
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>>> to light up but only when the power supply is on for that brief 1/2
>>>>>> 
>>>>>> second.
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>>> Would anyone have a schematic of the power supply or tips.
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>>> Thank you,
>>>>>>>> David Lessard
>>>>>>>> mr_fixit@xxxxxxxxxxxx
>>>>>>>> 
>>>>>>> 
>>>>>> --------------------------------------------------------------------
>> 
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>>>>>>> 
>>>>>>> Peter Neal
>>>>>>> Neal Electronics
>>>>>>> 1905 E. Wm.Cannon
>>>>>>> Austin,TX 78756
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>>>>>> Neal Electronics
>>>>>> 1905 E. Wm.Cannon
>>>>>> Austin,TX  78756
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