Tektronix® SCOPE rebuild page.
Model 465 Not affiliated with Tektronix but old logo's used with permission!
Below, I'm making sure my engine crank sensor work, or a cars CAM sensor or even see live high voltage spark with my HV inductive capacitive probes.
See my Tek 465 slide show. (bought in year 2000) ) 39 years old today.
My TEK , is a $50 scope sold by the old TeleCO auction. $3500 new circa 79' x8 that for 2016 dollars, ugh! (TEK today has a scope for $450 new , DSO it is)
My 465 still works like new...(only 1 cap failure, a tantalum. bit the dust and shorted.,easy to find and fix)
The Tek 465 service manuals (free PDF, are everywhere)
The scope as excellent documentation.
Rebuilding the 465: (me lacking official proper calibration tools )
Actions taken:, C125 shorted, in 2007. I used a new Tantalum Cap. then C302 failed too. Tant. fails are rare, the electrolytic, do not last forever.
The Vertical channels:
I now found 3 X1 and X10 lamps burned out, (1 was good) ( I used 5v rated green LEDS here, no external resistors at ALL the drop resistors are inside the LED casing.)
Wiring in Resistors here, would be a horror.
Since the lamps must be changed out, LED is the best choice.
Do not solder for more than 1 second or the weak plastic melts in the lamp buckets , see photos below. !
The 2 main screen Graticule scale (scale) lamps. were replaced with white LED (2v) are in series and 1x 220ohm resistors) (no 5v lamps at mouser in white)
The Graticule scale mod works, just by replacing Lamps with LED , 2 LEDS wired in series, then I added a 220 ohm series resistor, the stock scale driver , transistor ,I had to remove the transistor and jumper pads E to B on the Q1570 socket pads. The max current is about 15mA. tiny now.
The POT can drive. the low current LED's just fine. 0 to 7.5v is the drive,via the front panel POT. max .07watts way less that 1/8w total.
The 1x/10x LEDs , the S/N B250xxx and newer scopes, work perfect , early scopes, need the B250xxx update for the X1/X10 transistors. (simple, see the schematics)
Next actions completed:
While doing that , clean everything with IPA (91% Alcohol, never rubbing type). and used special electronics spray on all Pot.'s and Switches, reward?, all came back to like new life.
IPA means isopropyl Alcohol.
All switches were gummy, flush and clean as you cycle them, it's very easy to do this. (using switch cleaner, plastic safe)
One of the best things to do, with a scope #2 is SCOPE out, it's low voltage power-supplies for excess ripple, the service manual covers that, no need to show how.
LV means LowVoltage, HV means the CRT HIGH VOLTAGE sections.
On my TEK I shot gunned it out, with all new top brand, low ELECTROLYTIC ESR caps. from Nichicon (japan) I never touch tantalums ,they are long lived.
Plan on replacing the electrolytic caps. I replaced all the LV Power-Supply caps with Nichicon's (a top brand)
See this photo, for the magic jumper wires, at the Large CANS (gone) triad ground pins. The Caps from large jumper bars , that my new caps do not have.
This gets ripple noise, to a minimum. Especially on the 5vdc and 15vdc buss.
When the cap's were done, the scope trace looked factory new. a perfect flat clean in focus line, at all times. Nice. $15 cost.
I next did the full Vertical channel calibration in the manual and get stuck in the trigger section. 6-24.
Nobody I know wants to buy the $1500 in TEK calibration instruments, if can find the at all or a $1500 HP8640? used.
So in the spirit of Wes Haywards (ham call, W7ZOI book , Experimental Methods in RF design, chapter 7)
Wes, clearly demonstrates that you can setup any signal you want, with pads (or like I have here see the URM25d guts ?)
I use a calibrated scope and a cheap DDS board, to do that , I use the nice say 22xx or 24xx tech scope , (many are auto calibrated) and use that to set precision RF attenuator pads
My DDS cost me $50 for the best one made and $20 for the AD8367 RF amp board, (with pot to set level)
to the correct levels. (using off the shelf attenuator pads, or the above URM25 guts and 1db step attenuator. all off the shelf used, and cheap.
I and trim any DDS output to any level I choose. Into 50ohm load or 600 ohms.
I only calibrate old scopes, I need to be accurate , Vertical gain and Trim, and triggering, ( I did not attempt horizontal. freq fine tuning, $$$)
I don't need dead nuts accurate time base, with this scope. but does very well. (super well in fact)
The SM (service manual) , is targeted to the PRO Calibration shops, with their fancy TeK CAL rack and 11.5/-33v power supply. You will never have that , I bet?
As seen below.
So, what can you do, answer, lots ! Use a home made Signal Generator, and a DMM tool and a DSO to do all setups.
BNC cables, pads, and terminators, are dirt cheap and I have most of them are are BNC "T"
Do be aware the RF fittings come in many characteristic impedances, 50, 75, 93, 600 ohm, (we use RADIO PARTS) not TV, NOT CCTV, NOT TELCO.
Rule 2, if you mismatch fittings, you will get harmonic noise and the tests are now FUBAR.
One trick I use is, to take my very accurate DSO scope and use it to set my cheap crummy signal generator outputs, to an exact level (tedious but saves $1000's in correct gear)
Even better idea, is if you have a good scope already, then don't calibrate this scope, use it only for signal chasing or ham monitor duties, or, fill in the blank........
I do not have the TEK CT-3 SPLITTER , I had to make my own splitters (all major maker of these parts sell these tools) You do not need a CT3.
Then used my good DSO and DDS to set my cheap generator correctly.
Eng. The Digital storage Oscilloscope and my Digital Direct Synthesizer , the DDS is a super accurate signal generator with poor (none) voltage regulation
So the good old DSO lets you see the voltage and set it to spec. (takes longer but works and saves buying all this TEK gear below.)
The below drawing is my best hack, at decoding the words in the book.
I made a drawing the best I can for calibrating the Triggers.( reading TEK SM words"service manual = SM)")
My 465 scope does in fact fail, step 6-24-1e (the first 25MHz 30mv test) for triggered ! But I corrected this.
The Factory SM, is weak , only because they ASSUME the shop has all TEK, calibration tools on the self. Those weak words are.... page 6-24.
This chapter 6 setup, needs a powerful signal generator. (0 dBm) power full, at 50 ohms. 25-100 Mhz Sine wave (clean, no harmonics allowed)
0dBm means 1mW signal in to 50 ohms. That equates to 0.2236 v (224mV) (4mA of current drive is needed)
One way to best the system is to use DDS, and then a good scope, and set the DDS to .223v (rms) bingo, saved you $1000 on a used DEAD HP SIG-GEN.
The next checks are with a real RF HF SIG. GEN.
RF ! Radio Frequencies... the real deal.
I don't have nor ever will have a TEK SG-503 and power rack. The HP 86xx series (8640 is common) used, is one of the best buy's. at $1500. the cheaper ones are broken.
The 503 has a calibrated and regulated output!
You have NO 503! "shock , really" LOL (hihi)
This 503 puppy puts out 0-DBm (300mv, 224mV is spec) into a 50 ohm load) easy, Warning many cheap DDS, gens, may not muster up, 224mV rms volts. (I had to buy and RF amp)
The 503 is the way to go, it works perfect. (saves time and has stable out puts, making steps shorter ! , this is clear. But is super expensive device for one job.!
What is 224mV, its rms and peak is what, 1.414 times more, or 317mV peak or 633mV peak to peak on the scope, is this hard, any good scope can measure this.
RMS =root mean squared ,and that means the 1 VOLT AC RMS = 1VOLT DC. (SAME ENERGY LEVELS A THE SAME LOAD FACTOR)
Sure fixing or tuning a scope can take one more scope "monitoring" to get the job done.
This 503 has one more magic bit, it holds a steady level as you change frequencies, so mind that monitoring scope carefully.
$500 to $1000 used, and more calibrated.
Personally I'd buy a used $200 Tek scope, then a DDS, and go to town, if at all.
My 465 cost me $50 so why spend $500 more just to calibrate it? (a lab charges $300 for this, ouch)
Welcome to the 21st Century, or scopes now auto calibrate. (this magic happened when micro processors were added and built in calibration standards)
This autocal is plenty good for hobby, DIY, and HAM radio work. (and for sure cars EFI systems, as seen below)
My wife will never yell to me, "honey don't use that scope it's not certified, or the sticker is too old" .
So what are the DIY ways? (say under $100 bucks) below that , you need to just skip all this.
You need a clean 100Mhz RF Sign Gen. with 50 ohm grunt. 6.0 mA drive A.C min. that is what you need. 300mv p-p (peak to peak) or 0 dBm levels @50 ohms
RMS that is 224mv (my new Tek scope cursor shows RMS, values , so there you have all 3, 300/224mv-rms and 0dBm)
The correct output using 20Log(10) is 0 DBm, 1mw , 300 mv. if your GEN can not muster the energy level it's a bust.
Signal Generator or as we say a GEN.
Again, look it up here, push the buttons let the web page show you what to expect. (or any load)
That equates to 0.2236 v (224mV) (4mA of current drive is needed)
The SM (service manual) calls out slow Square wave, (use cheap function generator)
For the Slow Square waves , I have this USA chipped, but PCB card china made , by USA comp. AD9854.(I bought the card naked and built it up to my needs)
I will not cover DC inputs, anyone can create a noise free DC input and use a DMM to set it. (use a bench quite variable power supply or batter and POT)
Solutions ? HP 8648 used, is one of the best buy's (or a cheaper model and use a good accurate DSO to set levels on the dime)
The HP generators are good.
HP85xx series like 8640 , will be near $1000 used and calibrated.
8601A does 100mHz.
The 8640s are super popular. and expensive, new ones were $4200 the first ever sold.
The best source to find one is a HAM swap meet.
Or beg on Craig's list like me.
Chapter 6 , continued.:
First I got clean , RF and at the correct levels then:
I used my new scope to SET THEM. ( no auto leveling GEN requires this new step)
What I did, is make my own 50 ohm terminated signals the hard way, using accurate instruments, my 2430 is that instrument. and I just forced the correct voltage in to the
465 with a 50 ohm terminator attached, this is clear, on page 6-24 in the real TeK service manual. linked here.(free from TEK ! Thanks TEK !)
I have orig. hard copies of all books.
My 2430 scope shows the (cursors) as 224 mV RMS (x1.414 is about 300mV peak). now. (took some work)
This will allow me, to get my scopes trigger amps, all tuned and working spiffy. (mine are ALL messed up. Channel 1, but not channel 2)
The only way to fix triggers, is to do the Calibration, and then correct bad circuits, if the steps fail. (even the SM states that fact, in trouble section)
I'm all done rebuilding my 465 , just finished the Trigger, calibration. This scope is still popular. Analog 100mHz, easy.
My 465 is ready for 20 more years. (end 465)
I use these same Scopes, to calibrate and or align my HAM RADIO GEAR.
Use the scope to set RF signal generators, to exact output levels, as seen HERE.
Use the scope to fix other scopes, test projects I built or to fix cars.
I hope my page helps others fix their scope.
Buy a scope that has automatic calibration built in to it, this is your first buy.
Do not buy or own any Tube scopes. (unless pain is fun)
rev 16++++ 8-27-2013 (last edit, 9-6-2016) revised again Jan,29-2018 (battery swaps)
I'm on Eham.net, K5JXH.