2467 no power - Page 1
Forum section: electronics / testgear

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 24, 2013, 12:47:14 pm
content: Houston we have a problem!!!!!!Was trying to probe a ramp generator I'm building and the scope just shut off and wont come back onI wasnt probing anything at the time was looking at the schematic and went to use it and no display.Pressed the power switch and nothing not even the fan is coming on.Checked the fuse outside and both fuses inside all fine.No smell or smoke nothing visually burnt,bulging or leaking.It just turned itself off and wont come back on.Tried probing the power connector to one of the options and no voltage at all.(well several mV but should be like +5,+15,-15)Sent from my Milestone X using Tapatalk 2

author: BravoV
author_rank: Super Contributor
timestamp: August 24, 2013, 01:10:57 pm
content: Have you checked the J-119 for all voltages ? This will be a good start for trouble shootings should the power supply is acting up.Below the J-119 location pointed by arrow where you can probe those voltages, taken from your 2467 photo.

author: PaulAm
author_rank: Frequent Contributor
timestamp: August 24, 2013, 01:13:23 pm
content: Get a service manual, open it up and check the power supply test points. One or more of the LV power supplies is likely dead. Aging 24xx power supplies have issues with filter caps. I'd start there, anyway.

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 24, 2013, 01:17:12 pm
content: Thanks bravo ill check that as soon as I get off work.Sent from my Milestone X using Tapatalk 2

author: BravoV
author_rank: Super Contributor
timestamp: August 24, 2013, 01:18:08 pm
content: Just words of precaution, when turned on without the enclosure, those unobtainium hybrid ICs will not have enough air circulation to cool them down and will experience overheating, trust me, you don't want those pesky chips starting to accelerate their deterioration.Suggesting to have a big or quite powerful fan blowing the whole board when its powered on.

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 24, 2013, 01:20:24 pm
content: Thanks Paul I have one gotta get it printed hate trying to read a pdf.On a side note does anyone know how yo edit post in tapatalkSent from my Milestone X using Tapatalk 2

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 25, 2013, 01:04:54 am
content: Ok 2 pins have around 1.5 volts but its oscillating from 0 volts to 1.5No other pins have any voltage at all.Sent from my Milestone X using Tapatalk 2

author: Bryan
author_rank: Frequent Contributor
timestamp: August 25, 2013, 02:21:18 am
content: Sounds like power supply to me. Start with the fuses. There is also a fuse F1102 (I think) that looks like a resistor so it can be easy to miss.Post some pics of the power supply board. We can tell if the caps are original. The power supply board probably needs recapping as well as the A5 board. Have a look at this site.http://www.bestelectronicarticles.com/testing-equipment/analogue-oscilloscopes/tektronix-2465b-oscilloscope-restoration-repair.htmlThere is a good discussion on replacing the caps ont eh A5 board as well in this link. they are know to leak and can destroy the board.https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/

author: echen1024
author_rank: Super Contributor
timestamp: August 25, 2013, 03:33:38 am
content: It's probably one of those caps. They are known for going belly-up.

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 25, 2013, 04:29:06 am
content: Here are the pics of the low voltage/regulator side.Bridge has 116 Vac in326 Vdc outI checked voltage on J231a going to the inverter board.Front pin + middle=327 volts middle pin + rear pin=163.5All fuses good even the little buss fuse.At least ill have an excuse to get a capacitance and esr meter.

author: Bryan
author_rank: Frequent Contributor
timestamp: August 25, 2013, 10:00:53 am
content: Just a comment. if you are getting no voltage on any of the J119 pins then it could be that somewhere in the scope one of the areas is drawing too much power. The power supply will limit it's power and cut off the output.In isn't fun but you are going to have to read and read and read again the service manual on the power supply. It all looks like gobblygook but once you print it out and go over it diagnosing the supplies is fairly straight forward. Follow the flow charts on troubleshooting the power supply.You may luck out and find it's just one or two defective componentsp.s. The caps on the board are original and should be replaced.I spent a fair amount of time recapping two 2465b scopes and fixing one supply. Will offer any help you may need.

author: Bryan
author_rank: Frequent Contributor
timestamp: August 25, 2013, 10:24:14 am
content: Oh and if all failshttp://www.ebay.com/itm/Low-Hi-Voltage-Power-Supplies-for-Tektronix-2467B-2467-2465B-2465A-2445B-/400559718322?pt=BI_Oscilloscopes&hash=item5d43383fb2

author: rf-loop
author_rank: Super Contributor
timestamp: August 25, 2013, 10:34:17 am
content: As BravoV told.Repeat this warning: Do not use 2465/7x long time with case open without external service fan, specially if main board free airflow is not possible (ecample if it is on the table so that main board air flow is closed! Tek service manuals tell what 2400 models it is exatly nessessary to use external fan. I have some experience of repairing and calibrating these models and I will recommend external small fan for reduce some components temperature. Specially these hybrids tempetrature may rise to danger area and as we know they are expensive and difficult to find. So, care need and why take risk about damage.(case closed and when scope run, these airflows are carefully but some amount critically designed.)We can see in markets lots of these failed scopes with "backed" hybrids after poor service or fan failure or just random fail. (I can not understand why Tek have missed fan (airflof) control in this kind of equipment design. It is not money question, it is imho just mistake)

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 25, 2013, 12:05:05 pm
content: I have a 8 inch desk fan blowing on it.I turn it off as soon as im done probing voltages.Im trying to follow the diagnostic flow chart now.Will the supply operate out of the chassis.Sent from my Milestone X using Tapatalk 2

author: Orange
author_rank: Frequent Contributor
timestamp: August 25, 2013, 04:33:52 pm
content: This PSU is a switcher, you need to load at least the +5 volt and the + and - 12volts rails. 1 amp for the +5volts, 200 mA for the 12 volts railsIf you you don't load it the voltages are incorrect and PSU makes a lot of audible noise.Check and replace all RIFA oil-paper caps in the mains circuit, they will will eventually blow with a lot of nasty smoke. Also replace the secondary caps with LOW ESR types like the Panasonic FC or FM types. Also check the protection resistors in series with the oil-paper caps. Most of the times these are also pretty burn.Check also the twin Schottky diode mounted to the cooling chassis, I had this one failed on time. And for sure the fuse in the scope chassis :-)

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 25, 2013, 06:40:35 pm
content: Thanks orange I saw in the service manual on making the load for the 5 volt rail nut not the 12 volt one right now the power supply makes no noise when I turn it on its just like its unplugged.Fuse on the back was the first one I checked.Sent from my Milestone X using Tapatalk 2

author: Bryan
author_rank: Frequent Contributor
timestamp: August 25, 2013, 07:56:31 pm
content: You will require loading all the output rails. Manual recommends 100 ohm 5 watt for the +-15v rails and below. I found you need less resistance for the 5vd. Remember there is two 5v outputs, one labeleld +5v and the other +5vdFor the 87v and 42v I used a 2k 5 watt resistor. i found anything less in resistance and for some reason it loads it too much and all the voltages drop. Careful not to run with no load as the supply will "whistle" and there is a few components in the current limiting section that will go up in smoke . I believe R1071 and a transistor close to it.Once you have the supply properly loaded you can confirm if the supply is the issue and not something else on the scope that is dragging the power rails down.Have you started working from the flow chart in the service manual.?

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 25, 2013, 09:20:21 pm
content: Yes from what I've discovered its pointing me to the inverter board.But I have never tried to diagnose a switcher beforeSent from my Milestone X using Tapatalk 2

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 26, 2013, 03:56:35 am
content: Here are a few pics of one of the caps off of the inverter board.Top no bulge.Should the bottom be flat too or is this normal for the era the scope was made.(1987 by the way)

author: BravoV
author_rank: Super Contributor
timestamp: August 26, 2013, 04:07:12 am
content: Looks nice ... chubby cap !I think you should stop using that scope, list down the priorities and the to do list like cap refresh (like the one I posted the document at your other 2467 thread), change the leaky or about to leak cap at the digital A5 board, backup the cal data and etc.It will be really sad day to see this gem "IF" the bad power supply rails are affecting those unobtainium chips permanently.

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 26, 2013, 04:43:09 am
content: Couldnt use it if I wanted to but Im not gonna try to trouble shoot the power supply any more until I do a recap.Can the cal data be read in circuit I dont wanna risk damaging the ram module with solder braid or my manual soldersuckertrying to de-solder it.Or should I just get a de-soldering gun and remove it?

author: edavid
author_rank: Super Contributor
timestamp: August 26, 2013, 04:43:58 am
content: Don't listen to the recappers, that is just voodoo. Find and fix the real problem, don't worry about imaginary bad capacitors. Also, you can run the scope with the case off. It's the 2430s and 2440s that need airflow, the 2467 does not.

author: Bryan
author_rank: Frequent Contributor
timestamp: August 26, 2013, 09:46:32 am
content: Quote from: ahnuts72 on August 26, 2013, 03:56:35 amWhen I recapped my boards a lot of the caps looked the same. they still had a decent ESR and capacitance values. Think there was 2 or 3 that were getting clsoe to out of spec. think ti was the film capacitors actually. One way to tell if the caps are bad is put the whole lot in plastic bag. Have a sniff after a couple hours. If they smell like fish fertilizer they are leaking. As the other poster staed, replacing caps is probably not going to solve the problem unless there was some duds in critical areas of the power supply. You are going to have to follow the flow chart in the service manual and work your way through. My best guess is there is something in the inverter that is shutting the whole thing down. You can not test the power supply out of the scope without adding load resistors. If you don't it wills tart whistling and oscillating burning up R1071.

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 26, 2013, 12:37:03 pm
content: Right now the flow chart has me checking the mosfets on the inverter board.I still have my 475a so im gonna take my time trying to fix it.Ill prob still recap the boards though.Sent from my Milestone X using Tapatalk 2

author: valentinc
author_rank: Regular Contributor
timestamp: August 26, 2013, 01:12:03 pm
content: I recently repaired a Tektronix 2465A, which I assume has the same power supply as the 2467... The problem was the same, it didn't start at all...I first changed the X capacitors... The 2 bleeder resistors across them... And then the power supply still won't start... I checked almost everything, the transistors, the filter capacitors in the secondary side (and all of them were ok... both as ESR and capacitance... Not exactly the parameters as new ones, but still, it was clear that they were not the problem... I said that I'll change them later). And with the schematic in front of me, I first looked at the starting circuit of the TL594... And almost immediatley I found that the supply voltage of the IC was much lower than it would need to start... Then after a few measurements I found the electrolytic capacitor of 100uF if I remember correctly was way out... (measured only a few hundred nF and and ESR of a few hundred ohms)... I changed that... And the power supply started fine...Forgot to mention, the 100uF capacitor hadn't any buldge in it...And as I said, the output filter capacitors must be measured first... (in my opinion), because they're not necessary bad...

author: Orange
author_rank: Frequent Contributor
timestamp: August 26, 2013, 02:26:06 pm
content: Quote from: ahnuts72 on August 26, 2013, 03:56:35 amNot necessarily bulging, but they can also leak on the bottom side. You can see this on the PCB, it is like a wet stain :-)BTW there is no voodoo involved in replacing capacitors of 25years old in this switcher. You do this as a precaution to gain another 25years of service out of it.

author: edavid
author_rank: Super Contributor
timestamp: August 26, 2013, 02:56:42 pm
content: Quote from: Orange on August 26, 2013, 02:26:06 pmWhat's the advantage over fixing the scope when it breaks? It's more likely that you will break something else in the process, than accomplish anything worthwhile.

author: valentinc
author_rank: Regular Contributor
timestamp: August 26, 2013, 03:07:01 pm
content: As I mentioned earlier in my opinion, the order of the actions that must be taken is first make the supply work and THEN put the problem to do a service precaution... As changing all the electrolytics... That's the order they must be considered... Else it would take you longer to find the problem...

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 26, 2013, 06:04:48 pm
content: One thing I did notice was the service manual said that the 10 volt reference needed no load to work and I have no voltage on the test pin for it.Sent from my Milestone X using Tapatalk 2

author: Bryan
author_rank: Frequent Contributor
timestamp: August 26, 2013, 09:50:16 pm
content: Did you put a load on J303 the +5vd. Without a load the inverter will not start. (Assuming it's ok). See flowchart attached. If supply starts then you need to work your way down by the regulators. f not then it's more than likely in the invertedr

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 26, 2013, 11:15:33 pm
content: Yes that load was the only high wattage resistors I had on hand.Gonna have to order the stiff to build the other loads.Sent from my Milestone X using Tapatalk 2

author: Bryan
author_rank: Frequent Contributor
timestamp: August 26, 2013, 11:47:56 pm
content: I am trying to remember, but if I recall correctly, there needs to be a load for the 10v to start. Loading any of the rails will work, at least that is my recollection and experience. . The flow chart seems to suggest a load must be applied to +5vD to test the +10v.The service manual suggest 100 watt 10 watt resistors for +- 15v and below, a 2 ohm 20 watt for the +5vD. What tit does not specify is the load for the 42v and 87v rails. I found this a bit tricky. When I loaded them with 1k resistors all the other rails dropped by 10%,. This I believe is by design to protect the supply.I had to decrease the current draw and use a 1k on the 42v and a 2K on the 87v. Then all the voltages tested ok on all rails and within spec. This is a bit confusing, because I would have thought the 87v rail would be capable of supplying more than 100ma of current.

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 27, 2013, 04:53:19 am
content: Nothing with load on j303 remove combs from p233 and p234 no start either.Checked cr1060 and cr1070 no short.The mosfets will need to be removed to check them?

author: Bryan
author_rank: Frequent Contributor
timestamp: August 27, 2013, 06:21:20 am
content: Just to back up a bit, are you sure there is line voltage present at P231?. You may want to remove the comb filter to double check.

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 27, 2013, 06:34:52 am
content: I checked I have 160 or so volts with the comb out.One thing I don't understand is I have 116 volts ac in to the bridge and around 260 out.From my calculations I should only have about 160 dc output.Unless im figuring it wrong but thought it should be around ac*1.414 or so.Sent from my Milestone X using Tapatalk 2

author: Bryan
author_rank: Frequent Contributor
timestamp: August 27, 2013, 08:35:27 am
content: Perhaps that's a Peak to Peak measurement vs RMS.?

author: rf-loop
author_rank: Super Contributor
timestamp: August 27, 2013, 09:00:35 am
content: It is good to understand how this line voltage selection work.Tek service manual tell this principle very clearly. (and most of other things)Service manual is good to read before start diagnose and during diagnose prcess.There read exactly all information what need diagnose and repair.There is "theory of operation" and there is flow charts for diagnose and there is detailed schematics etc. These "theory of operations" are very useful to read carefully."With the selector switch in the 115 V position,therectifier and storage capacitors C1021 and C1022 operateas a full-wave voltage doubler.When operating in thisconfiguration, each capacitor is charged on opposite halfcycles of the ac input, and the voltages across the twocapacitors in series will approximate the peak-to-peakvalue of the source voltage.For 230 V operation, switchS90 connects the rectifier as a conventional bridgerectifier.Both capacitors charge on both input half cycles,and the voltage across C1021 and C1022 in series willapproximate the peak value of the rectified source voltage.For either configuration, the dc voltage supplied to thepower supply inverter is the same."

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 27, 2013, 12:51:02 pm
content: Thanks for the explanation guys after looking at the voltage source switch I was wondering if it formed a voltage doubler.(now I know)This is the first switching supply I've ever looked at.Wasn't gonna learn about switching supplies till I had linear supplies figured out.Im waiting on payday to get the manual printed trying to read it on the computer screen while im looking at the supply is making me miss alot.Sent from my Milestone X using Tapatalk 2

author: Bryan
author_rank: Frequent Contributor
timestamp: August 27, 2013, 09:58:26 pm
content: Try this test, power it up outside the scope for about 5 seconds, does it whistle, or oscillate and does R1071 get hot (careful that area has primary voltage). No longer than 5 seconds or risk burning up the resistor.. If so the inverter should be working.

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 27, 2013, 11:15:18 pm
content: I powered it up in the scope with the load on j303 and a load on j232b all other combs in place nothing no noise no fan no anything j234 and j233 combs removed as per service manual still nothing pretty sure its on the inverter board.Have to make the leads to power it up out of the scope should have them made in the next couple of hours.

author: Bryan
author_rank: Frequent Contributor
timestamp: August 28, 2013, 01:44:39 am
content: Could very well be. If you haven't already I would have a good read of the "Theory of Operation" of the power supply in the early part of the service manual. It is very detailed and informative. There is a couple components to the inverter that may be the issue. It could also be the current limiting circuitry (does the supply make any faint clicking sound).Note also in the schematics there is a number of test points to check, just note that from the schematic the reference is not necessarily ground, but two other rails.

author: envisionelec
author_rank: Frequent Contributor
timestamp: August 28, 2013, 02:04:59 am
content: The "bulging" capacitor pictured is NOT bulging. That is an epoxy bung - it's not going to "leak" the way our commonly recognized capacitors do today. In all seriousness, it will probably last 100 years.

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 28, 2013, 02:13:28 am
content: It makes no noise what so ever when switched on.No clicking no hum no buzz its just like you don't have it plugged in.Push switch and nothing.I saw the note in the schematics for ref 1 and ref 2.I should be able to get the manual printed on friday so much easier to flip pages back and forth for me as opposed to trying to scroll then zoom in to see.Sent from my Milestone X using Tapatalk 2

author: Bryan
author_rank: Frequent Contributor
timestamp: August 28, 2013, 07:08:16 am
content: I feel your pain when trying to read the service manual on a pc. What I did was cut and pasted the schematics into a word document and printed out on 11 x 17 paper. Anything smaller and you will have a hard time reading.Interested to hear back what the voltages are on the test points referred to by the schematic. Think You are getting close.

author: BravoV
author_rank: Super Contributor
timestamp: August 28, 2013, 07:29:47 am
content: +1 on getting it printed, attached an old photo when I was troubleshooting my Tek, its like night and day when I was trying to use my ipad to read the manual, scrolled the huge size schematic like crazy and ended up very dizzy and really tiresome.Its printed at big & long paper and nicely binded with spiral binder, compare the scope size with the manual to have a clue how big it is, and that was even not enough at certain area, had to print a separated zoomed view.

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 28, 2013, 12:36:28 pm
content: I had office depot print the manuals to my tm500 plugins came out great all the regular pages 8.5x11 and all the original fold out pages at 11x17.I only have 2 100 ohm 10 watt resistors and my 2 ohm are only 1 watt so im waiting on the correct wattage for the rest of the load resistors so I can power it up out of the chassis.Sent from my Milestone X using Tapatalk 2

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 29, 2013, 02:24:23 am
content: Ok now I've done it.Was probing r1025 to check the voltage at the emitter of q1021 to see if it was at 13.2 volts was at 17 volts or so.Here's the problem when I went to remove the probe somehow I touched the case of q1021 which shorted the emitter and collector.Needless to say lr1060 didn't like it one bit and now is a little crispy.Did I just ruin my power supply by killing something I can't replace.Sent from my Milestone X using Tapatalk 2

author: Bryan
author_rank: Frequent Contributor
timestamp: August 29, 2013, 06:19:42 am
content: LR1060 according to the manual is a 2.4uh inductor, lots of those around on digikey and newark, but not sure of the voltage and current rating etc. Think I would be more afraid of anything else that might have been fried.

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 29, 2013, 11:49:42 am
content: It was outside of the chassis so didn't hurt anything in the scope.I saw it was a 2.5 uH inductor wasn't sure if that was all it was it shows a resistor in parallel with it.Gonna have to pull the mosfets and check them for sure and prob the resistors on the gate of each of the fets.Sent from my Milestone X using Tapatalk 2

author: Bryan
author_rank: Frequent Contributor
timestamp: August 29, 2013, 08:55:29 pm
content: Does your service manual have the listing of parts and their values, some manual do and some don't. if you need the complete one send me a PM.

author: ahnuts72
author_rank: Regular Contributor
timestamp: August 30, 2013, 12:47:40 am
content: Yes it list it as coil,RF fixed 2.4 uHI guess im gonna have to take some heat shrinkand put a diaper on my probe tip tomake sure my clumsy ass doesn't do it again.Sent from my Milestone X using Tapatalk 2

author: Bryan
author_rank: Frequent Contributor
timestamp: September 05, 2013, 06:59:01 am
content: Any luck getting it going?

author: ahnuts72
author_rank: Regular Contributor
timestamp: September 05, 2013, 05:26:49 pm
content: Q1021 checks good but I want to replace it anyways.I have the same transistor but it is not the metal can it is a to-92 will it work for a replacement or should I get the same package as in the scope.Everything before checks good.The mosfets show as bad so waiting on a paycheck to order them.The gate resistors should be 47 ohms but read about 20 or so.They'll need replaced.Been busy with work so haven't checked much past the mosfets.I may get a refurbished supply to get the scope going in the interim.I just got my programmer so the next thing im gonna do is backup the cal data or this may be a moot point since the manual says any repair of the power supply requires a recalibration.But I have a lab about 20 min away that said they can calibrate it for 150 dollars.Sent from my Milestone X using Tapatalk 2

author: Bryan
author_rank: Frequent Contributor
timestamp: September 05, 2013, 11:58:55 pm
content: Well, sounds like you are making some headway. Here is a link to a DIY MOSFET tester. Can put it together for a couple bucks, apparently works quite well. Interesting about the gate resistorshttp://www.electronicrepairguide.com/test-mosfets.htmlHave heard conflicting statements on whether calibration is required after a power supply swap/repair. most say no unless the 10v reference was way out. You am need to perform some of the calibration for the CRT and DAC, but pretty sure that is not stored in the EEPROM.Which programmer did you get?. The TL866CS? I managed to get a free sample of the Dallas, $25.00 bucks save there.Recapped a working 2465A power supply and can not get it to work, Either something wrong in my repair or the new components have caused a aging part to eventually fail. Working through the flowcharts in the manual, frustrating, but at the same time challenging. Appears to be a issue with the inverter.What is the MOSFETs you have in your power supply. the ones in mine are not what is spec'd in the manual. I am wondering if they had been replaced previosuly. They were IRF820's

author: ahnuts72
author_rank: Regular Contributor
timestamp: September 06, 2013, 02:20:54 am
content: Yes the tl866cs is the one I got.My scope has irf820 for the mosfets.Even if I get a refurbished supply I'm still gonna fix this one.Luckily the regulator board was disconnected so no damage to it.I learn way more hands on than just reading in a book so I'll just chalk this one up to a learning experience and keep on going.I still have my 475a but its just not the same after using this scope.

author: rf-loop
author_rank: Super Contributor
timestamp: September 06, 2013, 06:45:32 am
content: Quote from: Bryan on September 05, 2013, 11:58:55 pmThere is not conflicting statements in Tektronix service manual about example calibration. It is only trusted source for know exatly what and how to do.