I have a chance to buy a Tektronix 502A oscilloscope from the 60s (seller doesnt know if it works or not) ,I like it partly cause I like old vacuum tube devices, already restored a tube radio and couple of tv-s.
there are surely some scope guys here
Now is the Tektronix 502A any good, I would be using it mainly on vaccum tube stuff and maybe some signal generators and a bit of the modern stuff
,Would it be good for TUBE amplifiers ??
I cant find decent information on it, like watis maximum input voltage and such
How much would you be paying for it?
Because like, as far as scopes go, you can probably do a lot better.
>>958654
he has it advertised for about 70 $,but I think I could lower it down a bit maybe close to 50$
If you can't find its input voltage, then you can't manage to find its schematics and calibration instructions. Get something else.
>>958659
For that price you could do much better.
You should be able to find a decent 20MHz scope for that.
Like a Hameg HM206 or similar.
Old scopes like that decay with time.
Personally I got lucky and scored a really nice HP 1741A 100MHz scope from a dumpster dive, been serving me really well.
But it's a massive brick, wish I had something smaller.
Still like Analog over Digital scopes though.
Auto range is overrated.
>>958662
yea but like I said I like old vintage equitment, and that is the only VACUUM TUBE type osciloscoppe I could find for sale
more fun fixing vacuum tube stuff with vacuum tube equipment,I already have a GoldStar 20Mhz full of chips and circuit boards
How much Mhz is the Tektronix 502A ?
>>958666
Well, according to the first result on google, it's a 1MHz scope.
>>958659
If there's a chance it doesnt work, I'd pass. Too high of a chance that you'd end up with a $70 doorstop.
>>958675
if he will let me look inside to check every tube is there and if I will not see any hacks done or burn components then I dont see a problem, right ?, also faceplate doesnt seem to have any wear on it which could again be an indication of low use
I hate curcuit based osciloscope, one time I injected just a bit too much votlage and blew out almost half of circuitry, here I just replace a tube and cap or resistor, that simple
>>958647
Okay. I don't recommend you buy a broken oscilloscope. If you want a pretty oscilloscope, the hameg hm 207 is a good idea. I had the possibility of buy one working for 60$ in a bid, but I lost it.
Repair an oscilloscope is not easy, and you must know it.
I have a Hameg hm 512. 2 channels, 20 MHz. I bought it because it´s pretty. It isn´t like the rest more new, and it have 2 channels.
>inb4 The seller doesn't know if it works or not.
If the seller says that, the seller know that it's broken kek
>>958683
I think maybe he know it hasnt been powered up in decades so he DOESNT want to risk of damaging something
also if he will let me take a look inside then and I dont see naything out of the ordinary then I will not go for it, also depends how low he would go with price
I am following it a bit and he has been selling it for a awhile, so maybe I can take advantageof that and say Im your only interest and then pull the old "take my offer or try selling it for the past 3 years"
>>958690
Also forgot
I am specifically interested in vacuum tube scopes
>>958692
That one seems to have transistors and other semiconductors as well.
Plus nuvistors. Mr. Murphy says your nuvistors are fucked.
Is this broken $70 1MHz scope really your best option?
>>958706
I cant find any other scope for sale of that vintage so ..., I quess so
>>958706
I also found a tektronix osciloscope Typ 561B ,have to contact seller for price first,but the seller has a picture of the scope making traces on the crt.
Is it any better
>>958707
And you can't wait until another one comes available?
Sounds like you've decided. Go buy your hipster scope.
>>958711
>works
>10MHz BW
Yeah, sounds much better.
>>958714
yea but
http://www.radiomuseum.org/r/tektronix_plug_in_oscilloscope_561b.html
it dont have any vacuum tubes ,so it doesnt fall into my category
If the seller says that he doesn't know whether it works or not, that means it definitely doesn't work. He's waiting for someone like you to pay $70 with the dream that they can fix it.
>>958721
well first I will go see it and see wt the seller tells me and then I will decide, also
have quite a bit of experience with vacuum tubes,mostly these old things have bad caps in them that need to be changed
I also like the blue phosphor it has and that the screen lights up with some bulbs around the screen
>>958647
pretty sure everyone is talking about it like they are going to use it as a tool. If restoring it and putting it on a shelf is what you want to do for $70 then go ahead.
>>958734
I would use it, especially with tube amplifiers and this one would look pretty slick
why so much negativity ?
>>958736
>why so much negativity ?
I think most of /diy/ are looking at you like a classic video game collector.
>Why would you pay for an original cart from 20 years ago when you can emulate.
>>958647
holy fuck did you even try to google this?
The first fucking result has a link to the manual.
http://w140.com/tekwiki/wiki/502
where's my DIY bingo card?
1) worth $70 for the gold and silver inside
2) you will never get it working again. Too many old caps, and you will never find the tubes. You can never replace the CRT, and that's pretty old for any CRT. You won't find any of the solid state transistors anymore, and they were all curve traced individually for each scope. You need a working scope to fix a scope.
3) tubes inside are not really good for audio
Might be a fun project if you had a couple of them and they were all free. When you are done, you still don't really have a decent tool.
Get a usb PC based Oscilloscope/spectrum analyzer combo. You can do more for less.
>>958801
1. good
2. I ve been working on vacuum tubes quite a bit have lots of the used/new so that shouldnt be a problem,CRT is a gamble that I know(if the seller gonna let me look inside then the state of components might tell me something about the CRT and its life),also scope crt dont work as much as tv tubes do, so that is also taking into consideration.I Already have a GoldStar 20Mhz scope
3.I dont intend harvesting it for tubes but using the scope on tube amps
It also seems to have a allignment generator built into it to halp calibrate it,dont forget Im also buying this to make my lab go a litlle back in time
>sb PC based Oscilloscope/spectrum analyzer combo
junk
>>958801
>2) you will never get it working again. Too many old caps, and you will never find the tubes.
I've pulled dozens of old scopes like that out of dumpsters. 75% of the time they work great despite being tossed in the bin, sitting in the rain, and any other abuse they went through before I found them. Old lab gear is built to last.
The capacitor plague didn't start until the 80s. I've never found an exploded cap in equipment that old. Capacitors drift slightly over the decades, but engineers in the 60s were awesome enough to anticipate that and work in various tuning knobs you can use to correct that. It's also not a big deal if your time base is 1.05ms when the knob says 1.0ms as long as you're aware of it.
If there's a problem it's going to be a dead tube. Often there's spare tubes taped inside the case for just that situation. If there aren't it's not hard to find a replacement on ebay.
>>958854
>The capacitor plague didn't start until the 80s
The capacitor plague was in the mid 2000's.
The just started making shitty caps in the 80's.
>mfw my mobo has as many blown caps and dieing caps than working caps.
>>958801
you just made 3 points that prove you know absolutely nothing about old equipment like this.
2 and 3 especially are bullshit. these scopes contain 12ax7's and other tubes that can sure as fuck be used in audio equipment.
10/10 full retard
>>959060
hes just jealous of OP getting that scope
>>958647
First of all, don't let others shitpost you out of having a cool (even if of limited use) piece of test gear. Yes, it could be junk. But I collect old gear (including a working 545 'scope) just for the lulz.
The limiting factor with this 'scope is going to be bandwidth. It's probably going to be limited to audio and maybe switching power supply work into a few hundred kHz. Otherwise, it's just going to be a cool gadget to fire up once in a while for the 'cool factor. At Halloween, I put up a 'mad scientist' display in my front window, including my scope with a signal generator plus some other crap.
For ~$100 you can get a nice USB scope that does analog, digital, better bandwidth and uses your PC or laptop to do capture and analysis that this beast will never do.
Also, learn about grounding and safety before you go probing around with this beast. It has a grounded chassis and smoke will come out if you probe the wrong points.
>>959129
So it would be fairly usefull for building different types of tube audio amplifiers
>>959138
>fairly usefull
Depends on the frequency. For audio, it will work. But poking around in tube amps is exactly where you are going to get into trouble with grounded chassis test equipment. If your goal is to have useful test equipment, I'd pass on this. If you want to clean it up and put it on display just for the cool factor (and $70 won't kill you) go for it.
Does this oscilloscope use P11 phosphor which is the bright blue phosphor ??
correcr me if im wrong
>>959373
Manual says P2 (blue-green) is the default and P11, among the others, is available as an option.
Why would you want P11 for a slow general-purpose scope?
My father in his lab in 1958
>>960138
is your father the gay one ?
>>960157
They're gay for each other
>>958647
Well I still havent bought it yet
waiting for guys response, still dont know why some people take this long to reply
>>961943
It'l work fine on tube amps, you really only need a simple signal counter and a decent generator to get a reading on a tube amp. I use an old russian LO-70 made in 1980. Its only a 80khz device. I do own a more modern 1999 Tectronix one with memory and stuff, but for riskier stuff id rather risk damage to this one since i got it got about 20$.
Depends on how mutch the seller is asking. Since it wont power on i would not give him more than 25ish bucks. It's not hard to fix, but chances are the parts may no longer be manufactured and you may need to dig really really deep to find the parts, and dish out a bit of money for the parts. Tektornix stuff is pretty well known so the schematics are out there.
If you can afford to throw 30 bucks down the toilet i'd say take the risk OP. Worst case scenario you have a bit of fun with taking it apart
>>961943
OP here
first masage I sent him he said he never plugged it in and the reason he didnt plug it in is cause it has the cord cut
he aslo said its complete.Now I sent him another massage and asked where is located preciselly and also asked If I can look inside to make sure no components are missing and its been a bit and he didnt replyed yet back to me so makes me a bit suspicious -
that hes trying to sell the scope with no inner components after I aksed him If I can look inside,cause ussually people respond back withing an hour or so via email when they have a potential buyer who is interested, but the guys seems to be in his 80-90s(maybe he forgot) ,but he also is a big collectrer and hates gutting instruments so maybe thats why he didnt tryed to bring it back to life cause it would temper with originality.
but 10 seconds look inside scope is gonna tell me everything I need to know
>>961945
Here you go. A manual
http://w140.com/tek_502.pdf
You're lucky. Yours isn't written in russian
>>961947
Also if he salvaged it or got it off a uni or army, cutting the cord is a polite way of saying the things is busted before they throw it away.
>>961945
maybe but he seems to be a hardcore collector and chances are if he cant sell it for some ammount hes probably gonna keep it
hes selling it for 70$ but I think he would take 50$ and like you said worst case scenario, like shorted CRT or power tranny,the rotary switches and other components could be used somewhere else then ...
>>961949
maybe it was tossed and scrappers ussualy cut cordes and such, or the uni or army known for example that it needs caps or a shorter filter cap and cutted the cord to prevent people who dont know electronics to harm it/destroy it even more
>>961951
The rotary switches are 99% busted and will need cleaning. The CRT can be fun. It has like 3 transformers in it, of very very high quality.
The caps are probably busted and need to be replaced with electrolytics.
>>961952
The uni i work at cuts cords off things that are shorted to the chassis. But this may very.
Just go with your gut.
>>961958
what kind of work you do at uni ??
>>961961
I'm a physical chemistry professors assistant 3/5 days. The rest of the time i spend doing plasma research, sample analysis for various institutes, doing number crunching for the professors etc.
At uni you don't really have just one job. Your payed to do one thing, but you get sent on weird ass errands all the time.
On occasion I'll be called in to calibrate a few instruments, fix a few things in the physics labs since I'm good with a soldering iron, and i don't mind the occasional extra income.
Okay just talked to the seller, he says when he got it the cord was already cut and they also told him why they cutted cause it wasnt powered on from the 70-80s and they didnt want and idiotblindly plugin it in to fry it.
from wat hes saying it seems the scope is original and nothing has been messed with,tommorow I probably will go look at it is there anything I should be aware of, especially whne looking inside, the guts and if tubes are original ,what brand did Tektronix used in there osciiloscopes ?
I heard this scope is extremelly accurate, when it comes to measurments
>>962340
I've got no idea what tubes they used back than, it could even very based on which factory made it.
I mean it has a 3% error like all electronic measuring devices. You will need to recalibrate it once you get it tho. The years will not have been kind to it.
Keep in mind its a 50kHz scope, so its fine for audio applications. No RF or clock tempering.
Todays norm is around 10Mhz
>>962357
its a 1Mhz scope or 1000 kHz
>>962367
Its bandwidth drops on higher sensitivities. 50kHz is the BW at 0.1mV/div.
>>962367
>1Mhz
>1000kHz
>Telling me that
Guy i tried to help, but if you're gonna call me names I'll just fuck off...
OP here
I got it, man this things is heavy my arms hurt, it has 1 missing tube ,two seem whitecapped and overall it seems all is there and original and never messed with, but its gonna need a lot of work cause I cant even turn some of the knoobs so much dirt in them
I tried to get him down with price he would only do it if he were to take the tubes for himself and that wasnt gonna work for me so, but it seems untouched.
I literally had to carry this thing thru town from and people were like wtf, this one time I put it on floor to get some rest and some guy wanted to take it, he thought it was going for the trash
>>962930
So... Pics?
>>963297
hold your horses anon
they are coming Im also in my first year of uni so time is very limited, but dont worry im not going to let the thread 404
>>962357
>Todays norm is around 10Mhz
rtard today's norm is around 200mhz or higher
>>958647
That should work for audio tube amplifier work. I don't think you will ever see frequencies over 500kHz (normally below 30kHz), and the pic on its wikipedia page shows the scope goes down to a 1us/div time base.
It has a high acceptable voltage on the input -> 20V which is good for you. Using a 10:1 probe will get you into the voltage ranges you will see in tube amps.
Do I think it is a good idea beyond novelty? Nope.
Is novelty enough? That's your call.
I have a newer tektronix oscilloscope, but still ancient (it is transistor based). worksforme.
I would expect that you would have to make some repairs to bring that scope to life.
>>963650
It really depends on what you want to do. I was looking at $10k scopes the other day. That is still only a mid range scope. It was a 4channel DSO. (I think 500MHz)
It would be stupid to use that 'high' end scope for certain applications. Ex. repairing a motor drive where the expected frequencies would be only a few MHz and a mistake will incinerate the front end (at the least).
A cheap Chinese 10MHz scope might work fine for tube work, if the input voltage is ok (which would be very tricky)
Also the old analog scopes had features like specialized delay time bases that were used for debugging circuits in use back in the day (analog TV repair). If you want to work on the old electronics, it might make sense to use the very tools designed to do so.
I already have a GoldStar 20Mhz but im scared Id blow out a amp in it cause maximum votlage per channel is 250v and tube amps have up to 1000v.
but if I do something wrong with this one I just replace a few resistors and a cap maybe or tube and good to go
>>963879
Hi OP, I own a Tek 585A (pic related).
First check DC with an appropriate DC voltmeter (no need for hi class, but ensure that all part are insulated upon the rated voltage you want to measure).
Then, check for AC signal with a 1:10 or 1:100 probe. Ensure that your scope as an input DC blocking capacitor rated for the residual dc voltage.
Anyway, you can always DIY a divier probe with a serial resistor (ok, that is crap, but enough to repair LF tube scope !).
>>963879
>"just replace a few resistors and a cap maybe or tube"
>"just replace a few resistors and a cap maybe or jfet"
I don't really see how the first is going to be much easier. Also, better avoid both.
1000V is enough to zap your probes and the front-end, unless you have high-voltage probes. So, better get suitable probes to go with your scope.
![IMG_20160319_220328[1].jpg](https://i.imgur.com/YDVELxT.jpg "IMG_20160319_220328[1].jpg")
Okay did some test on it
I apply-ed power to it over light bulb and light bulb didn't dim down which means we have a dead short somewhere now my first suspicion would be the filter caps
Also does this thing even have a power switch Im looking at it and cant find it anywhere, do you just plug it it in and out every-time ??
this thing is so good build and the quality of components, not even one broken solder joint
so beautiful to look at it !!
it has a missing 12B4 a socket transistor and two white cap 6AU6
>>964450
Are you sure you used a powerful enough bulb? A scope like that can probably consume somewhere around 200 W when idle, so you're gonna need a pretty big bulb in series.
>>964478
I used a 40w
>>964494
That's definitely not enough; it would light up even if the scope was new.
>>964450
>does this thing even have a power switch
The power switch on old scopes is often built into the trace brightness knob (sometimes labeled brilliance or intensity). Turn it up and you should hear a click.
>>964450
>I used a 40w
Power - Approximately 300 watts.
>power switch
It's on the scale illumination pot, below the screen.
Seriously, why don't you read the fucking manual?
>>964629
I don't have the printer toprint out 100pages
Even if I would power it on it wouldn't do much cause 3 tubes are shot and a missing transistor
the CRT neck,plastic base is also lose so that will also be a pain in the ass don't know how to heat all the pines at the same time to pull it off and re apply glue
...
>>964666
>Willing to spend $70 on a broken antique scope.
>Willing to spend time and money on repairing it.
>However, printing 100 pages is too expensive/difficult/tedious.
>Reading from screen is out of question.
Right. Inb4 you ruin something because reading manufacturer's maintenance instructions was a hassle.
>Even if I would power it on it wouldn't do much cause 3 tubes are shot and a missing transistor
Didn't stop you from giving it power and making "deductions".
This thread is a cringe comedy.
>>964685
I used a light bulb to see if it may have dead shorts
>>964704
300W load is going to look like a short to your 40W bulb. With filaments cold and fan stopped, the scope probably draws even more power. Also, as long as the rectifier tubes are cold, the test tells nothing about the state of the filter capacitors.
But hey, maybe it really is shorted, like you said. In that case the transformer would be one of the primary suspects.
can i power up the oscilloscope with 3 tubes missing and a transistor or shouldnt I ??
can something go wrong ???
>>964854
It's unlikely but not impossible for it to break further. I'd try it. Or just read the service manual to figure out what the missing parts do.
![IMG_20160321_005423[1].jpg](https://i.imgur.com/XJz25lW.jpg "IMG_20160321_005423[1].jpg")
i DID IT i POWERED IT ON
now we can say that this scope isnt going to be trashed.
now both channel seem to work I mean the knobs have an affect on the position and sizes of traces, but I cant get a trace on it only dot, trace as you see on pic is generated by wire with screwdriver.
it probably need those 3 tubes to function correctly,but we can say it does work great
its missing 2x 6AU6, a 12B4 and a 2N214 transistor
>>964907
That feel. When you actually did something right. Good work anon.
Vacuum tube oscilloscope has its use. And it is probing high voltage stuff. Of course with proper voltage dividers, but when you accidentaly put high voltage on the input, you will not destroy your precious oscilloscope.
>>958707
eBay is full of them for less than $50
