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Used Oscilloscope for under 250$
Posted by
Shawnk
on 11 Dec, 2017 19:33
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Is there a good used model of Oscilloscope 2 to 4 channel that i could buy on ebay or something like that for under 250$. Im going to use it for home and car audio amplifier repair. I would prefer a benchtop model but I’m open to other suggestions.
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#1 Reply
Posted by
Tom45
on 11 Dec, 2017 21:29
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#2 Reply
Posted by
Shawnk
on 11 Dec, 2017 23:47
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Thank you for the video. I have watched it. I have a snap-on 4 channel scop that i use at work but is not fast enough for my needs for amplifier repair. I am new to electronics repair (only the last 2 years). I would like to start getting more advanced and take it more seriously but i need a good Benchtop oscilloscope that will fill my needs. Like how many MHZ and the bit rate. Can i get a ok Digital one for that price or only analog. Is there any brands or models the work well and are user friendly. For the kinda of signals you see in a amplifier what should i get?
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#3 Reply
Posted by
boffin
on 11 Dec, 2017 23:51
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Thank you for the video. I have watched it. I have a snap-on 4 channel scop that i use at work but is not fast enough for my needs for amplifier repair. I am new to electronics repair (only the last 2 years). I would like to start getting more advanced and take it more seriously but i need a good Benchtop oscilloscope that will fill my needs. Like how many MHZ and the bit rate. Can i get a ok Digital one for that price or only analog. Is there any brands or models the work well and are user friendly. For the kinda of signals you see in a amplifier what should i get?
If you're doing audio amplifier repair, pretty much ANY scope will be sufficient, you only need perhaps 0.1MHz of bandwidth for audio
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#4 Reply
Posted by
Shawnk
on 12 Dec, 2017 00:26
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Ok thank you for the info. On my scope i was trying to watch the Tl494 driver for the switching power supply and i could only see a straight line because 1ms time is my fastest resolution.
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#5 Reply
Posted by
rstofer
on 12 Dec, 2017 02:02
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Ok thank you for the info. On my scope i was trying to watch the Tl494 driver for the switching power supply and i could only see a straight line because 1ms time is my fastest resolution.
That's a different story! It's not audio at all and the frequency may be much higher - the datasheet recommends 300 kHz. To see that adequately, you probably need 10 MHz of scope bandwidth. That's not much at all! Almost anything you find will be 50 MHz and up.
I would think you would be looking for something, analog or digital, with about 100 MHz of bandwidth. This is a hedge in case you get interested in microprocessor projects.
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#6 Reply
Posted by
David Hess
on 12 Dec, 2017 03:04
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If you're doing audio amplifier repair, pretty much ANY scope will be sufficient, you only need perhaps 0.1MHz of bandwidth for audio
Higher bandwidth is valuable for detecting higher frequency spurious oscillations in audio circuits.
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#7 Reply
Posted by
rstofer
on 12 Dec, 2017 03:41
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That Tek 2467 in the video still sells at a premium on eBay (like $700). I have the Tek 485 (also 350 MHz) that I bought for about $200 about 12 years ago. Today there is one for $325
https://www.ebay.com/itm/Tektronix-485-350-Mhz-scope-I-use-it-to-500-Mhz-all-the-time/253118975022?hash=item3aef110c2e:g:GyQAAOSwxbtZo1MEAt that price, it would be a toss-up whether to buy the used Tek or a new Rigol DS1054Z. I have both and I'm not going to get rid of the 485 any time soon. The Rigol can be unlocked (easily) to provide 100 MHz of bandwidth and 4 channels plus protocol decoding, etc. Search the site...
There is no comparison between an analog scope and a digital. The single shot capture alone gives the DSO the advantage. And for all of that, w2aew's videos (that I have seen) are done with analog scopes. There's not a darn thing wrong with using analog scopes. Just watch the videos!
I'm not going to recommend buying a used scope - analog or digital. If it doesn't work, you might be stuck. Some scopes use custom components that are no longer available. I would just as soon have a warranty. That said, I did buy my 485 used and it has been outstanding. Caveat emptor...
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#8 Reply
Posted by
David Hess
on 12 Dec, 2017 06:45
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I only linked the video as an example of why an oscilloscope with greater than the minimum bandwidth for audio is desirable. The 2467 is special for reasons other than its bandwidth and not the oscilloscope I would recommend.
There are lots of used analog oscilloscopes to be had for $250 or less and most suitable ones will be available for a lot less. The 50 MHz Tektronix 2225 shown in Dave's video is one of the better examples because of its low cost, 500uV/div sensitivity, and lower age but I would consider any similar oscilloscope. I've picked up Tektronix 2230s, 2232s, and 2236s for less than $150. The various 465 family oscilloscopes can also be had for that price or less but are more likely to have age related problems.
The largest problem however with used analog oscilloscopes is finding one in good shape. Novice users have difficulty evaluating them and repairing or maintaining them.
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#9 Reply
Posted by
Shawnk
on 12 Dec, 2017 19:12
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Thank you guys for your time. I think i have enough info to proceed. I would say im really in to car audio amplifiers and need something your looking at
power supply's. I think im going to buy a cheap 50$ Analog unit and save up for a few more months and try to get a decent new digtal one. I have one more question i hope someone could send be in the right direction or know somebody that can help me. I have a snubber Circuit on a car audio amplifier that keeps overheating the resistor that is placed in line between the two transformer secondary windings. It only heats up when the amplifier is under some load 20 amps or more. why does this typically happen. Why is the resistor being loaded. Is there a good source for understanding how the circuit works? And the resister is in spec and it gets up to 400f befor i shut it down.
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#10 Reply
Posted by
David Hess
on 12 Dec, 2017 19:21
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I have a snubber Circuit on a car audio amplifier that keeps overheating the resistor that is placed in line between the two transformer secondary windings.
Huh? Is this part of the power supply?
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#11 Reply
Posted by
rstofer
on 12 Dec, 2017 19:28
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I only linked the video as an example of why an oscilloscope with greater than the minimum bandwidth for audio is desirable. The 2467 is special for reasons other than its bandwidth and not the oscilloscope I would recommend.
As always, the video was excellent. I tend to see what equipment is being used in the various tutorials and then price it on eBay. No particular reason, just curiosity.
There are lots of used analog oscilloscopes to be had for $250 or less and most suitable ones will be available for a lot less. The 50 MHz Tektronix 2225 shown in Dave's video is one of the better examples because of its low cost, 500uV/div sensitivity, and lower age but I would consider any similar oscilloscope. I've picked up Tektronix 2230s, 2232s, and 2236s for less than $150. The various 465 family oscilloscopes can also be had for that price or less but are more likely to have age related problems.
The problem is, those asking about 'first' scopes are in no position to evaluate the alternatives. I suppose it already exists but a list of desirable scopes, in some kind of ordering, would be handy. "Here's your shopping list, start at the top and work down.".
When I was in college, the Tek 454 was fairly new and one of the other fellows worked for Burroughs and he had one. I decided that I wanted that form factor. It was 30+ years later before I bought the 485.
The largest problem however with used analog oscilloscopes is finding one in good shape. Novice users have difficulty evaluating them and repairing or maintaining them.
And this is the reason I don't recommend buying used <anything> but especially complex test equipment. Yes, there are some bargains out there but there is also a lot of junk. Repairing scopes isn't something I would think a newcomer was up to although there are forums that can help.
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#12 Reply
Posted by
james_s
on 12 Dec, 2017 20:02
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Used is always a gamble, but overall I've had excellent luck. There are plenty of less risky used options out there if one is willing to pay a premium, which should be possible within the $250 budget. There are reputable people who sell tested working/refurbished used gear, it costs more than as-is random used stuff but it's still often considerably cheaper than new.
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#13 Reply
Posted by
vk6zgo
on 12 Dec, 2017 23:50
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As always, I recommend having a look at Hamfests in your region.
There are often ,but not always, secondhand Oscilloscopes for sale, often running on the sale table.
All those I have seen at our local Hamfest have been well below the prices common on eBay.
Some years back, I bought a Tek 7613 for $A135 at just such an event.
Big & bulky?
Yes, but extremely capable.
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#14 Reply
Posted by
GreyWoolfe
on 13 Dec, 2017 00:16
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After buying a noname clunker at a garage sale, I bought my Tek 2225 on eBay for $125 shipped. I picked it for a few reasons. Dave had made two indepth videos on it, so I learned a lot about it in a hurry. Both the factory operator and service manuals were easily available online, very important. Finialy, I bought it from a seller with good feedback, and though he had no particular scope experience, he did offer returns. It had a couple noisy pots on the front panel, but I got a very good replacement board for $45. It all worked out well but you do take a chance. With new Rigol 1054Zs going under $350 new, if you have a need for a working scope I think that is a very safe choice.
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If you buy used, look for a scope that has a good track record of being repairable. The Tek 2225 is a great example of that. I have had a 2225 for 15 or so years and last month it up and died. With the service manual, I was able to repair it - bad cap and 2 fried transistors. Total cost about about $8 including about 6 other caps I replaced just to be safe. In retrospect it was actually pretty easy because the service manual showed test points and expected voltages. That pointed to what I should check and quickly found the culprits. For any scope over 15 or so years old, expect the caps to start failing. So, it's really a matter of when, not if - especially in the cheaper brands that didn't use super high quality caps.
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#17 Reply
Posted by
Shawnk
on 13 Dec, 2017 18:41
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Thank you for all your input. You have all been verry helpful. What do you think of these 2 options.
1 Tektronix TDS420 Four Channel Digitizing Oscilloscope 150MHz for 200$ shipped
2 rigol ds1052d for 200$ shipped.
What do you think would be the best option and why.
Obviously I completely understand that i’m taking a risk buying a used unit.
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#18 Reply
Posted by
james_s
on 13 Dec, 2017 18:55
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I do like the TDS400 series scopes but it's important to remember that they're ~25 years old and are notorious for leaky SMT electrolytic capacitors all over the place so if you buy one of those make sure it has been re-capped unless you want a project.
I have no direct experience with the Rigol but they are generally well liked as entry level DSOs.
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#19 Reply
Posted by
vk6zgo
on 14 Dec, 2017 01:41
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Thank you for all your input. You have all been verry helpful. What do you think of these 2 options.
1 Tektronix TDS420 Four Channel Digitizing Oscilloscope 150MHz for 200$ shipped
2 rigol ds1052d for 200$ shipped.
What do you think would be the best option and why.
Obviously I completely understand that i’m taking a risk buying a used unit.
I think you will be disappointed with the TDS 420 as a general purpose Oscilloscope, for the following reason.
Early DSOs have very limited memory, so that when you use them at longish time/div settings, they have to reduce the sample rate to fit into this low memory.
This is OK if you only look at sine waves, but things like looking at analog video signals at field rate are pretty much impossible.
In many specialist applications this is not a big handicap, but as I said above, they are not good general purpose instruments.
Modern DSOs , by & large, do not suffer from this problem.
i do not have one, or, indeed, any DSO, but the DS 1052d is well regarded by many on this forum, so I would recommend it as the best choice.
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Plus one on the 1052, but I have to think that soon they will be discontinued and discounted. Right now they are selling at the same price of a 1054z so I cannot think they are selling many. Something has to give. My 2 cents.
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#21 Reply
Posted by
David Hess
on 15 Dec, 2017 02:46
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I would rather have the TDS420 than a Rigol DS1052D but I would not recommend the TDS420 to a novice because of age related maintenance requirements. The TDS420 has peak detection and makes measurements on its acquisition record while the Rigol DS1052D lacks both of these things. The dual delayed timebase of the TDS420 largely makes up for its short record length although its record length is longer than "short".
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#22 Reply
Posted by
jgalak
on 15 Dec, 2017 14:41
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I was seriously considering a 2465B that I found at a good price, but after reading threads here about the need for recap, replacing the battery-protected RAM, and the other possibly overheating chip, I decided that this was too much work for a newbie like me.
So I got the Rigol 1054z. For $350, it's pretty amazing, especially once it was "unlocked".
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#23 Reply
Posted by
tszaboo
on 15 Dec, 2017 15:27
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Thank you for the video. I have watched it. I have a snap-on 4 channel scop that i use at work but is not fast enough for my needs for amplifier repair. I am new to electronics repair (only the last 2 years). I would like to start getting more advanced and take it more seriously but i need a good Benchtop oscilloscope that will fill my needs. Like how many MHZ and the bit rate. Can i get a ok Digital one for that price or only analog. Is there any brands or models the work well and are user friendly. For the kinda of signals you see in a amplifier what should i get?
If you're doing audio amplifier repair, pretty much ANY scope will be sufficient, you only need perhaps 0.1MHz of bandwidth for audio
Class D amplifier, I2S signals, SPDIF, IR remote, switching power supply, capacitive voltage doubler.
Just to name half a dozen things that are in an audio amplifier and require a 10+ MHz scope.
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#24 Reply
Posted by
Mr. Scram
on 15 Dec, 2017 15:30
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I was seriously considering a 2465B that I found at a good price, but after reading threads here about the need for recap, replacing the battery-protected RAM, and the other possibly overheating chip, I decided that this was too much work for a newbie like me.
So ingot the Rigol 1054z. For $350, it's pretty amazing, especially "unlocked".
Can't go wrong with the DS1054Z.