New owner of Tektronix THS710A, Questions & Discussions - Page 1
Forum section: electronics / testgear

author: BravoV
author_rank: Super Contributor
timestamp: September 28, 2013, 07:13:11 am
content: Edit :The original title was "Tektronix THS710A at $190, grab it ?" , updated since I already grabbed it and now questions and discussions at this handheld Tek scope.The frequency of measurement activities using scope is getting more and more at switching power supply, even though I have a 1Kva isolation transformer. Yes, I'm aware the limitation of using an isolation transformer and know how to use it properly, its just I'm getting tired of using it and also its error prone. For sure when it comes to mobility factor using bench type scope + iso-tran. is practically zero.The condition of the Tektronix THS710A physically is at 95% as the seller claimed, comes with complete all standard accessories like two genuine Tek probes, the pouch, Tek DMM probes and manuals.Another advantage point, I will be allowed to test and verify it physically, apart from the standard built-in diagnostic mode, since the transaction will be at the seller's place, I guess I will not be able to test it's measurement throughly, any hints or tips on this part ?Although its only 60Mhz bandwidth and with 250 MSa/s at only 2500 samples, am I on the right track if I trust the safety regarding it's isolation spec & design compared to cheap Chinese modern hand held scope which definitely have much higher specification on bandwidth, samples rate and samples size ?Again, I'm not looking nor expecting to use it in troubleshooting anything else except for "common" switching power supply. At 60Mhz is "adequate" enough right ? cmiiwSuggestions, comments & thoughts are welcome.Illustration quoted from it's manual regarding the isolation design attached below.

author: EEVblog
author_rank: Unknown
timestamp: September 28, 2013, 09:39:36 am
content: 60MHz is plenty for switchmode work.Sounds like a bargain, grab it.Yes, trust the Tek.The proper isolated Tek probes are important.

author: Fraser
author_rank: Super Contributor
timestamp: September 28, 2013, 10:46:37 am
content: I own the THS720. The asking price is a bargain for a 710A in good working order ! They sell for around $1000 on e*ay.Grab it. If you ever want to sell it you will get your money back on it or even a profit !

author: Shock
author_rank: Super Contributor
timestamp: September 28, 2013, 11:32:05 am
content: Factor in if the battery hasn't been replaced in a few years it's probably toast. That may also work to your advantage when you ask that question. You can also check the date on it I assume it will have one.http://ths710bat.blogspot.com.au/

author: BravoV
author_rank: Super Contributor
timestamp: September 28, 2013, 03:33:32 pm
content: Quote from: EEVblog on September 28, 2013, 09:39:36 amOur glorious leaderhas given the green light, I feel confident now, thanks Dave.Quote from: Aurora on September 28, 2013, 10:46:37 amGreat to hear another vote for confidence, btw, any tips apart from the standard self test to verify if its working adequately without signal generator in hand ? Remember, I will be testing it at the seller's premises.Quote from: Shock on September 28, 2013, 11:32:05 amGreat info, thanks a lot !Yeah, I'm expecting that, NiCd just can't last that long.

author: marshallh
author_rank: Unknown
timestamp: September 28, 2013, 03:50:30 pm
content: I had a THS720A for a while. The official batteries are ludicrously expensive.You can build an identical one withhttp://www.batteryspace.com/nicdbatterypack48v30ah4xcendtoendwithtabs.aspxI used alum. foil to bring down the pos. terminal to the spring contact using a band of aluminum foil.See the official battery for reference.The scope has a trickle charger circuit built into it so tha'ts all you need.

author: SeanB
author_rank: Super Contributor
timestamp: September 28, 2013, 04:15:28 pm
content: Simple test is to place a piece of wire in the input socket and look for a 50/60Hz hum signal. Will not be looking like a clean sine wave, but as long as it is the mains frequency and varies in amplitude as you move your hand closer or further away from the wire it is working. Sensitivity will need to be close to the max for this of course.

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 28, 2013, 04:23:10 pm
content: Quote from: marshallh on September 28, 2013, 03:50:30 pmNice, but $115 shipping is a bit too much for me

author: Fraser
author_rank: Super Contributor
timestamp: September 28, 2013, 07:15:01 pm
content: The original battery was toast on my unit but a newer one was supplied and that is still OK. I have looked into building a new battery as it is simple except for the unusual charging connection down the side of it. I have the batteries, heat shrink and self adhesive copper to make a copy. I recommend using self adhesive copper tape as it is possible to solder it where needed. I even considered modifying the DSO and connecting the charge wire to the positive battery terminal but decided it wasn't necessary.To test the input amplifiers you need nothing more than a 1.5V battery. Set the DSO to DC input and apply a positive input and then a negative input. If it deflects 1.5V, it is likely that the unit is working OK. These are well made units but the LCD can show its age in terms of contrast. Still very readable though.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: September 28, 2013, 07:56:37 pm
content: Hi,I can show you how I made my battery for a THS730A. The batteries for the THS710, 720 and 730 are the same.The original battery was constructed from 4 NiCad C cells.I found 4 Sanyo NiCad batteries with tabs welded to them. I soldered the tabs together to put the four cells in series. The tricky part is the positive terminal, this must be connected to a metal band around the bottom cell. I used thin brass metal for the connections. The brass is easy to solder.I held the whole assembly together with tape.Here are the pictures:Jay_Diddy_B

author: SeanB
author_rank: Super Contributor
timestamp: September 29, 2013, 05:42:53 am
content: Nice, I was looking to do the same for some Maglite battery packs, but decided the simpler thing is to just toss the 20 year old pack, gut the charger and replace the pack with a cylindrical lithium cell pack, using the spare space to install the charge controllers and LED drivers. just means I will have to draw some circular PCB's to stack in there. Long term project though, I have enough torches just the Maglites look so nice aside from the poor battery chargers.

author: BravoV
author_rank: Super Contributor
timestamp: September 29, 2013, 07:49:57 am
content: @SeanB & @Aurora, thanks for the advices, btw I brought 9V battery and it helps as expected, yes, done deal and it has a new home & owner now.@Jay_Diddy_B, thanks for the battery shots, really appreciate it.I think I got the whole shebang, complete with all those hooks, probe's accesories made by Pomona & Mueller, heck, even the multi-colored rings for the probe id are still sealed in the plastic. The lcd backlit is also still really bright, looks like the previous owner rarely used it and still looks so new, no even a scratch at the scope body and the screen is still shiny. And even the DMM probe tips are still protected with the rubber caps.The battery confirmed dead as expected, the scope was tested using the AC adaptor and works flawlessly. Now new homework to do, buy new C or AA cells and mod the battery pack.Again, thanks to all for the suggestions and comments given.Few eyes candies attached of my shiny THS710A below, freshly captured.

author: qno
author_rank: Frequent Contributor
timestamp: September 29, 2013, 08:36:44 am
content: Good job.I also have 2 of them. A 720 and a 710.What is the software version?Need some more info? Check outhttp://warped.org/tek/I use a program Wintek32 to capture screenschots to the pastebuffer.You can paste screenshots directly into your MS-Word research report.....

author: BravoV
author_rank: Super Contributor
timestamp: September 29, 2013, 03:18:28 pm
content: qno, thanks for link, damn, I didn't know there is a fan page for these Tek portable scopes.Firmware version is 1.11 dated back 1997, is there anything that I should aware of regarding this version ?Photos of the power-on diagnostic screen, and screen of detail firmware version attached below.

author: BravoV
author_rank: Super Contributor
timestamp: September 30, 2013, 04:22:24 am
content: Just thinking out loud about the battery replacement, obviously buying the genuine replacement is NOT an option for me.Say we're not discussing and forget for a while the troubles of making the tube with it's unique contact points, protection circuit against charging the battery while its inside the scope and etc, has anyone ever thought of using rechargeable Li-Ion cell as an alternative replacement for this really pricey battery ?Fyi, I can get a genuine Panasonic 18650 Li-Ion cell with 3.1 AH capacity (NCR18650A) at $11/pcs, while the genuine Tek battery replacement for example at Element14 cost $195, go figure.The Tek standard battery is just a stacked of 4 C sized NiCd cells rated at 2.8 Ah, and as the manual stated, the scope has approx 2 hours of "continuous" use from a fully charged battery, realistically from I gathered around the net is about 1.5 hours. Meaning the average current consumption only at 1.4 A, which is still within safe region say for a common 18650 Li-Ion cell.Of course with the "assumption" that the scope will terminate the discharge when the NiCd cells are reaching at 0.9 Volt/cell (3.6V), and this low volt threshold level should be compatible with the Li-Ion safe discharge voltage level, cmiiw.Any other thoughts about this idea just in case I missed something here ?

author: Fraser
author_rank: Super Contributor
timestamp: September 30, 2013, 02:45:30 pm
content: I considered alternatives but have a distrust of DIY Li-Ion as I am not familiar enough with the batteries needs.I personally planned to take a much easier and IMHO safer route. I bought four C size high capacity Ni-Mh batteries which have higher power density than the original Ni-Cd cells. The Ni-Mh cells are the easily available retail type that have the protruding nipple top. They fit in the THS-720 battery tube fine.To charge them without the daft hardware around the cells, all you need to do is open the DSO and rum a jumper wire from the tubes side (charging) contact to the tubes positive contact. This has little risk and is IMHO safer than the original design. So why did Tektronix use such an odd battery design ? My kind side says it was to prevent people trying to charge alkaline cells that were placed in the battery tube. My less kind side says it was a measure to prevent users buying replacement batteries from a normal battery supplierThe battery is nothing special at all, it is just the charge contact that makes it different to COTS 4 x C cell battery packs.IMHO using the method I have detailed above is the simplest, quickest and least damaging to the DSO's standard build. Nice high capacity C cells will give a longer run time. It is easily reversed by removing the jumper wire. replace my one working battery, it will be the modification that I employ.

author: qno
author_rank: Frequent Contributor
timestamp: September 30, 2013, 03:46:51 pm
content: The software did not change very much.Just some extra functionsZoom when in multimeter mode.Trigger on the multimeter input.Manuals should be on the net somewhere Haven't checked..

author: BravoV
author_rank: Super Contributor
timestamp: October 01, 2013, 03:40:53 am
content: Quote from: Aurora on September 30, 2013, 02:45:30 pmIf you're done making that, share it please.I've considered C size Ni-Mh too, like using high capacity 5000 mAH Imedion brand battery from Powerex, the problem I see is the trouble of charging them, this new generation NiMh batteries wont react too well if using slow charging method, minimal at 0.5 C in order to detect full charge state, meaning a whopping 2.5 A Ni based charger that DIY route is a must. Most commercial NiMh charger out there maxed out at 2 A, and only for AA size, not C or must be really hard to find. Currently I just can not afford the trouble in building this dedicated 4 C cells high capacity NiMh charger at the moment.Since AA size charger is almost everywhere, I'm also thinking to use the AA to C adapter like below photo, stack and stick 4 of them, while maintaining the open and close mechanism for battery replacement, and do some modding at the gap inside the case with cable from the top and route it to the positive contact band made by a copper strip outside like Jay_Diddy_B's work.

author: BravoV
author_rank: Super Contributor
timestamp: October 01, 2013, 03:44:47 am
content: Quote from: qno on September 30, 2013, 03:46:51 pmWhich version is that with that extra features ?I guess with this old generation scope, updating the firmware by user is not possible without cracking up the scope right ?What manuals are you talking about ?

author: Fraser
author_rank: Super Contributor
timestamp: October 01, 2013, 09:26:17 am
content: I am no expert on the latest Ni-Mh chemisrty but your suggestion that a charge rate of 0.5C minimum comes as a bit of a surprise.I have charged modern Ni-Mh C cells at currents as low as 100mA and achieved a full charge. The capacity was tested with a CBA III battery discharge analyser (constant current load) It was my understanding that fast charging cells meets the needs of the consumer but does reduce the cells life span. Historically, the best charge upload to a Ni-Mh cell has been a low current over a long time frame, followed by trickle charge current to maintain charge at 100%The RC world do treat batteries in a very different way to 'normal' consumers. They want fast charging and peak perfromance in terms of available current and duration. They are willing to cook their batteries to achieve this in competition use. An RC racer would laugh at me slow charging a battery. They tend to charge at 1C or even 2C !

author: BravoV
author_rank: Super Contributor
timestamp: October 01, 2013, 11:01:34 am
content: Quote from: Aurora on October 01, 2013, 09:26:17 amI'm not a battery expert too, its just there are too many "convincing" references that agree the only reliable method to determine when a NiMH cell has reached full charge state is using the Negative Delta Voltage detection (NDV) method. But using NDV method, the cell must be charge minimal at 0.5 C rate.Again, there are too many references on the net, picked and quoted few crucial points regarding the charge rate on NiMH cell from this popular web site that is specializing in battery.The NDV method to measure full charge shows only a faint voltage drop, especially when charging at less than 0.5C.It is difficult, if not impossible, to slow-charge a NiMH battery. At a C rate of 0.1 to 0.3C, the voltage and temperature profiles fail to exhibit defined characteristics to measure the full-charge state accurately and the charger must depend on a timer.At a sufficiently low charge rate, NiMH can remain totally cool and yet suffer from overcharge.NiMH cannot absorb overcharge well ...Read the rest yourself here ->Battery University : Charging Nickel-metal-hydride

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: October 01, 2013, 12:22:22 pm
content: Hi,I agree with BravoV. I have been involved with the design of several Nimh chargers. The biggest challenge with Nimh is determining when the batteries are charged.The biggest single problem is caused by not using enough charging current.The Linear Technology LTC4010 datasheet gives some insight into charge termination methods.Link to datasheet:http://www.linear.com/product/LTC4010If you don't use enough charging current you do not see the negative dv/dt and you do not see the rapid change in cell temperature.Jay_Diddy_B

author: Fraser
author_rank: Super Contributor
timestamp: October 01, 2013, 01:24:24 pm
content: Thanks guys. I have learnt some important information here. I have a bank of Ansmann XBase Delux chargers that I often use to charge my batteries and that unit permits charge currents as low as 100mA and I must admit that I have seen some false triggering of the charge endpoint on occassions when I have dilaied in a lowish current for a high capacity NiMh cell. All very interesting stuff.I have always been a little concerned with what I call 'Fast Charging' i.e. less tha 8 hours as I mistakenly believed that the batteries preffered more gentle handling and I wanted to avoid cell overheating as well.Thanks again.

author: BravoV
author_rank: Super Contributor
timestamp: October 02, 2013, 03:07:19 am
content: Noob questions just to make sure before I toast this fine scope or worst injured/killed my self, cause all this time I never even dream of using a scope to probe directly at mains voltage, btw the mains at my house is 220V (single phase).From the scope's manual :Since my activities only at home on my bench and no heavy machineries in my house, so its safe to categorize my electronic activity is in CAT II environment, right ? cmiiwNow, this is the "10X" standard probe's specification included with the scope package.Even I though I have not try it yet, and to be honest I'm still abit scared to do it, its clear and there is even an example in the manual that we can poke it directly at the mains line. Remember, this is a 10X probe.Next, the scope's input specifications.Now, questions ...- At the scope spec above (1), in CAT II environment, the scope's input should be safe to be connected "directly" at mains ?- At point (2), say we're using rated accessories, what and why the concerns regarding this earth ground vs common ? There is no exposed metal/conductive parts starting from the scope's body, BNC connectors and down to the probe, except at the tip and the scope's ground alligator clip (Common).- Point (3) at the channel to channel commons with such low voltage limit, what kind of situations that must be avoided before breaking this limitation ? Example or worst case scenario please.- Say I just want to monitor and observe low frequency signal directly at mains, maybe just in few Khz range (< 100Khz) and with max 20Mhz BW filter turned on. Is it safe to use the DMM probe at the scope input like below photo ? Remember, since this is direct connection, hence no attenuation what so ever (1X probe), and at the scope there is a menu to select the probe at 1X or 10X. Fyi, the banana to BNC adapter is fully isolated, high quality stuff from Philips/Fluke, and that DMM probes + hooks are the standard accessories from this Tek's scope for it's DMM function, and its manufactured by Mueller.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: October 02, 2013, 11:37:00 am
content: BravoV,The special feature of the P6117 probe is that the BNC connectors are insulated on the outside. The way the probe body is shaped it harder to touch the ground lead.The rating published by Tektronix are all about the benefits from having this insulated BNC connector.For example if you have two regular BNC cables connected, the safety limitation is from the safety hazard presented by having the two exposed (un-insulated) connectors.What is the mains voltage in your area?Jay_Diddy_B

author: BravoV
author_rank: Super Contributor
timestamp: October 02, 2013, 05:35:26 pm
content: Jay_Diddy_B, yes, the P6117 insulation is excellent, as my close up shot shows the narrow & deep gap just for the ground cable clip.Mains voltage is 220V, any chance on helping me to answer my questions about the voltage ratings and using 1X probe above ?

author: commongrounder
author_rank: Frequent Contributor
timestamp: October 02, 2013, 06:17:25 pm
content: I caught sight of this thread and though I would weigh in since I am an owner and regular user of a Fluke 199C scopemeter which is similar in function to your Tek THS unit.On point #1: It would be safe - on paper- to use your scope to monitor a 220vac mains directly without 10x probe. It is a bit nerve wracking though, because you do not have a very large amount of headroom for noise spikes. There would only be 80vrms ac, and there could be peaks much larger than that coming down the line (think lightning strike or trees crossing lines). The scope could handle some of this, but why risk it? That is why I really like and use the 10x VPS2xx series probes that are used with the Fluke scopemeters. They have accessory clips like alligator and spring grabbers that allow you to do what you are wanting with the multimeter leads and banana to BNC adaptor, but have the additional safety of a 10x probe, and the cat. rating that goes with.Point #2: The scope is isolated from ground, but there is a limit. The internal breakover point between the isolated shell of the BNC and the scope system ground is up to 600 volts. That is to protect you from floating the scope too high above ground and risking an arc-over that damages the scope - or worse yet - you!Point #3: The 30 volt rms limit is what most safety agencies deem the maximum voltage exposure that a human can contact before electrocution becomes a possibility (I happen to think it is possible to get shock injured at much lower voltages under the right circumstances). With uninsulated cabling or BNC connectors they want you to limit the voltage that might be present at the two BNC shells to 30 volts to prevent accidental contact shock hazards (human safety).The point of all of this is: Use insulated accessories as much as possible. Use Tek 10x probe as much as possible.If it were me, I would watch on e*ay for a Fluke VPS 2XX series scope probe with the accessory clips. I have no qualms about connecting my Fluke directly to a power service entrance panel for 110v or 220v monitoring using these probes and the fat alligator probe tips.Best of luck with your great find!

author: Unknown
author_rank: Unknown
timestamp: October 02, 2013, 08:25:01 pm
content: The 'Fluke' isolated scope probes are made by Multi-Contact (the IsoProbe series). You might be able to find them cheaper without the Fluke brands. They may also have been sold by HP/Agilent at some point. The Tektronix P5102 offered a similar amount of protection, but is somewhat bulkier.The P6117 (and later incarnations like the P2220) technically have insulated ground, but not enough to convince any safety certification lab (e.g. UL), so they're rated only for floating voltages that would be safe to touch. Connecting them to mains should be fine, but don't clip the ground clip to anything but ground (i.e. not mains or neutral), even though the manual may show examples of this and the scope would support it (with the correct probe).

author: BravoV
author_rank: Super Contributor
timestamp: October 03, 2013, 06:25:24 am
content: @commongrounder, thank you so much for the comprehensive explanations.About the VPS probe or IsoProbe branding as alm pointed out, thanks to both, I will start the stalking at ebay for cheap ones for sure. Just checked the price for new sets, its jaw breaking, way way too much compared to the price of my scope here.Ok, there will be no direct 1X probing for now and ever.Quote from: alm on October 02, 2013, 08:25:01 pmWow .. please elaborate further why ? What is the worst case example ? You're starting to scare me now.If the ground clip can not be used, and only at ground, then how to observe/measure the signal properly between Live and Neutral ?So the scope's manual is kinda giving a misleading information ? Here quoting the example from the manual, its clearly shows we can use the ground clip at one of the mains plug, and NOT the ground.

author: Unknown
author_rank: Unknown
timestamp: October 03, 2013, 02:09:33 pm
content: Quote from: BravoV on October 03, 2013, 06:25:24 amThis picture is fine, as long as you use the P5102 probe. With the P6117 it's one of those things that will usually work fine, just like measuring means with those cheap DMMs, but this does not make it safe. It might be OK in hands-off measurements, but I would still be careful.The P6117 is rated for 30 Vrms between the reference lead (ground lead is not really a good term for floating measurements) and earth ground. It assumes that anything connected to the reference lead would be safe to touch. This is not true for the neutral lead, which is why we don't make equipment with its chassis connected to neutral anymore. Electrical codes in general require the same amount of insulation for live and neutral conductors. If neutral conductor gets interrupted somewhere between the socket and the voltage on the neutral pin in the socket will rise to approximately mains voltage current limited to at least a few amps in most systems. Some supplier, the wiring systems (eg. ships) might have two live conductors and no neutral. And depending on the impedance of the neutral wire, a surge current may induce a voltage surge across this wire. Note that a CAT II 300 V input is designed for a 2500 V surge from a 12 ohm source. Do you expect the neutral to remain at earth potential under these conditions?You can use the two channels in subtract mode (just like on a grounded scope) to measure across mains. I would use the P6117 probe only for floating measurements in CAT I systems, for example to measure relative to the positive power rail in a 12 V system. For power measurements I would get the Tek P5102 or the MC/Fluke isolated probes.

author: BravoV
author_rank: Super Contributor
timestamp: October 04, 2013, 05:58:33 pm
content: So when it comes to probing common AC to low volt DC switchmode ps, the red zone (photo below) definitely out of my reach, right ?Sorry, this sounds so noob, but when it comes to mains, just want to be really-really sure about this, and for sure I trust you.Until I got P5102 or it's equivalent, no direct mains probing, period.Alm, just realized that you've been helping and assisting me a lot on various T&M noob topics in this forum all this time, really appreciate that, thanks a lot.

author: PA0PBZ
author_rank: Super Contributor
timestamp: October 04, 2013, 06:45:23 pm
content: You probably want to stay away from the left side of that optocoupler also.

author: qno
author_rank: Frequent Contributor
timestamp: October 04, 2013, 07:20:40 pm
content: measuring 240AC is not a problem. Its the probes. The 9 Meg resitor might lose some accuracy when using it over the rated voltage. The original high voltage probes are fully insulated. As long as you do not touch th metal BNC you are fine. You can even isulate them yourself by shrinking some shrinking tube over it. And if you do not trust yourself make it a double or triple layer. Only use the keyboard when measuring high voltage. Switch of the circuit when changing probe position.

author: BravoV
author_rank: Super Contributor
timestamp: October 05, 2013, 03:13:33 am
content: Quote from: PA0PBZ on October 04, 2013, 06:45:23 pmYou're right, missed that part. Anything that is galvanically connected to mains is a no-no.Quote from: qno on October 04, 2013, 07:20:40 pmAs alm said, I will do a total hands-off measurement if I desperately need to measure mains connected circuit. Thanks for the tips though.

author: qno
author_rank: Frequent Contributor
timestamp: October 05, 2013, 08:44:36 am
content: My software versions are 1.03 and 1.16.Does someone know the difference between the 60, 100 and 200 MHz versions?Is it software, Hardware or both?

author: BravoV
author_rank: Super Contributor
timestamp: October 05, 2013, 04:19:06 pm
content: No idea, and I was googling for a while and still can't find anything about this THS700 series firmware.Even though there is a newer version, I don't see how we can upgrade it easily.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: February 03, 2014, 03:57:45 am
content: Quote from: Jay_Diddy_B on October 01, 2013, 12:22:22 pmThe LTC4060 uses less external components.http://cds.linear.com/docs/en/datasheet/4060f.pdfThe NiMh batteries work great. I just used the old battery as a donor for the contacts.

author: Speleocaver
author_rank: Newbie
timestamp: March 08, 2014, 05:11:37 pm
content: I installed two 6 ah Li-ion batteries.One battery plain, wired in series with a li-ion protection circuit then attached to the second Li-ion battery. Now the voltage is too high to power the scope, its 8.2 volts when fully charged and I dare not fry my Precious THS720. I soldered 6 10A diodes in series. This would prevent THS720 charging the Li-ion's and keep them from EXPLODING! It also drops the voltage to 5.14 volts. The replacement charging system is a small RC race car battery charger. I use it for all my rechargeable projects like these... I have done this conversion DIY Li-ion mod on a Irobot Roomba, Underwater Dive light, 4 High power camera flashes, 2 portable radios, an Amp-meter, All work GREAT!!.. it should have been perfect! well apparently theTHS720 has a very smart battery monitoring system. As soon as I hit the power button It checks out the source and rejects it, Lights up shuts down, tried more voltage...5.5v less 4.8v no go.Or it could be the Li-ion battery protection circuit, it cuts power around 2 amps, the scope draws 1.89A calculated. Either that or the scope senses that it cannot charge the battery because it has no reverse resistance... because of the diodes... What a bummer... If it does not act like a ni-cad or ni-mh maybe it won't work... Perhaps?SO, I put in 4 loose nimh 4ah and soldered the red lead to the top + ( I had to open the case to get the red out) closed it up then stuffed some neoprene rubber to push the battery down into the - spring. Worked great! New batteries for $15 or Factory Rippoff $200.In the meantime I will try to run the scope again this time without the protection battery protection circuit and the meter will be given full current but still through the voltage drop diodes. If it happens to work this time then I will need to see If I can parallel the protection circuits to get 4 amps.The Li-ion's would double run time if I can get them to work...RichVoltage: 3.7vCapacity: 5800mAh6.8cm x 2.5cm - 2.67inch x 0.98inch26650 battery

author: BravoV
author_rank: Super Contributor
timestamp: March 09, 2014, 01:57:29 am
content: Rich, thanks for sharing this, I was curious too on how it performs using Li-Ion, keep us updated if you still pursuing for alternative battery for this scope.

author: Zucca
author_rank: Unknown
timestamp: June 08, 2015, 01:18:41 pm
content: Looks like now we have the schematics...https://www.eevblog.com/forum/testgear/tektronix-ths700-tekscope-component-level-information-package-and-schematic/

author: hibone
author_rank: Regular Contributor
timestamp: August 04, 2015, 11:28:25 am
content: The keysight U1561A Passive Probe are 10x with 250 MHz BW and cost about 150 €They are rated Cat II 1000V and Cat III 600V thus they may be a valid replacement.The only issue may be the compensation range.Suggesting other models may be useful since P5102s are discontinued and cost about 250 €