Tektronix THS7xxx Scope Hack/Teardown/Discussion - FW 1.16 found

[nixxon]

This is the original page that has the screen capture program:
www.bobblick.com/techref/projects/ths720/ths720.html

The URL is long gone but you can still see it using the Way Back Machine. I used the tek.exe program for many years with my THS720.

I have attached the Dos/Windows versions, a Linux perl version(remove the .txt) and the original qbasic source code(again remove the .txt). All of it is credited to the original creator Bob Blick.

It seems that the URL is still working bobblick.com/techref/projects/ths720/ths720.html

EDIT 2019-AUG-23: Removed "www" from the above link to make it work.

[HighVoltage]

The screen capture software that I have been using since 1999 is called WinTek32 and was made by Martin Lafferty under the company name of "Production Robots 1997" in England. In those days I was in contact with Martin and he added a few features for me.
The latest Version that he release, is the attached one v2.0.5.21

(I am pretty sure it was freeware at the time, so it should not be a problem, if I am posting the software here.)

I Just hooked it up this morning on my THS720P and it worked flawlessly right away on my old trusted IBM T43P.
Once installed correctly, you just press the hardcopy button on the scope and the transfer starts.
The beauty about the RS232 connection is that it stays connected, even if you disconnect the wire and hook it up to another scope. At times when I had to take a lot of pictures from several scopes, I just had a rotary switch hooked up to different scopes and switched the serial connection between them.

Another good feature about the software was the fact, that you could add a custom text to the screen shot at a position of your choice. With a "#" sign in the target file, you can save numbered sequences of your file.

Here are a few screen shots and the software attached.
Enjoy.

[BravoV]

The screen capture software that I have been using since 1999 is called Wintek32 and was made by Martin Lafferty under the company name of "Production Robots 1997" in England. In those days I was in contact with Martin and he added a few features for me.
The latest Version that he release, is the attached one v2.0.5.21

Complementing HighVoltage's post on WinTek32, attached below in PDF WinTek32 documentation.

[Fraser]

Thanks Guys 

Aurora

[HighVoltage]

There is a nice old "fan page" about the THS scopes that I had forgotten about and just found in my notes.
http://warped.org/tek/

It looks like all the following manuals are still available there:

tektronix-ths710-programming-manual.pdf.zip    070-9245-00    Programming Manual    THS710, THS720
tektronix-ths710-reference.pdf.zip    070-9257-00    Reference Manual    THS710, THS720
tektronix-ths710-service.pdf.zip    070-9246-03    Service Manual    THS710, THS720
tektronix-ths710-user-manual.pdf.zip    070-9247-02    Users Manual    THS710, THS720
tektronix-ths7xxA-programming-manual.pdf.zip    070-9751-01    Programming Manual    THS710A, THS720A, THS730A, THS720P
tektronix-ths7xxA-release-notes.pdf.zip    061-4241-00    Release Notes    THS720A, THS720P, THS730A
tektronix-ths7xxA-reference.pdf.zip    070-9741-01    Reference Manual    THS710A, THS720A, THS730A, THS720P
tektronix-ths7xxA-service.pdf.zip    070-9752-01    Service Manual    THS710A, THS720A, THS730A, THS720P
tektronix-ths720A-service-2.pdf.zip    070-9750-02    Service Manual Supplement    THS720A MOD NV
tektronix-ths7xxA-user-manual.pdf.zip    070-9731-05    User Manual    THS710A, THS720A, THS730A, THS720P

[posplayr]

Hi gang,
   I was reintroduced to this site while looking for ways to upgrade my THS730A. This thread in particular was very interesting especially the battery replacement options. After considering what was posted (maybe someone else already has done this) I decided rather than replace the expensive battery pack with another aftermarket Ni-Cd pack and also rather than go AA Ni-MH I found some relatively inexpensive C size Ni-MH (500 mAhr as compared to the 2800 OEM pack).

You can such on Amazon for Clear PCV shrink tubing:
2M 43mm 27mm Dia PVC Heat Shrink Tubing Clear for 1 x 26650 Battery ($6.06 with Amazon Prime FREE shipping)

I also thought these would be worth a shot; My scope sits on the bench a lot and so I don't really need to take it into the field and expect 10 hours everyday. Beside, I have enough PVC shrink tubing to redo the battery pack several times.
EBL 5000mAh High Capacity Ni-MH Rechargeable C  ($17.99 with Amazon Prime FREE shipping).

I just cut the PVC cover off of my old battery pack (Circa 1995), prised the metal tab off the positive post that had been welded. Reassembled in sections starting with the two inner batteries. After a little trial and error, it is best to shrink in the ends before trying to shrink the center. It pulls the two 1/2 together.

The starting point:



Assembled two middle batteries, being sure to extend past the ends to pull them together.



Finished product; there are 4 layers of PVC is most areas.



Quick look running without the charger. The batteries came with just over 4.6V with the series pack. After inserting the pack into the scope, the LOW BATTERY indication quickly came on. I charged them for a while and went back to show that the indicator stayed off (i.e. the internal charger is working). Basically this cost me $24. Even if the batteries do not work out, I can upgrade for a modest cost. The process seems to work and there is no need to solder or weld if you have an original battery. If not then a thin brass sheet would work well to replace the stainless .



No need for welding, the stainless strap is held in place with the PVC wrap.

[HighVoltage]

How did you re-connect the metal straps to the new batteries?

[posplayr]

The original post has an added picture (at the end) showing the strap.

I opened up the inner PVC cover of the OEM battery after completing this and saw that each battery has a tab welded between it's neighbor. Seemed overkill and perhaps why the pack costs so much. The flexible metal of the tabs is not stainless so it invites more corrosion between batteries but given the welds that doesn't matter much.

I do not see the need to weld the tabs to the battery ends except in the most caustic environments which my scope never sees and I doubt most never will either. The PVC does quiet well holding the pack in alignment and the battery lives in a battery compartment under axial pressure so there is plenty of contact pressure to flow the 1 odd amp that is required.

The resting voltage was 5.6V after charging overnight. If I get bored I might do a run down test but that is a big "if". Regardless, of the result, the methods appears to hold C size batteries together without welding. If you do not have the strap and use brass you only need to solder the length wise strap to the band. The PVC wrap will hold the rest in place.

[Fraser]

Nice job !

I have the batteries, metal strips and tab welder to do the same. I must get around to that this year. I am fortunate to still have spare working batteries, but they are getting quire old now so new ones would be a good idea.

Thanks for sharing your rebuild.

Fraser

[HighVoltage]

This is indeed a really nice way to prepare the batteries for the scope
At the moment I still have one good battery working with an original charger.
But the time will come to upgrade the scopes.

[posplayr]

Thanks guys 

Although I don't feel it is nessesary from to weld taps for this application from either an electrical or structural perspective here is a video of a home made spot welder.



I did not realize these were so cheap. I guess if you are going to setup production then it might be a good thing to have.

AC220V 18650 Battery Point Welder Machine Welding Machine Mini Notebook Mobile

http://www.ebay.com/itm/AC220V-18650-Battery-Point-Welder-Machine-Welding-Machine-Mini-Notebook-Mobile/391322379449?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D777000%26algo%3DABA.MBE%26ao%3D1%26asc%3D35006%26meid%3D867f670f564b4fa48c4070d375c7064a%26pid%3D100009%26rk%3D1%26rkt%3D1%26sd%3D311446206476

[Fraser]

That is the model of tab welder I bought. It works really well and you only need to file the hard drawn copper electrodes to keep it producing excellent welds. Electrodes are just hard drawn copper wire and so easy to replace.

IIRC I run my unit on setting 20 to 25 but the unit goes all the way to setting 40. I find my house circuit breaker pops at anything above 35 though.

I reviewed the contents of the unit in a thread on this forum. Pictures included. It is a transformer based tab welder with TRIAC control.

IIRC my tab welder cost me around GBP80 delivered to the UK. I wouldn't be without it now. I use it to add tabs to many memory backup Lithium button cells and for rebuilding expensive battery packs for my thermal cameras. The unit paid for itself after rebuilding one FLIR PM series pack that costs over GBP200 + VAT new. I have around 20 such battery packs !

Fraser

[posplayr]

Thanks for the added info; glad I stumbled back in here 

Given my prior ebay shopping patterns, I might have bought a cheap Chinese USB scope and taken a big step backward from my THS730A!

BTW, I contacted Tektronix about a replacement zero adjust knob for my A622 Current Clamp. Apparently there is one coming in the mail for free. First time I asked for anything after buying the scope 20 years ago.

I need to find a A622 break down thread that deals with high battery current consumption. Mine started to pull the 9V battery down real fast, but still runs off a power supply hooked to the 9V contacts.

[Fraser]

I have used a thermal imaging camera to view a PCB that was eating batteries. It was quickly clear that one chip was running hot. It turned out to be the cause of the fault. Do you know anyone who can use a thermal camera on your probes PCB?

The alternative is to systematically isolate the active parts of the PCB in an effort to see which component is drawing the lions share of the operating current. Tantalum capacitors can fail and load supply rails. In such a case, a thermal camera would reveal the effect rather than the cause, as other components on the supply line to the capacitor may warm up.

Fraser

[posplayr]

Good idea on the thermal imager. I was aware that caps can go out but not really any idea on how to isolate other than change them all out. I don't have a thermal imager, but do have a HF handheld unit that I might be able to scan on the board to detect a temp rise.
http://www.harborfreight.com/non-contact-infrared-thermometer-with-laser-targeting-60725.html

BTW, the complementary zero adjust knob from Tektronix just arrived in the mail today 

[hibone]

Hi there, when replacing the original battery, what do you use?

IIR each C-sized battery can be replaced with 4 AAA sized ones.

If thats the case, and taking into account that the internal charger is a trickle one (if I'm not mistaken), do you think it would be possible to replace the whole batteries with 16 AAA eneloop batterys (or similar hybrid nimh) and charge them within the scope?

[BravoV]

Had anyone ever measure the trickle charge current ?

The original cells are nicd, which is more forgiving than nimh cell, and one of the reason I use the detachable method so I can charge externally each at proper nimh charger.

[posplayr]

Good question, I guess I side the stepped of battery charging issue. The packaging works regardless of using Ni-CD or Ni-HM.
 don't know what precautions you take with AA Ni-MH batteries in your THD7xx but it sounds like you never run the device with the DC charge input connected?  Whatever charge rates an AA Ni-MH would have the C size is going to be about 1/2 the charge rate. (2500 Amp-Hr v.s. 5000 Amp-hr)

In the first post Zucca stated:

The battery charger works like this (according to my reverse engineering):

VBatt <3.5V: CC charge at 110mA
VBatt >3.8V: charge current [mA]= -187.27*VBatt[V]+1283.63
3.5V<VBatt <3.8V: Previous state

according to the formula the max charging current at 3.8V is .57 amps or 0.2C for a 2800 mAmp-Hr or 0.11C for a 5000 mAmp-Hr.

According to:

http://batteryuniversity.com/learn/article/charging_nickel_metal_hydride

On September 9, 2011 at 9:11pm
Edward wrote:
the best C-rate for chargeing NiMH is 0.2C-rate charge 6Hours

So the optimum charging rate for the Ni-CD and the Ni-MH is the same, but the apparently the Full charge detection is much more difficult and trickle charging is different.

However, this statement suggest that putting in a 5000 Ni-MH v.s. 2800 NiCd Amp-Hr battery is OK as we can probably assume that Tektronix put a quality charger into the scope and it trickle charges at C/10 as (the recommended optimum) That would put the 5000 NiMH at 2800/5000*.1=0.056C very close to the recommendation for trickle charging a NiMH.

NiMH dislikes overcharge and the trickle charge is set to around 0.05C. NiCd is better at absorbing overcharge and the original NiCd chargers had a trickle charge of 0.1C. The differences in trickle charge current and the need for more sensitive full-charge detection render the original NiCd charger unsuitable for NiMH batteries. A NiMH in a NiCd charger would overheat, but a NiCd in a NiMH charger functions well. Modern chargers accommodate both battery systems.

I left the NiMH in the THS730A overnight last night charging and the pack was only luke warm this morning. This is apparently OK.
There is this warning, so it is probably best to unplug the charger from the Scope when left off for extended periods. The built in NiCd charger is probably going to be worse on a AA battery than the higher capacity C size as the AA will be charging at close to twice the C rate.

The bottom line is that while I'm not going to get optimum performance out of the batteries using the built in NiCD charger, it is still going to charge the NiMH C pack within nominal recommendations and will probably only cause an issue if left for weeks on the charger without using the scope. That is easily avoided by unplugging the DC charger input to the scope.

I just checked in my Hardcase case and I see I have an extra battery pack (dated 1998 the first was 1995) and I also have the TEK-Scope battery charger. I guess I could open it up and convert it to a fast charge NiCD charger (another project?)   

To a certain extent, using the AA batteries because you can charge them in a real external NiMH charger causes a problem with excessive trickle charge rates if those same batteries are left in the scope. On the other hand if you put  Type C NiMH batteries with higher capacity, the charge rates are slower (as would be expected) but closer to acceptable trickle charging rate of the Ni-MH battery technology.

There is certainly nothing prohibiting converting the the external charger to NiMH and then if you are working a lot on battery power with the scope, you can much more quickly recharge the pack off grid.

I have a Tenergy TB6B Intelligent charger that I could probably adapt to do a 4 cell NiMH effectively and just not bother to modify the internal charger. http://www.tenergy.com/01321

Comments welcome, but with a small amount of care, there should be no issues leaving the battery pack in the scope overnight, just not indefinitely.

[BravoV]

As I posted at 2nd post in this thread, I use the AA -> C adapter and built the batt pack, ghetto mod and not pretty though, with lots of hot glue and shrink tubing, but it works flawlessly.

As the adapter designed, I can open the pack to replace the AA cells without having to lug many of the long, huge C sized 4 cells tubes as spare when working at the field.

Good LSD AA cells like Eneloop brand are enough to provide similar capacity as the original C sized NiCd cells, and also its convenient to carry many of them pre-charged inside the scope's bag.

Too bad I don't have my batt tube with me now, will post the photo of it once I had the chance.
To give you a clue, these picture below are the AA -> C adapters that I used to build the batt tube, it has latch sideway to access the AA cells inside for replacement of the depleted cells.

[posplayr]

I pulled the Quad "C" pack out of the scope and put into the external Tek-Scope "Fast NiCAD Battery charger". The pack was already pretty well charged (from the night before) as despite leaving the scope on it goes to sleep and I have not rigged a good resistive load yet to bleed it down.

I used the HF infrared thermometer   to monitor the temperature. The red LED on the charger started and the battery pack warmed up to luke warm. With teh charger being about 80 degF (the drywall behind at 72 degF) the battery rose to about 94 degF at center and closer to high 80's at the ends. The feel was consistent with what I discovered this morning when pulling the battery out of the scope after charging all night.

After about another 1/2 hour the battery mid section which gets hotest was at about 104 degF. It was not so hot that you could not hold it firmly. About luke warm. After a while longer the green charger light came on and I pulled the battery pack. By this time the charger was in float and the temperature dropped back to about 97 degF.

I pulled the pack and reinserted it into the charger and the LED went back red as if to restart a new charge cycle. I opened up the charger and there is a little PIC processor in there.

I just ordered another set of same batteries for $17.99 shipped so I'll have a backup as well. Plenty of PVC shrink wrap left.

[hibone]

I think 4 of these battery holders would do. Now the only problem is to find a nickel/brass/copper strip or whatever.

16 Eneloop batteries will cost almost half the price of the original battery but I guess they will last a heck of time, and can be recharged within the scope.

[posplayr]

I think you will be hard pressed to pay less than the 4 NI-MH C cells @ 5000 mA-Hr,($18) not requiring holders and they are far less likely to overcharge in the scope. On top of that they have more capacity. Am I missing something?

[TheSteve]

Eneloops have a very low self discharge so the meter can sit a long time and still be powered by previously charged batteries. At the cost difference though I think I'd lean more towards the 4 cheap C cells or just use 4 2500mAh AA cells as they still offer good run time and are pretty cheap.

[hibone]

I think you will be hard pressed to pay less than the 4 NI-MH C cells @ 5000 mA-Hr,($18) not requiring holders and they are far less likely to overcharge in the scope. On top of that they have more capacity. Am I missing something?

There is what TheSteve says about eneloops.
Also, if  I am not mistaken, eneloops should operate much longer before they wear out (10 years or so), with respect to standard ni-mh.

I am thinking of 4 AAA batteries, in place of one C-sized cells, because as far as i remember,  each C-side cell is made out of 4 AAA sized batteries all the same. Also eneloops seem to have a much more consistent voltage, with respect to other batteries, thus they are less prone to equalization problems when charged in parallel. Thus they can be charged within the scope, without disassembly the battery.

Of course there's the problem with the charge current, as well. That is the reason why I feel that replacing a C cell with one AA it won't do well.

Indeed the price it is high, maybe I should look for some cheaper replacement with respect to eneloops. In the end Sanyo is not the only one that makes hybrid nimh cells.

Well of course, all of this may be not worth the while.

[R_G_B_]

Hello,


I  had a go at using four AA eneloop batteries using a C cell adaptor. The problem is there's no room to close the cap on the top of the THS720 DSO.

Maybe its the type of C cell adapters I am using:

http://www.ebay.co.uk/itm/Newest-Panasonic-eneloop-C-Size-Spacer-4-Pack-Battery-AA-Cell-Adapter-Converter-/221993148950?hash=item33afd2a216:g:KaQAAOSwI-BWHRPY

Thanks

 R_G_B