Author Topic: Tektronix THS7xxx Scope Hack/Teardown/Discussion - WANTED FW1.16 PLEASE HELP US  (Read 57781 times)

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Offline posplayr

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #75 on: January 19, 2016, 09:35:19 am »
I would be wary of running AA batteries with the scope's NiCD charger as they are generally only about 2200 mA-hr v.s the C cell which is 5000 mA-hr. The C cell got a little more than lukewarm at 105 deg in a 72 degree room as per my tests) when charging in an open case Charger designed for a NiCD battery at .2C charge rate.

If you stick a 2200mA-hr AA battery (in a C adapter) in it's stead in the enclosed case of the Scope I don't know what temperature the battery will get to but it would certainly be a concern and possible thermal runaway???. Remember this a NiCD charger named "fast charge" operating on a Ni-MH. Not a good thing.

As I described before the 5000 mA-hr C cell effectively drops the "C" charge rate in 1/2 providing a substantial margin to avoid stressing and heating of the battery due the design spec of the NiCD charger for the 2800 mAmp hr NiCD C cells.
 

Offline TheSteve

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #76 on: January 19, 2016, 10:17:08 am »
We've had no issues with excess heat using 2500 mAh Eneloops cells. We only use the scopes built in charger and not the external fast charger. The factory battery was rated at 2800 mAh and was probably closer to 2000 after a few uses anyway, so I see no issue with the internal trickle charger.
VE7FM
 

Offline R_G_B_

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #77 on: January 19, 2016, 10:21:39 am »
I was trying to use AA 2500mah.

R_G_B
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Offline TheSteve

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #78 on: January 19, 2016, 10:39:01 am »
I was trying to use AA 2500mah.

R_G_B

The battery door on our THS730A will just close - but it is a tight squeeze!
VE7FM
 

Offline posplayr

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #79 on: January 19, 2016, 11:48:13 am »
We've had no issues with excess heat using 2500 mAh Eneloops cells. We only use the scopes built in charger and not the external fast charger. The factory battery was rated at 2800 mAh and was probably closer to 2000 after a few uses anyway, so I see no issue with the internal trickle charger.

OK Well that is good to know. I know some people were rationalizing the AA so they could be charged separately on a proper Ni-MH charger. I also did not know that the external charger had a faster charge rate than the internal? I would have thought the trickle phase would have been the same for either and so it would be twice as much as you would want for the NiMH without the increased capacity.

I bought a second set of C cells so for $40 I have two battery NiMH packs of 5000 mA-hr rating.
 

Offline TheSteve

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #80 on: January 19, 2016, 11:58:57 am »
Unless I somehow totally missed it the internal charger on the THS7xx series is trickle only. The external charger is a fast type charger which should use a negative delta V (peak detect) which is unsuitable and shouldn't be used for NiMH cells(they have a much smaller drop when charged).

Unless of course the charger is horribly designed and uses a timer, I haven't opened the one here.
VE7FM
 

Offline posplayr

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #81 on: January 19, 2016, 01:06:25 pm »
Unless I somehow totally missed it the internal charger on the THS7xx series is trickle only. The external charger is a fast type charger which should use a negative delta V (peak detect) which is unsuitable and shouldn't be used for NiMH cells(they have a much smaller drop when charged).

Unless of course the charger is horribly designed and uses a timer, I haven't opened the one here.

I don't know; the OP claimed to have "reverse engineer the battery charger" I assumed they meant the one inside of the scope. Using his numbers it would be charging at C/5.

Quote
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

To which I added in a prior post.

Quote
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.
« Last Edit: January 19, 2016, 01:08:18 pm by posplayr »
 

Offline HighVoltage

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #82 on: January 19, 2016, 08:24:30 pm »
I just opened my original Tektronix external charger and took some pictures.
Here you go:
 
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Offline posplayr

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #83 on: January 20, 2016, 11:38:05 am »
I just opened my original Tektronix external charger and took some pictures.
Here you go:

Looks like the one I charged the NiMH "C" cell stack with as reported above.
The little PIC controller tells me it must be "smart"  :phew:
 

Offline R_G_B_

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #84 on: January 24, 2016, 07:54:16 am »
Heres very simple mod to allow the use of eneloop 2500mah batteries:

AA to C converters two of them cut down.

Paper clip

Tape

multi strand Wire

The multi strand wire will push its-self against the cap no problems with this at all even if you give the scope a firm shake everything is a tight fit and stays in place.

R_G_B

 
« Last Edit: January 24, 2016, 07:57:00 am by R_G_B_ »
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Offline zucca

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #85 on: February 17, 2016, 07:38:31 pm »
I don't know; the OP claimed to have "reverse engineer the battery charger" I assumed they meant the one inside of the scope. Using his numbers it would be charging at C/5.

Right! I had the 12V DC External plugged in and a DC Load (BK Precision 8500) instead the battery. I was simply going up and down with the V on the DC Load and tracking down the current the internal scope charger was spitting out.

Those 5000mAh C size look sexy!

Anyway my dream is to mod the battery door into a little PCB:

- get rid of that funky OEM battery + terminal
- support for Li-Ion Cells (according to my investigation 3 cells could fit just right...)
- Leds on the outside for the State of charge
- Switch(light sensor  >:D) for the display back light (why has to go always on? that´s such a waste...)

and yes probably it would be not water splash proof anymore... I can survive with it.

I started to dig into the schematics to understad if I can mod the internal charger circuit so I have to do less circuit on the battery door.
In the not P models there is also plenty of room for another PCB above the scope middle, but holy cow I'm scared for EMI...

It´s not easy.
« Last Edit: February 17, 2016, 07:41:47 pm by zucca »
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Offline posplayr

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #86 on: March 09, 2016, 04:57:30 pm »
I don't know; the OP claimed to have "reverse engineer the battery charger" I assumed they meant the one inside of the scope. Using his numbers it would be charging at C/5.

Right! I had the 12V DC External plugged in and a DC Load (BK Precision 8500) instead the battery. I was simply going up and down with the V on the DC Load and tracking down the current the internal scope charger was spitting out.

Those 5000mAh C size look sexy!


Thanks for the confirmation on the charge rate. I have not burned my lab down yet so the 5000 mA-hr must be good right? :phew:
 

Offline zucca

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #87 on: March 09, 2016, 06:19:47 pm »
Thanks for the confirmation on the charge rate. I have not burned my lab down yet so the 5000 mA-hr must be good right? :phew:

I think so, don´t see any down side on the 5000 mAh/hr. Yea the eneloop hold the charge for very long period of time, but I think I will always charging up the scope the day before going in the field. In cases of emergencies they are not eneloop but they are not the opposite neither, so I think they will still be reasonabily charged up also after a year or so.
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Offline hibone

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #88 on: April 19, 2016, 02:51:16 am »
Dear all,

In my device, the "gentleman" who assembled the scope, left the flat flex cable of the LCD in the battery holder. As a result, the cable broke just when I needed the scope.

I suppose a replacement can be found pretty easily, but I am no expert, thus I wonder what aspects I should look for.
To me the cable appear as a 12 way 1mm pitch flat flex ribbon 9 cm long.
The pitch and the number of ways cannot change, of course, but I dunno if thickness and the length have to be the same as well.

In a printer I found a flat flex cable, 5cm long, with 50 ways or so. This cable is also a little more thick than the original. I cut out the 12 ways I needed, and put the cable in place.

Well, the screen lit on, but it remained blue without showing anything.
Now I wonder about the reason.
I dunno if the problem is due to:
- the pins that may be oxidized.
- the fact that the cable is not an original 12-way cable and the pins end out of place?
- the thickness, that may cause the cable not to touch correctly on the pins

Also, if I put on the original broken cable, and pinch it over the cut with my fingers, so that the broken ends of the cable touch, something is shown on the LCD.

Sorry for the much details. Please if you have any suggestion tell me.

PS.
Out of curiosity I "naively" asked Tektronix the spare part.
- "We are sorry but the part you request is out of production. However you can send your device for repair to our service center in Cologne." (I live in Italy)
- "How much would it cost?"
- 1k € plus shipping
 
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Offline HighVoltage

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #89 on: April 19, 2016, 03:53:05 am »
PS.
Out of curiosity I "naively" asked Tektronix the spare part.
- "We are sorry but the part you request is out of production. However you can send your device for repair to our service center in Cologne." (I live in Italy)
- "How much would it cost?"
- 1k € plus shipping
I have even heard, that when you send it to Cologne, it will be forwarded to the US for repair.

Anyhow, can you repair the cable?
Just get the insulation removed and fine solder it together?
May be you have a picture?
 
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Offline hibone

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #90 on: April 19, 2016, 05:33:19 am »
Actually, I cleaned the replacement cable with isopropyl alcohol and then everything worked just fine.

I tried to remove the insulation with fine sandpaper but it seemed quite hard not damaging the rest of it.

Honestly  I didn't feel all that comfortable about a repaired cable there. Thus I abandoned the idea.
The original cable is about 9 cm and should be folded under the lcd monitor, which has a metal shield.

A soldered joint there may have safety and reliability issues.

Hope my previous post can be of use to the forum.
Thanks anyway.


 
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Offline jcd06

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #91 on: November 16, 2016, 01:00:50 am »
Hi folks,
I've bought a secondhand THS720 lately and I found this exelent discussion while I was looking for some documentation.
I would like to be able to send screenshots to the PC and I could see here the different RG-45-to-DB9 cable pinouts discussed.
Unfortunately it's a bit unclear for me which of the pinouts is the definitive/right one.
Can someone point it out for me please?
Thanks,
Jean
 

Offline HighVoltage

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #92 on: November 16, 2016, 02:26:32 am »
Here you go for the original connector:
I made my own wire, because the original cable is sooo stiff.

RJ45   Wire Color   Function   9 pin (female)
1   (Brown)   DCD- Data Carrier Detect   7 - RTS
2   (Blue)      DSR- Data Set Ready   4 - DTR
3   (Yellow)   DTR - Data Terminal Ready    6 - DSR
4   (Green)   GND - Signal Ground   5 - GND
5   (Red)     RXD - Receive Data    3 - TXD
6   (Black)    TXD - Transmit Data   2 - RXD
7   (Orange)   CTS - Clear To Send   7 - RTS
8   (Gray)    RTS - Request To Send   1&8 - DCD/CTS

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Online TurboTom

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #93 on: November 19, 2016, 10:53:25 am »
Hacking the THS 700 series works perfectly well!  :D ...just converted a THS710A to a THS720P  :D

At 100MHz I measured a level drop of about 0.9dB. Didn't bother to measure the 3dB frequency. Also power measurements work (firmware 1.14 on mine).

If you have a 710A, just remove resistors R207, R213 and R205 (to make it a 720P) or R204 (to make it a 720A). Hacking it into a THS730A isn't easily possible since other front-end hybrids would be required among some other stuff.

Cheers,
Thomas
 
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Offline R_G_B_

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #94 on: November 19, 2016, 11:08:19 am »
Be interesting to see what each firmware does... I have a 720A firmware 1.03 I think it is. Also is there anyway to grab the latest firmware and has anyone attempted it yet?
« Last Edit: November 19, 2016, 11:10:04 am by R_G_B_ »
R_G_B
 

Online BravoV

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #95 on: November 19, 2016, 04:49:05 pm »
Hacking the THS 700 series works perfectly well!  :D ...just converted a THS710A to a THS720P  :D

At 100MHz I measured a level drop of about 0.9dB. Didn't bother to measure the 3dB frequency. Also power measurements work (firmware 1.14 on mine).

If you have a 710A, just remove resistors R207, R213 and R205 (to make it a 720P) or R204 (to make it a 720A). Hacking it into a THS730A isn't easily possible since other front-end hybrids would be required among some other stuff.

Cheers,
Thomas

Wow , thank you Thomas !  :-+

Mind share how you figure that out ? By comparing ?

I have 710A with 1.11 firmware, as R_G_B above, anyone know how to upgrade it ?
« Last Edit: November 19, 2016, 04:53:01 pm by BravoV »
 

Offline zucca

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #96 on: November 19, 2016, 05:49:00 pm »
Also is there anyway to grab the latest firmware and has anyone attempted it yet?

give me 2 more days
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Offline R_G_B_

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Re: Tektronix THS720A Portable Scope Teardown/Discussion
« Reply #97 on: November 19, 2016, 09:16:07 pm »
Hacking the THS 700 series works perfectly well!  :D ...just converted a THS710A to a THS720P  :D

At 100MHz I measured a level drop of about 0.9dB. Didn't bother to measure the 3dB frequency. Also power measurements work (firmware 1.14 on mine).

If you have a 710A, just remove resistors R207, R213 and R205 (to make it a 720P) or R204 (to make it a 720A). Hacking it into a THS730A isn't easily possible since other front-end hybrids would be required among some other stuff.

Cheers,
Thomas

Crazy the amount of money you can make on  just a couple of resistors!


Now Watch the eBay sale price on these go through the roof.


I remember the fluke 120 series you could buy a used one on eBay around 100 pounds. Forget that now they go for up to £600 for a 123 and around a £1000 now for a fluke 124 or 125. Insane!
« Last Edit: November 19, 2016, 09:24:56 pm by R_G_B_ »
R_G_B
 

Offline HighVoltage

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Re: Tektronix THS720A Portable Scope Hack/Teardown/Discussion
« Reply #98 on: November 19, 2016, 09:46:34 pm »
TurboTom
That hack is great.
I have a few "none P" versions and will try it out.
Thanks so much
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Online BravoV

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Re: Tektronix THS720A Portable Scope Hack/Teardown/Discussion
« Reply #99 on: November 19, 2016, 10:01:54 pm »
TurboTom
That hack is great.
I have a few "none P" versions and will try it out.
Thanks so much

HighVoltage, please, if its not too troublesome, do photos documentation and share it here, preferably before and after the mod.

I believe this mod will attract many of this Tek THS7x0x owners.  :-+

 :popcorn:
 


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