Tektronix THM56x Portable Scope Hack/Teardown/Discussion

[JWag]

I've been watching that dodgy eBay 565 for a while, hoping the seller does a Best Offer or something.

Does anyone have schematics of the PS, or understand what fails? We seem to be able to get schematics of every other Tekyronix scope, just not these.  Barring that, would anyone in the states be willing to pull the glass from the ET2020 and transplant it to my working 565? I really want the automotive features of the 2020. Obviously , you could copy the firmware for others to use.

There aren't any PS schematics I'm aware of, but it's not tremendously complex, especially if you have a working one to compare against. It is mostly two LTC1174s generating the positive and negative rail voltages for the whole device, plus a small LDO generating 5V for the Real Time Clock and SRAM.

I'd be up for doing a transplant (or maybe repair). The SMT on this is pretty easy to work with, and I didn't have any trouble removing the flash IC from mine. Plus, I have replacement caps for your RMS converter circuit, which (if hardcoreman and I are any indication) are probably leaking electrolyte. I'd love to have another 565 firmware to compare against.

[jal1234]

I've been watching that dodgy eBay 565 for a while, hoping the seller does a Best Offer or something.

Does anyone have schematics of the PS, or understand what fails? We seem to be able to get schematics of every other Tekyronix scope, just not these.  Barring that, would anyone in the states be willing to pull the glass from the ET2020 and transplant it to my working 565? I really want the automotive features of the 2020. Obviously , you could copy the firmware for others to use.

There aren't any PS schematics I'm aware of, but it's not tremendously complex, especially if you have a working one to compare against. It is mostly two LTC1174s generating the positive and negative rail voltages for the whole device, plus a small LDO generating 5V for the Real Time Clock and SRAM.

I'd be up for doing a transplant (or maybe repair). The SMT on this is pretty easy to work with, and I didn't have any trouble removing the flash IC from mine. Plus, I have replacement caps for your RMS converter circuit, which (if hardcoreman and I are any indication) are probably leaking electrolyte. I'd love to have another 565 firmware to compare against.

I'll send you a PM.

Thanks!

Jon

[hardcoreman]

565 flash is normaly working in 560   big sram and rtc installed

and in my 560 v1.0, i unlocked 565 features. just made copy of config area from 565 image to 560...

[JWag]

jal1234's meters have arrived. Here's the first dump, from the MAC ET-2020 (also known as the THM571). Note that this one is 256kB.

I have some ideas about its power supply failure. I think I'll make a repair thread about it.

[JWag]

jal1234's THM565 firmware is attached.

Despite having the same text on the sticker as my unit, they are significantly different. The firmware I posted earlier from my 565 has "VERSION 2.00" inside. The firmware attached here from jal1234's 565 is "VERSION 1.03". Obviously they were both updated at some point in their history?

[jal1234]

Interesting that the 2020 flash is larger than the 565. Probably all of the pre-set guided tests and templates for automotive use vs. general use. At least that's my theory!

[jal1234]

jal1234's THM565 firmware is attached.

Despite having the same text on the sticker as my unit, they are significantly different. The firmware I posted earlier from my 565 has "VERSION 2.00" inside. The firmware attached here from jal1234's 565 is "VERSION 1.03". Obviously they were both updated at some point in their history?

What's the build date on your hardware vs. mine? I think it's on the sticker on the back of the units.

[JWag]

What's the build date on your hardware vs. mine? I think it's on the sticker on the back of the units.

My 565 is dated April 1995, yours is April 1994. Your ET-2020 is dated May 1994.

[jal1234]

What's the build date on your hardware vs. mine? I think it's on the sticker on the back of the units.

My 565 is dated April 1995, yours is April 1994. Your ET-2020 is dated May 1994.

Thanks. Is there someway to upgrade my firmware to your newer version, but keep my calibration info? Tektronix is lousy at letting people know what is included in newer versions of firmware, but I assume it's bug fixes. Interesting that the flash labels stayed the same. They must have updated them as they went out the door.

[hardcoreman]

newest fw in this topic is v2.0

in v2.0 calibration is 0x19A00

in v1.x calibratioin is 0x1F000

simple copy is working.


in 571 , hm i think there is way to switch it to 565 (560,550) mode...

[hardcoreman]

https://www.tek.com/oscilloscope/thm5u02

firmware update module, to version 2.0

so it looks 2.0 is last version

[jal1234]

https://www.tek.com/oscilloscope/thm5u02

firmware update module, to version 2.0

so it looks 2.0 is last version

I wonder what the significance of thm5u02 is? How did you find this under that designation? Never heard of it before.

[hardcoreman]

i found it when i looking for info about calibration. i think it was a module which plug in expansion connector and then make flash update... flash update is only possible with ext. vpp source applied.

[JWag]

Thanks to jal1234, I have a second ET-2020 to tinker with. This time, it has version 1.03 firmware on an AMD AM28F020 flash.

The bare PCB is newer than my original '565, but it's had a harder life. That's a bonus, since I don't feel any anxiety about stripping it down further. I hope to publish a reverse-engineered schematic of the PSU section eventually.

[jal1234]

There is a brand new YouTube video on repairing the power supply on these, published Sept 2, 2019. Basically, the 4 electrolytic caps leak electrolyte, which flows under various parts, shorting the regulators, taking one or both out. Enjoy!
https://youtu.be/NGWSTz83dHw

Jon

[mrprecision]

Two years ago, I wrote a software for my THS720P for grabbing the image from the scope and copy it to the clipboard, save it to a BMP file or print it. It should work with all devices out of this family. The interface allows all the functions of the device. I have only used the interface to setup the hard copy function and to trigger the hard copy function from remote.

Have a try: https://www.schaeck.eu/download/?dir=THS7XX%20HardCopy

[reheld]

THM565 and THM571 are lame. They will never reach the THM575 


This unit also has an bad LTC regulator. It is AVL branded. AVL is an big austrian company at the automotive sector, they do nearly everything including engine development.

[reheld]

Was able to fix my unit, at the search for a new battery i‘ve found another branded Tekmeter, it was sold in black and silver as Textron Tempo Greenlee TS90 with custom firmware for telephone cable testing.

http://tedevco.com/wp-content/uploads/2016/10/MA5770-TS90-Data-Sheet.pdf