Products > Test Equipment
Keithley 2000+2015 THD
<< < (3/6) > >>
muvideo:
I didnt find info, it seem a resistor network, could it be
purpose built (or simply marked) just for keithley?
Do they sell spares, or you are forced to go to a repair centre?
Maybe the cost from keithley is not too high.

Fabio.

P.S. I didnt forgot about the roms :)
costas:

--- Quote from: muvideo on October 06, 2012, 05:52:07 pm ---I didnt find info, it seem a resistor network, could it be
purpose built (or simply marked) just for keithley?
Do they sell spares, or you are forced to go to a repair centre?
Maybe the cost from keithley is not too high.

Fabio.

P.S. I didnt forgot about the roms :)

--- End quote ---

Hello Fabio ,
Unfortunately I have none of recommended possibilities
Last Monday I sent out PCB's , probably next couple weeks will get it

WBR
Costas
costas:
Today I started very determined to try again solving TF245 problem,  I desolder  again good IC and did all the measurements possible with ohmmeter. its internal schema I do hope is correct and complete although I did not see any logic in the resistance arrangement, maybe someone has seen such a network of resistance and find an equivalent. Compared with a good IC , I found resistances 9K and 1k interrupted from terminal 9 and resistance of 27.5 k of pins 10-12. ExperimentaI l soldered the respective IC pins external resistance 0.4w 5% 1k, 9.1k, 27k, then I ran the checking test and surprise all errors are gone (Before running up test should expect to better cool the area where I did tinning)
Course is only a makeshift solution using ordinary low precision resistance. .. the idea would be to find an  equivalent for TF245 ,  but …after my schematics I do not think is possible
WBR
Costas
muvideo:
Pins 6,7,8,9 seem a voltage divider with 1:10:100 ratio.
As for 1->4 13->16 are that measured values or how
you imagine the resistors connected inside?
I think that there are many possible arrangements
for inner resistors for that part of the network.
Also, are you sure you are measuring resistances only and
not some semi junctions around?
You can test some of the values at different voltages to see
if the current is proportional to voltage to be sure.

Fabio.
costas:
TF245A's scheme represents measurements performed by me between IC pins and no resistance positions, I made another set of measurements (scheme "C") between pin 16 – common - and pin 1, 2, 3, 4, 15, 14.13. Comparing measurements the scheme "A" and the scheme of "C" resulting scheme "B" that corresponds to the positions and value  of the resistance . If somebody  have a different opinion please tell us .

WBR
Costas
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod