Electronics > Repair
Repair : HP 3245A precision DC/AC source
TheSteve:
Front panel connector loose? This rivals my last ebay score - HP network analyzer that was sold as dead, was a dirty 110/220 VAC switch.
Vgkid:
Thanks for the teardown. I assumed that it would bear some resemblance to the 34401A, but nope.
TiN:
Why 34401? This beast does not even have ADC :)
Article with more photos and details
As you can get hints from article, I plan to do some modifications and tweaks, such as replacing voltage reference with LTZ1000 module and adding lower gain output boards, so I could generate accurate low-noise millivolts/microvolts. There are two open BNC openings in front panel face, so I can install triax connectors for extra outputs. :-X
Vgkid:
Prices(1988 catalog pg 430) $4200 base, 2500 2nd channel, 400 waveform software option, option 002 is not in this edition.
lukier:
Hi TiN,
if in the future you'll be playing more with 3245A internals, would you mind probing XMSP/XMSN and XSLP/XLSN signals? I'm curious what is the scheme employed there, PWM or pulse density, what PWM frequencies (as we have 200 Hz and 194 Hz low pass filters), center aligned and complementary PWMs or what.
I'm analyzing their PWM DAC circuit and it is a bit cryptic due to the sheer number of analog switches involved in all the modes (and probably selftests). In HiRes scenario LSB PWM is connected with the MSB via RP100A resistors ?, then through low pass filter, but the LSB has its own path and LPF as well and both of them can be switched to the common DAC output. In these scenario the HS DAC seems to provide DC offset. In high speed scenario the LSB+MSB DAC seems to provide DC offset (called vernier)?
Very interesting device indeed. Maybe with HV option and LTZ1000 it could as well replace these bulky EDC voltage/current standards.
What INL can one expect from such PWM DAC? Linearity is not specified in the 3245A datasheet AFAIR, but if they say it is 6.5 digit I would assume 1 ppm.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version