Author Topic: EEVblog #540 - HP35670A DSA Repair - Part 4  (Read 20306 times)

0 Members and 1 Guest are viewing this topic.

Offline olafnew

  • Newbie
  • Posts: 3
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #25 on: March 20, 2014, 07:20:36 am »
I'd try changing that buffer, the LM6321, it does look suspicious - and it surely may be one of the key rpoblems for the output not working. Especially given, that you do have the nifty desoldering gun - desoldering dip 8 is surely quick and easy ;)
 

Offline mpep

  • Newbie
  • Posts: 3
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #26 on: March 20, 2014, 12:43:41 pm »
Just my opinion, but seeing as both the AC section of the power supply is damaged, and you've found voltage regulators damaged, I suspect that maybe Lightning Strike is the primary cause.

Good luck with trying to fault find, but as you've stated, most likely BER.
 

Offline Elandril

  • Contributor
  • Posts: 18
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #27 on: March 20, 2014, 07:31:28 pm »
I was wondering if I missed something in the other repair videos, but I distinctly remember that there was some I2C communication problem previously. Did this problem clear up, after fixing the voltage rails? If not, then there is still a problem on the digital side of things...

I also concur with what was previously stated for the -15v voltage regulator, which seemed much hotter than it's two companions.
 

Online EEVblog

  • Administrator
  • *****
  • Posts: 26643
  • Country: au
    • EEVblog
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #28 on: March 20, 2014, 10:45:46 pm »
Dave's done this thermal imaging trick for other problematic boards in the past (was it a Lecroy scope?), but I don't remember it ever working!

Maybe not in my videos, but I've used it countless times to find faulty parts.
Checking chip temps is a very standard troubleshooting technique.
 

Online EEVblog

  • Administrator
  • *****
  • Posts: 26643
  • Country: au
    • EEVblog
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #29 on: March 20, 2014, 10:47:28 pm »
So much for the schematic. My request has been turned down at the highest levels of the Agilent mothership.  :(
 

Offline BMac

  • Contributor
  • Posts: 43
  • Country: us
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #30 on: March 21, 2014, 04:30:43 am »
Is this still a supported product?
 

Offline pickle9000

  • Super Contributor
  • ***
  • Posts: 2132
  • Country: ca
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #31 on: March 21, 2014, 04:49:11 am »
Dave's done this thermal imaging trick for other problematic boards in the past (was it a Lecroy scope?), but I don't remember it ever working!

Maybe not in my videos, but I've used it countless times to find faulty parts.
Checking chip temps is a very standard troubleshooting technique.

As is freeze spray.
 

Online vaualbus

  • Frequent Contributor
  • **
  • Posts: 294
  • Country: it
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #32 on: March 21, 2014, 05:10:12 am »
So much for the schematic. My request has been turned down at the highest levels of the Agilent mothership.  :(

Really that guy on the forum seem to be favorable for the schematics.
Despite that next you could check the resistence beetweeen the -15 to gnd. Of course somethingh is wronf otherwise why the -15 is hotter?
So eventually some op amp could be shorted .
After I will try to inject a signal in the board and follow the signal path till you found where, If, it stop.
 

Offline Len

  • Frequent Contributor
  • **
  • Posts: 515
  • Country: ca
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #33 on: March 21, 2014, 05:33:43 am »
So much for the schematic. My request has been turned down at the highest levels of the Agilent mothership.  :(
"And by the way, our name is Keysight!" >:(
 

Offline RupertGo

  • Regular Contributor
  • *
  • Posts: 77
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #34 on: March 21, 2014, 07:12:19 am »
I was being facetious about using thermal testing to find broken components - have singed my fingers many times doing just that...

The ability of manufacturers to withhold servicing information is iniquitous, and illegal in the automotive market in the UK and US. Efforts to create a similar "right to repair" directive for all electronic goods haven't come to anything in the EU (at least, as far as I know), but the fight goes on.

 

Offline vlad777

  • Frequent Contributor
  • **
  • Posts: 283
  • Country: 00
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #35 on: March 21, 2014, 01:05:18 pm »

You should suck all them op amps. They suck really nice with a desoldering gun.
Make a schmitt trigger arrangement on a breadboard and test them one by one.
Make it a batch process.

I really want to see it fixed.
Mind over matter. Pain over mind. Boss over pain.
-------------------------
 

Offline han

  • Frequent Contributor
  • **
  • Posts: 308
  • Country: 00
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #36 on: March 21, 2014, 03:54:16 pm »
Thermal camera is great when troubleshooting high power device, like in industrial environment
but when used in low power board is useless
The only time the thermal camera is useful is when detecting intermittent problem.
It is difficult detecting functional fault without have comparison..
the only thing can detected by thermal camera without comparison is shorted fault component in VCC and GND , and it can easily detected using ohmmeter

 

Offline Kilroy

  • Regular Contributor
  • *
  • Posts: 85
  • Country: ca
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #37 on: March 21, 2014, 05:14:11 pm »
Given that this is a power supply failure I would tend to suspect any op amps on power rails to be highly susceptable candidates for failure. Usually, I would just go hard core....suck them out with a Hakko 808, stick them on an unpowered bread board, and compare them relative to a known good component. You feel like a complete hack when trouble shooting in this way, but it is often the quickest way to completely factor out a large number of possible and plausible failure modes.

With a Hakko 808...roughly 15 seconds to remove an 8 pin chip...about 4 chips in a minute...around 5 minutes or so for 20 chips. Pretty efficient use of time, really.

The fool generalizes the particular; the nerd particularizes the general; some do both; and the wise does neither.
 

Offline januszb

  • Newbie
  • Posts: 2
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #38 on: March 21, 2014, 11:40:54 pm »
There was an very interesting lead in this post:
  http://www.eevblog.com/forum/blog/eevblog-540-hp35670a-dsa-repair-part-3/msg318593/#msg318593
a followup to rs20's find:
  http://www.eevblog.com/forum/blog/eevblog-540-hp35670a-dsa-repair-part-3/msg318114/#msg318114
which gave an explanation for signal observed.
Could be an interesting starting point for investigation, maybe by probing the pins on the DAC as the digital input is probably fine and working the way from there.

Keep up these videos Dave, they're great and very educational (and with this particular one there is a certain element of suspense!)

 

Offline max666

  • Frequent Contributor
  • **
  • Posts: 367
  • Country: at
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #39 on: March 27, 2014, 12:15:08 pm »
Please continue trying to fix this puppy, Dave.
Even if it turns out irreparable in the end, like the Lecroy scope. I just love this failure hunting videos. 

How do they say? "The journey is the reward!"
« Last Edit: March 27, 2014, 12:21:40 pm by max666 »
 

Offline Agent24

  • Regular Contributor
  • *
  • Posts: 101
  • Country: nz
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #40 on: March 28, 2014, 03:16:10 pm »
With a Hakko 808...roughly 15 seconds to remove an 8 pin chip...about 4 chips in a minute...around 5 minutes or so for 20 chips. Pretty efficient use of time, really.

Couldn't agree more, when I got a desoldering gun it was night and day.. the old manual sucker gets hardly any use any more, besides, with PTH you basically *need* a proper desoldering tool unless you want to f**k around with braid all day.
 

Offline ckm

  • Contributor
  • Posts: 25
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #41 on: May 31, 2014, 08:05:46 am »
So much for the schematic. My request has been turned down at the highest levels of the Agilent mothership.  :(

The only conclusion to draw from this is that, if you are in the market for a DSA, you are far better off buying an older used one where the schematics are available unless there is a specific use-case for the capabilities of a new unit.  Or even keeping older units in working order....

That's what I'll be telling my clients when they ask.  Given their current cost-cutting affinity, I'm sure they will be very happy to hear this.
 

Offline TheRuler8510

  • Regular Contributor
  • *
  • Posts: 176
  • Country: us
  • RF Engineer
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #42 on: June 20, 2014, 12:40:24 pm »

Hey--whatever happen to this project? Is it just on the back burner?

Will we see another update?

I'd love to see a resolution... :-BROKE
"There are no facts, only interpretations."
--Friederich Nietzsche
 

Offline ziggyfish

  • Regular Contributor
  • *
  • Posts: 97
  • Country: au
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #43 on: August 30, 2014, 04:21:42 pm »
Looking around, you have tested LP4, but you haven't tested TP6 LPF2. If this is ok, then you can be 100% sure that the FPGA is working as it should. This is because LP6 is actually on one of the FPGA outputs (page 8-27 on service manual).

If its not ok, then then you know its the programmable low pass filter.

To narrow it down even test TP7 (Atenuator DAC) and TP3(DC offset DAC), and if that is ok, then test TP9, this should be the final output of the source. And if that looks ok, you know its between TP8 and TP9.

The other thing I found was the A5 board is actually part 35670-66505, so maybe that is useful for someone to find the schematic for the board.

The other thing that may help find the schematic is to look at the 35660 service manual (maybe they use the same design in both models).
 

Online vaualbus

  • Frequent Contributor
  • **
  • Posts: 294
  • Country: it
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #44 on: January 14, 2015, 03:03:24 am »
Hi dave you will continue with the series?
Can you post here the op amp names on the forum so some could send you the op amp as mailbag!
Wish to have another video, they are so interesting.
 

Offline Quarlo Klobrigney

  • Frequent Contributor
  • **
  • Posts: 355
  • Country: pt
  • Mild Mannered Time Traveller... Stuck In Forward
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #45 on: June 10, 2015, 07:27:20 am »
Not sure if it had been cross referenced yet, but that Raytheon part is a TRW TDC1001, ADC, 18 pins and all. Use your favourite datasheet search engine. At least some data will help including the parallel interface that the ADC chip apparently uses.
Voltage, does not flow, nor does it go.
 

Offline Towger

  • Super Contributor
  • ***
  • Posts: 1345
  • Country: ie
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #46 on: June 10, 2015, 08:34:15 am »
Come on Dave, time to send the patent to Dr. Shahriar...
 

Online EEVblog

  • Administrator
  • *****
  • Posts: 26643
  • Country: au
    • EEVblog
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #47 on: June 10, 2015, 08:38:30 am »
Shahriar would just waste his time like I have
 

Offline c4757p

  • Super Contributor
  • ***
  • Posts: 7805
  • Country: us
  • adieu
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #48 on: June 10, 2015, 08:41:00 am »
It's pining for the fjords, needs to be let go. Nobody's going to have half a chance at repairing this without schematics, and even with schematics it's likely that it has a lot of dead bits.

Thing just doesn't have any magic smoke left, and I doubt Dave has one of these.
No longer active here - try the IRC channel if you just can't be without me :)
 

Offline Quarlo Klobrigney

  • Frequent Contributor
  • **
  • Posts: 355
  • Country: pt
  • Mild Mannered Time Traveller... Stuck In Forward
Re: EEVblog #540 - HP35670A DSA Repair - Part 4
« Reply #49 on: June 10, 2015, 10:52:27 am »
After reading this "35670A schematics are proprietary - we cannot share them" Well kiss my ass Keyshite.

Dave, I have done similar to this board and worse without schematics. Can't you just remove and replace all the op-amps and try to see if it works? Surely they can't be that expensive. A vacuum desolder station helps rather than solder-wick. As far as the ASIC/CPLD well you're of course SOL. The ADC-DAC IC's I don't know about them as far as price.
I have a Spectrum Analyser from HP. I can't upgrade the firmware (fixes & features) for the same reason.

 :--Screw them that would offer no support and then orphan the user. No one wants to replicate their ancient technology to make money from it anyway. Shame indeed. Goodbye HP-Agilent-Keyshite or whoever you are today, and hello disposable, hackable China. And you wonder why your going out of business.
Voltage, does not flow, nor does it go.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf