[SOLVED]Datron Wavetek 4800 current output doesn't work

[Zermalmer]

Hi everyone,

I'm new to this forum... I find it during my search for informations about a Time Electronics calibrator.

I'm after long time of non electronic job back in electronics and have to learn again a lot of things.

Now to the problem:
I have a problem with a Datron Wavetek 4800.
The current output in all ranges go immediately to overload.
I'm nearly sure that I didn't overload it at any time.
Only thing was, that it was transported before the failure, so assumed a connector slipped off, but I didn't find anything (no obvious fuse, no slipped off connector, cards plugged again).
I would be very glad if someone can give me a hint where I can check or have to search to get the current output get back to work.

Thanks in advance for any hints.

Best regards
Andreas

[pelule]

I unfortunately don't have the 4800, even I am searching for one long time already.

This doc may help:
http://www.ko4bb.com/manuals/92.211.4.78/Wavetek_4800_4805_4808_Multifunction_Calibrators_Users_HandBook.pdf

Also this site may offer some tips, even it is related to the 4910
https://xdevs.com/fix/d4910/

BR
PeLuLe

[Zermalmer]

Thanks PeLuLe.
The Handbook I already have but unfortunatly it doesn't contain hints for troubleshooting for this cases.
There are general descriptions in it for, but no detailed things.

The 4910 isn't comparable with the 4800 in my opinion...
At first it is a DC voltage device... the 4800 is a calibrator for more than that.
Also the construction is absolutly different.

[ManateeMafia]

Andreas,

Isn't there a self-test function on the 4800? Maybe an error code can be generated that may apply to the the 4700 or 4000A. I don't think the designs were too dissimilar.

Also, on the 4700 and 4000A, many parts are socketed. I would look at the current/ohms assembly for obvious parts that may have unseated themselves.

Look here    https://doc.xdevs.com/doc/Datron/4708/DATRON-4708-CH-SH%20c20030307%20%5B590%5D.pdf     for the 4708 calibration/service manual. Quality is not the best, but it could still be useful.

[ap]

Unfortunatelly the 4800 is pretty complex and you will need to go into the schematics and analyze. Many different internal part malfunctions can cause this behaviour.
Where in Germany are you located?

[Zermalmer]

Andreas,

Isn't there a self-test function on the 4800? Maybe an error code can be generated that may apply to the the 4700 or 4000A. I don't think the designs were too dissimilar.

Also, on the 4700 and 4000A, many parts are socketed. I would look at the current/ohms assembly for obvious parts that may have unseated themselves.

The 4800 have selftest, but it end with "PASS" 
So I think it is somewhere located outside of the logic of the selftest, because selftest can't check if the physical connection to the output itself.

[Zermalmer]

Where in Germany are you located?

Hi ap,
I'm right at the middle... near Frankfurt (Main).

Unfortunatelly the 4800 is pretty complex and you will need to go into the schematics and analyze. Many different internal part malfunctions can cause this behaviour.

Unfortunatly the schematics for this device are look like to be rare...

[ap]

I may be wrong but the schematics of the 4808 should be helpfull (i.e. very similar; I only have 4808 schematics and no 4800). They should be available online.
The roblem seems to be in the current amplifier output stage so no error occurs. Still, lots of parts involved (at least with the 4808)

[TiN]

I have maybe stupid question, but did you check output current when you try to source any current?
What does ammeter read?

Since selftest passes, it should be something in output driver PA in between DAC output and output terminals.

[Zermalmer]

I have maybe stupid question, but did you check output current when you try to source any current?
What does ammeter read?

Since selftest passes, it should be something in output driver PA in between DAC output and output terminals.

The output do absolute nothing to the plugs...
Even try to output uA instantly bring display to Overload, which is only normal when nothing is connected to the plugs.
I tried also a analog ohmgaug, but this also didn't bring any 'swing' to the needle.

I could try to 'track' the terminals to the mainboard and try to determine which way the wires are going and then go to the bus structure and lead to which board aso., but the place to do this in a 4800 is ...ehm a little bit tight.
And without circuit it is more difficult, because I only have some minor general clues which board is doing what out of the user manual.

I tried to find the schematics of 4808, which ap mentioned, because this model is mentioned with the 4800 in the user handbook, but so far without success.

[ap]

Unfortunatelly copying it is not an option, it is big and has folded sides, so having that done will cost a fortune, you easier buy one from a manuals vendor.

[Zermalmer]

Unfortunatelly copying it is not an option, it is big and has folded sides, so having that done will cost a fortune, you easier buy one from a manuals vendor.

ehm...at first I have to find one... copy or scan is the smaller problem (if only A4 is available then some additional work is necessary, right)... to get one (even for copy) is the bigger problem in my opinion.

Actually I only find always the same sources with the user handbook, which I already have.
I also find here and there manual sites with references, but looking closer bring nothing clear to front because this stupid search add searchengines always place the keywords without having a result.

[lowimpedance]

 At work there are three 4800's, (one 4808 which has fried output amps), and I did find the power supply modules had dried out caps possibly from poor air flow due blocked air filters etc. and in the case of the fried 4808 the bad power supply was most probably the cause of its "very smokey" death.
 Sorry I do not have any schemattics either or have found a source for such yet. One thing comes to mind is that there are some fuses on the base motherboard just behind the ouptut module set, (somewhat obscured from veiw), are these still good?.

[Mickle T.]

Find the difference:

[Zermalmer]

One thing comes to mind is that there are some fuses on the base motherboard just behind the ouptut module set, (somewhat obscured from veiw), are these still good?.

Reffering to the 2nd picture of Mickle T.
I only find obviouse the fuses on the modules in the upper left corner. (they are all ok)
Are there some more hidden ones?

[Mickle T.]

You can download the 470x Service Manual and find all other fuses.

[Zermalmer]

Thanks Mickle T. and all others
it's looking scary identical... so I give it a try to find remaining fuses and maybe blown caps aso.

[lowimpedance]

OHH that is an interesting side by side comparison, thankyou for that Mickle T.
The supply PCB's to the left of the 'big transformer' had some bad radial electrolytics on two of the three units at work.
The other 'glass fuses' from my scratchy memory are just behind the output stage block which is in the top right side of the picture.
(I could be wrong though  )

[dacman]

Please don't take this wrong but are you using the I+ and I- terminals?

[Zermalmer]

Please don't take this wrong but are you using the I+ and I- terminals?

Don't know exactly if you replay to me or one of the others.

Yes, I use the main I+ / I- terminals, BUT only for small current.
I have also a 4600 to "drive" bigger current.

Or may this info give a hint for searching on the problem?

[Zermalmer]

OHH that is an interesting side by side comparison, thankyou for that Mickle T.
The supply PCB's to the left of the 'big transformer' had some bad radial electrolytics on two of the three units at work.
The other 'glass fuses' from my scratchy memory are just behind the output stage block which is in the top right side of the picture.
(I could be wrong though  )

You right, downbelow on mainboard are also 2 fuses.
In my case this two are also ok.

I started to search in the service handbook and find the first hints for my fault case.
Depending on work I maybe can check the referenced sections to get closer to the problem.

[quarks]

Unfortunately I missed this until now.
Is the problem fixed?

[Zermalmer]

Unfortunately I missed this until now.
Is the problem fixed?

Hi quarks,
yesterday I had time to have a closer look to the service manual and located the problem.

So here are the solution for my problem:

Hello everybody,

I first want to thank you all for the hint to the service manual and your attention.

The quality of the manual isn't the best, but the needed parts for current is good to read.
("ERROR OL" troubleshooting is on page 60)

I study the board layout and circuit for the current/ohm assembly (page 372 to page 377).

There I find 4 fuses... F2 to F5.
I crosschecked it with my real board of the 4800 and yes...there are the 4 fuses soldered to the board.

On page 256 is a diagram of the routing for the current/ohms assembly

(Picture 1 in attachment)

Fuse F5 is the main fuse for the "I Drive" output of the board to the PCB bus.

I check the fuses and detected that F2 to F4 are ok, but F5 is open.

I replaced it now temporarily with another fuse (I try to catch an original one)
and now the 4800 is back on work in its entirety

To complete the information I attach also a picture of the real board and location of the fuses and the values of the fuses from the manual.

(Picture 2 in attachment)
(Picture 3 in attachment 4800 I/Ohm Board fuses)

Selftest doesn't cover this fuse...the selftest finish with "PASS" even the fuse F5 is blown.

Btw. on page 64 is a complete list of ALL fuses of the device and where they are located.
Crosscheck with partlist and real fuse to be sure of the value.

(all page numbers are pagenumbers of adobereader, because not all handbook pagenumbers are included or good to read)

Best regards
Andreas

[quarks]

Great and thanks for the update

[TiN]

Good job, one more happy 4800 is saved.

Also did I miss something, or you have electronic service manual for it? Perhaps we can host it so others can enjoy it?