Datron/Wavetek 4910 restoration

[nikonoid]

I am just starting a restoration for Datron 4910.



The unit is from 1993 or 1994. It looks fairly clean on the inside but has some electrical fire smell to it, so I have not tried to power it up yet.




Right now I am on a search for a service manual and also a source for replacement SLA batteries.
Can someone help me there?

My unit came with 15 original 6V 2Ah batteries that are completely dead. It is very hard to find replacements on the same size. Worse come to worse I can rebuild the battery compartment to accommodate different batteries, but would prefer not to do that if possible.

I am planning to document the restoration process here.

[CalMachine]

Very nice!!!  I'm excited to see this 

Here are the batteries you will need.  There might be cheaper ones around, but it's what I picked up for our 4911 and will get for my own 4911, in the near future.

https://www.mouser.com/ProductDetail/Power-Sonic/PS-621F1/?qs=sGAEpiMZZMso%252bSMtTqBO3073LIrlST7LWiXQ%252beQmRkk%3D


I am also in search of the service manual

[nikonoid]

Thank you very much, CM. I will give them a shot.

The size is a little bit smaller than original and placement of contacts is different. Did you have to mount them on their side?

[TiN]

This will be interesting, new Quad LTZ bonanza
I don't have much info on 491x, just the shameless plug of MM's work.

[nikonoid]

That is an excellent article. I actually read it few hours ago. That article is literally the first thing that comes up in google when searching for Datron 4910.

Thanks MM!

[ap]

It is strongly recommended to replace all Tantalum caps, those started to blow up on mine one after the other, so I changed them all.

[quarks]

very nice, thanks for sharing

about the batteries, afaik they are from Powersonic
http://www.power-sonic.com
so you can ask them for a replacement type

[ManateeMafia]

There are some additional pics that didn't make it into the article.

I found a bad regulator that was hidden below the pcb with the row of 15-pin connectors.

I will see if my editor ever got them and maybe post a few to the article. 

[Dr. Frank]

Would you mind to determine the oven set point & temperature of each of the LTZ modules?

Although there exists a roughly measured schematic reproduction of the VISHAY resistor array, I doubt that it is fully correct, as probably being measured 'in circuit'.

The divider ratio can best be determined by a voltage measurement on the - input of the LT1013, and the real temperature by fast monitoring of the BE diode of the reference during warming up.

Thanks.
Frank

[CalMachine]

Thank you very much, CM. I will give them a shot.

The size is a little bit smaller than original and placement of contacts is different. Did you have to mount them on their side?

Yeah the sizing isn't exactly the same.  This size is what was included with the unit when it was purchased, and they all needed to be replaced, so I just ordered the direct replacements.  One of the thermistors that monitors the temperatures of the battery banks had to be replaced, as well.

https://pasteboard.co/HizvlUj.jpg
https://pasteboard.co/HizvV1f.jpg

[nikonoid]

Would you mind to determine the oven set point & temperature of each of the LTZ modules?

Although there exists a roughly measured schematic reproduction of the VISHAY resistor array, I doubt that is fully correct, as probably being measured 'in circuit'.

The divider ratio can best be determined by a voltage measurement on the - input of the LT1013, and the real temperature by fast monitoring of the BE diode of the reference during warming up.

Thanks.
Frank

Dr. Frank, I can definitely do the measurements, once I get the beast working. I have a feeling that it had not been on for at least 10 years.

I will PM you for details on measurements.

[nikonoid]

Thank you very much, CM. I will give them a shot.

The size is a little bit smaller than original and placement of contacts is different. Did you have to mount them on their side?

Yeah the sizing isn't exactly the same.  This size is what was included with the unit when it was purchased, and they all needed to be replaced, so I just ordered the direct replacements.  One of the thermistors that monitors the temperatures of the battery banks had to be replaced, as well.

https://pasteboard.co/HizvlUj.jpg
https://pasteboard.co/HizvV1f.jpg

CalMachine, I just ordered Power Sonics. One of you pictures look like an acid damage to the connector. Scary! 

I am a little bit concerned about putting foam in between batteries, as it will trap the heat. I am considering making thin rubber rings outside of each battery to build it up to the size of original batteries.

Strangely in my unit not only two ribbon cables were disconnected but also each of battery banks was disconnected at a thermistor and clip held in place with tape. Someone really prepped the unit for long term storage.

Guys, thank you for suggestions. My next step is to disassemble and inspect all boards while I am waiting for batteries.

[CalMachine]

Thank you very much, CM. I will give them a shot.

The size is a little bit smaller than original and placement of contacts is different. Did you have to mount them on their side?

Yeah the sizing isn't exactly the same.  This size is what was included with the unit when it was purchased, and they all needed to be replaced, so I just ordered the direct replacements.  One of the thermistors that monitors the temperatures of the battery banks had to be replaced, as well.

https://pasteboard.co/HizvlUj.jpg
https://pasteboard.co/HizvV1f.jpg

CalMachine, I just ordered Power Sonics. One of you pictures look like an acid damage to the connector. Scary! 

I am a little bit concerned about putting foam in between batteries, as it will trap the heat. I am considering making thin rubber rings outside of each battery to build it up to the size of original batteries.

Strangely in my unit not only two ribbon cables were disconnected but also each of battery banks was disconnected at a thermistor and clip held in place with tape. Someone really prepped the unit for long term storage.

Guys, thank you for suggestions. My next step is to disassemble and inspect all boards while I am waiting for batteries.

Unfortunately our 4911 didn't come with the black plastic battery separator below the metal top, so I had to figure out a way to keep the batteries from moving around too much.  You're right about the extra heat, and something that I was contemplating.  hopefully, the thermistors will compensate the battery supply voltage properly as the temperature fluctuates. 

I just got the idea to 3d scanning/printing up the one in our 4910, so I can remove the foam in the 4911

[nikonoid]

That is a great idea with 3D printing, CalMachine!
The file can even be customized to fit PS-621 batteries perfectly.

[CalMachine]

That is a great idea with 3D printing, CalMachine!
The file can even be customized to fit PS-621 batteries perfectly.

Very much so!  Looks like I've got another project on my hands as well

[quarks]

Would you mind to determine the oven set point & temperature of each of the LTZ modules?

Although there exists a roughly measured schematic reproduction of the VISHAY resistor array, I doubt that it is fully correct, as probably being measured 'in circuit'.

I guess I already posted what you are looking for, have a look here

https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg273274/#msg273274

[Pipelie]

Would you mind to determine the oven set point & temperature of each of the LTZ modules?

Although there exists a roughly measured schematic reproduction of the VISHAY resistor array, I doubt that it is fully correct, as probably being measured 'in circuit'.

I guess I already posted what you are looking for, have a look here

https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg273274/#msg273274

I removed and measured the vishay 315532  six years ago.
and here is the result:

there are at least five resistors in the TO-CAN.
PIN:7-8->21Ω
1-7->39k
2-3->127Ω
4-5->659Ω
5-6->9k

315532 measured by hp34401a, 4Wire
PIN 1-2：48.7795K  1-3：48.6536K  1-4：48.6543  1-5：47.9947K  1-6：38.9950K  1-7：38.9952K  1-8：39.0165K
2-3：127.422ohm  2-4：127.326ohm  2-5：786.248ohm  2-6：9.78619K  2-7：9.78629K  2-8：9.80740K
3-4：0.3380ohm  3-5：659.267ohm  3-6：9.65917K  3-7：9.65927K  3-8：9.68048K
4-5：659.163ohm  4-6：9.65910K  4-7：9.65920K  4-8：9.68033K
5-6：9.00017K  5-7：9.00028K  5-8：9.02140K 
6-7：0.3355ohm  6-8：21.5500ohm
7-8：21.4520ohm

[GEOelectronics]

Would the Daytron 4910/4911 Users Handbook help? Its an 80 page document.
Is there a FILE storage area on this chat group, can I post a 5.7M file to a regular post or should it go on my web page and post a link here?

Thanks for the help.

George Dowell

[ManateeMafia]

George,
The files are already here. https://doc.xdevs.com/doc/Datron/4910_4911/ but it never hurts to have an alternate location.

Cheers.

[texaspyro]

George,
The files are already here. https://doc.xdevs.com/doc/Datron/4910_4911/ but it never hurts to have an alternate location.

Cheers.

Like ko4bb.com

[nikonoid]

George, I think we already have the document you are referring to and this is the same document on xdevs server and ko4bb.


I am slowly progressing with the project.

I started with power supply. Taking it apart was not difficult. Under metal shield I found a toroid transformer, generating 5 isolated 26V outputs plus another line out of about 11V. Here are few quick pictures. I will take high resolution photos and post them later on.





This is my current understanding of pinout of connectors coming to battery compartment. Please note that I numbered pins in a way how they correspond to pins on IDC connectors on power supply board. This is not a standard numbering for DB9 and DB15 connectors.

There are 5 channels of batteries with 3 batteries in each. Each channel has a 10k thermistor at positive terminal of the first battery (all connected to DB15 connector). First channel also has a thermistor on negative terminal of the last battery. I have not traced how it is used yet. Solid dots on DB9 diagram are negative terminals for each of 5 battery channels.



Without service manual I was not really sure what to expect for power output from supply. There are two output power IDC connectors on power supply: 10 pin and 16 pin.

For now I recorded all pairwise voltages between them:


20 VDC is directed at charging each battery channel. 24.5 VDC is actually 4.5 VDC relative to 20 VDC that comes to each thermistor. So far this makes sense. However areas in yellow look a little bit out of the pattern to me, so this is what I will be investigating next. I want to be sure the power supply is not going to destroy something before I move further.

[Pipelie]

hello, nikonoid,

my 4912 didn't come with the 'connector board', I asked my friend to help me with the circuit recovering. and then I can rebuild the connector board,
in order to replace the SLA battery to 18650B battery, I remove the NTC resistor and replaced it with a resistor network,  show as the picture below.

this NTC resistor is part of the feedback resistor of the regulator and causes the output voltage of the charger circuit to decrease as the battery temperature increase. but I'm NOT sure the purpose of the extra NTC.

[nikonoid]

Thank you, Pipelie. This is a clever approach in switching batteries to 18650.

I am still waiting for replacement SLA batteries. I will be working on it next week and will compare your schematics against my connector board in battery compartment.


Sent from my iPhone using Tapatalk

[Dr. Frank]

Would you mind to determine the oven set point & temperature of each of the LTZ modules?

Although there exists a roughly measured schematic reproduction of the VISHAY resistor array, I doubt that it is fully correct, as probably being measured 'in circuit'.

I guess I already posted what you are looking for, have a look here

https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg273274/#msg273274

I removed and measured the vishay 315532  six years ago.
and here is the result:

there are at least five resistors in the TO-CAN.
PIN:7-8->21Ω
1-7->39k
2-3->127Ω
4-5->659Ω
5-6->9k

315532 measured by hp34401a, 4Wire
PIN 1-2：48.7795K  1-3：48.6536K  1-4：48.6543  1-5：47.9947K  1-6：38.9950K  1-7：38.9952K  1-8：39.0165K
2-3：127.422ohm  2-4：127.326ohm  2-5：786.248ohm  2-6：9.78619K  2-7：9.78629K  2-8：9.80740K
3-4：0.3380ohm  3-5：659.267ohm  3-6：9.65917K  3-7：9.65927K  3-8：9.68048K
4-5：659.163ohm  4-6：9.65910K  4-7：9.65920K  4-8：9.68033K
5-6：9.00017K  5-7：9.00028K  5-8：9.02140K 
6-7：0.3355ohm  6-8：21.5500ohm
7-8：21.4520ohm

Thank you.
Then the divider ratio of the oven controller would be 9k over 659 = 13.7, which would yield about 75°C oven temperature, which is way too high.
The Fluke 732A/B and the Datron 7001 are all running on about 45°C, so I would have assumed that the 491x ref would do the same, to achieve a stability of around 1ppm/yr.

In the manual for the 4910, page 1-4, they describe the oven temperature as being ' a few °C above the instruments maximum ambient operating temperature.', which is specified on page 4-1: 'Temperature: Operating:  0° to 40°C'.

So also from that numbers, a 50°C oven temperature is much more probable.
Maybe there's a detail in the schematic, been overlooked up to now, which reduces the oven temperature.
 
So I would like to ask you, to really measure the oven temperature.
Thanks.

[nikonoid]

Batteries came. I ordered powersonic PS-621, like CalMachine suggested. Surprisingly new battery is about half the volume of old, while caring the same 6V 2Ah spec:




I have finished checking out the power supply and found nothing wrong with it.

Then while testing the connector on the back of the unit responsible to monitoring battery voltages from outside, I found that all negative terminals of all 5 batteries are tied together. This is happening on main board (not on the battery compartment side or power supply side).

Is there any good reason why 5 isolated channels would have all their negative sides tied together? Or is it an indication of a possible fault?

At this points I am ready to dig into main board. I can see from the side view that I have at least two capacitors that are leaking. I am not 100 percent sure how to remove main board. Any recommendations on the procedure?

[ManateeMafia]

I used the same batteries on my 4912.

I had some bad tantalums on the main board so I removed the battery tray and the frame around it. I could replace the parts without removing the main board.

[nikonoid]

I used the same batteries on my 4912.

I had some bad tantalums on the main board so I removed the battery tray and the frame around it. I could replace the parts without removing the main board.

Thank you, MataneeMafia. I like this idea. I will give it a shot tomorrow. I am making a rule not to work on anything very sensitive or high voltage after 1am

If/when you have a chance, can you test if pins 1 though 5 on the back of the unit are all tied together? I am now using the pin numbering from Dayton’s manual below:



PS. I am considering 3D printing plastic brackets for PS-621 to bring them up to size of original batteries.

[ManateeMafia]

I will try and give it a shot. It isn't located in an easy to reach location as my pyramid of 10v references has the Datron at the hardest to reach location. 

I seem to recall all 5 supplies were independent and have separate ground paths. Maybe transit mode switches all grounds together? J601 should also read the same as J103.

[ManateeMafia]

I think your links on the references are causing this. They are the "AVERAGE" links and are probably all connected. If they are, disconnect them and see if this changes for you.
The links tie all LO outputs together.

[nikonoid]

Pyramid of 10v references.... oh my!

I already tried transit switch yesterday: 5 battery channels all had common ground regardless of switch position.

I will try to undo “AVERAGE” links tonight. Thanks.

[nikonoid]

ManateeMafia, you were right on the money with averaging mode links causing all negatives for all 5 battery channels to be connected together. Thank you.

Yesterday I took the unit almost completely apart.
Luckily there is no visible damage to the unit. 3 electrolytic capacitors show minor leakage. I was going to replace them all anyways.







On main PCB there is a large red bank of micro switches. Would anyone know what they are for?

[nikonoid]

Another short update.

I replaced electrolytic capacitors on main board. It was just is time: in few places electrolyte started to eat into the board under the cap, but no traces had been killed yet. One of old capacitors was shorted out (channel 4) it killed this VP0808M transistor.



I will have to find and buy a substitute. For now the cell 4 is out of power.

Meanwhile with new capacitors unit did power up without problems. On power up all lights for cell 4 were off and for cells 1-3 I got:
1) “battery” led solid red (no battery connected)
2) “temp” led solid red and it would change to solid green if I let unit warmup and pressed reset button at the back
3) “average” led is solid green regardless of me putting cell in average mode or not. This is strange.

Voltage outputs on individual cells were all under 0.5v, and readings from average, buffered, 1V and 1.018V did not make any sense at all. Sometimes hung else must be wrong beside blown transistor.

With help of ManateeMafia and Pipelie (thank you, guys), found that DB15 connector that leads into the cell is providing 5V power correctly, but PWM signals on pins 11-14 are missing. I get 5V on pin 14 and 0V on others. There is a high frequency noise there but it is very small (millivolts).

This led me to the module below. Unfortunately I have a hard time opening it, as power pins (red and black wires) seem to be soldered directly into the PCB on inside. Would anyone know if there is a way to open this without desoldering pins? Thanks.

[Pipelie]

Hello, Nikonoid
you have to desolder the pins.
upload a photo  for your reference

[nikonoid]

Thanks. These pins were quite difficult to carefully remove.

Here is my photo to compliment yours.
These is possibly a missing component and also one IC does not look original. So this had possibly been worked on before.

[nikonoid]

And we finally have 10 volts!!!!



Keithley 2001 is not a meter to judge Datron 4910 by. I just had it handy, since I used it while repairing 4910 and it was already warmed up. It may not be very precise, as I calibrated it against another calibrated K2002, but it is pretty good. While not scientifically significant, there is is something very satisfying in seeing six zeros there considering neither K2001 or 4910 were adjusted for the occasion.

Four individual channels read about +/- 1ppm of average. Buffer, 1v and 1.018v all seemed spot on. All in all a good result so far.

These are the parts that were bad:


Capacitor shorted then transistor overloaded and blew up. Independently 8mhz oscillator was bad.

I replaced original oscillator with ACO-8.000MHZ-EK
I hope it is good enough.

There is still more capacitors to be replaced, cosmetic cleaning and battery compartment to work on.

I will be uploading high def photos to XDEVS server soon.

[kj7e]

Nice work!  And I'd say 0.8ppm is pretty dang good.

[TiN]

Oscillator got tired of oscillating and become stable  .
Good job, looking forward for proper measurements.

Perhaps would be interesting to compare cells in differential mode to establish relative stability.

I'd join suggestions to replace all tantalum/electrolytic caps everywhere.

I will be uploading high def photos to XDEVS server soon.

Thanks. I think we can expand unfinished 49xx article to better state, using your feedback as well.

[nikonoid]

Finally all the caps are here including all tantalums. Time to recap.

Meanwhile, in two weeks measuring with 3458a the 4910 had been rock stable: The biggest move I saw was 0.2ppm when ambient temperature changed by 2C. Running autocal on 3458a brought it back to spot on. Otherwise normal noise periodically goes by about 0.05ppm up or down.

I had to power down the 4910 for an hour. When I powered it back on, it was within 0.2ppm of old value in 15 minutes. After 4 hours it got back exactly to the value before power down.

So far I am VEREY IMPRESSED with 4910.


While waiting for caps here is a preliminary design of the 3D printed bracket to convert commonly available batteries to old size.





Special attention had been paid to provide mechanical support compatible with original enclosure, while keeping as much surface area open as possible for proper dissipation of heat.

[CalMachine]

I like the battery solution!  Good idea   

[nikonoid]

I am attaching the STL model for the battery holder that I used. It adopts new SLA batteries PS-621 to the size of the batteries originally used in Datron/Wavetek 4910/4911/4912.

It allows to use original hardware for holding batteries and all original cables, while providing enough thermal air flow to dissipate heat for battery charging. 

[Echo88]

Regarding transit-switch S601 in the Datron 49XX:
Its used to switch the complete device into transit-mode and i cant find any contemporary switch that could be used as a substitute for this switch, is it a special construction? 
Page 123/124 in the service manual shows it: https://xdevs.com/doc/Datron/4910_4911/Datron_Wavetek_4910_4911_sm_service_manual.pdf
https://xdevs.com/doc/Datron/4912/set%201/IMG_1296.jpg Middle left side show the switch-pins: 8 rows a 12pins corresponding to Pins A1-12...H1-H12
Its only capable of switching between two positions: normal and transitmode, by opening and shorting its respective pins A1-A12...H1-12.
An example of this is visible on page 124 top right side: During normal mode the switch-pins f4-e4 is open and f3-e3 is closed, changing to transit mode switches the open/closed switches. This double SPST-scheme is used also to control the power supplies for the cells and the DC-input doubler/tripler.
The BOM lists only NSF as the manufacturer and no real partnumber.
https://www.elma.com/-/media/products/products-files/08_datasheet_e.pdf could the switch be (in theory, just wanting to understand it) be replaced by such a standard configurable rotary switch and a suitable pole-configuration?