Effratom Powersupply repair

[MicorRT]

Gentlemen,
I have a Smartzone 3.0 with Effratom site standards in use. Whenever a powersupply looses power it will not come back on again. Since MoM doesn't support these any more we are trying to repair these in house, however I can't locate schematics or info on them. I have shotgunned these parts so far R2, R5, CR2, Q1, R102, R103, CR101, CR102, R7, U1, and U2. Still no joy. Any and all info would be greatly appreciated.

Thanks,

[Astro Spectra]

Google is often useful ...

FRS

FRK

M100

[MicorRT]

Google is often useful! However those are the same files I found. My model is the black Efratom then bought out by Symmetricom which was made by Datum. Efratom Part number 105450-001 model MPS-AC (same numbers for Datum). I've spent several hours googling and probably will some more. I was hoping someone over here might have had some experience with this freaky little beast. The closest thing I can find is an anodized model that is one generation older over on ebay. Well I appreciate your time and response. This system is old and needs to be replaced. Thanks again!

[MicorRT]

Here is a link to the only info I can find on it. This is the exact unit I have...

http://www.symmetricom.com/media/files/ ... n-mfts.pdf

Thanks for looking!

[Astro Spectra]

OK - will have another look. To clarify it's the PRS-Rb Module internal PSU or the frame AC MPS Module?

[MicorRT]

It is PRS-RB and I believe that is considered the internal MPS. What I have is pictured on page 23 (or page 26 of the actual PDF) of the pdf above (rear view).

Thanks for giving this a look.

[xmo]

When Motorola discontinued support for the Efratom clocks they offered to sell us new Track clocks at half price. Did you miss out on that offer?

Also, what is you migration strategy? Replace the whole system or an incremental upgrade path via SmartX?

If you don't get any help here for your clocks - try the folks at time-nuts

http://leapsecond.com/time-nuts.htm

[MicorRT]

XMO, Hello again. My employer decided against the Track swap out and wanted to put the money toward a new system. However, they're dragging their feet... Thanks for the link I will check them out. Have already torn down both zone controller powersupplies and rebatteried them in house. As for the migration strategy - thats not for me to say I'm a dum monkey - what would I know. The 'smart people' (you can tell who's smart and who's dum by pay grade) will figure that out and tell me to maintain it...
Thanks again I will check that link out. Have a Happy New Year.

[Astro Spectra]

Is this closer?

LPRO repair guide

This is the internal Rb standard used in the PRS-RB module.

[MicorRT]

That might be useful in the future but doesn't look to cover the powersupply. I'll keep poking around if I come up with anything I'll post it over here. Thanks again for the help!

[d119]

Crap. I have an MFTS here at home that I use from time to time but I don't keep it continually powered up... How often are you seeing failures on these?

[MicorRT]

d119,
I don't believe that intermittent use is a problem. Ours are on 24/7 and show components being hot for a long time or getting hot. Not sure how long they will go till you have an issue since ours are on UPS and running undisturbed. The issue is when we loose power i.e. a UPS failure or a circuit breaker tripping. Many of them have been on for almost a decade if not a decade, however, once the power is dropped thats it. They will occasionally fail on their own but not too often - out of 52 supplies we may loose one a year not due to a power loss. I've been out of the office allot so I haven't been able to devote much more time to working with one of these.

[W6WAW]

You might also consider posting an inquiry on the "time-nuts" list. The folks over there focus on time and frequency standard equipment. You may well find someone who has dealt with this before.

https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

[d119]

OK. I haven't powered mine up in quite some time, but the last time I did it worked fine. I was considering putting it on the line full time, but maybe I'll not do that...

[Rick700]

I just fixed two of these MPS-AC supplies. No thanks to Symmetricom who considers the schematic proprietary even though they didn't invent the thing.

There are two 220uF electrolytics on the board.
#1 C14, near the 8-pin dip next to the backplane connector had leaked on both my units. You may want to make sure the electrolyte didn't damage other conductors.

#2 C24 is about 1.5" from the front panel at the top edge of the board. The UC2844 PWM chip at Pin 7 derives its first power on from the filtered DC of C24. C24 is charged from a high valued resistor, like 100k, from the rectified
AC line voltage. If the switcher starts successfully, about 12VDC is taken from the supply to keep the UC2844 going.
If the switcher fails, the power on Pin 7 drops. A restart will take place as soon as C24 charges sufficiently. C24
was open in one of my units with signs of leakage.

Behind C24 is a 100K 2W metal film resistor. You will find this part has been hot for a long time and the color
coding on it faded significantly. The last two unit I had one of them open and the other had a changed value of
242K. Replace this part and put some space between the part and the board. Longer leads will reduce board
damage and add to the heat sinking ability of the resistor.

The UC2844 can fail with improperly applied DC power, like having a bad C24. One indicator of health for this
chip is finding 5 Volts on Pin 8. Therefore, if you replaced C24, make sure to check for the 5V reference on Pin 8.

You might want to change out the other caps on the board. The 330uF caps are hard to find in stock. The 1200uF
caps are easier. Make sure you get the right size.

Currently, I am investigating a drop in replacement for this switcher assembly. It may become necessary if one
of the caps explodes making the board unusable.

The ON-Semiconductor datasheet for the UC2844 has a good app note showing a typical schematic for the switching supply.

I hope this helps.

[MicorRT]

Rick,
Thank you! I've since handed it over to another tech who has been reverse engineering them. I can't devote that kind of time to these... I passed on your info to him and if he has any input I will post it here as well. Thank you again!

[radiokev88]

Since I can't identify some parts (like CR3 and R5) and the power power supplies are failing left and right in my 7 EFFRATOM MFTSs, I had to find another option since new TRAK systems cost about $18,000. I unsoldered the connector from the powersupply module and wired a 24v external power supply to that connector and plugged it into the EFFRATOM backplane receptacle. It's been working for over 3 weeks without fail (I only hooked one up because I don't know how the originals load share, so I have no installed backup). I used a Meanwell 22A, 24VDC supply only because I had that to spare, it's overkill but not sure of exact minimum amperage requirement. The connector on the power supply module is an ERNI # 413638. If you don't want to tear up your power supply module, I've seen the 413638 online for as low as $18.00. FYI: Symetricom(?) will repair a whole EFFRATOM shelf for $3100.00, but if the 2 power supplies are all that's bad, that's pretty expensive.