Fluke 8846A / 8845A / DMM4040 / DMM 4050 AC Mains transformer details

[Kiriakos GR]

For any lost soul seeking for Fluke 8846A / 8845A / DMM4040 / DMM 4050 AC Mains transformer details I am presenting here a picture this explaining availability of voltage outputs = many.

Originally amount of output wingdings they are four.

a)  20V # 15V # zero center tap # 15V # 20V    =  2x15V  & 2x20V (approximately 1A) 

b)  3.3V # zero center tap # 3.3V

c) zero tap # 5V  (approximately 1A)

e) zero tap # 50V  (approximately 1A)

By assuming that these lost souls are not kids, you may simply analyze wattage of components in use for DC transformation and voltage stabilization, and their limits will give you a proof of how much current they are designed to handle.
By making the sum you are close to discover transformer wattage.

Voltages mentioned over AC Mains transformer they are in DC Volts.
This translates that actual ACV voltages may be lower but such percentage it may also calculated according to Voltage boost caused by a simple diode.
   

From the very few tears full stories over the web, it is unclear of how this transformer was burned? especially in the USA.
   
Almost in every city there is a small shop repairing motor winding and transformers.
You may test your luck by trusting the experts instead doing lots of guessing work.
 

 

[liviu2004]

Hi, my name is Liviu, and recently owner of an Tektronix 4450, ebay purchase. Hobby playing with automotive stuff. Not really into electronics, more like basic measurements stuff.

I bought and got this on a Friday, did some measurements, and Monday smoke came out. Basically it burned the AC fuse. And a replacement. Input trafo resistance is somewhere at 72 ohms.

Long story short, I don't know what to do with this unit. I made a claim to paypal against the seller, as I think this unit had history. No serial tag either.
But I want this unit so badly, if I would be able to find someone somewhere to fix it. Unit is still sealed, and I plan to keep it like that in case I can send it somewhere to repair it.

What would you advise, I searched around a bit, no way to get a trafo. I don't know a company which repairs them. I am willing to ship this trafo anywhere around the world, if I can get a fix.

Help?

[Kiriakos GR]

I bought and got this on a Friday, did some measurements, and Monday smoke came out. Basically it burned the AC fuse. And a replacement. Input trafo resistance is somewhere at 72 ohms.

Hi, in which position was the Mains voltage selector (at the back) before the fireworks?   

[liviu2004]

It was at 240V when it came in. I don't know its history.

I'm lost of words, I literally measured few resistors and capacitors, to see how this works, played around with some functions and switched it off. I haven't measured mains voltage or anything like that. For sure smoke came out, because I smell it.

If I replace the fuse, unit will boot for a few seconds, before burning the fuse again.

[Kiriakos GR]

It was at 240V when it came in. I don't know its history.

I'm lost of words, I literally measured few resistors and capacitors, to see how this works, played around with some functions and switched it off. I haven't measured mains voltage or anything like that. For sure smoke came out, because I smell it.

If I replace the fuse, unit will boot for a few seconds, before burning the fuse again.

I am using 240V also, transformer coil resistance = 85 Ohms + Mains cable with plug.
Did the burned fuse is the one hidden at Mains voltage selector?
 
Check this link and report back ...
https://www.ittsb.eu/forum/index.php?topic=1482.msg3616#msg3616

SCHURTER KG10 or KG10.6101.151 ( IEC C14 ) Power entry module review

[liviu2004]

Yes, the fuse at the main selector burned. It has a small resistor in as well. Thanks for the primary resistance, this confirms my suspicion.

I'll check the link, thanks for your time.

[Kiriakos GR]

Yes, the fuse at the main selector burned. It has a small resistor in as well. Thanks for the primary resistance, this confirms my suspicion.

I'll check the link, thanks for your time.

Yes check entire link for more info.
Fuse with resistor this is for protection of transformer coils, the resistance this is an current limiter.
I am assuming that your transformer this is still alive.
Did you replace the Fuse and try to power it on?

[liviu2004]

Sorry, had to run to a shop and now have to run to a broken car. Yes, I've tried another fuse. Unit powers up, on display I see initializing and after max 3 seconds, fuse burns again.

I'll read the topic somewhere this afternoon - evening and report back.

Do you advise to hold on this unit? It looks mint otherwise.

[Kiriakos GR]

Sorry, had to run to a shop and now have to run to a broken car. Yes, I've tried another fuse. Unit powers up, on display I see initializing and after max 3 seconds, fuse burns again.

I'll read the topic somewhere this afternoon - evening and report back.

Do you advise to hold on this unit? It looks mint otherwise.

I do avoid guess work, technically the unit has two basic DC power circuits.
a)  VFD display high voltage.
b) DC Power for the IC due a few stabilization components.

Give me a last clue, are you the one which removed the calibration shield (small round sticker ) over one of four bottom screws?

Manufacturing of such units this started (Product release date the year of 2005~6)
My unit it is fresher (this decade).
If your unit this is too old?   it might have sorted electrolytic capacitors and this is a tiny cost so this unit to be saved / rescued. 

Any person making TV electronic repairs in your town, he might be able to help.



 

[liviu2004]

All right, car if "fixed", water damage in the forward smart fuse box, making a canbus network storm. I can't make these things up.

Back to 4050, no, the seal at the bottom screw is still there, unit has not been opened and will not be, unless is in the hands of someone which can do it? I don't know ... now back to that topic, need to read it top to bottom. 

I'm still worried that I smell smoke. Something is burned out, not sure if capacitors smell this way.

[liviu2004]

Ok, I've read the link, actually I've seen it few weeks ago when I was researching DMM 4050. What I learn is, Tek does not provide spare parts outside UK, nice.

I'm back to square one and honestly I feel more like I will pursue paypal claim and return this to the seller. 678 euro paid for a unit which worked for 10 measurements. 

[Kiriakos GR]

Ok, I've read the link, actually I've seen it few weeks ago when I was researching DMM 4050. What I learn is, Tek does not provide spare parts outside UK, nice.

I'm back to square one and honestly I feel more like I will pursue paypal claim and return this to the seller. 678 euro paid for a unit which worked for 10 measurements. 

Shield intact this translates to that nobody has open up this case other than Tektronix or Fluke calibration team.
The age of these DMM this can be discovered due the factory calibration date, that is displayed at VFD screen at specific menu.

Consumer to consumer advice, those DMM are still priced close to 2000 EURO.
If VFD display this is bright enough? then you may also contact service-emea@tektronix.com about getting their price - repair estimation.

The quick way out, of this unpleasant experience this is Paypal and to return the unit, but this is your choice to make.