Author Topic: Fluke 8400A; No display.  (Read 21832 times)

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Offline neoTopic starter

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Re: Fluke 8400A; No display.
« Reply #75 on: November 29, 2017, 10:37:32 pm »
In that case leave it, it was obviously designed to be like that.

We can't do anymore now until we can check / replace the caps and the transistors.

Thanks for your help so far, i will get the caps relatively soon, either December 1st or 2nd.
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline Specmaster

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Re: Fluke 8400A; No display.
« Reply #76 on: November 29, 2017, 11:22:55 pm »
I don't know but you mind find this useful if you require spares for it as well?

http://www.dontscrapit.com/Ohio-/Construction-/Fluke-8400A-s-range-benchtop-dmm-digital-multimeter-rm.php5

I've sent you a personal message as well.
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Offline neoTopic starter

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Re: Fluke 8400A; No display.
« Reply #77 on: November 29, 2017, 11:29:48 pm »
PROGRESS!!!!

I re-soldered the joints on the power supply and checked my work twice for flaws. Now instead of being immediately unstable it has a bit of delay and then a much more gradual fall.

So not fixed but i at least made some progress.
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline Specmaster

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Re: Fluke 8400A; No display.
« Reply #78 on: November 29, 2017, 11:31:49 pm »
PROGRESS!!!!

I re-soldered the joints on the power supply and checked my work twice for flaws. Now instead of being immediately unstable it has a bit of delay and then a much more gradual fall.

So not fixed but i at least made some progress.
Maybe when the caps arrive it might be fixed then  :-//
Who let Murphy in?

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Offline neoTopic starter

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Re: Fluke 8400A; No display.
« Reply #79 on: November 29, 2017, 11:32:55 pm »
With that link you sent me, will they ship it and how much is the item itself?  :-//
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline Specmaster

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Re: Fluke 8400A; No display.
« Reply #80 on: November 29, 2017, 11:34:56 pm »
With that link you sent me, will they ship it and how much is the item itself?  :-//
I have no idea, you have the same info as I have there. I was searching for a manual and found that link.
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Offline neoTopic starter

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Re: Fluke 8400A; No display.
« Reply #81 on: November 29, 2017, 11:42:42 pm »
I kinda want it, if for nothing else the rack ears alone. The ears are rare it seems, my fluke has none and my HP5340A has 1.
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline Specmaster

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Re: Fluke 8400A; No display.
« Reply #82 on: November 29, 2017, 11:44:04 pm »
send em a message then and see what they say.
Who let Murphy in?

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Offline neoTopic starter

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Re: Fluke 8400A; No display.
« Reply #83 on: November 29, 2017, 11:57:01 pm »
send em a message then and see what they say.

I have, speaking of messages check yours.
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline neoTopic starter

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Re: Fluke 8400A; No display.
« Reply #84 on: November 30, 2017, 12:12:20 am »
Well this is interesting, may even give us something to work with.

This is being caused by the regulator, at the capacitor this is not there.
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline Specmaster

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Re: Fluke 8400A; No display.
« Reply #85 on: November 30, 2017, 12:22:37 am »
Where on the circuit are you taking this from?
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Offline neoTopic starter

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Re: Fluke 8400A; No display.
« Reply #86 on: November 30, 2017, 12:24:39 am »
The test point, specifically test point 1 for 200V line
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline Specmaster

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Re: Fluke 8400A; No display.
« Reply #87 on: November 30, 2017, 12:30:00 am »
What do you at C1? is Q1 the large TO66 transistor on the heatsink?
Who let Murphy in?

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Offline Specmaster

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Re: Fluke 8400A; No display.
« Reply #88 on: November 30, 2017, 12:31:31 am »
You say to check my messages, which ones, emails or a PM, because I have checked the PM's and there is no message there?
Who let Murphy in?

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Offline neoTopic starter

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Re: Fluke 8400A; No display.
« Reply #89 on: November 30, 2017, 12:33:27 am »
No the large transistor is Q6, when i measure the 200V line at the capacitor i get what i expect, a little ripple but not much.

I sent what you asked for to your email.
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline neoTopic starter

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Re: Fluke 8400A; No display.
« Reply #90 on: November 30, 2017, 12:52:40 am »
Q6 hits temps as high as 70C perhaps higher.
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline Specmaster

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Re: Fluke 8400A; No display.
« Reply #91 on: November 30, 2017, 01:48:19 am »
you measured Q6 with your thermocouple then yes, or is that 70C a guess? If it then I'd say that was way to high and you need to measure the current being drawn on that 5V line, maybe the ADC is faulty? I got the manual now, thanks
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Offline neoTopic starter

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Re: Fluke 8400A; No display.
« Reply #92 on: November 30, 2017, 01:55:53 am »
With my thermocouple.

I found a smoking gun.

no cards, 80v stable copacetic ripple with no noise. Nothing on the display.
All cards except A8 and A9 the same.
Add A8 and A9 it goes up to 200v but adds noise and parts of the display turns on.
« Last Edit: November 30, 2017, 01:59:43 am by neo »
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline Specmaster

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Re: Fluke 8400A; No display.
« Reply #93 on: November 30, 2017, 02:01:07 am »
With my thermocouple.

I found a smoking gun.

no cards, 80v stable copacetic ripple with no noise. Nothing on the display.
All cards except A8 and A9 the same.
Add A8 and A9 it goes up to 200v but adds noise and parts of the display turns on.
Now we're getting somewhere, what about if you just A8 or A9, what happens then?
Who let Murphy in?

Brymen-Fluke-HP-Thurlby-Thander-Tek-Extech-Black Star-GW-Avo-Kyoritsu-Amprobe-ITT-Robin-TTi
 

Offline Specmaster

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Re: Fluke 8400A; No display.
« Reply #94 on: November 30, 2017, 02:06:16 am »
I take it for granted that you've checked to make sure that the correct boards or cards are plugged into their correct slots, if their like the 8505A, they have to be in the correct sequence or else nothing works properly. :palm:
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Offline neoTopic starter

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Re: Fluke 8400A; No display.
« Reply #95 on: November 30, 2017, 02:12:52 am »
I take it for granted that you've checked to make sure that the correct boards or cards are plugged into their correct slots, if their like the 8505A, they have to be in the correct sequence or else nothing works properly. :palm:

Yes i have checked that, at least twice.

If only A8 and A9 the same result as having none except that that 80V is not stable, it drifts down.

EDIT: Amendment, the no card state is 102V relatively stable, more testing is required then i will post a list.
« Last Edit: November 30, 2017, 02:15:55 am by neo »
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline Specmaster

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Re: Fluke 8400A; No display.
« Reply #96 on: November 30, 2017, 02:25:33 am »
Some good points, Logic Card has 3 test points and they are all accessible from the top of the card when in situ, and the ADC card has 7 test points and likewise all accessible in situ from the top of the card.

I'm off to bed now, catch you tomorrow.
Who let Murphy in?

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Offline neoTopic starter

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Re: Fluke 8400A; No display.
« Reply #97 on: November 30, 2017, 03:51:33 am »
No card= No display, 106V initially dropping to 102 though relatively stable at floor. No heat on Q6, mild heat on Q3. Copacetic ripple.
A2= same
A3= 86V erratic behavior, no settling but swing between 85 and 90. Copacetic ripple, same heat patterns, no display.
A5= same as with A2
A6 and A7=same as with A2
A8 and A9= 200V relatively stable, noise on the line 1V peak to peak square wave + previous ripple on top of each other Q3 hot, Q6 unaffected, Q2 warm.
A10=80v initially drifting down to 75, copacetic ripple, no display, same heat patterns as A2
A11 same as A2
A12, same as A2
A13 same as A2 except it starts at 76V and settles to 74
A13 and A2 = same as just A13
A13 and A3 = same as just A13
A13 and A5 = same as just A13
A13, A6 and A7 = same as just A13
A13, A8 and A9 = same as just A8 and A9
A13 and A10 = same as just A13
A13 and A11 = same as just A10
A13 and A12 = same as just A13
A12 and A2 = 110V settling to 103V
A12 and A3 = 85V settling to 78V
A12 and A5 = 107V settling to 103V
A12, A6 and A7 =107V settling to 103V
A12, A8 and A9 = Same as A8 and A9
A12 and A10 = 80V settling to 77V
A12 and A11 = 80V settling to 75V


Each test given a minute.
If i wasn't so invested in this thing i might be tempted to take it out back and shoot it.  :horse:  :-DD


A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline neoTopic starter

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A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline Specmaster

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Re: Fluke 8400A; No display.
« Reply #99 on: November 30, 2017, 07:59:22 am »
i bought this https://www.ebay.com/itm/128-64-LCD-NPN-Transistor-Tester-Capacitance-ESR-LCR-Meter-Diode-Thyristor-BL/121684741402?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
That is good let's hope it arrives in a couple of days, it will be one of the most used items in your toolkit. It does PNP & NPN transistors, diodes, zeners, mosfets, caps, inductors, and resistors. I was a bit dubious about buying it myself when I started in electronics. I had heard so much from others about the Chinese stuff being crap. Fact is however that it isn't, when see that bigger global and well known and respected brands are putting their names on Chinese produced products, so that you can buy the same thing from different companies with their names on, makes you think, don't it?

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Who let Murphy in?

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