Fluke 73 series 1 Multimeter repair

Thread Starter

Mugiwara303

Joined Jun 14, 2015
10
Hi everyone, i have bought this Fluke 73 series 1 but it's not turning on, I can't find schematics for the series 1 i have found only series 2 and 3, and based on that i have tried the test points and i got wrong voltages, is there any way to fix it! it got some corrosion that i cleaned but no luckScreenshot_2026-11-08-22-31-26-559_com.miui.gallery.jpgScreenshot_2026-11-08-22-33-07-183_com.miui.gallery.jpgScreenshot_2026-11-08-22-33-16-909_com.miui.gallery.jpg
 

wayneh

Joined Sep 9, 2010
18,182
I don't like the looks of this. Is it really broken off as it appears in the photo? Whatever that chunk is seems to be directly opposite the multi-pin chip on the other side of the board. Is it maybe a heat sink of sorts?
Image 11-9-26 at 10.40 AM copy.jpg
 

panic mode

Joined Oct 10, 2011
5,439
yup, it looks like it had date with Zeus...

Hi everyone, i have bought this Fluke 73 series 1 but it's not turning on, I can't find schematics for the series 1 i have found only series 2 and 3, and based on that i have tried the test points and i got wrong voltages, is there any way to fix it! it got some corrosion that i cleaned but no luck
and what exactly is that supposed to tell us? you measured what, where using what and got what result?
how does it behave when you power it on? any sign of life? anything on display?
 

nsaspook

Joined Aug 27, 2009
16,512
I don't like the looks of this. Is it really broken off as it appears in the photo? Whatever that chunk is seems to be directly opposite the multi-pin chip on the other side of the board. Is it maybe a heat sink of sorts?
View attachment 373083
Just a cutout (maybe for thermal, solder or testing) under the battery.That's only a part of the chip on the other side. Looks normal.
1794419667752.png
I have my old 73 that still works (10A section was lost decades ago)
1794419598014.png1794420648655.png


1794419642696.png
1794425600455.png
Negative battery test point.

Battery 8.84V
Switch on ACV, measured from the top going clockwise.
1794420046442.png1794420207992.png

0
0
8.84
2.87, probe connect here causes display to change.
0
5.75
8.84
8.84
8.84
5.75
5.75
8.84

To the OP, check these voltages with a fresh battery. Report back here, I'll be glad to help if possible.
 
Last edited:

ZhangSheng

Joined Sep 25, 2026
13
Good call from nsaspook on the test points — do those with a genuinely fresh 9V first, and measure the battery while the meter is switched on. A 9V that reads 9V open-circuit but sags below about 7.5–8V under load, or a corroded battery clip, will give exactly these 'wrong voltage everywhere' readings. Also try the continuity beeper: if it chirps, the main chip is alive and the fault is likely the LCD zebra strip / display contacts, not the power rail. Clean the rotary switch contacts with isopropyl alcohol too — on a meter this age a dirty range switch drops more voltage than you'd expect.
 
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