atkelar | Fluke 5100B - Part 2 @atkelar | Uploaded July 2024 | Updated October 2024, 19 hours ago.
Workshop Project #34 - Fluke 5100B - Part 2
After taking the unit apart, cleaning things and starting to assemble the case again, I start to do some recapping and replacing of thermal paste in this episode, leading up to the power supply adjustments and validations.
A quick note #1: based on comments from part one, I did double check on the "RTC" (=real time clock) on the regulator board. It's pointed out in this part specifically. It's a 60Hz 5V rectangle generator. The manual only says it's used by modules for time keeping. But a closer inspection reveals something of a bit more overkill. You see, the modules - especially the digital controller and related ones - are standard modules that also are used in other instruments of that era. For example, there's a benchtop DMM hat has the same controller (probably a different ROM), isolator and IEEE card. Add that to these components being made for several years, there are changes adding up. What I found out is: only the controller board uses this 60Hz signal! And there, the input section is clearly meant to take non-TTL levels. My assumption is thus: originally, there was a transformer tap that fed the mains frequency directly into that as a sine wave. Fluke eventually replaced that with a 555 timer and now has 60Hz timing even on 50Hz mains. That sounds like a perfect explanation. Oh: and the ONLY place that timer is acutally used on this version of the controller board: Triggering the CPU reset signal. So this timer is indeed doing the digital version of the "POP" generator... I'm sure Fluke would have made that much simpler if it weren't for the modular design...
Quick note #2: The binding posts might also have been some specific copper alloy; they look a bit mre reddish on the video than in person. But there was at least one replaced contact for sure and they were worn out and beaten up. I stand by my decision to replace them, but depending on technical requirements might come back with a different style later on.
0:00 Intro / Power Regulator PCB Recapping
3:12 Transformer Board Recapping
4:50 Extended Range and HV Board
8:00 Wideband Amplifier
9:40 Wideband Oscillator + Overview
10:49 Front Panel Buttons / Waver Switch Cleanup
14:09 Clenaing Panel Buttons
15:55 Ranging PCB + Binding Posts
19:14 Removing and Replacing "Foam"
20:05 [Power] Amplifier PCB
22:05 TO-3 Post Issue / Thermal Paste / Hot Relay
24:24 Remounting the TO-3s
25:20 Power Regulator Checks
26:10 Summary / Credits / Outtake
Music (in order)
My Train's A Comin' - Unicorn Heads
Nine Lives - Unicorn Heads
Wrong - Dan Henig
Town of 24 Bars - Unicorn Heads
Light Expanse - Unicorn Heads
(YouTube Audio Library)
You can support me on Ko-Fi: ko-fi.com/atkelar
and also on Patreon: patreon.com/Atkelar
and now also here by using the "Super Thanks" feature!
Thanks to everybody who signed up already!
Workshop Project #34 - Fluke 5100B - Part 2
After taking the unit apart, cleaning things and starting to assemble the case again, I start to do some recapping and replacing of thermal paste in this episode, leading up to the power supply adjustments and validations.
A quick note #1: based on comments from part one, I did double check on the "RTC" (=real time clock) on the regulator board. It's pointed out in this part specifically. It's a 60Hz 5V rectangle generator. The manual only says it's used by modules for time keeping. But a closer inspection reveals something of a bit more overkill. You see, the modules - especially the digital controller and related ones - are standard modules that also are used in other instruments of that era. For example, there's a benchtop DMM hat has the same controller (probably a different ROM), isolator and IEEE card. Add that to these components being made for several years, there are changes adding up. What I found out is: only the controller board uses this 60Hz signal! And there, the input section is clearly meant to take non-TTL levels. My assumption is thus: originally, there was a transformer tap that fed the mains frequency directly into that as a sine wave. Fluke eventually replaced that with a 555 timer and now has 60Hz timing even on 50Hz mains. That sounds like a perfect explanation. Oh: and the ONLY place that timer is acutally used on this version of the controller board: Triggering the CPU reset signal. So this timer is indeed doing the digital version of the "POP" generator... I'm sure Fluke would have made that much simpler if it weren't for the modular design...
Quick note #2: The binding posts might also have been some specific copper alloy; they look a bit mre reddish on the video than in person. But there was at least one replaced contact for sure and they were worn out and beaten up. I stand by my decision to replace them, but depending on technical requirements might come back with a different style later on.
0:00 Intro / Power Regulator PCB Recapping
3:12 Transformer Board Recapping
4:50 Extended Range and HV Board
8:00 Wideband Amplifier
9:40 Wideband Oscillator + Overview
10:49 Front Panel Buttons / Waver Switch Cleanup
14:09 Clenaing Panel Buttons
15:55 Ranging PCB + Binding Posts
19:14 Removing and Replacing "Foam"
20:05 [Power] Amplifier PCB
22:05 TO-3 Post Issue / Thermal Paste / Hot Relay
24:24 Remounting the TO-3s
25:20 Power Regulator Checks
26:10 Summary / Credits / Outtake
Music (in order)
My Train's A Comin' - Unicorn Heads
Nine Lives - Unicorn Heads
Wrong - Dan Henig
Town of 24 Bars - Unicorn Heads
Light Expanse - Unicorn Heads
(YouTube Audio Library)
You can support me on Ko-Fi: ko-fi.com/atkelar
and also on Patreon: patreon.com/Atkelar
and now also here by using the "Super Thanks" feature!
Thanks to everybody who signed up already!
