Miller Boost Circuit Board Assembly NO. 200841

Question

Hello everyone,

Let me tell you small story

While back I have purchased dead "MIller Dynasty 200DX"

After some repairs I have found damage to Boost Board that has internal ground planes burnedout.

I have realisedthat i would need board replacement, however, board is dicontiniued and replacement board will cost me 2000 dollars if I found one.

After fiew hundret emails and phone calls to different suppliers without even one ansfer I have desided recreate board from scrach and make my own.

Fiew month later after reverse engineering pcb to schematic and later on from schematic to PCB i have finally received new boards.

I have solder necesseryparts and run test on new assembled board, however, I have forgot take a maguments from resistor R86

Could some one be so kind and provide value number between pin 2 & 3 on R86?

Here is some pictures from original board and final my creation:

A3JBNE · Accepted Answer

The value of R86 as it says in the technical manual adjusts the limit for the line current, by default it is approximately 10 ohms. R86 makes a voltage divider with R99 adjusted from 0 to 7.5V approximately, it is compared with the current of the HD1 transducer of 6.25A per volt. For example if you want to limit it to 43 amp, you would have to adjust the voltage divider R86 and R99 to 7Volts.

lanuser · Answer

Josh, First of thank you for your reply. Is to easy to reverse engineering this board, however, it is time consuming a speacially when team of one working on entire project. I'm planing some changes for Rev 2.0 of this board, such as an absolite unshielded inductor L1, VR4 LDO that converts +30V to +15V and getting HOT under formal coating without heatsink by manufacturer, adding fuses. After reviewing design i came to conclusion! When VR4 fails under heat it damages boost board that cost $2000 dollars and also damages the main board that cost $1600. None of these boards has ANY fuses! In any case, if i could get Ohm value between pins 2 and 3 on R86 it will really help. R86 has 3 pins and it is a verablabe resistor. pins 1&2 are shorted together by design and pins 2-3 has Ohm /K Ohm value between 0 to 10K

jjohn76 · Answer

Hi Alex, I just saw your post and am troubleshooting a Dynasty 200SD as well. My board is showing 0.430 ohms between pins 2 and 3 on R86. I found my first problem was a burnt connection on the input relay (PC2, main board back left corner). What voltage do you get on pins 7 and 8 for RC1 when you measure against the ground plane (pin 3)? My tech manual says I should get +15V on pin 7 and -15V on pin 8, but I am only seeing exactly -12V on pin 8. If it were a random voltage other than exactly -12V, I would suspect a bad zener or reference voltage for the controller, but it just seems like exactly -12V is too coincidental. Would you be willing to share the schematic? Jon

alvideo · Answer

Hi Alex, I had this board. Still You need value between pins 2 and 3 on R86?

Miller Boost Circuit Board Assembly NO. 200841

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