Help...Shunt Reg. issue

[rockpassion]

No longer need help.  I rewetted most of the pads on the Shunt Regulator PC Board my issues got worse.  I removed the board and noticed after that the trace from the bB pad had lifted and broken off and the trace from the 0B pad had also lifted and broken off.  So I will call Eileen and get a new board and all the components.  I do not want to have to remove the ones I have on the board and remount them, it is too much trouble.

Richard




This maybe a little long.  

I finished my Eros last week.  The resistance readings all were close.  But when I turned it on the Voltage readings were way off, plus none of the Tubes glowed or got warm, but all my LED's lit.  So I disassembled by removing the Shunt Regulator and the two Plate load/servo PC boards.  I found one miswire, some poor soldering and 4 wires that broke very easily.  So I made corrections and resoldered everything.  I went back through the build process step by step and boy that was tedious but it obviously found some mistakes.  

I then remounted the 3 PC boards, which was also a pain trying to get the wires back through the holes that I had unsoldered.  Once again I checked all the resistance readings and they all got better and were well within the 10 - 15% range.  So I turned it on again and the LED's on my A side of my Shunt Regulator PC Board did not light.  So just for grins I checked the Voltages on the Plate load/servo PC board on the right side (the board over the B tube socket) where the LED's lit and these are the readings:

IA - 222VDC
bA - 0VDC
OA - 153VDC
OB - 97.6VDC
Kreg - 1.787VDC
breg - 98.5VDC

I did not measure the board over the A socket since none of the LED's were lit.  Should I have?

I am using a Fluke 115 Digital meter if that makes a difference.  

Any thoughts on what might be miswired/not connected well that would cause this.  I am hoping someone can lead me to what might be miswired or not soldered correctly so that I do not have to disassemble this again.  I truly found the disassembly and reassembly to be a real pain in the arse.  

Thanks in advance.  

Richard

 

[Paul Joppa]

The good news is that the B side voltages look good.

The fact that the LEDs are not lit on the A side of the shunt reg board indicates it is not functioning. On page 58 of the manual (at least the version I have) are instructions for checking the shunt reg circuit. Do those tests (you will have to backtrack to identify the connections). While you are there, measure the voltages at the A side of the board - OA, IA, kreg, -, +reg , breg ,  bA. From this we can try to figure out what is wrong with the regulator, hopefully without further disassembly! While you are at it, try to see if both heaters are lit on the shunt regulator tube.

Be careful and patient here! This is the high voltage supply. Use clip leads, no hands while the circuit is hot, and let it sit after turning it off for enough time that the voltage drops, as described on page 58.