WAD PSU and No Heater voltage

[colin.hepburn]

Hi All
Well just powered up my WAD PSU and No Heater voltage I get the 45v but no 6.3v any idea on this I have changed out the 5volt reg
Thanks, Colin

[John Caswell]

Hi Colin,
When you say you get 45V but no 6.3V I guess you are measuring between chassis and the heater rails, in which case the 45V is correct.
First check the 9Vac from the transformer onto the PCB, by measuring directly across the PCB pins, then the 9Vac input into the heater bridge rectifier, then the 14Vdc approx dc out put from the bridge rectifier then the 14Vdc into the regulator finally the 6,.3V output from the regulator All the DC heater voltages must be measured from the -Ve side of the heater of the heater supply not chassis.
Either the transformer is u/s, or the bridge rectifier is u/s or you just have a broken wire.

John

[colin.hepburn]

Hi john
Just checked the TX and get 10v with no load 0 Volts at LED so looks like bridge rectifier is dead or broken track the PCB issue one has seen better day needs replaced and rebuilt really
Thank john
Colin

[colin.hepburn]

I may have happened last week. I had inadvertently left it switched on and just turned it off the next day when I saw it was still on. think I will email matthew and see if he can let me have a new board as this one is passed it now
Colin

[bob orbell]

Colin, you may or may not know that the new board uses a LD1084 regulator and the heatsink is the chassis, it is fitted under the board not on top and requires a insulating kit, the two diodes are now redundant and replaced with a 130 R8 and 560 R9 ohm resistor. Bob

[colin.hepburn]

Originally Posted by bob orbell

Colin, you may or may not know that the new board uses a LD1084 regulator and the heatsink is the chassis, it is fitted under the board not on top and requires a insulating kit, the two diodes are now redundant and replaced with a 130 R8 and 560 R9 ohm resistor. Bob

BOB
Yep Matthew has got a new board and v-reg in the post for me didn’t know about the resistors though thanks for the update on that bob
Colin

[bob orbell]

And don't forget the insulator kit Colin, most important. Bob

[John Caswell]

Couple of extra points,
Some of the regulators are now in an all plastic casing so do not need the isolation kit, I think the LD1084 is one of them. If you get one of this type don't fit the insulating kit as it will degrade it's performance!
Colin if you need the resistors I have the odd 100s of each value in stock, so an email/phone and I will stick them in the post FOC.
I believe the method shown originally mounts the regulator on the chassis , lined up with the holes in the PCB, and is then soldered to them.
Better to solder short leads to the regulator pins and insulate them, plus solder pins into the PCB and wire up accordingly, makes life a bit easier for fault finding and component replacing. Make the leads long enough but no too long, ie 2 Metres

John

[colin.hepburn]

Hi Bob/John
Thanks for the updates and reminders about the v-reg installation if needed. I’m sure I would have remembered these famous last words
And thanks to John for offering to send the resistors I am putting order into Hi-FI collective so can add them in are 0.5watt ok for R8/R9

I have just come across the full builder’s manual for the PSU 3. And see that the outputs on the schematic don’t have C3- C4 plus the 200v Zener for the CF pre-Amp on the schematic but looking at the images in the manual shows placements for them but not fitted I am assuming I can just fit them in as normal to run the CF pre as before on the PSU2.
Thanks
Colin

[bob orbell]

Spot on Colin, I have now configured mine with HT regulators, works and sounds very good. Bob