Help Phono 2 PSU HT High

[colin.hepburn]

HI All
OK I have been running my Phono 2 for about 5 years plus now knowing phono HT was a little high @367v but phono works fine at this voltage
However, today I decided to add the other parts to run my WAD CF Pre
So following the CF guide in FAQ

I added R4 to 18K add new ZD1 200v diode and 100uf 450v cap
HTvoltage off load phono is 367v as before CF HT is the same at 367v
Checking voltage of the cathode side off ZD1 364v Anode 270v installed ZD1 as marked on the PCB

[colin.hepburn]

Panic over forgot to solder underside of board
New off load Voltages are phone 334v CF HT is now106v the drop is now to low CF calls for 200v under load

[bob orbell]

I was just looking at your post Colin, saves me getting the books out. BOB

[Richard]

Hi Col shouldn't the anode be at 0V? Is signal ground missing or made by an external connection?

Ah, see you found it

[colin.hepburn]

Originally Posted by bob orbell

I was just looking at your post Colin, saves me getting the books out. BOB

Hi Bob
Yep trying to get that WD CF pre I got from you up and running its been in the loft but WAD PSU Pre HT is now only 106v Off load it would be some think like 220v i think R4 is the 18k as the faq instructions

[colin.hepburn]

Dam it i have just wiped my DMM out 100 lines i need to remember to switch back from ohms the DCV luck is its a cheapo DMM **** all work stopped

[bob orbell]

Sod doing the lines Colin, get caned instead, its quicker. Think you need check the PSU out, you should have 345 no load to phono, 210 no load to PRE, 250 loaded phono and 200 loaded PRE. Cant remember if I put a capacitor and load resistor in PRE?. We all await the arrival of your new meter, Fluke are very good but pricey, but you may never need to buy another. BOB

[colin.hepburn]

Originally Posted by bob orbell

Sod doing the lines Colin, get caned instead, its quicker. BOB

Yep trouble is the hangover takes longer to go away these days thou
Yes, you did put a resistor and cap in the pre BOB
It’s the psu phono out is 335v pre out 106v
Added R4 18k ZD1 is a 1N5378B 3.3v 200v 5w cap 100uf 450v
One thing is I checked the choke with my LCR choke marked on label 15H LCR said 5.5H Resistance is 496R maybe the LCR thou i have been advised that thay are inaccurate reading inductance

[bikerhifinut]

Originally Posted by bob orbell

Sod doing the lines Colin, get caned instead, its quicker. Think you need check the PSU out, you should have 345 no load to phono, 210 no load to PRE, 250 loaded phono and 200 loaded PRE. Cant remember if I put a capacitor and load resistor in PRE?. We all await the arrival of your new meter, Fluke are very good but pricey, but you may never need to buy another. BOB

I bought one of the middle range Maplins DMM's, True RMS reading, and a few other useful things like a capacity range. But the good thing was that its got overload protection so if you accidentally leave it on resistance it cuts out and doesnt fry itself............. yep I have done it too! I think it was only about £60.
I also have an old fashioned Moving coil multimeter and an AVO model9 which I bought for not a lot at an audiojumble all serviced etc. I use these for the initial testing and also any automotive work where DMM's can sometimes give false readings. Both 20k per volt and perfectly good for our valve gear. In fact I prefer to Avo up the voltages on my Leak as it was originally specified using an AVO 8, DMM's can give slightly high readings especially on the lower voltages where the resistance of the moving coil meter can have an effect.
A bit off topic but maybe worth a ponder?

A.

[colin.hepburn]

Right i have just rechecked the manufacturer of Zener Diode I have as a on-semiconductors Data sheet says 3.3v 200v seems this 1n5378B can be a 100v depending who make it the zener i have has ON marked on its case i take it this is a on-semiconductors zener Diode