D-lator finished but with voltage issues. (Solved)

[Guitarman18]

I've just finished my D-lator and all seems to be working except......

I'm using a 230V tranny, that should be putting out 135V into the standard voltage doubler. My house mains is 245V (UK ~+6%), so I'm getting 142V from my tranny, which is spot on, given the higher mains. The problem is that once rectified, at B+1 I'm getting 353V (not 368V) and at B+2 I'm getting 237V (not 256V) inspite of the fact that my mains is hotter than it should be. Are these voltages within 'acceptable ball park' or could it be that the diodes I used in my rectifier were taken out of a previous build and may have got shagged in the process?


My other issue is that my heater are up at 6.87V. Any opinions on the way forward?

Any thoughts will be greatfully received.

Many thanks in advance.

Cheers,

Paul.

[jelle]

These voltages should be fine EXCEPT the heaters....this will reduce tube life a lot. You could use a separate heater transformer. For one 12ax7 this should be cheap.

jelle

[Guitarman18]

Thanks for the reply jelle. What would your thoughts be as far as using resistors to drop the heater voltage or is this likely to put strain on the tranny?

[jelle]

I have never done that but I'd be interested to hear suggestions. A voltage divider along those 100 ohms resistors could work I guess.

Guys?

[Funkalicousgroove]

The posted D-lator voltages are not necessarily correct. The Transformer used in these is a triad R2C and it has a 115v primary. If you plug that into a 120v source you get higher b+

The other thing to check is that your filter caps are low ESR, and properly grounded.

[Guitarman18]

Funk wrote:

The posted D-lator voltages are not necessarily correct.

Funk, Would my voltages cause you any concern?

Heater wise, I'm going to lower the voltage with some series resistors, as in the article I found yesterday. http://www.tubecad.com/july2000/ . In my case 1 ohm on each leg should do it.

Funk wrote:

The other thing to check is that your filter caps are low ESR, and properly grounded.

That may be an issue. I salvaged the first stage caps from a previous build, so I will add a new set of caps to my next order to see how that might change things.

Cheers,

Paul.

[Funkalicousgroove]

You may consider running DC heaters that can be regulated.

If you disconnect the voltage doubler, what is the AC voltage of the red wires?


I had a situation kind of like this one over the weekend. Plugged in a new build, fired it up and it made 360v on the plates, turns out the main 220uf filters weren't grounded properly(still scratching my head there, it all looked and tested fine!) I replaced the power supply board, and now it's right at 440. A filter cap with High ESR, or a broken internal lead that makes an intermittent connection could cause similar issues.

Do you ever order from Radio Spares? gotta be cheaper than Mouser over there-

[Guitarman18]

Funk wrote:

If you disconnect the voltage doubler, what is the AC voltage of the red wires?

With the voltage doubler disconnected, I have 145V (Mains is 245V). 6%hot.

I see from UltraHookedOnPhonix's D'lator that his voltages were down 6% on the schem listings for both the CF and recovery, whereas mine is down by 10% on the recovery side and 15% on the CF side.

Having started this build four months ago, I realise I have the 'original Schem' values (e.g. 10K to ground on the CF and 1.5K on the cathode of recovery. Could this explain why the percentage difference on my CF side and recovery side are so different to other builds?

Do you ever order from Radio Spares? gotta be cheaper than Mouser over there-

Radio spares never quite seems to have all the required parts, so I'd have to use multiple suppliers. Also the exchange rate is pretty good still for buying from Mouser and shipping is a flat $25 (as cheap as shipping within Europe!). The killer is the duty. (I had to pay $65 on my Funk chassis- but it was worth it. )

[UltraHookedOnPhonix]

Before posting those voltages I was using the 15K dropping resistor but have since replaced it with a choke. I never bothered taking new readings becuase I found it to be quieter but voltages should be up slightly since the series resistance of the choke is around 150 Ohms VS the 15K.

You could try modifying the dropping string a bit to see more voltage.

[Funkalicousgroove]

Other than the heater voltage, the rest sounds fine to me. I would change to the 1.8K/27K cathode follower, other than that the important thing is to "Listen" to it.

The units I build don't have voltage anywhere near the voltage in the posted schematic, but like I said, those voltages are based on a trannie with a 115v primary getting 120v.

I have an R2C, and like all triad Magnetek trannies, the specs are printed right on it:

115vac
135v @ .015A
6.3v @ .9A


If it were my unit, I'd run the heaters regulated DC, and just play it and see how I like the sound-

[Guitarman18]

Thanks for the response UltraHookedOnPhonix. Initially I was only really concerned about my heaters, but the more I've reseached, I realise that A/C heater taps can be a bit hit and miss. (I guess I've been lucky in the past with my limited experience) They can easily be sorted though with the series resistors.
From memory glasman discussed aiming for voltages lower than mine, so now I'm not too sure if I should be concerned or not. Are there ideal voltages listed anywhere?

Given the tolerances of components, I'd say 10% isn't too bad, but that is again based on my limited experience. The resistors in my dropping string are 1% tolerance, so I suspect the guilty parties are my first stage filter caps, which supprises me that they could make so much difference. Hey ho, such is life

I've taken your advice and ordered a choke so I can see how that may change things.

Cheers,

Paul.

[Guitarman18]

Thanks Funk. I missed your response, we must have been writing posts at the same time.
I have spent time listening to it today, and even with my mock-up SE 6V6 D'clone, it does tame the top end in a great way. Cleans are particularly articulate and full, especially with the recovery bright switch on.
I wanted to build it with the original posted values a) because I didn't have the other parts at the time and b) so that I could hear how the sound changed with evolution.

Thanks everyone for your input, it's a good feeling to get my first official piece of HAD design up and running.

Cheers,

Paul.

[Guitarman18]

I have just completed mods to heaters (now running at 6.30V (lucky or what!!!)) and have converted to 1.8K/27K CF. Voltages now read B+1= 359, B+2= 260.

Thanks everyone for helping out.

Cheers,


Paul.