开云体育

I can see a couple of potential issues:

1. The transformer voltage should be the off-load voltage rather than the rated voltage. If you can't find out from the transformer manufacturer, try taking the rated voltage of 240V and adding around 5%-8%
2. I think 96mA is a very high current draw for a single 6V6 and an EF86, I would be inclined to go for around 50mA in the absence of solid data

Try those and see if the results end up being closer to what you expect.

Regards,
Duncan

Thanks for the clarification regarding off-load voltage and rated voltage.

About the current draw... the schematic is for a stereo amp so I estimated around 96mA for two 6V6 and two EF86. The arrow at the node that reads 258V translates as "To other channels."

That said, maybe I'm reading the schematic wrong and the 258V reflects only that one side of the amp... but wouldn't you model the entire current draw (all tubes) on the power supply?

Thanks for letting me know about the other channel, it was in Japanese, but I should have done the decent thing and waved Google Translate over it, apologies.

I've keyed your schematic into PSUD2 and I'm getting exactly the same results. I tried it in (the unreleased) PSUD3 and it's giving 10V more and a "thump" at the start. So there's a problem in PSUD2. If you simulate PSUD2 for about 10-20mS it shows a substantial amount of dithering so the simplified model is getting confused.

Here's what PSUD3 shows:



Here's the bump at the start in more detail:



By increasing the transformer off-load voltage to 260V which is a typical value (base + 8%) it will give 257-258V output. However, the results are still low on PSUD2, here's the dithering at the start of the simulation I mentioned earlier - a sure sign that it's struggling to do the calculations:



Conclusion: PSUD2 has some holes in the simulator and they are showing up on the schematic you keyed in. There's no bug fix that I can apply as the PSUD2 simulator engine is broken as designed. I'll put a beta of PSUD3 out on here about 2nd / 3rd week in August; being a beta it will probably have a few issues of it's own but at least it's accurate and any issues that are found should be fixable.

Regards,
Duncan

Hi Duncan,

Thank you so much for your thoughtful response.?

I thought I was going crazy, glad to know it wasn't just me. I wonder what that thump is all about?

That said, the programs is wonderful and look forward to PSUD3 later this summer.

Best,
Jonah

Hi Jonah,

The thump is to be expected - the CLC filter is a resonant item. Solid state rectifiers apply power straight away and the sudden increase in voltage to the system causes the CLC filter to resonate slightly. I didn't see it on PSUD2 which is what made me think something was wrong.

Regards,
Duncan

Regarding the offline transformer voltage to use. When I have the actual transformer, I measure the actual secondary open circuit voltage. With the transformer already in the circuit, which I think is so in your case, I would just pull out the 5Y3 rectifier so you can measure the unloaded voltage. You can also measure the actual secondary resistance with the circuit powered down. I realize that you are already on the path to fix an issue with PSUD2 but it's nice to know the actual characteristics of your power transformer when possible. When I do the measurements that I described, I often find variations from the printed schematic values.
Cheers,
Tom