converting tube rectifier to solid state rectifier.

[tubo]

hi,


please help. i converted my 5y3gt rectifier to a IXYS DSEI8 solid state rectifier and the fuse keeps blowing up. i i wired the anodes of the ss diodes to the power trans secondary and wired the cathodes together to the 1st filter cap.

1. did i wire something room? cause ive rechecked.
2.is the sand diode not appropriate

here is the data sheet and scheme.

http://ixdev.ixys.com/DataSheet/DSEI...DSEI8-06AS.pdf
6v6 music machine build help!



thanks pls help.

[kevinkr]

I can only surmise one or both of your rectifiers is bad since their 600V peak repetitive reverse voltage rating (VRRM) is far too low for this application.

Based on an off the cuff calculation these diodes probably have over 800VRRM on them at nominal line in your circuit - I would expect they would short more or less instantly under these conditions.

Two of these in series per leg, or a much higher VRRM rated diode is required here. I don't think even 1kV diodes leave enough margin for line transients and other line borne issues.

[DougL]

please help. i converted my 5y3gt rectifier to a IXYS DSEI8 solid state rectifier and the fuse keeps blowing up.

What is your goal in making the conversion?
The tube rectifier has low switching noise and slower startup compaired to SS diodes.

If I were making the conversion, I would completely redesign the power supply using PSUDII, and a regulator if necessary.

Doug

[kavermei]

Unrelated to the fuse blowing but important to remember is that the resulting B+ will be quite a bit higher with SS rectification than before. If the B+ is not regulated, this will cause all tubes to run a little "hotter". It will also build up B+ much faster so I would recommend to definitely have a standby switch and allow the tubes to heat up prior to applying B+.

[Arnulf]

... and to put some voltage dropping resistors ahead of diodes.

[Ultima Thule]

tubo,

how quickly does your fuses blow?

If it happens more or less instantly it might be because of following, your SS rectifier conducts current instantly and when you switch on the power the PS filter caps draws a hefty current at power up, in that case you have to incorporate a soft starter.

[Ultima Thule]

couldn't edit my post any more, but...

I had look at the schematic in the first post of your link, if you replace the 5Y3 with SS, you must have 1000 Volt diodes! Your 600 Volt diodes may be dead...

Between point 4 and 6 you have (340+340)*sqr2 ~960 Volt Pk-Pk

[satelitis]

Originally Posted by tubo

hi,


please help. i converted my 5y3gt rectifier to a IXYS DSEI8 solid state rectifier and the fuse keeps blowing up. i i wired the anodes of the ss diodes to the power trans secondary and wired the cathodes together to the 1st filter cap.

1. did i wire something room? cause ive rechecked.
2.is the sand diode not appropriate

here is the data sheet and scheme.

http://ixdev.ixys.com/DataSheet/DSEI...DSEI8-06AS.pdf
6v6 music machine build help!



thanks pls help.

I believe that you haven'd disconnected the 5V from the circuit. Do this and I think everything will be back to normal, except a higher output voltage. So both the cathodes of the SS diodes will be connected directrly to the common node of the 1uF Capacitor and the 10mH choke.

Chris

[analog_sa]

Originally Posted by DougL

What is your goal in making the conversion?

To kill the sound? It apparently achieved even more.

[Nige64]

Turbo,

If you really want to change to solid state rectifier, then i would check that the 5v heater for the tube recifier has been isolated from the circuit.The piv for the diodes should be rated at least double your secondary voltage, I use 1n4007 or connect 2 in series to make sure as they are cheap enough. You would expect to see an increase in your ht voltage of about the voltage drop thro the 5y3gt, could be as much as 30v. removing the 1uF cap thats there and connecing straight to the choke will turn it into a choke input filter (you would have to check the choke is suitable for choke input) this would lower your ht voltage and provide better regulation. agree psudii is a usefull program and might help you also.