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I've just added 2 relays to my custom amp. They are both dpdt 12v relays. One is a DS2Y http://pewa.panasonic.com/pcsd/produ...f_cat/ds2y.pdf.
The other is a JW2SN http://pewa.panasonic.com/pcsd/produ...ech_eng_jw.pdf. These 2 relays control a few things. One of the relays (JW2SN) controls the amplified zeners which drop the B+ and screen voltages, the other relay (DS2Y) controls a paralleled bias resistor and a paralleled cathode resistor. All in all they control dropping the plate/screen voltages and the bias operation of the power tubes. Basically I'm dropping plate and screen voltages by 200v and then rebiasing the tubes to maintain the same quiescent current. I previously had this setup as a mechanical dpdt switch which only controlled the amplified zeners for the screens and B+, and was not changing the bias. While that technically worked with no problems, the tubes were in cutoff and not sounding right. So I concluded I needed 2 dpdt relays to control the 4 elements. With me?
Here's the problem, now the amp makes a "crack" noise, like shorting a filter cap to ground kind of a sound, then hums like it's drawing lots of current. I smelled some burning and shut it off right away. From the datasheets it seems these relays are rated to work at this voltage and current. I'm wondering if my regulated relay supply is the problem. I'm attaching the schem if someone can take a look and see if they can help out with this. Yes I have the reverse biased diode across the relay supply contacts. Also of note is that the 2 new relays are in parallel w/ eachother and turned on/off simultaneously so I used 1 reverse biased diode (1n4002) for both. Not sure if that's bad practice. This is all in the "Tweed Mode" box of the power supply schem.
The other is a JW2SN http://pewa.panasonic.com/pcsd/produ...ech_eng_jw.pdf. These 2 relays control a few things. One of the relays (JW2SN) controls the amplified zeners which drop the B+ and screen voltages, the other relay (DS2Y) controls a paralleled bias resistor and a paralleled cathode resistor. All in all they control dropping the plate/screen voltages and the bias operation of the power tubes. Basically I'm dropping plate and screen voltages by 200v and then rebiasing the tubes to maintain the same quiescent current. I previously had this setup as a mechanical dpdt switch which only controlled the amplified zeners for the screens and B+, and was not changing the bias. While that technically worked with no problems, the tubes were in cutoff and not sounding right. So I concluded I needed 2 dpdt relays to control the 4 elements. With me?
Here's the problem, now the amp makes a "crack" noise, like shorting a filter cap to ground kind of a sound, then hums like it's drawing lots of current. I smelled some burning and shut it off right away. From the datasheets it seems these relays are rated to work at this voltage and current. I'm wondering if my regulated relay supply is the problem. I'm attaching the schem if someone can take a look and see if they can help out with this. Yes I have the reverse biased diode across the relay supply contacts. Also of note is that the 2 new relays are in parallel w/ eachother and turned on/off simultaneously so I used 1 reverse biased diode (1n4002) for both. Not sure if that's bad practice. This is all in the "Tweed Mode" box of the power supply schem.
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