I'm hoping to draw on the knowledge and insight of this community to help me prevent a problem with my 845 power amp. I've attached a schematic of the circuit in question (filament circuits not shown).
I built this amp about 4 years ago, it sounds amazing and I love it. but during its life, on two separate occasions, something has happened that has rendered my power transformer inoperable. It seems as though the secondary has internally shorted. Now I believe in both cases this was in response to my rectifier tubes dying in some fashion.
In my schematic you can see the most recent design, which includes 1KV 600mA fast blow fuses in each leg of the HT secondary. I am hoping that if the rectifier dies in the future that these fuses would pop before the secondary has a chance to short.
I am wondering if there are any other suggestions anyone has to protect this (rather expensive) power transformer that I have just received from Monolith.
Any help is greatly appreciated.
I built this amp about 4 years ago, it sounds amazing and I love it. but during its life, on two separate occasions, something has happened that has rendered my power transformer inoperable. It seems as though the secondary has internally shorted. Now I believe in both cases this was in response to my rectifier tubes dying in some fashion.
In my schematic you can see the most recent design, which includes 1KV 600mA fast blow fuses in each leg of the HT secondary. I am hoping that if the rectifier dies in the future that these fuses would pop before the secondary has a chance to short.
I am wondering if there are any other suggestions anyone has to protect this (rather expensive) power transformer that I have just received from Monolith.
Any help is greatly appreciated.
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I would recommend you do some fuse assessment using the PSUD2 simulator, along the lines of the linked article, as a means to provide some justification for your choice of fuse.
https://www.dalmura.com.au/static/Valve%20amp%20fusing.pdf
I also recommend you insert an ss diode in series with the anode of each 6CJ3. The choice of a suitable ss diode would require some selection from what you can easily obtain, but could be as simple as say 4-5 1N4007 in series - some design guidance is provided in the link below.
https://www.dalmura.com.au/static/Power%20supply%20issues%20for%20tube%20amps.pdf
https://www.dalmura.com.au/static/Valve%20amp%20fusing.pdf
I also recommend you insert an ss diode in series with the anode of each 6CJ3. The choice of a suitable ss diode would require some selection from what you can easily obtain, but could be as simple as say 4-5 1N4007 in series - some design guidance is provided in the link below.
https://www.dalmura.com.au/static/Power%20supply%20issues%20for%20tube%20amps.pdf