I have the first version of the BH EL34 boards, with power supply onboard.
Just consider that the negative voltage supply is filtered through an RC with R being 270 Ohm and a current of few mA, that means way less than 5V drop, so that’s why that table is fine and the voltage supply won’t change (or better, will change less than what will be due to the 115/230V variation).
Just consider that the negative voltage supply is filtered through an RC with R being 270 Ohm and a current of few mA, that means way less than 5V drop, so that’s why that table is fine and the voltage supply won’t change (or better, will change less than what will be due to the 115/230V variation).
I think I'm missing something....
On the latest group buy PCB's, the PSU has +HV, -Vbias, +Vdriver and I can see where these connect to the amp board.
What is the 15vDC supply for?? (refer bottom left in the attachment ie not the +15v driver supply).
Thanks
Andrew
On the latest group buy PCB's, the PSU has +HV, -Vbias, +Vdriver and I can see where these connect to the amp board.
What is the 15vDC supply for?? (refer bottom left in the attachment ie not the +15v driver supply).
Thanks
Andrew
Attachments
Making progress!
The boards are stuffed and soldered. The case is nearing completion, although I managed to drill a hole in the wrong position. I think I'll be able to cover it up. The finish will probably be black Hammerite on the aluminium with wood side panels.
The transformers from Toroidy showed up yesterday, and the output transformers look fantastic. Really massive things. The power supply was tested today, and it worked without blowing up. I will test the amp boards later this week, before taking it all apart and finishing the case.
The boards are stuffed and soldered. The case is nearing completion, although I managed to drill a hole in the wrong position. I think I'll be able to cover it up. The finish will probably be black Hammerite on the aluminium with wood side panels.
The transformers from Toroidy showed up yesterday, and the output transformers look fantastic. Really massive things. The power supply was tested today, and it worked without blowing up. I will test the amp boards later this week, before taking it all apart and finishing the case.
Attachments
Hi 77seriesIII,
The chassis is from eBay (China). The block with the heat sinks is a DC-DC buck converter which steps down the voltage on the PSU-board (15V to 6.3V). I'm not the best person to ask exactly why it's being used, but you can find more information about it earlier in this long and rather unwieldy thread. Search for "buck", "dc-dc".
Trond
The chassis is from eBay (China). The block with the heat sinks is a DC-DC buck converter which steps down the voltage on the PSU-board (15V to 6.3V). I'm not the best person to ask exactly why it's being used, but you can find more information about it earlier in this long and rather unwieldy thread. Search for "buck", "dc-dc".
Trond
Hi,
See the attached post by Marc some time ago, shows connection of buck converter to linked 6.3 outputs on the Toroidy power transformer.
See the attached post by Marc some time ago, shows connection of buck converter to linked 6.3 outputs on the Toroidy power transformer.
This is chassis I'm using: Aluminum Wood Panel Chassis for Tube Amplifier Metal Case Amp Box DIY Enclosure | eBay
Did you set the buck converter to max current and then adjusted the voltage back to 6.3 v without load first?
Yes, I adjusted the voltage to 6.3v without load, after having turned the current adjustment many turns clockwise (they don't seem to come to a stop). I then installed the tubes, checked the voltage again and then adjusted the current until it started to drop.
Perhaps adjust to allow more current for the initial heating up period, or the voltage could drop until heated.
Everything looks correct in your set up. What tubes are you running?
Everything looks correct in your set up. What tubes are you running?
I tested with JJ EL34 and 6N2P tubes. Also tried ECC83. Double checked the jumper setting when switching between 6N2p and ECC83.
Measured current into the buck converter to 3.4 Amps with all tubes installed. With only 6N2P installed it dropped to 0.3 Amps (rectifier quite warm, but not super hot).
Is it possible that the rectifier is defective? Seems more plausible that I have made a mistake somewhere I think.
Measured current into the buck converter to 3.4 Amps with all tubes installed. With only 6N2P installed it dropped to 0.3 Amps (rectifier quite warm, but not super hot).
Is it possible that the rectifier is defective? Seems more plausible that I have made a mistake somewhere I think.