Aleph J illustrated build guide

Jump to Latest
#682
I am using 5U chassis and the diodes in the bridge are really hot - hotter than the output transistors. I do not have a thermometer but I cannot hold my hand on their radiators for long. I use radiators that came with the kit from 6L6 - pretty big actually. I set the bias at 500mV. Should I decrease it? Thank you!
 
#685
17 volts at output

The first time I powered up the amp I had 17 volts at the output I have replaced the MOSFETS ( found a piece of solder across the pins) still have 17 volts however if I adjust r7 I can lower it to half. As I increase the voltage at 50-60 volts the offset is neg. the right channel powered up at 417mv bias and 12mv offset and has been adjusted to specs. Don't know what to do now.
 
#689
6L6 said:
Something is wrong, they should get only warm.
Click to expand...
I disconnected both amp boards (with CRC connected) and the diodes are cold. I connected amps one by one and the diodes get warm. I connected both amps and the diodes are hot again. It does take some time to warm up and they get hot only when I close the chassis. I use 400W Antek transformer and it gets a little warm. With 500mV I understand that the total current from the power source is about 4A. I assume that it drops about 0.7V on a diode so it's about 2.8W / 4 = 0.7W per diode. Should be barely warm with these radiators.

The amp seems to work just fine! I wish I had a scope. I would appreciate any thought!
 
#690
Finally was able to take some photos. The slow start board is from the ebay: 110V 220V Class A Power Soft Start Delay Temperature Protection Board | eBay. It's really piece of junk and I will replace it in the future. I did try without this board with the same results.

Never posted images on this forum. Hopefully it will work fine.

An externally hosted image should be here but it was not working when we last tested it.



An externally hosted image should be here but it was not working when we last tested it.



An externally hosted image should be here but it was not working when we last tested it.



An externally hosted image should be here but it was not working when we last tested it.
 
#694
I have a F5T using those exact diodes and heatsinks, and they do get warmer than I remember - they pass the 10-second test, meaning that after 10 seconds holding them they are rather uncomfortable, but there is no need to let go.
 
#695
17 volts at output

First off let me say to ZM I'm sorry for blowing you off the other day and for the stupid questions. My mom died and I've had to deal with that. Anyway I need to think about something other than that so I've taken some measurements. R8-8.5 volts R17 0 volts and 17 volts at R18. What now?
 
#696
life first , hobby second ;

sad to hear for your loss .

regarding amp - I repeat - post either exact schm or link to it

also - when you say voltage at resistor ......... try to use terms as "across" or "ref. to gnd , node wit xx" , corresponding to actual measurement
 
You must log in or register to reply here.
Top Bottom