Hi,
A long time ago i bought one set of aleph boards from Chipamp. I am now in the process of finishing them.
I have populated the boards as per the "Brians PCB Aleph - parts list" see attachment. I cannot remember where i got the parts list, perhaps from Chipamp.com before it closed..
It is a dual mono config with 2x25vac Toriods.
These are my findings when power voltage is +/-34 vdc from PS:
The output transistors does not heat up, just 2,2mv across R40 and even less on R39.
Q1, 2, 3 does heat up.
Voltage over z5 = 9V
Voltage over R8 = 5,2V
Voltage over R18 =3,3V
Q5 Gate to source =1,6mV
DC on output = 96mV
Any thoughts?
Appreciate all input
A long time ago i bought one set of aleph boards from Chipamp. I am now in the process of finishing them.
I have populated the boards as per the "Brians PCB Aleph - parts list" see attachment. I cannot remember where i got the parts list, perhaps from Chipamp.com before it closed..
It is a dual mono config with 2x25vac Toriods.
These are my findings when power voltage is +/-34 vdc from PS:
The output transistors does not heat up, just 2,2mv across R40 and even less on R39.
Q1, 2, 3 does heat up.
Voltage over z5 = 9V
Voltage over R8 = 5,2V
Voltage over R18 =3,3V
Q5 Gate to source =1,6mV
DC on output = 96mV
Any thoughts?
Appreciate all input
Attachments
The input 9610's (Q1-3) and even the ztx450 (Q4-5) are matched. Both cards shows the same values under test. I have populated the cards as per the BOM posted.
If there is an error i must have made it on both cards.
I have checked the cards and it looks like the parts are installed in the right places
Any sugestions to what to look for?
If there is an error i must have made it on both cards.
I have checked the cards and it looks like the parts are installed in the right places
Any sugestions to what to look for?
I just looked up the Vgs for a batch of 9610s I matched for a Group buy. 3.8volts would be pretty typical for. Looks like 23.5ma total current but only 8.4m across r18. 3.8volts is not enough to turn on the output fet. I see a lot of resistors are TBD. Do you have the recommended values in place? If you can’t find any problems you could try a 1k pot in place of R18. Start with it at 0 ohms and adjust it for the correct bias current.
Hi, have tried both shorted and not, theres no difference, the amp acts the same. Also no load on spk output.inputs shorted , no load , while setting
Hi, yes i'm starting to suspect that. Q4 arrangement is some kind of limiter/protection circuit? Bussy at home to day, havn't had time to look at this, will try to morrow.Could Q4 be conducting and preventing the voltage from going higher? Check Q4 orientation to make sure it’s the correct pin out. Also check Vbe to see if it’s conducting.
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