Is it producing both positive and negative rail and regulated voltages?
Does the amp have a preamp board connected to the main board via a ribbon? If so, confirm that the preamp board is receiving regulated voltage and confirm that audio is getting from the preamp board to the main board.
If it's using the plastic RCA jacks, confirm that the shield ground connection is not broken.
Does the amp have a preamp board connected to the main board via a ribbon? If so, confirm that the preamp board is receiving regulated voltage and confirm that audio is getting from the preamp board to the main board.
If it's using the plastic RCA jacks, confirm that the shield ground connection is not broken.
ok heres what i have on the outputs
on the tip41 c 1.88
a968 1.48
c2238 1.18
then there 2sc or 2sa chip i cant make out the numbers since they are worn off but they read 1.18
all middle legs is where im getting my readings and ground to the chasis of amp
Getting no negative reading on the middle legs of theese parts
on the tip41 c 1.88
a968 1.48
c2238 1.18
then there 2sc or 2sa chip i cant make out the numbers since they are worn off but they read 1.18
all middle legs is where im getting my readings and ground to the chasis of amp
Getting no negative reading on the middle legs of theese parts
I'd probably use an IRFZ44. What value are the gate resistors?
When measuring the voltage on the primary side of the power supply, you need to use the chassis ground terminal as the reference (black probe). When measuring the voltage on the secondary side (audio side -- outputs, op-amps...), you need to use a non-bridging speaker terminal or the secondary center-tap on the power transformer. On many amps, you can use the chassis ground terminal for all measurements but on some of the old Lanzar and ZED amps (and a few others), the secondary is completely isolated from the primary and you have to use the proper ground. Here, it appears that you were not using the chassis ground because the 3rd leg of the FET is directly connected to chassis ground and should have read ~0.00v DC.
When measuring the voltage on the primary side of the power supply, you need to use the chassis ground terminal as the reference (black probe). When measuring the voltage on the secondary side (audio side -- outputs, op-amps...), you need to use a non-bridging speaker terminal or the secondary center-tap on the power transformer. On many amps, you can use the chassis ground terminal for all measurements but on some of the old Lanzar and ZED amps (and a few others), the secondary is completely isolated from the primary and you have to use the proper ground. Here, it appears that you were not using the chassis ground because the 3rd leg of the FET is directly connected to chassis ground and should have read ~0.00v DC.
Follow the circuit back. Does the gate resistor go to a PNP driver transistor?
You'll need to reduce the value of those gate resistors. Anything between 47 and 100 ohm resistors should be OK with the Z44s. After you get the amp working, you'll need to reduce the power supply voltage from ~13.5v to ~11v. If the current draw drops or remains the same at the lower power supply voltage, the supply is likely OK. If the current draw increases when you decrease the power supply voltage, you'll need to do further testing.
You'll need to reduce the value of those gate resistors. Anything between 47 and 100 ohm resistors should be OK with the Z44s. After you get the amp working, you'll need to reduce the power supply voltage from ~13.5v to ~11v. If the current draw drops or remains the same at the lower power supply voltage, the supply is likely OK. If the current draw increases when you decrease the power supply voltage, you'll need to do further testing.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.