Resistance Question - Voltage Error
- Thread starter schweigc
- Start date
Yes, those readings just need to not be anything resembling 0 Ohms.
-PB
-PB
Thanks for the response. I did my Voltage checks and I have some problems. First the LED on A3 does not light and none on the Low Current board and the high current board near the power switch. The Following are my Voltages:
LC Cs4:
IA: 149.5 V
OA: 75.5 V
KregA: 5.9 V
bRegA: 149.5 V
IB: -297 mV
OB: -.71 V
KregB : 1.24 V
bRegB: -294 mV
HC Cs4 (Near Selector Switch)
IA: 205.5 V
OA: 149.5 V
bA: .5 mV
IB: .5 mV
OB: 95 V
bB: 149.5 V
HC Cs4 (Near Power Switch)
IA: 1.5 V
OA: -275 mV
bA: .2 mV
IB: .2 mV
OB: .466 V
bB: - 215 mV
HJ:
Tip: 0
Ring: 48 mV
Any ideas? Thanks,
LC Cs4:
IA: 149.5 V
OA: 75.5 V
KregA: 5.9 V
bRegA: 149.5 V
IB: -297 mV
OB: -.71 V
KregB : 1.24 V
bRegB: -294 mV
HC Cs4 (Near Selector Switch)
IA: 205.5 V
OA: 149.5 V
bA: .5 mV
IB: .5 mV
OB: 95 V
bB: 149.5 V
HC Cs4 (Near Power Switch)
IA: 1.5 V
OA: -275 mV
bA: .2 mV
IB: .2 mV
OB: .466 V
bB: - 215 mV
HJ:
Tip: 0
Ring: 48 mV
Any ideas? Thanks,
The high voltage just isn't available to one channel.
This starts at IA on the board where you aren't seeing ~200V.
On the lucky end of things, half your amp is working perfectly. Both IA pads wire to B+, what voltage do you measure at terminal 24 vs. terminal 30? If you have very low voltage at one of these terminals, which feeds that flaky IA, and your 270 Ohm resistor isn't smoking, then you have a flaky solder joint preventing the B+ from making it's way to that channel.
-PB
This starts at IA on the board where you aren't seeing ~200V.
On the lucky end of things, half your amp is working perfectly. Both IA pads wire to B+, what voltage do you measure at terminal 24 vs. terminal 30? If you have very low voltage at one of these terminals, which feeds that flaky IA, and your 270 Ohm resistor isn't smoking, then you have a flaky solder joint preventing the B+ from making it's way to that channel.
-PB
Sure, those ought to work just fine.
-PB
-PB
Do you have a backwards 220uF capacitor?
Yes, that is correct.
The next step would be to check the connections and jumpers on the large C4S board with the low voltages. Somewhere, there is a jumper that isn't where it's supposed to be, or a connection has been reversed that is creating quite a short in your amplifier.
-PB
The next step would be to check the connections and jumpers on the large C4S board with the low voltages. Somewhere, there is a jumper that isn't where it's supposed to be, or a connection has been reversed that is creating quite a short in your amplifier.
-PB
Ok, I'll check it over. When I find the problem and replace the 270 Ohm resistor again, I will have to clean up the 2 terminal blocks as well. If I damage a rectifier while doing this can I replace it with any UF4007 rectifier? What I have on hand is mouser # 625-UF4007 E3/54.
The rectifiers should be fine, you'll just need to find the wiring error that is causing that excessive current consumption.
You can temporarily remove the red going to IA on the big board of the offending side, then check the voltage at the 220uF capacitor after the 270 Ohm resistor that is smoking. In my opinion, you will not find an issue with this testing, but it will eliminate the capacitors, rectifier diodes, and resistors in the power supply.schweigc said:
It's really important not to fixate on which LED's do and don't light up. You have a short in your amplifier that is drawing enough current to blow up a 5 Watt resistor quite quickly. This would tend to be a significant wiring error or two components touching that shouldn't be.schweigc said:
It can often be helpful to post some photos of your build also, in particular the high current C4S board on the offending side, as well as the small PC board in the middle (top and bottom), and the 7 pin and 8 octal socket.
-PB
I swapped the high current boards and I get the same voltage readings. So I have been focusing on the low current board. I have noticed that the A & B sides are symertrical except for the outboard -reg. On the A side it is attached to 1U but is empty on the B side. Is this accurate?
There should be a jumper to -reg. If you didn't have this jumper, you wouldn't have the issues that you're having, but if this jumper isn't in the correct place, it could cause some issues.
Regardless, the C4S that is IA/OA should limit the current drawn from the power supply, which makes me suspicious that there is an error on that PC board.
Regardless, the C4S that is IA/OA should limit the current drawn from the power supply, which makes me suspicious that there is an error on that PC board.
