Grainger49
New member
The voltage checks are typically from a point, terminal or PCB pad, to ground. PB is asking you to measure from one PCB pad to another. It just might be different.
New Construction. Some issues solved. Some not. Need advice.
- Thread starter harv-e
- Start date
OK. Maybe I'm not understanding. The lower right hand corner of the power supply board, next the the nut on the screw, has a + and a - "pad" just under the 6.3vDC stencil. I checked this voltage with the two probes from the meter. Then moved the negative probe to pin 23 of the terminal strip, leaving the positive probe at the + on the power supply PC board. These two voltages were the same.
Is this what is being asked?
Harvey
Is this what is being asked?
Harvey
Grainger49
New member
That is good. The measurement on the board says that it is producing the right voltage, the measurement to a ground lug says that the circuit is grounded as it should be. (I'm assuming you are saying that the voltage is right.)
Do let us know about the other meter, getting anything that is lower than about 6.25V or higher than 6.35V is very suspicious there, and getting the same voltage with your black probe in the two different places tells us that your grounds are wired in.
On the other hand, if you do end up finding that you have that very low voltage there, you have have found the entire problem with your Eros (but good to double check before we go further).
-PB
On the other hand, if you do end up finding that you have that very low voltage there, you have have found the entire problem with your Eros (but good to double check before we go further).
-PB
OK. Borrowed a friends GB meter. Here are the voltages with this meter.
Line 119.1
Power Supply: T4/5 8.5vAC T6/7 126.7vAC 6.3vDC measures 6.21 to pads (6.22 to ground pin 23) 275vAC measures 299vAC
LEFT Board Kreg 1.1 breg 95.4 OB 93.2 OA 158.5 bA 0 1A 297
RIGHT Board Kreg 1.1 breg 97.3 OB 96.6 OA 160.5 bA 0 1A 298
Hope this gives better information for you.
Line 119.1
Power Supply: T4/5 8.5vAC T6/7 126.7vAC 6.3vDC measures 6.21 to pads (6.22 to ground pin 23) 275vAC measures 299vAC
LEFT Board Kreg 1.1 breg 95.4 OB 93.2 OA 158.5 bA 0 1A 297
RIGHT Board Kreg 1.1 breg 97.3 OB 96.6 OA 160.5 bA 0 1A 298
Hope this gives better information for you.
Just a reminder about the underlying issue. The music sound and quality is terrific. But there is an underlying low frequency motorboating putt-putt noise coming out of both speakers that can be heard during quiet music passages and even with the turntable unplugged. Switching the tubes and tapping them has no effect.
Just a reminder about what this is all about.
Just a reminder about what this is all about.
We are getting somewhere now!
Measure the pads on the power supply board, specifically IA/IB, OA/OB, and Kreg.
-PB
Measure the pads on the power supply board, specifically IA/IB, OA/OB, and Kreg.
-PB
Yes, sorry, the regulator board just under the power supply board.
This board is the same board placed up front over the EF86 tubes, it has the "IA", "OA", "IB", and "OB" pads in all the same places.
breg and +reg can't be 1 with everything else you've told us, perhaps you need to turn the range up on the meter?
-PB
This board is the same board placed up front over the EF86 tubes, it has the "IA", "OA", "IB", and "OB" pads in all the same places.
breg and +reg can't be 1 with everything else you've told us, perhaps you need to turn the range up on the meter?
-PB
Putting it all in one place for you:
Line 119.1
Power Supply Board
T4/5 8.5vAC T6/7 126.7vAC 6.3vDC measures 6.21 to pads (6.22 to ground pin 23) 275vAC measures 299vAC
Regulator Board
LEFT A side: bA 0 Kreg 9.0 OA 224 1A 273 breg 224 +reg 225
RIGHT B side: bB 0 Kreg 8.9 OA 224 1A 273 breg 224 +reg 224
LEFT lower Board Kreg 1.1 breg 95.4 OB 93.2 OA 158.5 bA 0 1A 297
RIGHT lower Board Kreg 1.1 breg 97.3 OB 96.6 OA 160.5 bA 0 1A 297
Line 119.1
Power Supply Board
T4/5 8.5vAC T6/7 126.7vAC 6.3vDC measures 6.21 to pads (6.22 to ground pin 23) 275vAC measures 299vAC
Regulator Board
LEFT A side: bA 0 Kreg 9.0 OA 224 1A 273 breg 224 +reg 225
RIGHT B side: bB 0 Kreg 8.9 OA 224 1A 273 breg 224 +reg 224
LEFT lower Board Kreg 1.1 breg 95.4 OB 93.2 OA 158.5 bA 0 1A 297
RIGHT lower Board Kreg 1.1 breg 97.3 OB 96.6 OA 160.5 bA 0 1A 297
I'd pop up a couple of photos of the underside if you can. This is very odd, generally motorboating is a ground connection that's missing or a failing cap, but you appear to have neither.
-PB
-PB
Grainger49
New member
There is another cause of motorboating that I discovered the hard way. But it doesn't apply to the Eros. I got the poles of my coupling and output caps too close together in a PAS 3 rebuild and it made the woofers pump back and fourth a good 2".
The things that jump out at me are:
1. Long resistor leads, I'd go back and look at how they are installed in the manual, tightening them up a bit for consistency.
2. Non-factory 47K resistors at the inputs (Were they missing? Have any other parts been substituted?)
3. Ground wires everywhere. Look at the 6922 socket in the manual, all the black wires are laid against the chassis and tucked away nicely. I would try to mimic this as much as possible.
4. Similar to #3, wire routing between boards is up in the air, not tucked away as the manual shows.
5. Be sure the foil on the STP heater wires do not touch anything. I am looking at the 6922 socket, and wondering if the foil is contacting any parts? This is dealt with in the manual by stripping the black insulation back a fair amount, leaving a good length of exposed twisted pair so that the larger body and its foil can be positioned further away.
Let me know if any of these checks reveal anything. The layout stuff may seem nitpicky, but it can add up to an unstable circuit.
-PB
1. Long resistor leads, I'd go back and look at how they are installed in the manual, tightening them up a bit for consistency.
2. Non-factory 47K resistors at the inputs (Were they missing? Have any other parts been substituted?)
3. Ground wires everywhere. Look at the 6922 socket in the manual, all the black wires are laid against the chassis and tucked away nicely. I would try to mimic this as much as possible.
4. Similar to #3, wire routing between boards is up in the air, not tucked away as the manual shows.
5. Be sure the foil on the STP heater wires do not touch anything. I am looking at the 6922 socket, and wondering if the foil is contacting any parts? This is dealt with in the manual by stripping the black insulation back a fair amount, leaving a good length of exposed twisted pair so that the larger body and its foil can be positioned further away.
Let me know if any of these checks reveal anything. The layout stuff may seem nitpicky, but it can add up to an unstable circuit.
-PB
Paul Joppa
Moderator
The lower board IA (input to the A-side C4S) should be connected to the regulated voltage from the regulator board, so they can't be different - you are showing 225v on one, and 297v on the other. I assume this is a measurement error, since the highest voltage available anywhere off the PSU board is 273v (IA, IB on the regulator board) is 273v. Other than that, these all look quite good.harv-e said:
