New Construction. Some issues solved. Some not. Need advice.

[harv-e]

OK.  Found OA and 1A....they were blocked by the heat sinks and I missed them.  And the scale was incorrect on breg and +reg.  The readings are as follows:

LEFT    OA 224   1A 273   breg 224   +reg 225
RIGHT  OA 224   1A 273   breg 224   +reg 224

[harv-e]

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

[harv-e]

Hi.  Just curious about suggestions for the next step since all suggestions have been followed through and things have been quiet here since my last post with all voltages a few weeks ago.   Thanks.

[Paul Birkeland]

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

[Grainger49]

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".

[harv-e]

Photo 1

[harv-e]

Photos 2

[Paul Birkeland]

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

[harv-e]

Good advice on the layout stuff.  I'll go through it and see what I can "tighten up."

There were four resistors missing that I did make substitutes for.  But with the issue persistent with the inputs shorted I negated this as the source of the trouble.

Harvey

[Paul Joppa]

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

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]

Hello.  I finally got around to taking the preamp out and resoldering the connections.  Tested it......and found a new issue that I can't seem to solve.  Looking at the kit from the back, the lower left light on the middle board is out and all the lights are out on the right lower board.  I can't seem to find the broken connection on the middle board.  Can you steer me towards the right direction?  Thanks.

[Paul Birkeland]

Hello.  I finally got around to taking the preamp out and resoldering the connections.  Tested it......and found a new issue that I can't seem to solve.  Looking at the kit from the back, the lower left light on the middle board is out and all the lights are out on the right lower board.  I can't seem to find the broken connection on the middle board.  Can you steer me towards the right direction?  Thanks.

Voltages?

[harv-e]

Here are the voltages:

Line  125

Power Supply Board
T4/5  8.6             T6/7  134            6.3vDC measures 6.22              275vAC measures 318

Regulator Board
Left A side:    bA  0      Kreg 0.7       OA  0      IA  316      breg 0      +reg 0
Right B side:  bB 0       Kreg 8.8       OA 224   IA 317       breg 224  +reg 223

Left lower board:     Kreg 1.36     breg 99.6       OB 98.1       OA 145.5     bA 0 IA 224
Right lower board:   kreg 0          breg 0            OB -.02        OA 0            bA 0 IA 0

Thanks.  Any help would be GREATLY appreciated.

H

[Paul Birkeland]

Your regulator board is not passing any voltage through on one side.  I'd do your best to reheat all the "A" side joints.

-PB

[harv-e]

I tried reheating the joints.....no joy.

Could you please be a little more specific as to where the issue might be?  I can read schematics, so that is not a problem for me.  Oddly, now that I have gone over the schematic, D1 on the A side is out but D2 is working. The only way I can see this happening is if R1 is shorted.  Yet with D2 lit, power should be getting to  V2.

Any ideas from this point?

Thanks.

H