Help with Eros v reading and crackle red channel [resolved]

[Alby0521]

Hi all

I just finished to build the eros. Now the resistance checks on the pins 1 to 15 looks like I have about 15% more resistance constantly on all the pins that should have resistance. Example: on a 74k I will have 84kohm.

I went on and did the V check and all the points on the pc boards are spot on a part 1. This one is OA on the red side ( with the plate flipped that would be the left pc board. This OA reads 209 instead than 170. I tried the Eros in my system and as I was expecting the black channel works and the red channel I get very low signal (music) and lots of crackle. Is this related to the reading on OA pc board of the red channel? I can attach some pics if needed.
I already re soldered pin 9 and the red cable that goes to the OA board with the problem but nothing changed.
Please any help would be greatly appreciated!

Best

AB

 

[Paul Birkeland]

Pics are helpful.

On the channel that isn't working, it would be helpful to know these voltages on the C4S board siting above the EF86:

IA
IB
OA
OB
Breg (b)
Kreg (b)

I'm also going to assume that the voltage test on page 52 is still something that your Eros will pass.

 

[Alby0521]

Hi
The values at page 42 were spot on. Now with the tubes in I get:
Pin 1-2: I get 0
Pin 4-5: I get 8.4
Pin 6-7: I get 124

Here the values on the board that doesn’t work:
IA: 219
IB: 219
OA: 209
OB: 101
Breg: 104
Kreg: 1

Any possible idea?

Thanks a lot in advance.

AB

 

[Alby0521]

I attach pictures here.

If there is any particular picture you need I'll take it in detail, just let me know.

Thanks again in advance for any help. I'd really love to play some music with this little pearl!

Best

AB

 

[Paul Birkeland]

The values at page 42 were spot on. Now with the tubes in I get:
Pin 1-2: I get 0
Pin 4-5: I get 8.4
Pin 6-7: I get 124

Not sure what these are.  Pins refer to tube sockets usually, but which one?

Here the values on the board that doesn’t work:
IA: 219
IB: 219
OA: 209
OB: 101
Breg: 104
Kreg: 1

This is an electrically good set of values.  Seeing Breg just a little above OB and Kreg being about 1V means things are biased to function properly, but seeing 209V at OA is not so good.  It wouldn't be surprising if the solder joints on the MJE350 feeding OA need to be well reheated.  I would also suggest checking that all the little brown Dale resistors are where they should be. 

 

[Alby0521]

You just made a happy man!!!! I re heated the mje 350 and all numbers spot on.
I’m playing music now. Sounds great!!!!!
Thanks you very much. My Saturday is now a good one.

Best

AB