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.
New Construction. Some issues solved. Some not. Need advice.
- Thread starter harv-e
- Start date
harv-e said:
Voltages?
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
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
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
-PB
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
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
The single lit LED is generally a poor ground connection from the bias string, or a funky solder joint on a transistor in that C4S. (The 0V at the output supports a bad transistor solder joint)
OK. That's fixed. I cleaned off the board with some alcohol and found a tiny solder bridge shorting that transistor. So the regulator board and been completely "resoldered." All lights work. Audio from both speakers.
And so now I am back to the original problem - motorboating sound coming out of both speakers even with the inputs shorted. I am OK with hiss. But not this constant putt putt puttering. To my mind, this is a power supply problem since it is coming from both speakers.....and I do not believe it is a solder connection as I have gone over these on the regulator board (I have not redone the joints on the power supply board). I have to believe that it is a bad component.....but I do not have a clue as to which one it is.
The voltages before the "resolder all the joints" issue seem to be within specs......and that's why I was advised to resolder the joints.
This is very annoying. I have been patient trying to fix this, but I don't know what else to do.
Thanks.
Harvey
And so now I am back to the original problem - motorboating sound coming out of both speakers even with the inputs shorted. I am OK with hiss. But not this constant putt putt puttering. To my mind, this is a power supply problem since it is coming from both speakers.....and I do not believe it is a solder connection as I have gone over these on the regulator board (I have not redone the joints on the power supply board). I have to believe that it is a bad component.....but I do not have a clue as to which one it is.
The voltages before the "resolder all the joints" issue seem to be within specs......and that's why I was advised to resolder the joints.
This is very annoying. I have been patient trying to fix this, but I don't know what else to do.
Thanks.
Harvey
We do offer repair services if you would like us to get it up and running for you.
-PB
-PB
I understand that you are frustrated. The suggestions may not have solved your original problem, but that does not mean our answers to questions are unreliable as you seemed to have had other issues come up that you were coached on fixing. I can't think of any other Eros that we have heard of having this motorboating problem and thus we don't have any previous experience dealing with it. You could just send it to us and let us fix it for you. If the issue is a bad part there will be no charge. If the issue is a construction error you will get a very nice preamp for a reasonable repair fee.
Hello Harv-e,
I got into your repair yesterday afternoon and this morning, and I found that a couple of resistors may have been damaged on the 12BH7 socket, so I replaced them with more robust parts.
I also found some other parts that may have been a bit loose, and I tightened them all down to prevent any further contact issues.
Also, the ground wire from one of the input RCA jacks to the terminal strip was loose in the terminal strip and not soldered down. This presented us with significant hum while running the amp in until I was able to find it by poking around with a pencil. This is most likely to be the primary issue you were facing, and when you ended up replacing the tubes, the physical jarring of the Eros would have temporarily re-established this connection for you for a while.
I did end up replacing one of the C4S boards in the process of debugging, but in retrospect it wasn't at all necessary.
We'll keep running the amp for a few days with the inputs shorted and the outputs driving speakers so we can be sure that you won't have any additional noise issues.
Sincerely,
PB
I got into your repair yesterday afternoon and this morning, and I found that a couple of resistors may have been damaged on the 12BH7 socket, so I replaced them with more robust parts.
I also found some other parts that may have been a bit loose, and I tightened them all down to prevent any further contact issues.
Also, the ground wire from one of the input RCA jacks to the terminal strip was loose in the terminal strip and not soldered down. This presented us with significant hum while running the amp in until I was able to find it by poking around with a pencil. This is most likely to be the primary issue you were facing, and when you ended up replacing the tubes, the physical jarring of the Eros would have temporarily re-established this connection for you for a while.
I did end up replacing one of the C4S boards in the process of debugging, but in retrospect it wasn't at all necessary.
We'll keep running the amp for a few days with the inputs shorted and the outputs driving speakers so we can be sure that you won't have any additional noise issues.
Sincerely,
PB
