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Simple SE help desperately needed

ejr12

Member
2018-11-21 2:17 am
I have been trying for the past week to get my SSE up and running again with no luck.

As of now, I have one channel. The second channel, if I turn up my source input, I can hear through an output transformer but not the speaker.

The working channel only works if both rca connectors are plugged in.

I have taken all the wires off and follows the wiring diagram implicitly. I have also taken both the source selector and volume switch out of the circuit. Any help is greatly appreciated.
 
As of now, I have one channel. The second channel, if I turn up my source input, I can hear through an output transformer but not the speaker.

The working channel only works if both rca connectors are plugged in.

I’m going to bet you have two separate problems.

I’d temporarily remove the ground on the secondary of the OT and I’d remove the speaker binding posts from the chassis. I had that first situation once when the red binding post shorted to the chassis after a shipping mishap.

The second clue sounds like your source signal finds it’s way to ground through the other channel rather than through the pcb trace. I’m guessing R11/21 are not properly soldered at the ground. Try injecting the signal across R11/21 while you have the off board components disconnected from the board and then jumper the negative to a good ground.
 

ejr12

Member
2018-11-21 2:17 am
I’m going to bet you have two separate problems.



I’d temporarily remove the ground on the secondary of the OT and I’d remove the speaker binding posts from the chassis. I had that first situation once when the red binding post shorted to the chassis after a shipping mishap.


I have a non conductive chassis. Does this change the testing procedure? I am completely new to this process.
 

ejr12

Member
2018-11-21 2:17 am
Ok, I am now at a complete loss and I am wondering if I need to start from scratch with a new board.

I removed all options (except for the choke and the capacitor) and wire the board up without any switches or, volume, etc.

For a while, I had the same results. I had output on from T3-pri but nothing from t2-pri. To rule out tubes, I switched those. To rule out the output transformers, I switched those. Same results each time.

Now, with further testing, I have no output from either side. The only major change before this complete loss of sound was to test resistors r19, r13, r23, and r29. I found that the first two showed 444v and the later showed about 222. But now, I have no sound (with and without a rectifier tube)

Do I need to start from scratch.
 

Mr_Zenith

Member
Paid Member
2009-08-20 3:16 pm
KC Metro
Hi ejr12, unless you've lifted a bunch of traces off the PC board then I doubt you need to start from scratch. As frustrating as it is, it's probably something extremely simple. We've all missed stupid mistakes on occasion.

Is there any way you could post a few pictures of your board thus far? They'd go a long way toward helping us help you. :)
 
... Do I need to start from scratch. ...

No, but you need a more methodical approach to solving the problem.

Do you have any test equipment? If all you have is a DMM/VOM, can it reliably read small AC voltages?

You need to make sure the board is working properly, and then reinstall it in the chassis, checking everything for proper working order as you go.

If you can, I would check the board by putting an ac signal into the input of one channel, then look at the ac output of each stage, there are only two, to see that the signal is still there, undistorted, and amplified by the correct amount. Then do the same for the other channel.

You can also check the dc voltages to make sure they are correct, but they don't tell the whole story, because all the static dc voltages can be correct, but if there is no ac signal to amplify, the stage is just going to sit there doing nothing with the correct static voltages.

Then put the working board in the chassis, hook up an input and an output, and you should have sound, if they are hooked up correctly. No sound, at least you know the problem is not the board.
 
Well, after posting pictures of your board, then the next step would be to locate the thread in this forum about taking simple resistance and dc voltage checks on completed SSE boards.

Finding that thread and doing the resistance / voltage checks on your board would be a reasonable starting point and good experience learning about the board. I suspect your board is fine since there's not much to go wrong - the CCS chips are about it.

Your problem likely is / was incorrect input wiring, it almost always is.
 

ejr12

Member
2018-11-21 2:17 am
Sorry for the delay and lack of pictures. Work has been busy. And, although the board was probably okay, I decided to start from scratch with a new board. This gave me a chance to clean up the solder joints, etc. (Once I get one amp working, I will probably work on chasing the problem down and setup a second amp).



I have the new board working, but I have encountered two problems:


(1) The rectifier tube does not appear to work (no glow and no sound when tube rectifier is selected). I am not sure if my tube went bad or if something else. Advice on how to check would be greatly appreciated.


(2) When I select UL (CFB not installed yet), everything works fine for 5 to 10 minutes. Then, I get a terrible squeal/feedback noise. Any idea what may be causing this. My setup is Edcor Transformers (GSXE).


Thanks
 
Ejr12.

Eventhrough i find it hard to understand the two quistions, i can tell you that the squeek you hear are MOST properly dc going through somewhere. If you for example have some volumecontrol/potentiometer, and DC is passing there, you for sure gets squeksss among other unpleasant noises, but again i cannot understand the two quistions you have?

Howto meassure the rectifier tube i did see a post here about it.

Good luck.

Jesper.
 

ejr12

Member
2018-11-21 2:17 am
Ejr12.



Eventhrough i find it hard to understand the two quistions, i can tell you that the squeek you hear are MOST properly dc going through somewhere. If you for example have some volumecontrol/potentiometer, and DC is passing there, you for sure gets squeksss among other unpleasant noises, but again i cannot understand the two quistions you have?



Howto meassure the rectifier tube i did see a post here about it.



Good luck.



Jesper.



Thanks for the effort to help. I’ll try to explain a bit more.

I set the amp up in standard triode mode as suggested on the tube lab site. All worked well.

I then decided to add the UL switch. I followed the wiring diagram from the we site. When I turn the amp on, I hear music and all sounds right. But after about five to ten minutes of playing, I suddenly get very loud feedback/squealing.

The speaker terminals are directly wired to the output transformers at this time, as I have not tried CFB yet.

I have a choke and run time cap installed.

I do not have a volume pot yet. So source rca (using an iPhone right now) are directly connected to the board.
 
Hey...

I do not have a volume pot yet. So source rca (using an iPhone right now) are directly connected to the board.

When i build my AlephJ i also used an Ipad to connect directly via 3.5" jack, like you do with youre phone right now. I had with one (defective? i donno for sure) cable, the sourceresistors got hot and the amp was bahaving very very strange in one channel, until i tried another 3.5" jack-cable... Just saying! - Can you perhaps try another source just to be sure?

Good luck.

Jesper.
 
This squealing problem never happens unless you are in UL mode, is that correct? You listened for hours in triode with no issues? Then I’d have another look at the wiring diagrams supplied with your output transformer to see that you have correctly identified the the UL tap and that you have wired it per the drawing. I’d also get the feedback loop working to see if that stops the oscillation. That’s what feedback is for.

The rectifier may not have the 5 volt winding connected properly. Check to see that the yellow leads are connected to the board at the correct block. Next test it at the tube base. This can be exceeding dangerous to test because while that winding is only 5 volts at AC, it’s at lethal voltages at DC. The full B+. So switch off the power, let it set for a few minutes, Check for no B+, set up your meter across pins 2 and 8 with clip-on test leads. Test for AC by powering up the amp while you are standing back. Do this with the solid state rectification switch open.

EDIT: A safer and simpler way would be first to test the 5 volt AC at the tube would be to first pull the tube. Do this with the solid state rectification switch open. Be safe. Use clip leads.
 
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ejr12

Member
2018-11-21 2:17 am
Thank you both for the ideas. I will give these a try this weekend.

As for the tube rectifier, I am pretty sure I have the yellow taps in the correct location, but I will check again. The tube was working (ie glowing), when I first tried the amp, but in subsequent tests it stopped. I do not recall what, if any changes, occurred between the working/not working state. I noticed the problem the next day when I was trying some additional tests.

As for the UL taps, I believe I got them right. But, again I am new to this. I have included the transformer wiring diagram with this post. I have the blue/white wire connected to the UL tap.

IMG_1949.png