finished stereomour II amp

[Smoses01]

pics:

[Paul Birkeland]

I'll go through these 1 at a time.


In this photo, there are several problems.  The wire going to pin 9 on the tube socket isn't routed properly and is potentially touching the resistor leaving the center post of the socket.  If this happens, you're likely going to smoke the power transformer.

The resistor going from the center post to pin 8 on the tube socket isn't properly routed and is extremely likely to cause operational issues with the amplifier. 

The tinned buss wire going to the center post needs to be routed right between pins 1 and 9 right in the middle. 

I would review how these components and wires are routed in the manual and make corrections where possible.  If it touches pin 9, that will damage your power transformer.  If it touches pin 1, that could damage your C4S board.

[Paul Birkeland]

In this AC input wire, the foil shield on this shielded twisted pair wiring is earthed to the chassis.  The metal strip on the IEC power entry module that it looks to be touching carries 120V AC.  If these two touch, you will constantly blow fuses.

I have attached the photo from the manual of what's desired.

[Paul Birkeland]

There seems to be a missing black wire here.

[Paul Birkeland]

Can you carefully measure the voltage between terminals 41 and 44?

I would suspect blowing fuses should happen based on the photos, but if you are getting proper AC voltages coming out of the power transformer, you should see about 400V appearing between 41 and 44.  If you have that voltage there, but it's not making it out of there, then there's going to be a soldering issue or a missing wire.

[Smoses01]

I’m getting 0.235 volts dc. Strange!

[Smoses01]

I will carefully review what you have commented on from my pictures. Thanks!

[Smoses01]

With the crazy voltages I have been getting, I almost suspect the power transformer is not working correctly, but I did the primary and secondary voltage tests, as per the instructions, and they were normal.

[Smoses01]

I have previously successfully built a crack amp and a sex 3.0 kit. Unfortunately, with the past few years in my early 70s, I have developed some shakiness, which is not very good for successful soldering outcomes. Still, I would like to get my Stereomour II kit up and running.  It's possible I may need a new power supply, what with no B+ power coming to either channel. I guess the best thing at this point is to return my unit to Bottlehead for repair.

[Smoses01]

How do I find info for submitting a support ticket? I have checked the forum page, but can’t find anything relevant to submitting a support ticket. Thanks!

[Paul Birkeland]

With the crazy voltages I have been getting, I almost suspect the power transformer is not working correctly, but I did the primary and secondary voltage tests, as per the instructions, and they were normal.

If the proper voltages are coming out of the power transformer, the power transformer is not the problem.

If you use your meter to measure a 9V battery, what voltage appears on your meter? 

Your wiring around 41 and 44 looks correct, and a short that would drag that to 0V would burn up the 130 ohm resistors, so I would expect to see about 400V DC there. 

[Smoses01]

Just discovered an unattached white wire where couldn’t see it because was in area of 42u. That would explain lack of B+ power. Will re-attach and see what happens.

[Smoses01]

Ok, I have re-attached a loose white wire to 42L and now have B+ voltage to one side all the way down to the large tube. All along I never have had B+ voltage to the other side. I did a continuity test on the working side and there was continuity between the red wire on the bottom of the plate choke to the red wire on terminal 1. Not so for the other side. I think I may have strained a wire when pulling them through the hole near the plate choke. What is the cost of a new plate choke?
Thank you.

[Paul Birkeland]

With the amp off and the power supply discharged, set your meter to DC resistance.  Now measure the DC resistance between the blue and black wires on the plate choke you believe is bad.  Now compare that to the resistance reading on the blue and black wires on the plate choke you believe is good.

For what it's worth, I cannot ever remember a plate choke being damaged in this manner. 

[Smoses01]

I am getting approx.1 ohm of resistance on both sides between the blue and the black wires.