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SOHA II Builders Thread - Page 13

post #181 of 1686
thanks guys

I'll let you know how I get on
post #182 of 1686
Thread Starter 
Yes, please let us know what those critical voltages are as soon as you can measure them.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #183 of 1686
got my kit today. can't wait to get started on the build.
post #184 of 1686
Thread Starter 
Quote:
Originally Posted by rhester View Post
got my kit today. can't wait to get started on the build.
Great news! Keep us up to date.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #185 of 1686
Sorry it's took a while for me to get back to this but I've now plugged the transformer back in and I've checked the voltages.

I get about 24.5V dc across C3P,C4P and C6P and no smoke!
post #186 of 1686
Thread Starter 
OK!! An auspicious start.

I assume you get 24.5 on C3 and -24.5 on C4 and C6?

Next step is to install the regs one at a time starting with the heater reg, the LV+ and then LV-. Before you install each reg make sure that there is no continuity between the metal tab on the regulator and the metal pins sticking out the bottom of the heatsinks. Also make sure that nothing on the output side of the regulators is accidentally shorted to ground.

And be sure to get LV+ and LV- in their correct spots.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #187 of 1686
er....

If I measure voltage across those caps with the red probe on the + side of the cap each time then they're all +24.5V
post #188 of 1686
Thread Starter 
OK. I see. And makes sense.

We'll wait for the results of the next step.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #189 of 1686
thanks. I haven't ordered the replacement regulators yet - I wanted to wait and see if there was anything else I might need, some more insulating washers perhaps? lol

anyway, I'll keep you posted.
post #190 of 1686
What is correct way to wire up the Avel transformer?

I have blue/violet tied to neutral and grey / brown tied to hot onj primary side. Then have yel / black tied together with orange and red alone. Should read 15V each at orange and red referenced to ground and 0V at the yellow / black combo?
post #191 of 1686
Thread Starter 
Correct. Although on mine I tied the red/orange together as the CT and used the Yel and Blk as the 15VAC leads. But it makes no difference.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #192 of 1686
Did that and powered up. Not such good results. I got 120mV reading on TB+, 4mV reading on TL- and then smoke came out of C12. Where to start?
post #193 of 1686
Thread Starter 
Well, first thing to do is to check the orientation of all the diodes (band facing up) and the capacitors. In particular, is C12P oriented backwards?
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #194 of 1686
Thread Starter 
Quote:
Originally Posted by Uncle Bob View Post
Sorry it's took a while for me to get back to this but I've now plugged the transformer back in and I've checked the voltages.

I get about 24.5V dc across C3P,C4P and C6P and no smoke!
Uncle Bob I forgot to ask you what the voltage is at C12P?
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #195 of 1686
C12 and C4 got swapped during populating the board (guess you really shouldn't have wine with youir solder).

Swapped them back and still get only mV readings and no negative readings. Will order new caps just in case fried them. But where should I start checking V at? Check J1 and J2 to ground to see if +/- 15V (to check C4)?

Do still have LEDs lit.
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