need help with turning my chip amp into an amp

[pjpoes]

Ok so I finished my assembling my pcb's, and I want to mock it up so that I can test it, make sure everything works ok before putting it into the box.

First, I have an Avil Lingberg 330va tranny. The color coding goes like this. Blue-Grey/Violet(2x115V)-Brown for the primaries and Black(0v)-Red(25V) Orange(0V)-Yellow(25V). I hooked the primaries up so that the Grey and Violet are twisted together and the Brown and Blue are twisted together. Is that correct, I have a wierd feeling that isn't correct, but wasn't sure what to do. For the Secondaries I have it hooked up so that AC1 on the left is red and AC1 on the right is black. I have it so that AC2 is yellow on the left and orange on the right. Is that correct.

Then from the recto board I have it so that V+ goes to V+ and V- goes to V-, same for the PG's. Is that correct.

I currently have no ground as I was just testing it, but could hook one up easily enough if needed.

I plugged it in as I described and I heard a lot of crackling noise coming from the amp, which was not hooked up to a source or load yet. The transformer began to get pretty warm. In all of about 10 seconds this happened and I unplugged it. I wasn't sure if I did something wrong, but thought I should check with the experts before trying again and testing the voltages. The tranny never got hot, just warmed up quickly for ten seconds.

[jaudio]

On the primary side blu & violet are twisted together and gry&brw are twisted together



One the secondary side blk(25volt),yel(25volts) and red(0) & orange (0)


Use a fuse.

[pjpoes]

you sure, thats not what the transformer says on it? Unless I really misread it, I will check again, but just wondering where you got that from, cuz like I said, not what I read from the tranny.

Ok I just checked and its written as I wrote it, with the primaries showing the outer wires as what I said, and the inner ones as 115v.

Does it matter how the wires are hooked up to the rec bridge, I understand one size needs 25v-0 and the other needs 25v-0, but what about the order, should it be the same on each side or doesn't it matter. I never thought it mattered, but wanted to be sure.

[DC Dave]

This is the wiring from Avel's site.


You want the primaries in parallel for 115v as shown in the top drawing. Blue and Violet together, Gray and Brown together. I think you have this wrong.

It sounds like you have the secondaries correct. Black and Red make up one secordary and Orange and Yellow make up the other.

Make sure you test everything before you connect your amp boards. Power up the tranny and see what AC voltage you get at each of the secondaries. Next connect the power supply board and see what DC voltage you get between V+ and GND, V- and GND. If they are the same only opposite polarity (i.e. +26 and -26) you should be set to connect the AMP.

You should connect the ground as well.

[pjpoes]

I will try as you recomend, thanks.

What did doing what I did do, would it explain why I had my lights suddenly dim.

[pjpoes]

Thankyou very much all, It now seems to be working. I tested each part seperate, its all good.

Only thing, Peter Daniel had said to put the 10uf cap only on the negative side. I did as he said, on the V- PG- side. When I tested the voltage, it was substantially lower on the V+ side. When I then inserted a second cap, this went away. Is this normal and to be expected. I didn't realize the cap was what raised the voltage.

[jaudio]

Originally posted by pjpoes
Thankyou very much all, It now seems to be working. I tested each part seperate, its all good.

Only thing, Peter Daniel had said to put the 10uf cap only on the negative side. I did as he said, on the V- PG- side. When I tested the voltage, it was substantially lower on the V+ side. When I then inserted a second cap, this went away. Is this normal and to be expected. I didn't realize the cap was what raised the voltage.

I know nothing about Peter"s board but if you are using a dual power supply then you must add a cap on the v+ side. What you do on the v+ side must be done on the v- side. Yes it is normal.

[Audiophilenoob]

Originally posted by pjpoes
Thankyou very much all, It now seems to be working. I tested each part seperate, its all good.

Only thing, Peter Daniel had said to put the 10uf cap only on the negative side. I did as he said, on the V- PG- side. When I tested the voltage, it was substantially lower on the V+ side. When I then inserted a second cap, this went away. Is this normal and to be expected. I didn't realize the cap was what raised the voltage.

is there a particular reason for this?

[Greg Erskine]

pjpoes

If I understand the situation correcty, you are trying to measure peak DC voltage (expecting VAC x 1.4 ??) on the rectified side of the diode bridge without smoothing capacitors. From memory the DC voltage without caps will be less than VAC. Even adding one little cap on the negative side will increase VDC on that side. Using reasonable size caps will end up giving VDC of approx, VAC x 1.4 (less a little drop over the diodes)

When the PSU is connected to the Amp PCB the caps next to the chipamp does the smoothing.

[pjpoes]

yeah that is what I did, and I just didn't realize it would look like that. And yeah, I was seeing a lower voltage like you said, which confused me, thanks.