18 watt TMB build,no sound?

[chuckb]

Hey guys, I just finished up a 18 watt TMB build and when I powered it up everything lights up,ie;indicator light,tubes etc but i have no sound.
checked the speaker,speaker cable,input and output connections and it all seems to be fine. Can't seem to track down the reason for it. any help would be greatly appreciated.

Chuck.

[JoeM]

No sound at all, not even a slight hum or noise of any kind?

[chuckb]

No sound at all, not even a slight hum or noise of any kind?

Hey joe,no nothing.

[Chuck H]

Voltage reading at the tube pins???

[chuckb]

Voltage reading at the tube pins???

Hey chuck I tried taking some voltage readings and everything comes back a negitive reading,even the B+.
Some examples of readings I've taken are;

V1-pin 1=-0.979vdc
pin3= 13vdc
pin 6=-1.027vdc and dropping.
pin 8= -0.005vdc
This is consistant on all the tubes, all negative readings?

Chuck.

[chuckb]

I'm using a separate 6.3v transformer for the rectifier tube as the trannys I'm using doesn't have a seperate winding for the rectifier.

Chuck.

[loudthud]

Link or post a schematic please.

[chuckb]

Link or post a schematic please.

hey loudthud, I'm using the ceriatone 18watt TMB schematic but I haven't got one on file to post. I have the layout which i have gotten from the ceriatone website,if that helps.

chuck.

[Chuck H]

Something in the power supply (at least) seems to be miswired. But do check the HV secondary voltages.

[chuckb]

Something in the power supply (at least) seems to be miswired. But do check the HV secondary voltages.

Yes chuck, That's what i was thinking. The power tranny has windings for 120v and 240v but I wasn't to sure how they were wired for 120v. Here is what is printed on the power tranny;Input: BLK-Blue - Orange Brown-yellow
fuse-100v- 120v fuse - 120v

Output: 266vac @150ma (red)
27vac @ 100ma (Vio)
6.3vac @ 200ma (wht)

I have the orange and yellow wired together on one side of the on/0ff switch.The other side of the on/off switch goes to the end lug of fuse.
I have the brown and black wired together on one lug of the IEC terminal. The other lug of the IEC socket is wired to the center lug of the fuse. The center lug od the IEC socket is wired to ground.
I suspect I have it wired wrong though.

Chuck.

[olddawg]

Yes chuck, That's what i was thinking. The power tranny has windings for 120v and 240v but I wasn't to sure how they were wired for 120v. Here is what is printed on the power tranny;Input: BLK-Blue - Orange Brown-yellow
fuse-100v- 120v fuse - 120v

Output: 266vac @150ma (red)
27vac @ 100ma (Vio)
6.3vac @ 200ma (wht)

Chuck.

I thought you said you had no filament winding?

[chuckb]

Hey chuck, i'm sorry about that but I didn't think that the winding I had was sufficient for the rectifier as well so I added anothe seperate 6.3v tranny for that.

[chuckb]

Hey chuck,I thought I needed a separate winding for the rectifier?

chuck.

[Chuck H]

That was olddawg who asked after the filament supply. I read that your using another tranny for that. And rightly so since I don't even know what a 200mA 6.3V tap is good for.?. Since your tubes are glowing let's ignore that tranny for now.

As to the primary wiring, not much info in your post. What you say is written on the transformer regarding the primary just looks like color names without designations to me. And there aren't any absolute standards either. Do you know the transformer MFG? Where did you get it? You already tried turning the amp on and it seems nothing blew up. So is there HV on pins 1 and 7 of the EZ81?

[olddawg]

Sorry guys. I thought the 6.3v @ 200ma was a typo. Just trying to simplify things, wondering if the filament was working at all. The standard HV secondary for an 18 watt clone is around 290-300v.