fired up this morning and low voltage on the filter caps?

[pompeiisneaks]

That's a good way of doing it. Often the guys at hoffmans forum say to print it out and use a highlighter before first fire up, Check all connections, check all components, etc. Just like you did with paint. Works a charm

~Phil

[skyripper2]

Well I have redone all the bad resistors and now have no smoke and have been taking readings. I think all is looking good and am ready to put some tubes in , and see weather i have a working amp?

do these readings look ok for my build with the tubes out?
Is there something else i should check before trying with tubes in and on my 60 watt bulb limiter?
I just don't wanna pop tubes as there pricey......
Thanks in advance
Skyripper2

[pompeiisneaks]

They seem to be tolerable to me. They'll drop quite a bit once the tubes are there and they conduct etc. If there was a wiring issue, where you'd shunted power to ground or osme other such thing you'd not have the decent voltages along the rail, you'd drop to 0 somewhere and burn something up, or fire off a light bulb limiter etc.

Let us know how the tube test goes!

~Phil

[martin manning]

What I don’t see there is the available bias voltage. Measure the min and max value on pin 5’s, and set it to the minimum (most negative) before you install the power tubes. And, don’t forget to connect a load to the speaker output.

[skyripper2]

Thanks for your help...... much appreciated.
The range on pin 5's are between -35.5v and -48.7v
i have set it at -48.7v
and yes i will plug a speaker in ........and thanks for the reminder.

[skyripper2]

I just loaded it up with new glass bottles.......tubes that is...........

[martin manning]

Were you able to set the power tube bias? I’d suggest about 40 mA and then see where the plate voltage is. 420V without tubes is on the low side for an ODS.What PT are you using and what is the AC voltage at the red leads?

[skyripper2]

the pt is a Hammond 290fx and makes 320v at each red lead for 640vct.
and i will set the bias as you said . 7am here .......coffee first.....

[skyripper2]

She's making Noise Boys....... I ran her with the limiter first and everything looked right so i plugged in a speaker and ran her strait into the power bar and ...........turned up the volume knobs slowly ......I could hear a hiss!!!! so I grabbed a patch cord and plugged a guitar in and i got to hear what i put together for the first time!!!!
So now on to the voltage readings and biasing . I am feeling so pleased right now.
You guys remember yer first amp build right.

[drew]

Pretty cool, eh? Congrats.

[skyripper2]

well i played out of my amp this morning and used the loop with my old Boss me5 .After lowering the overall output on the me5 the sound was good, better in fact than without using it? I am thinking my amp is starting in the OD channel? as the OD is there to use ,and also when i turn the amp off i can hear the relay click. So I am not home free yet , but am happy and can already hear the potential of what i have.
there is also a noticeable hum that chases the note being played and i noticed the hum was way down when i used the effect unit in the loop , in fact you could hear the noise floor drop as soon as i plugged into the loop on the amp. I;m thinking it will be a ground or something going to ground that shouldn't be.

[martin manning]

The return loop jack might have a poorly functioning switch contact. Does the noise get better with just a short patch cable jumping the loop jacks? Do you have the rear mounted OD trim as shown in the C-tone layout? That might introduce noise.

Note also the C-tone OD relay wiring is different from the 124 layout, with OD being on when the relay is not energized.

[skyripper2]

thanks for your reply Martin
I do not have a pot installed for OD. I have a trimmer . I was reading that my OT primary may need switching as others have had to do , but am not sure if that is my issue.
Martin are you saying to patch the send and return on the loop with a single patch cable?

So when the OD switch is on i get sound ,when the switch is in pedal i get nothing? I was thinking i should hear the clean channel when in pedal,but it's not there?
As far as getting my clean channel to be the default when turning the amp on I am thinking of flipping the diode position around and switching the positive and the negative on the OD relay. Does that sound like the right approach ? I believe my OD relay is being energized as i hear it click when i shut the amp down and I feel that is backwards to what I need .

[skyripper2]

so i have switched the wiring on the OD relay and it now goes to the overdrive channel when switched but still no clean channel when in pedal mode on the switch? I also tried putting a patch cable to the send and return on the loop and still have a lot of hum and buzz,so not much change there.
there is way too much noise on the volume knobs and something is not wired right

[skyripper2]

well i can rule out the OT primary as i did a swap and what a sound.......cough.....Lol.