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Hi All,

First build sIII from kit w/ Trinity transformers. I'm having problems with the initial startup voltage check. I finished the build, double checked all connections and layout, and turned it on with no tubes. Light comes on with no smoke or fire. Mains read 120VAC, heaters 3.2 VAC to ground each, good on all tubes, and recto reads 313 VAC on pin 1 and 7. I then installed the recto....B+ read ~300V at this point things looked pretty good but p1v1 reads 400+V so does p1v2. What would cause the voltages to be so high? Photos are of the amp in various stages of completion. I would appreciate any help you can give me.

Greg

http://s177.photobucket.com/albums/w236/GregoryJ3/

Pull all the tubes except the recto.

Voltage across recto pin 1-7 should be 570 VAC.

What is the B+ measured at the filter cap?. Should be more than 400 VDC.

Put the tubes in, what's B+ now? should be about 350 VDC.

If the B+ is not aroundthat mark, make sure the cathode pairs for V1, V2 are grounded at one end.

If the B+ is off, try putting in one tube in at a time & measuring to see which tube circuit is causing the problem. The go from there looking for a defect.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

"If the B+ is not aroundthat mark, make sure the cathode pairs for V1, V2 are grounded at one end."

These are the ground connections to the buss wire, right?

I havent done any tests with any tubes other than the recto in because the voltages have been inncorrect. If pin 1 of v1 and v2 is 3x what its supposed to be (~400v) wont it fry the tubes if i put them in to troubleshoot?

Check the voltage across recto pin 1-7 and then with recto in, measure the B+ at the filter cap. Should be more than 400 VDC.
If thats all OK, should be fine.]

High voltages are a result of no load on the power supply. i.e. no tubes installed.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Success....mostly. B+ no tubes was 430VDC and then 350VDC with all tubes. Recto pin 1 and 3 were each 294VAC. The rest of the voltage check out was all within <10% of the listed voltages. I couldn't get a reading off of V3 pin 2 or 7 because they gave a very loud boom through the speaker even with the volumes set to 0. I dunno if that indicates a problem or not. I get a pronounced hiss at the upper volume settings but no hum, squealing, or crackling. Got to play the normal channel...sounds good. Thanks for walking me though it.....I was expecting the voltages to only be slightly different without tubes but they are a lot different.

I've got a problem with the inputs on the low input of the normal channel and on both inputs of the TMB channel. No guitar sound through these inputs but the hiss rises and falls with volume change so I think everything is fine except the input itself. This isn't really suprising since I found the inputs to be the most difficult part of the build.

Good news. Yes, big differnce. Not Solid State!!




Quite Normal - good way to test things!


Use this layout to check your input jacks - IF you installed the jacks so that the lugs point in the direction on the diagram.



Hiss at high vol is also Normal - Carbon Comp Resistors do that.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps