trinityamps.com

Hey all. I have been reading this board for some time now and decided to take a stab at building the sIII. I am anxiously awaiting to hear this beast. I finally assembled the kit and prepared for the initial power up, but it has no heartbeat. The amp light comes on but that is all. I am a newby to the electronics field, but my buddy has some experience under his belt. He helped me take some readings and we discovered that there is power running to the OT, but not out of it. We have checked the layout and cannot figure out the problem. Any advice would be appreciated. Thanks

Tweeds,

When you check the voltage out of the trasnformer, remember they are all AC volts. Set your meter accordingly. Do all this testing before you install any tubes.
Silly but, make sure that you connected the input to the power tranny. Which tranny did you use? s2? If so 120V to Black & Black/White.

Maybe you can post some pics so we can help you through it. I just sent you a high voltage layout.

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

A picture is worth 1000 words

Hi Voltage Daigram For All to see.



Full Size for printing:

http://www.trinityamps.com/ForumGallery/trinity/Trinity18HiVoltageWiringv2.jpg

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

I appreciate the help. I actually found a mistake and made the change. I checked everything again and fired up the amp. I have the original channel working like a champ. I will do a full sound review later because I have some more mistakes to find. The TMB channel needs work, and I am finding the tubes to be running quite hot. Any suggestions on the power tube temps.
Thanks again.

The power tubes do get quite hot. If the plates are not Red hot inside, you should be OK. Confirm that you have a 120 - 150 ohm cathode resistor and 100 ohm plate resistor. If you ar econcerned, you can measure the voltage drop across the cathode resistor and calculate the current / ppwer.

Go see how at: viewtopic.php?t=462&highlight=

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

All i can say is WOW. I finally have all the kinks but one worked out. The master volume is having some problems. When i turn it up, it gets very grainy and, simply put, horrible sounding. It scratches and pops very badly. What would cause this?

There's not much to the Master Volume.

At what setting does it start to break up?
Does it sound good otherwise?

Check the wiring around it, reheat all the solder joints on it and the solder connection at the ground buss. Maybe the coupling capacitor off the wiper as well . Spray some contact cleaner into it - good to have some if you dont .

Worst case, you may need a replacement pot if none of that works out.

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

Well, after a little time away, I am determined to finish my first amp correctly. I am trying to get the voltages on the tubes. Everytime I read v1 v2 and v3, the nubers are almost non existent. Dumb question, but how do I do this (how is the meter set)? The amp sounds good but it is completely clean. It is as if the preamp tubes aren't getting any voltage. What would cause this. Thanks

All voltages should be measured to ground with a meter, this means you should attach the common probe (black) of your meter to the chassis and being careful not to short anything use the live (red) to measure your voltages. Be aware that apart from the heaters all voltages after the rectifier are DC. If your meter has a number of ranges make sure you choose an appropriate one for the voltage you are expecting at a particular part of the amp. Work carefully and don't fry yourself
Nigel

According to the measurements, I am right. Why would i not be receiving any voltage to the tubes, heating is correct, and still get a good sound?

Here is a quote from 18watt.com.

"Once you are sure that these are ok, then you can start checking voltages. Don't put any tubes in yet. The first think you should check is the HV going to the EZ81. Set your meter to AC VOLTS, and up the range because you are going to be looking at about 300V. Plug the amp in and turn the power on (oh yeah.. did you put a fuse in the fuse holder??).

With the black probe connected to the chassis, measure the AC voltage at pins 1 and 7 of the recitifer socket. You should be getting about 300 volts at each pin.

Lower the range of your meter to the 20V scale. Take the black probe and put it on pin 4 of the rectifier tube. Place the red probe on pin 5. You should read about 6VAC. Check the AC volts on pins 4 and 5 of the EL84's. You should read about 6 volts there as well. Place the black probe (since we are measuring AC it doesn't matter what color probe goes where) on pin 9 of one of the 12AX7 sockets. Place the red probe on pin 4 and check the voltage. It should be about 6VAC. Now place the red probe on pin 5. It should read the same as pin 4. Do this for the remaining two 12AX7s."

I did all that and it tested perfectly. What now?

Well if you followed what you have said you have only tested the AC incoming to the rectifier and the 6.3V AC heaters. Now you need to test all the DC voltages after the rectifier, with your meter set to measure DC and your common probe (black) connected to the chassis try measuring pins 1 and 6 on each of the 12AX7 tubes.

If your meter is set to AC and you are trying to measure a DC voltage, you will get very low and strange results. Check your settings.

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

On v1, v2, v3, pins 1 and 6, all neasure at 1.2 volts DC. ??

Stephen posted the following in another post:

Voltage chart of a working sIII.

AC Mains Voltage 123VAC; B+ 440 VDC no tubes installed

(Then with the tubes in)

V1 - 12AX7
--------------
Pin Volts
1 154
3 1.0
6 160
8 1.0

V2 - 12AX7
--------------
Pin Volts
1 184
3 1.6
6 278
8 184

V3 (PI) - 12AX7
--------------
Pin Volts
1 222
2 55
3 80
6 217
7 54
8 80

V4 - EL84
-----------
Pin Volts
3 11.7
7 364
9 354

V5 - EL84
-----------
Pin Volts
3 11.7
7 366
9 354
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I can't believe you have sound with the voltages you are suggesting, I suspect that you may not be setting your meter range correctly.

Between V1, pin 1 and chassis ground you are measuring 1.2 volts DC?

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

that is correct, and the meter is set right. I don't get it.

Trace the wire back to the turret board to where the wire is soldered to the turret. Put some pressure on the probe and measure.

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

the turret gives the same reading.

Tweeds2, can you post some pictures of your board. Can you make sure the underside of your board is wired correctly, there is a picture in this forum under "Builders Guide Photos", I suspect a missing connection or an incorrect value resistor in the power supply. What kit did you use?