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Last week I received my new PT from Stephen and I installed it on the weekend. All worked great and my new Deluxe sounded wonderful.

Well...the wife went for groceries so I decide to do some loud playing. The bright channel worked fine at full volume on the test. The normal channel worked fine too, but if I had the normal volume near 12 and moved the bright volume say to 7 or above, I'd get a loud static sound.

So I figured I could find that later. I continued to play in the normal channel at high volume when suddenly the volume dropped considerably and the sound become very buzzy/fuzzy. I tried all the inputs with the some sound...low volume, fuzz. So I decided to let it lie until tonight. I hooked up a different speaker in case the other had blown (that's what it sounded like) but it's still the same. I swapped out preamp tubes to now effect.

So I'm wondering before I dig too deep, do these symptoms sound familiar to anyone? Low volume, very distorted buzz sound when playing. I'm fearing the OT may now be gone but hoping not.

Advice or suggestions always appreciated.

Thanks.

Hi Duke, it could be one or more things. First, I would suspect a cold solder joint...somewhere. Chopstick it. The vibration likely rattled something loose.

If you got any debris dropped into the opening of one of your pots, it's possible the wiper could lose good contact as well. If you have an air compressor, give a shot of air into each of them.

Stephen supplies his kits, I believe, with Belton sockets, so bad contact there is unlikely. But...if you're using JJ 6V6s, beware that the pins on those are smaller in diameter than other 6V6s, so you may have to re-tension the contacts of the sockets to accomodate.

I'd be willing to bet it is a bad/cold solder joint.

Good luck, you'll find it. CraigB

Thank you for the reply Craig.

I have chopsticked every connection and found that the resistor on V4 pin 5 had a broken soldier joint. I repaired that. I did retension the tube sockets because I'm using the JJ 6v6s. I also blew out the amp and pots really well in case I had missed a trimmed lead or something similar. It seems to be the same still.

It sounds exactly the same with 1 power tube in either position as it does with both power tubes installed. I used both tubes by themselves with no difference in sound.

I was wondering if the power tubes should get so hot that you can smell them? The get extremely hot quickly. I definitley would get a good burn if I touched them at all. Also, would a blown power tube give me these symptoms (buzz, low volume)?

I looked at your photos in the other topic and I notice that the solder is not flowed entirely into the socket terminals, and also in some of the eyelets. I'm still suspicious about your solder joints. An amp that works and all of a sudden drops volume but still works wouldn't indicate a blown ouput transformer, and not necessarily a bad tube, though that's possible. It's more likely a bad connection, whether solder joint or broken wire. Use your meter to check continuity of the leads going to and from the board. And also check the value of every resistor. It's a simple circuit and the parts count is small so it's worth the effort if you haven't done so already.

Also check your voltages again. If a power tube has gone bad, what often happens is it will start sucking current, so your plate voltage will go waaaaay down, and you may notice a big orange glow, or even red-plating. Look at the tubes at idle in low light to check.

Divide and conquer - you will figure this out - CraigB

All completely normal. Power tubes operate at very high temperatures, and new ones smell as they burn in.

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Great tones come in small glass jars!

Okay, I did a bit more today and this is what I found.

I replaced all the tubes: No difference.

I checked all the leads to/from the board as well as all the jumpers on the board for continuity: All checked fine.

Then I checked all the resistor values and found two things strange: 1. The 1 meg resistor on the normal channel was way off. The bright channel resistor checked fine. 2. The two 68 k resistors that carry the bright channel input signal both read 34 k instead of 68. The two 68 k resistors that lead to the normal channel are fine.

So I'm thinking I have a problem with the inputs. Would a bad resistor on the normal channel affect give me these symptoms (low volume and fuzzy tone) on both channels? What might cause both 68 k resistors on the bright channel to read at half their value (short?)?

Again, advice is appreciated.

Here are the voltages. I think they are good.

12ay7 (v1)
Pin 1 - 122.8
Pin 3 - 2.0
Pin 6 - 118.4
Pin 8 - 2.1

12ax7 (v2)
Pin 1 - 162.0
Pin 3 - 1.2
Pin 6 - 201.0
Pin 8 - 43.0

6v6 (v3)
Pin 3 - 358
Pin 4 - 331
Pin 8 - 20.6

6v6 (v3)
Pin 3 - 361
Pin 4 - 331
Pin 8 - 20.6

BTW...The 1 meg resistor on the normal channel input is reading open. Could this be the culprit with this circuit?

That 34K is supposed to be like that, don't worry.

On other resistor though...are you trying to get values while the resistors are still connected and in the circuit?

Yes, and I got the values I expected except for the two 68 K (which are okay) and the 1 meg on the normal input.

check the gorunding on the input jacks. I had a problem like yours ( but I completely forgot to solder the wires there)


Also check to see if the coax wire is not grounding out to the chassis use a chop stick to move the wire near the tube when the amp is on and see if you get sound.

Amazing what a good OT will do.

So it was the OT then?

Do you know what caused the first one to lunch?

Now that I'm done teaching for the summer, I have managed to finish my cabinet. Yes, the new OT made all well. After countless hours of research, I decided to put a BBQ Vintage Series 12F150 25 watt speaker in it. Lots of tweed spank in there. Here's the final product!

Early this summer I began to get a sizzle/popping sound when playing my Les Paul. I went through everything with an amp tech, checked the board, all the connections, and all was good (appearing anyway). Last Friday I plugged in Lester and within 30 seconds the OT was kaput. With everything checking out (voltages and connections), I'm wondering if it's just a coincidence I was playing my LP both times I've blown a transformer. I play the strat just as often and it has not happened with it and the syptoms (sizzle/pop) are rare.

Stephen recommends a beefier OT. Thoughts on a replacement would be appreciated.

Phil?

The Tweed Deluxe OT is an exact clone of the original Tweed Deluxe. It has very fine wire (#36) on the primary and in some cases, with today's modern voltages, and overdriving the amp and we have seen 4 failures. We have replaced them all.

Three options:

Use NOS rectifier to lower the B+ instead of the modern 5Y3 supplied.
Drop in a Zener diode & reduce the B+ like we do on the TRIWATT
Both of the above
Design and use a beefier OT (underway at Heryboer)

To be extra safe, any replacement OT should have a primary winding of 70 to 80 ma.

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Stephen
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