New TMB w/reverb Build

[Bieworm]

No, this is it right here. Just sitting on top of this pot.

It's an illusion, partly caused by the smaller size image. If you don't look closely, it looks connected to the pots. But I knew you got it right anyway, since you got all the docs.

My bad... you attach the grounds from the pots directly to the ground buss.
I usually add an extra ground buss at the pots and connect the end of that buss to the input ground.

input grounds.png

[JMPGuitars]

My bad... you attach the grounds from the pots directly to the ground buss.
I usually add an extra ground buss at the pots and connect the end of that buss to the input ground.

Don't forget he's got the PCB, so it's all labeled and done on the board.

[foreverstrung]

I'm having a hard time understanding the footswitch and manual switch(s) for trem and reverb. Is it smart to add 2 switches? 1 switch?, or just use pedal? If I do just use the pedal and no switches, I'm confused on how to hook this input jack up. It's not real clear.
To clarify, I'd really like to add both manual switches, but I'm confused on how to wire this up.
Recommended switches would be appreciated too.
I understand that this will be linked in after running the amp through a preliminary run and voltage tests.
Thx

[Bieworm]

I'm having a hard time understanding the footswitch and manual switch(s) for trem and reverb. Is it smart to add 2 switches? 1 switch?, or just use pedal? If I do just use the pedal and no switches, I'm confused on how to hook this input jack up. It's not real clear.
To clarify, I'd really like to add both manual switches, but I'm confused on how to wire this up.
Recommended switches would be appreciated too.
I understand that this will be linked in after running the amp through a preliminary run and voltage tests.
Thx

I never make my reverb switchable. It's just as easy to dial the reverb knob to zero when you don't want reverb.
The tremolo gets a footswitch from me. I don't see the point of having a toggie switch as well.. just use the footswitch.

[JMPGuitars]

I'm having a hard time understanding the footswitch and manual switch(s) for trem and reverb. Is it smart to add 2 switches? 1 switch?, or just use pedal? If I do just use the pedal and no switches, I'm confused on how to hook this input jack up. It's not real clear.
To clarify, I'd really like to add both manual switches, but I'm confused on how to wire this up.
Recommended switches would be appreciated too.
I understand that this will be linked in after running the amp through a preliminary run and voltage tests.
Thx

The two switches in the chassis are for the tremolo. One is to turn the tremolo on and off, and the other is to change the speed range for the tremolo. Follow the layout for those switches. If something isn't clear, let me know, and I can help with that.

The footswitch is setup only to turn the tremolo on/off, and to turn the reverb on/off. I would ignore the footswitch itself until the amp is complete. Just wire the footswitch jack per the layout.

Thanks,
Josh

[JMPGuitars]

I never make my reverb switchable. It's just as easy to dial the reverb knob to zero when you don't want reverb.
The tremolo gets a footswitch from me. I don't see the point of having a toggie switch as well.. just use the footswitch.

The toggle switch is very useful...for example, if you don't want to deal with a footswitch. Or don't have the space on your pedalboard. Or forgot it in your car.

Switchable reverb isn't useful for everybody, but if you're on stage, you're not always next to your amp. Sometimes, NO reverb is the effect you're going for, and sometimes just for one moment in a song.

Everybody plays different.

Thanks,
Josh

[foreverstrung]

So I've powered up with a dim bulb tester with no issues. As far as checking voltage throughout the amp, is there a detailed step by step you'd recommend? I'm getting 123.9v coming in @ the power cord, everything else after that, DC and mV, I'm not 100% and what I'm getting when checking against using the Voltage test sheet isn't making sense.
Then, to add insult to injury, the speaker cable I had connected while powering up was defective. I was surprised that there was zero sound after the dim bulb test and I connected straight to the wall. So I started at the cable as it was new, (bought on Reverb) and it was defective. The +/- on this cable are touching. There is no separation. I was F-ing with this load attached this way for 3-5 min while powered up before I checked the cable. I replaced it with one from another amp, and I'm still not getting sound. at all. No hiss, nothing. Hopefully that defective load didn't burn something up. Tubes are lighting up and I'm looking to check voltages and that's where this post started. Any direction of attack with voltage testing would be greatly appreciated.
Thx

[JMPGuitars]

So I've powered up with a dim bulb tester with no issues. As far as checking voltage throughout the amp, is there a detailed step by step you'd recommend? I'm getting 123.9v coming in @ the power cord, everything else after that, DC and mV, I'm not 100% and what I'm getting when checking against using the Voltage test sheet isn't making sense.
Then, to add insult to injury, the speaker cable I had connected while powering up was defective. I was surprised that there was zero sound after the dim bulb test and I connected straight to the wall. So I started at the cable as it was new, (bought on Reverb) and it was defective. The +/- on this cable are touching. There is no separation. I was F-ing with this load attached this way for 3-5 min while powered up before I checked the cable. I replaced it with one from another amp, and I'm still not getting sound. at all. No hiss, nothing. Hopefully that defective load didn't burn something up. Tubes are lighting up and I'm looking to check voltages and that's where this post started. Any direction of attack with voltage testing would be greatly appreciated.
Thx

Assuming you've already connected and soldered everything...

First, visually inspect the amp for good connections, no floaters, etc. THen. highlighter test the whole build and make sure all of your connections make sense with both the layout and schematic.

After you've highlighter verified, and making sure you have a load connected to the OT now, try taking your voltages again, with no bulb limiter connected.

To test your voltages, connect the negative lead of a decent quality DMM to ground. Set your voltage to AC, and check the PT voltages and heaters. Then switch to DC voltage, and continue testing through the B+ line and tubes as marked in the voltage test chart. The layout shows what A, B, C, etc. are.

Thanks,
Josh

[foreverstrung]

Well, I'm going to take a break for the night. I'm starting to see crosseyed.
Everything appears to be hooked up correctly. (but obviously no). I've magnified glass checked everything. reviewed layout and schematics and it looks good. I went through resistor by resistor, cap by cap and checked, verified, and marked off the the right component was in it's right spot. But I'm not getting the right readings. To be honest, IDK when to cross from V to mV. I'm not even getting close to the reading in the spreadsheet.. I'm getting 123.9 at the PT. 3.6v at the heaters. and for some reason, I'm getting 562 mV on pin 9 @ V5 and 6. Or when I measure in volts, I get -0.57. I'm very discouraged. I've been going over this with a fine tooth comb. As far as I can tell, I'm not getting squat to the OT. That's why i'm not getting any sound. Maybe you can see something I'm not seeing.
Tomorrow is another day.
Thx

[JMPGuitars]

So... What's going on here?

capcan.jpg

Visual inspection + highlighter testing means:
Look at EVERY component value and CONNECTION in the SCHEMATIC.

Highlight each component, then each connection, only after verifying they're correct.

Thanks,
Josh

[foreverstrung]

I'm not seeing it unless it's xicon resistor. Calls for a 5w 2.2k.
220k between the ground and standby
It's wired up like the "layout" shows it. From my novice reading of the schematics it looks right too. The solder connections could be cleaner, but there solid. I'm really not seeing what the problem is. I've got no problem taking that entire area apart and doing it again, but what is it I'm going to be correcting? I don't want to guess and I'm really not seeing it.
I'll take the schematics to bed n review before calling it a night.
Appreciate all the help

[JMPGuitars]

I guess I need to clarify this in the layout:

capcan2.jpg

The Zener diodes are option to drop the B+ voltage to the target range. If not using them, then you need to connect a wire between those two points. The standby wire is what powers your OT and the B+ line.

In other words, if the orange wire and red wire don't have some form of electrical connection, there's no juice.

This is also why I say to highlight based on the schematic when checking values and connections:

tremtmbschem.jpg

On the bottom left corner you can see the standby switch connecting to the 220K resistor, point A, 32uF first half, and 2.2K 5W. The Zeners are not in the schematic, because they're a mod and only applied as needed. Which they usually are with modern electricity.

Now look at the top right corner where the OT is, and you can see the red wire connects to point A.

Does that make more sense?

Thanks,
Josh

[Bieworm]

Josh is right. You are not getting any power anywhere but the heaters.

B+ fault.png

[foreverstrung]

Thx. That was the ticket. At least it gets me in the door.
Here's my voltage sheet. I have to be honest, I don't know what this says. I don't know where to go from here. There's obviously something up with the phase inverter. Pin 2, when I first hit it with the MM leed, it made a lot of noise and from the corner of my eye I could swear the meter surged to 562v. However everything after that was near zero. Not getting squat. No noise either
to speak of unless I increase the volume knob. And pin 8 isn't much better.
So anyways, I appreciate you guys telling me what you see here.
Note: V4 P3 is 18.8 and IDK what HV1 and HV2 are or I would have added those #'s as well
Thx

[Bieworm]

Man.. those are really wrong. What is the cathode resistor of the EL84s value?
The PI is way off too. Please post detailed pics of the entire amp. Details of the PI components, power amp components, filter caps,...
Also the tube socket soldering...
It looks like you grounded the 2nd half of the PI
You didn't by accident put a 22k dropping resistor between A and B? Should be 2.2k.. and drop about 20V

You can't check HV1 and 2 because you directly connected the rectifier diodes and put heat shrink there? I don't do that .. i w1nt to be able to check those, always.
I make a longer board and put the rectifier on the board. On my current build I have a full wave bridge rectifier, because my power transformer doesn't have a CT on the HV.

16690640453834098107314312281349.jpg

[foreverstrung]

Appreciate your feedback. I've got 10 pics here. Tell me if there's anything else you want to see.
I damaged the 220k resistor at the rectifier from the standby to ground. It's obviously damaged. IDK if that would cause these numbers to be off or not. It's in the first pic. I moved the bus bar up to get better pics of the sockets.
Thx

[JMPGuitars]

Appreciate your feedback. I've got 10 pics here. Tell me if there's anything else you want to see.
I damaged the 220k resistor at the rectifier from the standby to ground. It's obviously damaged. IDK if that would cause these numbers to be off or not. It's in the first pic. I moved the bus bar up to get better pics of the sockets.
Thx

With the amp powered off, test the resistance to ground of the 221K resistor on the cap can. If it's not good anymore, remove and replace it.

You need Zener voltage dropping diodes to drop about 30V instead of the red jumper wire you added on the cap can. You can find my recommendation by scrolling down to Zener here: viewtopic.php?t=25173 - though the ones I normally use won't be available until next month. You could try two of these in series instead: https://www.mouser.com/ProductDetail/637-1N5352B

You should remove the FX loop. I don't remember, but I think I put in the manual that I don't add that in until all the testing/troubleshooting is done. It's in the way right now.

Your tube sockets are...not ideal. The heater wiring is sketchy, the solder joints generally don't have mechanical connections, and you have too much bare wire extending from the solder tabs. Review the soldering videos again, and review some of our build photos to compare.

You can see additional photos of my build here: viewtopic.php?t=25689&start=345

That should give you some ideas on how I wire and prep things.

My suggestion would be to not plug the amp back in until you've properly verified your build with a highlighter as I mentioned previously. If the 221K resistor at the cap can is suspect, then you can't highlight it, and your build isn't ready. But you need to verify everything. Enjoy the process, this isn't a race.

HV is where the rectifier diodes connect to the transformer (yellow heat shrink in your photo below). Measure AC voltage, same as the wall AC 120V reading on the voltage chart (though I'm guessing you were switched to DC on the chart?).

You can't check HV1 and 2 because you directly connected the rectifier diodes and put heat shrink there? I don't do that .. i w1nt to be able to check those, always.

He can check HV fine, he didn't cover the tabs:


Thanks,
Josh

[JMPGuitars]

Follow-up question:

Where is the black wire in this photo going from the cap can?


The cap can should be grounded at the star ground right in front of it.

Thanks,
Josh

[foreverstrung]

Right on. No it's not a race. Question tho, the tube sockets being sketchy, what would I do now? Rewire completely or just clean them up best I can?

follow up question is that black wire from the can goes to a star ground right there next to it. You just can't see that it loops in this pic

[JMPGuitars]

Right on. No it's not a race. Question tho, the tube sockets being sketchy, what would I do now? Rewire completely or just clean them up best I can?

I would love to pretend that those are two different options, but they're the same thing. Redoing them is the best you can. Watch the soldering videos and review the photos I linked before you proceed though.

Then take your time and highlighter test TWICE before powering back up.

Those are Belton Micalex sockets if you need to replace them. AmpifiedParts.com is a good source.

Thanks,
Josh