New TMB w/reverb Build

18watt-specific Tech Talk - Building, Fixing, Parts, Mods...

Moderators: CurtissRobin, colossal, zaphod_phil, Daviedawg, Graydon

Post Reply
User avatar
foreverstrung
Occasional poster
Occasional poster
Posts: 241
Joined: Sun 10/10/21 5:53 pm
Location: Seabrook Texas
Contact:

Re: New TMB w/reverb Build

Post by 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
You do not have the required permissions to view the files attached to this post.
0 x

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 3955
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: New TMB w/reverb Build

Post by JMPGuitars »

foreverstrung wrote:
Mon 11/21/22 5:27 pm
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?).


Bieworm wrote:
Mon 11/21/22 3:47 pm
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:
Image

Thanks,
Josh
2 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright

Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info


Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 3955
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: New TMB w/reverb Build

Post by JMPGuitars »

Follow-up question:

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

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

Thanks,
Josh
0 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright

Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info


Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale

User avatar
foreverstrung
Occasional poster
Occasional poster
Posts: 241
Joined: Sun 10/10/21 5:53 pm
Location: Seabrook Texas
Contact:

Re: New TMB w/reverb Build

Post by 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
0 x

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 3955
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: New TMB w/reverb Build

Post by JMPGuitars »

foreverstrung wrote:
Mon 11/21/22 6:51 pm
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
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright

Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info


Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale

User avatar
Bieworm
Verbose Moderator
Verbose Moderator
Posts: 2287
Joined: Mon 02/10/20 8:24 am
Location: Belgium

Re: New TMB w/reverb Build

Post by Bieworm »

FWIW I can clearly see you've done your best to work as intended, with the heat shrink and all..
Your work will be better with more practice. It's not the hardest, but surely not the easiest amp to build. But it's a fun amp to build, and when she's done... THAT SOUND!!!!

Here's where I'm at with my new tremolo TBM Reverb. I have the controls of the reverb on the back side. I also have a dwell pot by the way... IMHO an essential part of reverb.
20221121_230739.jpg
20221121_230743.jpg
20221121_230747.jpg
20221121_230756.jpg
20221121_230802.jpg
You do not have the required permissions to view the files attached to this post.
1 x
"THIS should be played at high volume..preferably in a residential area"

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 3955
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: New TMB w/reverb Build

Post by JMPGuitars »

Bieworm wrote:
Tue 11/22/22 3:06 am
Here's where I'm at with my new tremolo TBM Reverb. I have the controls of the reverb on the back side. I also have a dwell pot by the way... IMHO an essential part of reverb.
I made the first 1 or 2 versions of my reverb with the dwell pot, but I never really adjusted it below full resistance, so I swapped it for the 1M resistor. I guess if I needed to add an extra pot to a build for some reason, I might add it back in. 🤣

Hey, if you wanna show him some inspiration photos, show him your first build before and after reworking it. That was an awesome difference. A link to the post is good too if you remember where it is lol.

Thanks,
Josh
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright

Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info


Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale

User avatar
Bieworm
Verbose Moderator
Verbose Moderator
Posts: 2287
Joined: Mon 02/10/20 8:24 am
Location: Belgium

Re: New TMB w/reverb Build

Post by Bieworm »

JMPGuitars wrote:
Tue 11/22/22 10:20 am
Bieworm wrote:
Tue 11/22/22 3:06 am
Here's where I'm at with my new tremolo TBM Reverb. I have the controls of the reverb on the back side. I also have a dwell pot by the way... IMHO an essential part of reverb.
I made the first 1 or 2 versions of my reverb with the dwell pot, but I never really adjusted it below full resistance, so I swapped it for the 1M resistor. I guess if I needed to add an extra pot to a build for some reason, I might add it back in. 🤣

Hey, if you wanna show him some inspiration photos, show him your first build before and after reworking it. That was an awesome difference. A link to the post is good too if you remember where it is lol.

Thanks,
Josh
I get that, but I like to have lot of reverb in the mix.. without the long wash...

Good idea.. Will look that build progress up and post the link👍
1 x
"THIS should be played at high volume..preferably in a residential area"

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 3955
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: New TMB w/reverb Build

Post by JMPGuitars »

Bieworm wrote:
Tue 11/22/22 12:06 pm
I get that, but I like to have lot of reverb in the mix.. without the long wash...
That's in interesting point. I might revisit the Dwell knob again on a future build.
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright

Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info


Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale

User avatar
Bieworm
Verbose Moderator
Verbose Moderator
Posts: 2287
Joined: Mon 02/10/20 8:24 am
Location: Belgium

Re: New TMB w/reverb Build

Post by Bieworm »

This is a pic of my 1st build ever, a Classic 18W Tremolo (1974 type):
20200406_222327.jpg

Here is one of my first Tremolo TMB build.. it was my 2nd build ever, it's an unfinished version. But I had too many issues with it so I decided to start from scratch (next post):

20200309_224020.jpg
You do not have the required permissions to view the files attached to this post.
1 x
"THIS should be played at high volume..preferably in a residential area"

User avatar
Bieworm
Verbose Moderator
Verbose Moderator
Posts: 2287
Joined: Mon 02/10/20 8:24 am
Location: Belgium

Re: New TMB w/reverb Build

Post by Bieworm »

Here's my 3rd build, well a total make over of the Tremolo TMB. This is what I refer to as the prototype. It's the first operational Tremolo TMB ever. Look at my progress, most credits go to Josh for nearly whipping me like a slave. If there's one thing I call a talent of Josh is that he can really rub your face into the mess you made... you'll thank him later for doing so :D :D :D
20200419_153437.jpg
20200422_192005.jpg
You do not have the required permissions to view the files attached to this post.
1 x
"THIS should be played at high volume..preferably in a residential area"

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 3955
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: New TMB w/reverb Build

Post by JMPGuitars »

And here I thought I was being restrained and kind in my feedback. I guess that's why Belgium has the best chocolate. 😉😉 🤣🤣🤣🤣🤣
0 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright

Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info


Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale

User avatar
Bieworm
Verbose Moderator
Verbose Moderator
Posts: 2287
Joined: Mon 02/10/20 8:24 am
Location: Belgium

Re: New TMB w/reverb Build

Post by Bieworm »

My input wired:
16692254565566867703406055371915.jpg
You do not have the required permissions to view the files attached to this post.
2 x
"THIS should be played at high volume..preferably in a residential area"

User avatar
foreverstrung
Occasional poster
Occasional poster
Posts: 241
Joined: Sun 10/10/21 5:53 pm
Location: Seabrook Texas
Contact:

Re: New TMB w/reverb Build

Post by foreverstrung »

Great Pics
Dim bulb tester question.
I'm not sure I'm getting the right bulb. i've tried 2. Both incandescent. 1st one rated 50w-100w-150w. It's the one I used on the first trial with the amp start up. I tried it with my 74 Vibrolux and then on a Hot Rod Deluxe, first, before using it on the TMB build. Both when fired up, lit up and then faded to a very very dim light. So when the TMB did the same when I took the voltages, I thought it was fine as the other 2 amps were fine......Well, fine enough to test for voltages anyways........So since I'm going thru everything again with a fine tooth comb on the TMB, I thought I'd go ahead and build another tester. Nice and clean, with a diff incandescent bulb. 100w.......Same thing with the 2 amps. the vibrolux lit brighter then faded to a very dim light immediately and the Hot Rod just stayed a very dim light. I had to turn off the overhead lights to see it.
Is this ok? Everything I'm reading about these DIY testers is that when everything is cool, there's no light, at all. I know I've wired the tester together correctly, but either I'm not using the right bulb or there's something wrong with the other 2 amps I've got here now. OR, of course, something else I'm completely missing
Also, fyi, I did not fire up the TMB yet. I've not finished going thru it all yet. Just trying to be prepared
Thx
0 x

User avatar
Bieworm
Verbose Moderator
Verbose Moderator
Posts: 2287
Joined: Mon 02/10/20 8:24 am
Location: Belgium

Re: New TMB w/reverb Build

Post by Bieworm »

I cant' comment on that but I have a different kind of light bulb current limiter.

It's a 250W Halogen yard beam light. I attached it to a power brick, where in the circuit also resides. It works perfectly and never lights up whatsoever, unless there is a short in the amp. Works for me...
1 x
"THIS should be played at high volume..preferably in a residential area"

Daviedawg
Superior Amp Tech
Superior Amp Tech
Posts: 748
Joined: Fri 01/08/10 2:00 am
Location: Scotland

Re: New TMB w/reverb Build

Post by Daviedawg »

In my experience the bulb goes bright on switch on, immediately starts to dim, then stays at a low dimness after that. Variables in dimness depend on the power of the bulb versus the power of the amp. I use mine on the floor beside my desk out of bright light. So that you see it quite dim without straining.

What you describe is what I have experienced. If it stays bright something is wrong. Switch off right away.

Dd
3 x

User avatar
foreverstrung
Occasional poster
Occasional poster
Posts: 241
Joined: Sun 10/10/21 5:53 pm
Location: Seabrook Texas
Contact:

Re: New TMB w/reverb Build

Post by foreverstrung »

Happy Thanksgiving.
Grateful for y'alls help
Ran a 2nd voltage test. After installing the voltage dropping diodes. Then I rewired all the pots. Just because they were not really pretty. I went through all the tube sockets. Thoroughly. A few times with a large lighted magnifying glass and as they are "sketchy" and not real pretty, there is no grounding.
I went through the layout diagram and highlighted all the connections. I've been taking long segments of time and reviewing the schematics. I do understand (see) how the flow of the drawing goes. All that being said, I powered it up with a dim bulb tester and then directly to the wall and let it warm up. I got some better readings (because of the zener diodes) and some are still not cool.......I'm really wondering if I didn't damage something at the PI with that surge the other day when testing pin 2. I'm still not getting anything. In fact all my PI numbers suck. Is there a chance I burned something up.
As for the other pre amp tube sockets, even tho they appear clear and connected as should be, I'm going to rewire all of it. Valves V1-V5. I've got replacement sockets coming tomorrow. I'll just rewire the entire heater section. Then run the highlighter thru everything again. But as I do this, do you guys have any ideas about the possibility of frying something? Like I said after the first voltage test, When I measured V3 P2 on the PCB board there was a loud output and I caught the MM read high, briefly. like .5 seconds n it was gone. Since then, nothing. No sound, no reading.
Also, the HV1 and 2. Am I not measuring them correctly? I've marked the reading I got. Something is no bueno.
Thx
You do not have the required permissions to view the files attached to this post.
0 x

User avatar
foreverstrung
Occasional poster
Occasional poster
Posts: 241
Joined: Sun 10/10/21 5:53 pm
Location: Seabrook Texas
Contact:

Re: New TMB w/reverb Build

Post by foreverstrung »

Pics of the Zener Diode(s) install and new 221k resistor and pic of new wire on pots.
Also, doing the highlight review I found 2 mistakes. Looking at the numbers above, does not appear like it made too much of a difference tho
Thx
You do not have the required permissions to view the files attached to this post.
0 x

User avatar
Bieworm
Verbose Moderator
Verbose Moderator
Posts: 2287
Joined: Mon 02/10/20 8:24 am
Location: Belgium

Re: New TMB w/reverb Build

Post by Bieworm »

Did you try other tubes?
What's up with node B on the B+??? Maybe your cap can is corrupt?
0 x
"THIS should be played at high volume..preferably in a residential area"

User avatar
foreverstrung
Occasional poster
Occasional poster
Posts: 241
Joined: Sun 10/10/21 5:53 pm
Location: Seabrook Texas
Contact:

Re: New TMB w/reverb Build

Post by foreverstrung »

HV1 is 306 and HV2 303. I was testing in DC with the voltage sheet posted tonight. When I went thru other correspondence, I found Josh mentioned that.
I've ordered some new components and like I said, I'll rewire the heaters completely. I picked up a couple cap cans just in case and for another project after this. That B side being so low bothers me. That is a 2.2K resistor, I checking it with a MM tonight and it checked out. As I was cautioned, do not guess, but if the cap can is bad, I'm prepared. If it's not, I've got a couple extras. After cleaning this all up, I'll do a highlight trace again carefully.
That PI still bugs me tho. It's wired correctly. V1 as well. It's not getting the voltage expected Maybe new sockets will help. I very well could have f'd them up.
I've swapped tubes in these spots a few times. And I've bought some new tubes too
0 x

Post Reply