18 watt tmb tremolo build question

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Re: 18 watt tmb tremolo build question

Post by colossal »

Although the "arrow" indicating the direction to ground printed on the sleeve is pointing towards your ground, that G-Luxon 1000uF cathode bypass cap looks like it's in backwards (polarity reversed). Usually the tapered/fluted end indicates the (+) terminal. Might be something to check.
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Re: 18 watt tmb tremolo build question

Post by Bieworm »

colossal wrote:
Mon 03/09/20 9:31 pm
Although the "arrow" indicating the direction to ground printed on the sleeve is pointing towards your ground, that G-Luxon 1000uF cathode bypass cap looks like it's in backwards (polarity reversed). Usually the tapered/fluted end indicates the (+) terminal. Might be something to check.
You're right! That might be wrongly printed or wrapped. Can I check that somehow?
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Re: 18 watt tmb tremolo build question

Post by Bieworm »

20200310_045609.jpg
20200310_045448.jpg
Appears I have various electrolytics like that of which I know they operate correctly. Even though the waist is on the negative side. They are radial types. I think the general rule only appplies for axial types
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Re: 18 watt tmb tremolo build question

Post by JMPGuitars »

Bieworm wrote:
Mon 03/09/20 11:53 pm
They are radial types. I think the general rule only appplies for axial types
That's correct, that rule only applies to axial style. Radials have the negative stripe next to the negative terminal rather than pointing at it. The fluted waist is next to both terminals in that case. Your photos make it look confusing because you have the radials disguised as axials the way they're laying down. ;)
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Re: 18 watt tmb tremolo build question

Post by Bieworm »

Cooked my Power Transformer. The leg from the rectifier resistor was broken at the diode side. It sparked and then the tranny was starting to melt and gave smoke. The cables from the filament wires. Makes sense?
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Re: 18 watt tmb tremolo build question

Post by colossal »

Oh no! :| Sorry to hear the bad news about your power transformer. As for that cap, I would probably not use it, especially if there is a question about quality control.
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Re: 18 watt tmb tremolo build question

Post by Bieworm »

I found a solder that connected V2 pin 6 and 7. Is this short a possible reason to make the transformer start to smoke?
I checked the transformer with a DMM. All windings have continuity, but the resistances on some windings are too high or too low.

primary:
spec= 0-120 = 3.38 / measured = 4.3
spec= 120-240 = 7.44 / measured = 6.7

secondary:
spec= 290-290 = 97.26 / measured = 6.0
spec= 0-6.3 (h1+2) = 0.072 / measured = 0.8
spec= 3.15-3.15 (f1+2) = 0.047 / measured = 0.7

I didn't make these controlings before, so is there severe dammage when you look at these numbers?

edit: transformer is cooked anyway. I connected it to wall voltage and it immediately starts to smoke.
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Re: 18 watt tmb tremolo build question

Post by JMPGuitars »

Bieworm wrote:
Wed 03/11/20 4:56 am
edit: transformer is cooked anyway. I connected it to wall voltage and it immediately starts to smoke.
Time to cut the leads and use it as a paper weight. It sucks that's it's dead, but better to be safe than sorry.
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Re: 18 watt tmb tremolo build question

Post by geoff 1965 »

it's hard to see what you've done with the diodes/sag resistor,i presume the diodes are in the heatshrink going to the 10W 120R but it looks like one of the leads is soldered to the fuse holder!
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Re: 18 watt tmb tremolo build question

Post by Bieworm »

It might look that way, but it's not. It's 2x 2 1N4007 diodes in series, joining at the resistor. The resistor is wired to the upper standby-switch-lug. The lower lug is going to the cap can.

To be honest... I fired up the TMB tremolo JMP design yesterday. I had all kinds of noises and very low volume + overdrive from the start on the volume knob. You know, the turrets were really hard to solder. Solder just wouldn't stick to it directly without using the flux liquid. So I assumed it could be anything, anywhere/everywhere on the board giving me bad connections. Not to mention the heat the components must hav experienced. I decided I just want to enjoy the amp without the quest for solutions for now. So I reinstalled the previous board (18W classic). In the run I had to swap the resistor at the rectifier back to 220K (SS rectifier), but the wire from the resistor to the diode appeared to have broken at the resistor. It was sparking when I lit up the amp, and the transformer started to smoke.

Today I inspected the chassis for other errors or causes of trouble and I noticed that the lugs 6+7 on the PI tube socket were joined by solder..not just touching, but really flowed into one another :(

Now my big question is:
Could the smoking of the PT come from the sparking loose wire on the resistor? Or is the origin of the problem rather the joined lugs on the PI tube socket?

I ordered a new transformer, and before I juice it up with power I would like to determine the cause of the burning TF.

What do 'yee of more knowledge' suspect to be the problem? How can I determine this without trying and smoking my new TF?

( so you see, when one works too fast and too anxious... damn! And I was working so clean for my newbie standards)
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Re: 18 watt tmb tremolo build question

Post by geoff 1965 »

with turrets you need a high wattage soldering iron to put the heat in fast and use heatsinks on your components,i've got one that's at least 80W which i use for the turrets and a 40W i use for leads,tube pins & pots etc.
yeah you need to check over things before fitting the new PT, i think i've cooked my PT experimenting with current limiters,i got stable with heatsinked 25W resistors but i had the amp running on 8W & 14W's for a good 3 or 4 hours before which got very hot.i've noticed some of the resin/varnish has leaked out of the cover so the HT winding must have heated enough to melt it! so now i don't trust it and it's coming out! it only cost £35 so not so bad,if it was a heyboer i would have been really pi**ed off.
keep at it, you get 10 out of 10 from me for having a go!
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Re: 18 watt tmb tremolo build question

Post by Bieworm »

geoff 1965 wrote:
Wed 03/11/20 8:35 am
with turrets you need a high wattage soldering iron to put the heat in fast and use heatsinks on your components,i've got one that's at least 80W which i use for the turrets and a 40W i use for leads,tube pins & pots etc.
yeah you need to check over things before fitting the new PT, i think i've cooked my PT experimenting with current limiters,i got stable with heatsinked 25W resistors but i had the amp running on 8W & 14W's for a good 3 or 4 hours before which got very hot.i've noticed some of the resin/varnish has leaked out of the cover so the HT winding must have heated enough to melt it! so now i don't trust it and it's coming out! it only cost £35 so not so bad,if it was a heyboer i would have been really pi**ed off.
keep at it, you get 10 out of 10 from me for having a go!
I use my weller solderstation. It's 450°C, so plenty hot. The turrets on the previous board were very easy, but the ones I used on the TMB tremolo board are really bitchin' hard. And even after cleaning they seem to sweat out some kind of resin like substance.

But for the new trannie ... how will I be sure of what went wrong last night? The soldering of lug 6+7 on the PI? Is that possible?
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Re: 18 watt tmb tremolo build question

Post by geoff 1965 »

not sure,other than going over the whole circuit checking.some of the senior amp techs might be able to point you at a specific area that caused the failure?
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Re: 18 watt tmb tremolo build question

Post by Bieworm »

It's a pitty I don't have equipment to check caps. Don't have the knowhow either .
Is my cap can ruined? Are caps ruined? What should I replace just in case?...
I'm lost somehow...
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Re: 18 watt tmb tremolo build question

Post by JMPGuitars »

Slow down, you'll be okay. Personally, I solder my turrets at 380C, so if your iron is really that hot, then it SHOULD be able to solder the turrets. That said, not all turrets are equal. Some turrets are terrible.

See my thread here for the stuff I use: viewtopic.php?f=25&t=25173

The first two meters on that page can both test capacitors. In some cases, you will need to lift one side of the capacitor out of the circuit to be able to test.

I use Keystone 1509-4 turrets exclusively. Amplified Parts / CE sells them as their "premium" turrets. Other companies sell them too including Newark and Mouser. If you can't solder a turret, it's either the turret, the iron, or the technique at fault. You need to figure out which.

I just added this to the page: https://amzn.to/2IHNDVW - that can test your soldering iron temperature and see if it needs to be calibrated or replaced. There's also cheaper generic versions that work. I'm still using the Aoyue solder station I listed there.

I highly recommend using the "Kester No Clean Solder" listed on that page. It works great, and doesn't make a mess.

Anyway, you need to inspect your amp thoroughly to make sure there's nothing else that stands out as obvious like those lugs soldered together by mistake. Then you need to go through the amp with the layout AND schematic, and highlight every single connection, and component only after verifying their values and connections. You might need to do this more than once to be thorough.

Always take your time and be thorough. Looking at your photos, I suggest you watch the videos I linked in the solder technique sticky thread: viewtopic.php?f=4&t=25396

Thanks,
Josh
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