My new build ,high volyage readings

Share your home builds, knock offs and ground up customs.
Post Reply
DG45
New Member
Posts: 46
Joined: Tue Sep 22, 2015 2:57 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by DG45 » Sat Jan 09, 2016 8:04 am

I did not read this thread so I don't know what the specific issues are and I apologize if this has been addressed.

Just from looking at the photos on page 1 and the Tube Depot wiring diagram ... on the wiring diagram there is a jumper from T28 (where the + of the 47uF cap connects) to T26 (where the red wire connects to V2 pin 6). Maybe I'm missing it but I don't see that jumper in your photo's.

As I mentioned, I haven't read the thread and I don't want to confuse the issue. It's just something I noticed in the photos.

fixer2
Senior Member
Posts: 212
Joined: Wed Jul 29, 2015 7:23 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by fixer2 » Sat Jan 09, 2016 8:35 am

tube depot had me put the jumpers under the board I did put a second set on the top later after more trying and testing I have to now try re melting in the joint you say .just get busy that time is one thing we all could use more of.But if it looks like Iam missing a wire or such ,iam looking for any body that has built a tube depot jtm 45 plus kit and it works,everybody here has been very very good lots of info and i like that,so I will keep on trying just been away from it for alittle but Iam get to it soon and tell my testings my findings and share how it is going. Cant wait to take it to the next level of building and with a second and third build I like vintage amps just the real one cost to much so why not build it.I know first things first get this one going ,( walk before you run ) thanks again all.

DG45
New Member
Posts: 46
Joined: Tue Sep 22, 2015 2:57 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by DG45 » Sat Jan 09, 2016 10:21 am

I've built that kit. That's why I took a quick look at your photos and compared to the layout. I didn't spend much time, that jumper just stood out to me. I read a few posts on the last couple pages and I can tell you that I am not as tech savvy as danman responding to your post. So, despite my having built this kit, I don't think I can do any better in the technical department than the guys already helping you. There isn't anything really unique about the TD kit. The layout varies a little between the available kits but that's mostly it. But, I'll try and read through the thread when I get a chance and see if there is maybe anything that I notice.

For the record, my amp works fine. My voltages were all easily within 10% sticking to the testing procedure in the manual. I'm not a meticulous, expert builder, but it wasn't my first go round. It's surely not the most vintage correct of the JTM 45's. Metal film resistors aren't exactly "vintage", and there were obviously some changes in the Tube Depot design, PS filtering being one of the most obvious. More like a hybrid of a few of the early Marshalls. But at any rate, it does work and it gets the Marshall tone even if it's not the most vintage Marshall sounding of the available kits. I really dig mine. I rarely play through anything else since I finished it, several months ago now. Point being, stick with it, you'll get there.

fixer2
Senior Member
Posts: 212
Joined: Wed Jul 29, 2015 7:23 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by fixer2 » Sun Jan 10, 2016 2:09 pm

DG 45 Do you have any inside pictures of your tube depot build ,so I can compare with may be I will see then if i missed something .Where did you get your learning from books dvds class do you have a electrical back ground . I have been reading up on the subject of tube amps repair and so on I have recent got a dvd on it.But this is a good learning on trouble shooting a amp.I want to learn more on it ,but just not on my first build but thats what I got,so I keep on with it .Question to all how do you not get too much of a build up of rosin on the joints,I have been cleaning up more in the amp and notice on the turrets in questions of cold joints I suck off the old solder and there is alot of rosin too.

danman
Senior Member
Posts: 1099
Joined: Tue Sep 10, 2013 9:09 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by danman » Sun Jan 10, 2016 4:14 pm

If you are referring to the crust that is left around the joint after you solder, that is normal. Some solder leaves more than others. You can take denatured alcohol and wipe it off immediately or I usually just take a small screwdriver and flake it off after the joint has cooled.

fixer2
Senior Member
Posts: 212
Joined: Wed Jul 29, 2015 7:23 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by fixer2 » Sun Jan 10, 2016 6:17 pm

I think some of the rosin was in one of the joints you said I should re heat for a better non cold solder joint I used my new de-soldering tool and figure to try cleaning things up.could this rosin be insulating the connection ? I have not finished yet re-soldering and cleaning ,so I havent powered the amp up yet to see if it works ,by now getting power to V1

DG45
New Member
Posts: 46
Joined: Tue Sep 22, 2015 2:57 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by DG45 » Sun Jan 10, 2016 6:22 pm

I think I have some photos but they are still in the camera. I'll go through them and see what I have. I know that I don't have any detail shots though. But I'll put up the best of what I have.

I was a field tech but not in electronics per se. Honestly, I'm not very tech savvy with electronics. I struggle with a schematic, although I usually figure it out if it's not a very complicated circuit. Give me a wiring diagram and I can build it though. What I do know, I taught myself over the years. I'm not exactly a young man.

I'll work on those photos and try and get them up in a day or two.

DG45
New Member
Posts: 46
Joined: Tue Sep 22, 2015 2:57 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by DG45 » Mon Jan 11, 2016 7:49 am

Ok fixer, these seem like the best photos I have.

Note that I made a few changes from the original layout:

First, I have installed LarMar type post phase inverter master volume (PPIMV) which consists of the potentiometer on the back panel with the gray wires connecting to the turret board. Because of this, you may notice that the two 220K bias resistors are not on my turret board.

Second, the connection at T4 is different than the wiring layout. I connected the 820 ohm resistor and 330uF cathode bypass capacitor for the normal channel to T2 instead of T4. T2 is not used in the original layout. I then connected a piece of buss wire as a jumper between T2 and T4. The modifications section of the manual gives the option to wire V1 as shared cathode or split cathode. I have wired the V1 12AX7 for split cathode. Wiring to that resistor and capacitor to T2 and jumping to T4 allows me to more easily convert V1 to shared cathode if I want to. All I would have to do is remove the jumper connecting T2 to T4 and solder one in from T4 to T6.

Third, you may notice that my negative feedback switch on the back of the chassis looks different. I built a small circuit board to attach the switch, resistors and wires to. Makes no difference in sound, it just allows me to easily change the feedback resistors if I want to without having to worry about overheating the switch by soldering and desoldering.

Finally, you may notice that the electrolytic capacitors, C1, C17 and C18 are not the same as you got in the kit. My kit came with Sun Tan brand capacitors for those positions. They are most likely perfectly fine but I just wanted to go with components that I was more comfortable with. I used Sprague Atoms for C17 and C18 and, I think, a Vishay for C1. It likely wont make a lick of difference. Just didn't want you to wonder why yours looked different.

I think that's the only changes that I made. Hope the pictures show up ok and can maybe help you. Sorry that there are not detail shots of specific areas.

Let me know if you have any problems with getting the images enlarged. I'm seeing some formatting issues from my computer, but it may just be this machine.


http://i130.photobucket.com/albums/p243 ... etnnt1.jpg

http://i130.photobucket.com/albums/p243 ... 1rv8w7.jpg

http://i130.photobucket.com/albums/p243 ... xiy0sn.jpg

http://i130.photobucket.com/albums/p243 ... vywpns.jpg

fixer2
Senior Member
Posts: 212
Joined: Wed Jul 29, 2015 7:23 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by fixer2 » Mon Jan 11, 2016 8:47 pm

Thanks the pictures did alot they are very clear and nice clean build ,my is messy,but I now get sound yes all I now get sound,my stand by switch does not work the amp is always in play mode in either up or down .I seem to be getting a little back ground noise like crumpling papers so I will move around my wires with a chop stick to to see what helps,also my guitar sounds a little out of tune like flat and the normal channel is deep tone which is good but it is also louder,Iam putting a stock 1994 gibson sg standard into the amp tune to e with a set of 9-42 on it the bass at 3 mid at 9 treb 10 vol 10 I will have to get some voltage readings to tell you guys.last night I was done re doing the joints that were not getting voltage and I was testing and slipped touching the test probe very quickly to t28 to t30 where the jumper wire is and for a short moment (about 5 seconds ) it came alive that I could hear crackling when I was holding the guitar cord I have plug in to the input .So I was up most last night re checking and thinking of both the signal path and the path of the voltage feeding the tubes.So then when I was re looking at any pictures I have of other jtm 45 and when I saw these I got it.Now I have to get the sound clear not out of tune and I think the bright channel should be louder or may be not,I dont know never played a old marshall jtm 45.And I need a good working stand by switch.Thanks again to all I have learned alot and see why to be neater builder is a must.ThanksI going to contiue cleaning it up and then after I finish get it in full working order and in its cab etc then I will look into the next amp I just now fell like I can do this , just really want to keep learning more tech stuff etc .

DG45
New Member
Posts: 46
Joined: Tue Sep 22, 2015 2:57 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by DG45 » Tue Jan 12, 2016 9:19 am

That's progress. Excellent. Glad the photos helped.

That "crumpling" sound could be tube rush but that's usually a low level noise. Playing loud would drown it out. Could be a bad tube too, but based on your having to mess with the guitar cable to get sound, and the clean up you had to do with the soldering, I wouldn't rule out still having a questionable solder connection or two, assuming that everything is wired correctly. Poking around in there with a non-conductive probe (wooden chopstick for example) should help you pin point where the problem is. Just stay safe.

Not sure that the guitar sounding out of tune would be related to the amp, but I guess there could be something going on sonically with the amp that makes it sound that way.

The normal input is definitely dark/warm. I'm not sure if the treble input is technically louder ( measured with an spl meter) but to the ear, the treble input should seem louder with both volume controls at the same setting. Our ears should be more sensitive to the increased brightness of the treble input relative to that of the normal input. Well, It does sound louder to my ear anyway. I'm sure danman can elaborate (or correct me).

If I'm plugging straight in, I normally jump the inputs. If my pedal board is in the signal path, I use an ABY switch and toggle between both inputs and, usually, just the treble input. One of things I've always liked about these type amps is the ability to blend the two inputs with the respective volume controls.

Keep working at it. Sounds like you are down to just a few bugs to work out. Good job sticking with it.

fixer2
Senior Member
Posts: 212
Joined: Wed Jul 29, 2015 7:23 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by fixer2 » Tue Jan 12, 2016 6:01 pm

I was so glad when it came alive that I did not notice that I was still plug into/threw my dim bulb to save the amp just in case of a short.I tryed it again with the cord plug straight in to the wall and most of that crackly noise was no more much clearer and punchy and a little louder.I remember late last night when I could not fall a sleep with joy.That I did not bias the tubes it is still all the way cool ,so I have to wake up the power tubes bit more and get them even out.After I re wire my stand by switch I need to proper warm up and slowly cool them down before shutting the power off.My tube depot kit has a different style switch than other but I either get this one going or get a metro style switch .But thank you again to all that have helped.

danman
Senior Member
Posts: 1099
Joined: Tue Sep 10, 2013 9:09 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by danman » Tue Jan 12, 2016 6:18 pm

Congratulations Fixer!! It's been a long road getting everything sorted out but I am sure that you have learned alot in the process. Enjoy :rock:

fixer2
Senior Member
Posts: 212
Joined: Wed Jul 29, 2015 7:23 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by fixer2 » Wed Jan 13, 2016 6:27 pm

Yes thanks danman you sure have been helping the most big part of me looking and re soldering and cleaning up joints ,sucking the old solder off and re doing and then I got the pictures and then I got a mental picture of were the voltage stopped and when I was getting voltage readings with my fluke meter and I slipped a little and touched t30 and that was it , it made me really thinks and then I reviewed the pictures of DG 45 and I got itso again thanks.Iam now going to drain it down take my stand by switch out and see if I got the wiring wrong and that is why it does not work right I need a stand by.I wish in this amp the big caps were on the top with the tubes like the later Marshalls.But yes I have learned a lot which is really good I want to be a good trouble shooter I have two other tube amps I got for really cheap price that need some fixing.

DG45
New Member
Posts: 46
Joined: Tue Sep 22, 2015 2:57 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by DG45 » Thu Jan 14, 2016 8:42 am

Test the switch with your meter. They are good switches but overheating them when soldering can fry them.

fixer2
Senior Member
Posts: 212
Joined: Wed Jul 29, 2015 7:23 pm
Just the numbers in order: 13492

Re: My new build ,high volyage readings

Post by fixer2 » Thu Jan 14, 2016 6:13 pm

I tested it and they are sending me a new one .

Post Reply