Hey Gavin

I cant find anything jumping out of those pics that would cause the noise issues other than possibly your heater wires being ran somewhat close to some of the pre-amp tube wiring. Maybe try lifting any wires atleast a 1/2 inch away from the heater circuit wires if possible. Also make sure and roll your preamp tubes as well to make sure you dont have a bad or microphonic tube causing the noise.

Let us know if that doesn't do it

Todd

Cool man
I  havent had time to look at the pics yet but when i use my OD on my HRM there are only 2 settings for me
1 clean   both OD and PAB off
2 OD      bothe OD and PAB on

If you engage the OD only, your signal goes through both the TMB tone stack and the HRM stack and to me is useless sounding.

I will let you know if I see any issues with the pics that may cause the noise issues your experiencing. BTW the relays are fine if your footswitch is working correctly

Todd

I understand, for me this ampbuilding thing is a hobby. Bill has made a career out of it and I believe he's even spent some time with real Dumbles so I am sure you will be in good hands. BTW got the pics and no problem going over them. I was an electronics/fire alarm systems service tech for 10 years before I changed careers a little over 2 years ago so troubleshooting electronics is fun for me.
Anyways hope to here from you once you get the bugs worked out in that amp

Todd

Sure thing,
Yeah on the other pics you sent me I noticed some other strange components that to be honest I dont know what the tech was trying to achieve by installing. If I had that amp on the bench I would go through it and revert it back to the original OTS 124 specs to start.
Why did the tech make all these mods? Other than the PT blowing were you unhappy with the sound prior to it blowing?

Todd

A couple of obvious questions first

Does your foot pedal work, do the lights turn on and off and are the swithes on the back of the amp set for the pedal?
If the PAB is on the TMB knobs will have no effect!
Does PAB work?
If you swap V4 and V5 does the 50mv reading follow the tube? if so they are not matched and I would suggest getting another pair.
Are your relays installed in the correct position/direction?
If you can post some pics of the amp guts.

Todd

Hey Bdog

I sent you a PM with my email!
I've been looking at the second picture you posted and it appears it is something between the OTS and the OTS SM50.
There are a few suspect components for example the 2 large orange drop caps on the far right ( input side ) are 715p caps rather than 6PS I cannot see the value of each cap from the pic but they appear to be the same size and they shouldnt. There is what looks like a tantalum capacitor paralleled across a resistor towards the bottom middle of the board that has no place on any D-style amp so that one has me scratchin my head.
I'll have to go back to your previous posts but did you buy this amp new from Nik in 2008?

Todd

Hey Bdog

If I ever am in the Redding area I may just take you up on that beer. I actually live in Colfax but commute to Sac M-F for work. I am sure Bill at Sebago will make that amp sound the way it is supposed to sound.  Could you post the pic of your amp guts that you sent Bill, I am curious as to what would be different in your amp compared to the current OTS layout.

Todd

if you are in the Sacramento area ever let me know I would be happy to give your amp a thorough checkup.
Regarding your HRM thread I would suggest you be sure to get this OTS running correctly first before considering another D-style amp. The differences between HRM and non-hrm are more subtle than you may think!

Todd

Hey
Regardless of the wire color you have 3 taps all AC 
1. 120 vac input on one side ( should be labeled )
2. 6.3 vac for the heaters that go to the tube ( should be labeled on the trannies paper
3. And then the 135 vac ( should be labeled as well )

Are you asking this because it does not label which lead is the 0volt?


Todd

Make sure and check your amp with the C-lator out of the loop as well. I have had a bad 12ax7 in the C-lator make the clean channel sound like the OD channel!

Also I have had bad output tubes make a fuzzy crackling sound when going bad. Tends to be more pronounced when you hit the strings harder! If you change them you will need a digital multi meter and then follow ceriatones instructions for biasing in the OTS owners manual. All this can be done without even opening the amp chassis.

Hope this helps

Todd

I would suggest you get a C-lator as well whether you go 50 or 100 watt. Even if you do not use the effects loop it will provide you with one of the most useful master volumes of any of the other amps I've ever tried.
In other words there will be no need for an attenuator or half power switch with the OTS amps whether you go 50 or 100 watt. I built 2 50 watters because I dont think I'd need the extra headroom you'd get from 100 watts but have since been in a situation where I wished I had gone 100 watts.
Now if you get a trainwreck express an attenuator you may need. Based off the your previous posts I doubt you would like the TW express ( you said you dont like Marshall's ), I built one and out of the 6 amps I now have it gets the least play time. The volume knob on that amp goes from off to loud as heck.

Todd

There is a jumper between pin 1 and 8 of the power tubes so electrically there is no difference between pin 1 or pin 8

Todd

Hey francois

On most of the trannies I've used ( Classic Tone usually ) the OT primaries are red and blue and the CT is white.
Hammond may use different colors but you confirm this on your spec sheet.

1st On most all tube amps V1 is the smaller pre-amp tube furthest from the larger output tubes. From V1 the next tube is V2 and the next is V3 and so on....
On the JTM 45 you got
V1 - 12ax7
V2 - 12ax7
V3 - 12ax7  Phase Inverter
V4 - KT66
V5 - KT66
V6 - GZ34 rectifier
Hope that makes sense..

Anyways, Once you figure out which 2 wires are you OT primaries they will land at both V4 and V5 pin 3. You have a 50% chance of having them reversed ( so leave enough wire length). If they are reversed you will know immediately when you power the amp up, it will be the loudest most annoying squealing sound you have ever heard! No worries just desolder and swap the 2 wires and as long as every thing else is wired correctly your amp will be working.

Hope this answered your question

Todd

Hey Francois

Welcome to the addiction!

The trannie mounting plate is mainly just to distribute the trannies weight equally in case you are using a weak or flimsy chassis. Niks chassis would be fine without it butif you have it you might as well use it. The bracket also gives you a couple points at which you can zip tie your wires to which may be useful.
There is no need to isolate the magnetic core from the chassis!


Todd

If you want to build an amp that can be used with both guitar and bass, I wouldsuggest the plexi bass 1986, Fender Bassman, or JTM45. The only problem with the 3 amps I suggested is they are all 50 watters and you mentioned wanting a low powered amp.
I just finished a Plexi Bass build a couple weeks ago and can say this amp has a very inspiring tone. It can also very easily be modded to the plexi lead 1987 circuit if you find it too bassy!

Todd