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    TM36 Backlighting Issue

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    TylerD94

    Posts : 3
    Join date : 2018-01-31

    TM36 Backlighting Issue

    Post by TylerD94 on Wed Jan 31, 2018 10:41 am

    Hello there.

    I'm new to the forum but haven't seen anything on this. Here or anywhere. I've owned a TM36 since summer 15. Served me very reliably and never had any major issues. Some little quirks but nothing too major.

    The one that's been bugging me for about two years now is after a while, my neon lights died out. May have been shock from transport knocking something loose, I'm not sure. I'd love to get it to illuminate again and was wondering what I could use to either bring the blue LED's back to life, or even swap the color out, to something like purple.

    If anyone has any ideas on how to go about this I'm all ears. I took all the covers off once but didn't want to dig too deep into it without any real know-how on these amps.

    Happy playing
    -Tyler
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    mtsv

    Posts : 2
    Join date : 2018-01-23

    Re: TM36 Backlighting Issue

    Post by mtsv on Sat Feb 03, 2018 12:12 pm

    TylerD94 wrote:Hello there.

    I'm new to the forum but haven't seen anything on this. Here or anywhere. I've owned a TM36 since summer 15. Served me very reliably and never had any major issues. Some little quirks but nothing too major.

    The one that's been bugging me for about two years now is after a while, my neon lights died out. May have been shock from transport knocking something loose, I'm not sure. I'd love to get it to illuminate again and was wondering what I could use to either bring the blue LED's back to life, or even swap the color out, to something like purple.

    If anyone has any ideas on how to go about this I'm all ears. I took all the covers off once but didn't want to dig too deep into it without any real know-how on these amps.

    Happy playing
    -Tyler

    In fact, when I took of the cover of my TM18 to change the tubes, I remember that the lighting was in fact strip LED. I presume you may open and take it out for a replacement. Maybe it is just out of its socket (which is pretty small) and you may put it back.
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    bordonbert

    Posts : 985
    Join date : 2015-01-28
    Age : 98
    Location : Southern England

    Re: TM36 Backlighting Issue

    Post by bordonbert on Mon Feb 05, 2018 11:59 am

    The lighting is on a long thin strip of PCB material held between the top case and the acrylic front panel.  It is held in place by four metal clips which slip over the front panel and sit under the top panel with the LEDs facing down into the acrylic.  It is fed current by a pair of thin red/black wires which go down the side of the front panel and into a socket in the chamber below on the end of the mainboard.  If you remove the top panel by the proper procedure so you don't void the warranty you will find it there easily accessible.  You have to be very careful with them when you refit the case so the PCB sits right across the front and the clips are fitted correctly.  If you don't know the proper opening procedure to get into the valve chamber let us know and we can advise, it's simple enough but leaves the anti-tamper devices in place which means your warranty is still ok!

    The LEDs are blue surface mount devices and as such are pretty small.  They can be a bit of a bugger to hand solder so changing colours is absolutely possible, but impossible unless you have good soldering technique and a good quality iron, (better a soldering station)!

    The LEDs are all in series so any problem with a break in the system will shut them all down.   The PCB is basically two thin tracks which run all the way down the board and back with all four LEDs in series on one side.  If you have a meter handy you could simply measure the voltage on the two pads at the end where the cables are attached.  This should be the same voltage as the four LEDs in forward bias mode.  That could be anything between about 10V and 16V, it's very imprecise without knowing the actual model of LED they use, but it will be obvious where the problem lies.  If it measures -22V then there is a fault somewhere on the PCB between the meter probes and the LEDs, If it reads 0V there is a problem with the wiring from the meter probes down to the supply below.

    The problem could be with broken tracking on the PCB (unlikely unless it has been badly handled), cracking of one of the LED solder joints, a break in the wires feeding current to the PCB, a duff crimp joint in the plug on the wires (unlikely), the fit to the socket in the lower chamber such as dirty contacts (just needs a removal and refit to clean it with the wiping action but it means taking the base panel off to get access to the lower chamber), or a dead LED (unlikely).  One thing to look for which is quite likely is if the wires have been nipped and broken when the case was closed up after being open for something like a valve swap.
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    TylerD94

    Posts : 3
    Join date : 2018-01-31

    Re: TM36 Backlighting Issue

    Post by TylerD94 on Tue Feb 06, 2018 11:21 am

    bordonbert wrote:The lighting is on a long thin strip of PCB material held between the top case and the acrylic front panel.  It is held in place by four metal clips which slip over the front panel and sit under the top panel with the LEDs facing down into the acrylic.  It is fed current by a pair of thin red/black wires which go down the side of the front panel and into a socket in the chamber below on the end of the mainboard.  If you remove the top panel by the proper procedure so you don't void the warranty you will find it there easily accessible.  You have to be very careful with them when you refit the case so the PCB sits right across the front and the clips are fitted correctly.  If you don't know the proper opening procedure to get into the valve chamber let us know and we can advise, it's simple enough but leaves the anti-tamper devices in place which means your warranty is still ok!

    The LEDs are blue surface mount devices and as such are pretty small.  They can be a bit of a bugger to hand solder so changing colours is absolutely possible, but impossible unless you have good soldering technique and a good quality iron, (better a soldering station)!

    The LEDs are all in series so any problem with a break in the system will shut them all down.   The PCB is basically two thin tracks which run all the way down the board and back with all four LEDs in series on one side.  If you have a meter handy you could simply measure the voltage on the two pads at the end where the cables are attached.  This should be the same voltage as the four LEDs in forward bias mode.  That could be anything between about 10V and 16V, it's very imprecise without knowing the actual model of LED they use, but it will be obvious where the problem lies.  If it measures -22V then there is a fault somewhere on the PCB between the meter probes and the LEDs, If it reads 0V there is a problem with the wiring from the meter probes down to the supply below.

    The problem could be with broken tracking on the PCB (unlikely unless it has been badly handled), cracking of one of the LED solder joints, a break in the wires feeding current to the PCB, a duff crimp joint in the plug on the wires (unlikely), the fit to the socket in the lower chamber such as dirty contacts (just needs a removal and refit to clean it with the wiping action but it means taking the base panel off to get access to the lower chamber), or a dead LED (unlikely).  One thing to look for which is quite likely is if the wires have been nipped and broken when the case was closed up after being open for something like a valve swap.

    This is exactly what I was hoping for, thank you! I've had it apart a few times now, so I'm pretty sure I voided the warranty. Almost had it three years anyway so I wasn't super worried about that.

    Would it be possible, rather than resoldering the existing LED's, or replacing an individual one if its bad, to just run a brand new LED bar across the top? My soldering skills are adequate enough to solder wires together, but I know I'm not skilled enough to go poking around on the PCB.
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    TylerD94

    Posts : 3
    Join date : 2018-01-31

    Re: TM36 Backlighting Issue

    Post by TylerD94 on Tue Feb 06, 2018 11:26 am

    Also, from what I saw, none of the wires were broken. I took a look at the LED strip but that was about two months ago. The amp is currently at my drummers, but I should have it back this weekend and I can open it up and take another look. I changed the tubes on it back in late 2015, and the lights worked fine for about 6-8 months after that.

    As far as getting into the lower chamber, that's where I stopped last time. I had no safe way to handle the valves at the time, and didn't know enough about how the amp went together underneath. Last thing I want to do is turn one issue into five.

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