Hello! I just got a Trace Elliot head second hand and when first plugging it in, everything seem to work fine (it goes loud and then some, built-in compressor is great etc.). However, I discovered quickly that the solid state to valve blend doesn't seem to work. When all the way to solid state the sound is loud and when turning towards valve it gets progressively quieter until there's no sound at all when it's all the way to valve.
I tried swapping out the tube with a known working tube but that changed nothing. I got it for a fairly good deal and the cost of repair quoted by a pro (£100) would be more than the cost of acquisition. It may still be worth it, but I wanted to check my option first... Is there a way for me to diagnostic the issue and see if it's worth fixing?
In addition, when I use pedals in between the bass and the amp, there's a loud pop when the effect is turned on or off. That doesn't happen with my other amp.
I found the repair manual online so I have the full schematic which is cool. I've got a multimeter and some basic tools and I'm willing to learn (if it's not too dangerous of course).
I tried swapping out the tube with a known working tube but that changed nothing. I got it for a fairly good deal and the cost of repair quoted by a pro (£100) would be more than the cost of acquisition. It may still be worth it, but I wanted to check my option first... Is there a way for me to diagnostic the issue and see if it's worth fixing?
In addition, when I use pedals in between the bass and the amp, there's a loud pop when the effect is turned on or off. That doesn't happen with my other amp.
I found the repair manual online so I have the full schematic which is cool. I've got a multimeter and some basic tools and I'm willing to learn (if it's not too dangerous of course).
Last edited:
Hi,
are the tube's heaters lit?
Please note that the pin numbers are wrong in this schematics! An ECC83's/12AX7's plate is either at #1 or #6, the cathodes are at #3 and #8.
Best regards!
are the tube's heaters lit?
Please note that the pin numbers are wrong in this schematics! An ECC83's/12AX7's plate is either at #1 or #6, the cathodes are at #3 and #8.
Best regards!
I get continuity between pin 9 and 4 and between pin 9 and 5 on the tube itself which seems to indicate it's ok. The tube does light up but the glow is faint. Pic attached.
On the amp, with the multimeter set to 20V DC, I get 14.8 on pin 5 and -0.2 on pin 4 (which is odd... the value started around -0.5 and increased to -0.2 slowly). I've put a picture of the insides as well in case there's something obviously fried that I'm not seeing (it's a bit dusty, sorry!).
On the amp, with the multimeter set to 20V DC, I get 14.8 on pin 5 and -0.2 on pin 4 (which is odd... the value started around -0.5 and increased to -0.2 slowly). I've put a picture of the insides as well in case there's something obviously fried that I'm not seeing (it's a bit dusty, sorry!).
As I said: The pin numbers are wrong in the schematics! 14.8 V @ pin 5 is ok, but I'd expect 1,2 V @ pin 4 after tube warmup.
Anyway, what's the voltage at pins 3 and 6, respectively? Does the amp hum when the tube bleeder control is set fully to tube and you touch pins 3 or 6 with the probe?
Best regards!
Anyway, what's the voltage at pins 3 and 6, respectively? Does the amp hum when the tube bleeder control is set fully to tube and you touch pins 3 or 6 with the probe?
Best regards!
These are the latest measurement, measured, on the contact from the board with the tube in place.
Pin 1: 8.42
Pin 2: 0
Pin 3: -0.65
Pin 4: -0.70
Pin 5: 14.75
Pin 6: 2.29
Pin 7: 0
Pin 8: 0
Pin 9: 0
All the way to valve, the only pin that gives a hum is Pin 4, everything else is quiet. For the sake of clarity, I'm counting the pins from left to right, which may be incorrect! I've attached a picture to be clear (just in case what I'm counting as Pin 4 is in fact Pin 6!).
Thanks so much for all your help!
Pin 1: 8.42
Pin 2: 0
Pin 3: -0.65
Pin 4: -0.70
Pin 5: 14.75
Pin 6: 2.29
Pin 7: 0
Pin 8: 0
Pin 9: 0
All the way to valve, the only pin that gives a hum is Pin 4, everything else is quiet. For the sake of clarity, I'm counting the pins from left to right, which may be incorrect! I've attached a picture to be clear (just in case what I'm counting as Pin 4 is in fact Pin 6!).
Thanks so much for all your help!
The official tube pin numbering is just the other way round! Putthe tube in place again, flip the PCB, power the amp, and measure again!
Best regards!
Best regards!
Sorry about that... I did read about the numbering afterwards since it didn't make sense!
New measurements with the numbering from right to left:
Pin 1: 0
Pin 2: 0
Pin 3: 0
Pin 4: 2.29
Pin 5: 14.73
Pin 6: -0.77
Pin 7: -0.64
Pin 8: 0
Pin 9: 8.43
There's a hum when Pin 6 is measured and the blend is all the way to valve.
At the moment, the PCB is still in the chassis, haven't taken it out to see the other side as that looks like and extensive job (remove all the front panel etc.).
New measurements with the numbering from right to left:
Pin 1: 0
Pin 2: 0
Pin 3: 0
Pin 4: 2.29
Pin 5: 14.73
Pin 6: -0.77
Pin 7: -0.64
Pin 8: 0
Pin 9: 8.43
There's a hum when Pin 6 is measured and the blend is all the way to valve.
At the moment, the PCB is still in the chassis, haven't taken it out to see the other side as that looks like and extensive job (remove all the front panel etc.).
I get a slightly fluctuating value between 168 and 170 on one side and the other side unfortunately has hot glue on it so it's a little hard to reach but from the measurements I could do I got a value between -0.5 and 0.8 once and around 1 but slowly decreasing the other time. Not super helpful sorry!
In contrary, very helpful! Replace shorted electrolytic capacitor C8, 22 µF 160 Vdc.
Btw, I'd like to know what the other triode (pins, 1, 2 and 3) does. Is it not connected to anything at all?
Best regards!
Btw, I'd like to know what the other triode (pins, 1, 2 and 3) does. Is it not connected to anything at all?
Best regards!
Oh that's great to know! Looks like it's less than £1 for the part... but now I think I'd like to find someone a bit more handy than me to switch it out. Great remote diagnostic though, thank you Kay!
Regarding Pin 1, 2 and 3, I'm really not sure... If I flip the PCB I will let you know!
Regarding Pin 1, 2 and 3, I'm really not sure... If I flip the PCB I will let you know!