I bought this amp used several years ago, and it's wonderful. However, it died on a gig last night, and I need it for another gig on Thursday. I've purchased and downloaded the service manual with the schematics, but the parts list page for the preamp stage is wrong.. it's a duplicate of the parts listing for the power output stage.
In any case, here's the symptom, and I've never had an amp do this before. I'm hoping someone can point me to where to start searching for the cause..
While playing, it started to buzz very loudly and steadily, and turning the output volume and preamp gain down all the way didn't reduce the loud steady buzzing sound at all. I powered off the amp (I use it as a right channel in a small-room keyboard rig) and continued and limped through the gig using an SWR bass amp I use for the other channel and low end. I powered up the Trace a few more times throughout the gig, hoping it had just overheated or something. Upon power up, it sounded great... for a few seconds, then the loud steady buzz started up again. I gave up.
Sooo... I'm about to open the amp up, schematics in hand, and have a good 'scope, multimeter, function generator, and good soldering skills. What I don't have is a lot of experience troubleshooting. Any help would be GREATLY appreciated.
Thank you.
In any case, here's the symptom, and I've never had an amp do this before. I'm hoping someone can point me to where to start searching for the cause..
While playing, it started to buzz very loudly and steadily, and turning the output volume and preamp gain down all the way didn't reduce the loud steady buzzing sound at all. I powered off the amp (I use it as a right channel in a small-room keyboard rig) and continued and limped through the gig using an SWR bass amp I use for the other channel and low end. I powered up the Trace a few more times throughout the gig, hoping it had just overheated or something. Upon power up, it sounded great... for a few seconds, then the loud steady buzz started up again. I gave up.
Sooo... I'm about to open the amp up, schematics in hand, and have a good 'scope, multimeter, function generator, and good soldering skills. What I don't have is a lot of experience troubleshooting. Any help would be GREATLY appreciated.
Thank you.
WOW... you are GOOD!
Took me a while to see it, but yes, there's a definite bad solder joint/crack there, obvious under magnification.
Also... the ground connection has a good amount of corrosion surrounding it. What would cause that?
I've cleaned off and will reapply new thermal paste between the heat sink and case. There's a thermal pad (I think) without any compound on it between the heat sink and the power IC1, a TDA1514A, which has a metal surface mating to that pad. No thermal paste there. Is that correct? Just want to make sure prior to reassembly.
I can't tell you how much I appreciate the help. Hopefully, this was the problem!
Please post the schematic here so we can also see it and suggest useful answers.
Even if you solved your problem today (thanks Jon Snell), other Musicians can have other problems on the same model amp in the future.
Even if you solved your problem today (thanks Jon Snell), other Musicians can have other problems on the same model amp in the future.
Last edited:
I understand, but am not sure if it's allowed. I couldn't find a publicly available service manual, so I bought one here...
Trace Elliot Service Manuals
Trace Elliot holds copyright; anybody else selling unauthorized copies has no Legal (or moral) rights to force anybody to respect what they din´t respect themselves.
Just sayin´
Just sayin´
@JonSnell Electronic - You nailed it in one! Amp is back together and has been sounding great for the past half hour. Thank you VERY much. Don't know where you're based, but if you're ever in the Syracuse, NY area, refreshing beverages and great food are on me!
Well, don't I feel silly. Sigh. I did look for one, but didn't find it. Now, of course, that I'm not quite as panicked, I do see them on ElektroTanya, among others. The site I bought exactly the same one you posted only charged 1$ US, but still... I didn't know they were public domain. The unfortunate thing is that this service manual has an error in it.. there is not parts list for the preamp board; the power supply and output board parts list is duplicated on page 4 and 6. If, by some chance, someone has the REAL and accurate service manual with the correct page 4, please let me know. Thanks.
Even I sometimes do not search wel. So, don't blame yourself.
To go on with the Trace Elliot.
Well, like we did in the old days.
1. Make a copy of the page you're interested in.
2. Write down every resistor on a piece of paper. Number and value. Same with all the other components.
3. Use a fluo marker to identify the noted component.
4. If you use Excel, then you can sort the list in any way you want.
5. Print the list and give it page number 4 or 8 or whatever.
6. Now take a beer and enjoy your work.
ps: we had no photocopier, nor excel at that time (1960..1970). Everything whas copied by pencil and paper.
We used paper with 5 mm squares. Easy to draw strait lines of a schematic.
I hate to see these quick-quick drawings shown in the forums.
Allthough they may be correct, but a bit of fine drawing techniques makes a schematic a lot easier to read and pleasant to the eye.
That means that you have to draw it possibly 4 or more times.
Take another beer then and enjoy again.
To go on with the Trace Elliot.
Well, like we did in the old days.
1. Make a copy of the page you're interested in.
2. Write down every resistor on a piece of paper. Number and value. Same with all the other components.
3. Use a fluo marker to identify the noted component.
4. If you use Excel, then you can sort the list in any way you want.
5. Print the list and give it page number 4 or 8 or whatever.
6. Now take a beer and enjoy your work.
ps: we had no photocopier, nor excel at that time (1960..1970). Everything whas copied by pencil and paper.
We used paper with 5 mm squares. Easy to draw strait lines of a schematic.
I hate to see these quick-quick drawings shown in the forums.
Allthough they may be correct, but a bit of fine drawing techniques makes a schematic a lot easier to read and pleasant to the eye.
That means that you have to draw it possibly 4 or more times.
Take another beer then and enjoy again.
Thank you for your generous offer but I am in Great Britain. Pleased to help.
The capacitors are heavy, the amp vibrates when in use and the solder joints crack.
It is as simple as that.
Enjoy that bit of history and play on.
PS. if you hover over anyones avatar and they have listed their country, you will find it.
@JonSnell Electronic and anyone else....
This amp is still working and sounds clean, powerful, and undistorted, but it has developed an unusual amount of static "hiss," independent of gain and volume controls. No buzz or distortion, and no increase in this baseline "hiss" as gain and volume are brought up. In use it really doesn't matter...it's more than covered up by ambient noise in the performance venues...but it still worries me. I suppose it may have always been there and I just never noticed it, but I doubt it; it's pretty significant.
Thoughts as to the cause and remedy? Thank you again for the help last year!
This amp is still working and sounds clean, powerful, and undistorted, but it has developed an unusual amount of static "hiss," independent of gain and volume controls. No buzz or distortion, and no increase in this baseline "hiss" as gain and volume are brought up. In use it really doesn't matter...it's more than covered up by ambient noise in the performance venues...but it still worries me. I suppose it may have always been there and I just never noticed it, but I doubt it; it's pretty significant.
Thoughts as to the cause and remedy? Thank you again for the help last year!