Enjoy the benefits of a premium membership!
Upgrade Account
-
TalkBass has been independent since 1998. Add your voice.
Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
Join free Log in
Want zero display ads or expanded classifieds tools? Compare plans.
Nice play on words! 
Well, you can only discuss a dead amp for so long, stare at it, ponder it, study up on it, but the only way to get it fixed is to actually get busy and repair it.
I haven't read ALL the posts in this thread, but have you checked the fuse in the plug? Sometimes they can blow but not look like they are blown. Put a new one in and see what happens.
Chris.
Chris.
Check the manual if your amp have a protection mode, in this state the amp will not run. In the manual you will meet instructions for run in normal mode. Protection mode can run in case of incorrect impedance of the cabinets or overload power....
This is a class D amp. I tried to find a schematic but apparently, TC is stingy with those. Anyway, it's hard to tell without it if anything is in the power supply current path before the switch. It's always best to check voltages as a first step. So I would start by checking continuity of the switch itself (power off). Then start going through to see if you have (AC) voltage anywhere after the switch. Be careful. These are lethal voltages. It's best to put the black meter lead on the neutral line and use just one hand while checking for voltage as you work along the AC path.Check for continuity across the small round thing marked NTC (power off). That is a thermistor that limits inrush current. It's in series with the AC mains. After the AC goes through the copper coils (those are line conditioning filters), it will come to a diode rectifier that converts it to DC which is what the amp runs on. The damage will almost for sure be in the power supply, not in the amp itself. My guess is that some component in the AC path got fried. But the only way to find out is by following the traces on the circuit board and see where the voltage becomes zero. If you can talk TC out of a schematic, it would be of great help.
- Feb 12, 2006
- 60,947
- 5
- 220,546
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
So has his amp, apparently
So has his amp, apparently
apologies for the silence!I have asked a couple of the local repair guys to find me the replacement thermistor, as soon as they have something I will be reporting back!
I had a similar thing happen to my Markbass Littlemark ll (power surge )
The breakers on our power distro did not save it .
This is what I learned
A lot of the new light weight amps are built with something called surface mount technology.
The way the circuit boards are built ( by machine ) there is nothing you can fix and you have to replace the whole
board or module .
The prices I was quoted for this repair where about the same as buying a good used replacement amp .
I was told I had to replace the main board which I have enough skill to do but the part is very expensive
and also has to be shipped .
I decided to write it off and get a new amp .
After looking at most of the lightweight amps out there
I purchased a Mesa D800 as the preamp is still made from regular components .
And built by hand I believe .
Also sounds fantastic and has tons of power .
I don't leave it plugged into anything until I am going to play .
My advice is to stop wasting your time on it .
Like a lot of the new electronics it's not worth fixing (disposable )
I hope your problem is just the thermistor.
Also if anyone wants to buy a mint shape littlemark ll paper weight ?
The breakers on our power distro did not save it .
This is what I learned
A lot of the new light weight amps are built with something called surface mount technology.
The way the circuit boards are built ( by machine ) there is nothing you can fix and you have to replace the whole
board or module .
The prices I was quoted for this repair where about the same as buying a good used replacement amp .
I was told I had to replace the main board which I have enough skill to do but the part is very expensive
and also has to be shipped .
I decided to write it off and get a new amp .
After looking at most of the lightweight amps out there
I purchased a Mesa D800 as the preamp is still made from regular components .
And built by hand I believe .
Also sounds fantastic and has tons of power .
I don't leave it plugged into anything until I am going to play .
My advice is to stop wasting your time on it .
Like a lot of the new electronics it's not worth fixing (disposable )
I hope your problem is just the thermistor.
Also if anyone wants to buy a mint shape littlemark ll paper weight ?
I might take a crack at it. I have the smd equipment. What do you want for it?
Yes! good for you
It's surprising what people can actually fix versus what others say can't be fixed.
Had a rh 450. Blew a capacitor in the power supply. Didn't want to send to states to get repaired. TC electronics would not tell me what the capacitor value was as they wanted the repair fee. Capacitor not labeled. Found a technician here in NZ who was able to sort for less than $200. TC,s wanted $400 to fix plus shipping. Also 450 watt amp not really 450 watt. If you can't get fixed locally and cheaply I would look at a different supplier who supplies good service.
take a multi meter and put the leads on the plug ends one on the hot and one on the neutral. turn the power switch on, there should be continuity through the primary of the power transformer, a few hundred ohms at most. if it reads an open circuit (infinity) then the p.t. is smoked on the primary side. if you have continuity, place the test leads on the secondary/s (typically there are more than one) and check the same way. if it reads open, fried. check the power switch like that also, it might have fused the contacts, double check the fuse, sometimes they look good and can still be bad. check your filter caps for leakage, swelling or arcing (carbon trace). there may also be a second fuse in there that's not obvious. if the p.t. shows good, lift the secondary leads (take a picture and mark them) and power up the tranny. you must be careful, that voltage will hurt you. one set of leads (pre-amp) will read ~ +/- 18 vdc, one set will be ~ 50-75vac (collector voltage), the last set (bias voltage) should be ~ 30/40 vdc. I'm guessing at the voltages since I don't have a schematic to look at but most solid state amps work close to these values. I would have to believe that the surge affected the power supply.
If you have sufficient experience and the right equipment you can fix SMD stuff.
It gets a bad reputation because your average Joe with a soldering iron doesn't know where to start so the myth that SMD is non repairable perpetuates.
Yeah, it's really no different than through hole circuit boards - just smaller. You need a microscope and smaller tools but the same principles apply.
- Feb 12, 2006
- 60,947
- 5
- 220,546
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
If you are going to offer troubleshooting help to somebody who probably doesn't by his own admission understand electronics very well, I'm going to suggest that it would be helpful if you yourself understood more about the amp that you are offering (incorrect) information about.
On these types of amps, it's unlikely that you will see any continuity because the transformer is siolated from the plug by a bunch of other components, including a LF bridge rectifier and FET bridge switches. In the case of this amp in particular, there are also components that control the input voltage doubler.
The rest of your troubleshooting information has absolutely no relevance to this amp or most other amps either. You are mixing little bits from all kinds of different topologies, which tells me that you are a hobbiest that probably doesn't understand what you are saying, and this sort of advice could lead somebody else down the road to a dangerous situation. You have mixed bits from solid state and tube amps in the same troubleshooting suggestions, NONE of which apply to the OP's amp.
Correct, the comments above show how bad information gets perpetuated throughout the internet, and the scary thing is that plenty of people believe this crap, some even get hurt doing stupid things! (especially when the mains voltage is 230V)
The only exception is where the parts are held in place by epoxy dots, these can be very difficult to remove if they are sitting on top of fine traces without damaging things.
