This post describes a burning.... My son's Violin/Guitar KLA amplifier started smoking and a loud hum.m.m came from the speaker. Couldn't have happened at a worse time for him with a Group Class Concert on Saturday 26th March. I have dismantled the unit and, apart from the TDA2030 getting immensely and hugely HOT I can see no other identifiable reason. Does anyone have any ideas as to why the circuitry should produce this horrid phenomenon? If it's the TDA2030 which has copped it, where can one buy a replacement? Michael
DigiKey has got them.
Linear - Amplifiers - Audio | Digi-Key
It might not have gone By By. If you have an ohmeter you need to check for shorted componets. Possibilties include the power supply capacitors, and the power supply diodes. Here is where a schematic would be helpfull. The power supply caps are probally the biggest caps in the amp. There should not be 0ohms accross them. Do you intend to troubleshoot it yourself? If so, folks on the forum will probally walk you through it. How much time do you have? Oh -- and post the brand and model number of the amp.
Linear - Amplifiers - Audio | Digi-Key
It might not have gone By By. If you have an ohmeter you need to check for shorted componets. Possibilties include the power supply capacitors, and the power supply diodes. Here is where a schematic would be helpfull. The power supply caps are probally the biggest caps in the amp. There should not be 0ohms accross them. Do you intend to troubleshoot it yourself? If so, folks on the forum will probally walk you through it. How much time do you have? Oh -- and post the brand and model number of the amp.
Thanks Firechief! I do propose troubleshooting myself. Having successfully fixed my Gale Storm 8 Subwoofer problem (capacitors) I'm all set to get in there! Thanks for the tip. I'll try the power smoothing caps first for '0'ohms or whatever. The Amp (with 8" speaker in the box) made in China for Kustom Music, Cincinnati, Ohio has no other identification other than it is a KLA10. with a power input 40Watts Maximum 230VAC 50Hz. and a Power Output of 12 Watts Maximum 7v rms 4 Ohms. Unhelpfully the two Power smoothing caps are stuck together with hot glue and their values are unreadable. Prising them apart I find: 25v 1000uf +85deg. CD-SG (whatever that means!) Measuring across each cap in the power cct I get 160 Ohms reading on my cheapo RX10 scale. So they're not 0 Ohms. Hmm. Yes, I agree, a Cct Diag would be v.useful! Michael
The Diodes I'm measuring now: Across their soldered contacts. Two pairs of Diodes each pair having a common connection (thus satisfying the full-wave rectifier Cct?) In the first pair of Diodes we get 200 Ohms in one direction and 160 Ohms in the other. In the second pair we get 200 Ohms in both directions. I have a smeaking feeling that those 1000uf caps were discharging on my first reading - which was 160 Ohms and quickly raised to 200 Ohms. Strange thing is there's a fuse on this PCB which hasn't blown... No other I.D. except each component is helpfully marked on the PCB by such writings as D5 D6 D7 D8 D9 D10 (those last four being the rectifier Cct) The resisitors are all marked as expected R1, R2.... &c. There's even wire straps in there mareked as W1 W2 W3 W4. There's also my friend from the Subwoofer in there too - a chip called 45580JRC. There's that other pair of smaller Diodes close by the TDA2030. One reads 40 Ohms in both directions, but the other... reads 0 Ohms in both directions. Do we have our rogue component do you think?? Michael
I have removed one of the suspect diodes and measured it with my Ohm meter. Whereas in the Cct it reads 0 Ohms, out of the Cct it reads 200 Ohms in one direction and ~ Ohms in the other. So I unsoldered one end of the other Diode and measured it which produced identical readings. ergo those Diodes are OK. Now this is where a Cct Diag would really come in useful. Being in close physical proximity to the Integ. Chip TDA2030 I am wondering whether the chip itself is suspect. Michael
You asked how much time do I have...? Well, if I can fix it on Friday (tomorrow) that would be wonderful as my son's Group Electric Violin Concert is on Saturday morning. Somehow I doubt I shall manage this so my son has cobbled together an amp using the speaker unit and a separate amplifier. However this cannot continue indefinitely so I must fix his KLA10 pretty pronto. Michael Sussex, UK
OK - good troubleshooting so far, sounds like its time to buy the TDA 3020
In the UK check out Farnell at this link.
Browse for Products | Farnell United Kingdom
They are cheep so I suggest that you get one on the way. Unfortunetally the shipping will cost more than the part so Im trying to think of anything else you should get at the same time.
I think you are right about the diodes, when they go they usually read 0ohms in both directions.
I expect more people to chime in anytime.
Bob
In the UK check out Farnell at this link.
Browse for Products | Farnell United Kingdom
They are cheep so I suggest that you get one on the way. Unfortunetally the shipping will cost more than the part so Im trying to think of anything else you should get at the same time.
I think you are right about the diodes, when they go they usually read 0ohms in both directions.
I expect more people to chime in anytime.
Bob
I have downloaded the spec sheet on TDA2030. I have also removed the TDA2030 from the PCB. With my test Ohm meter I find: dead short pins 4 & 5. Approx 30 Ohms pins 3 & 4. According to the provided Test Cct. Pins 4 - 5 have a diode between them as do Pins 3 & 4. Pin 4 is the common output Pin to the Speaker. Ergo (like that word?) there should be the same impedance between Pins 4 & 5 as there is between Pins 3 & 4. But there isn't. There's a dead short between Pins 4 & 5. Do I rest my case? Well, I have an email telling me the replacement TDA2030 has been posted...
Michael from a sunny Sussex UK
Michael from a sunny Sussex UK
Ergo is a good word. I must find a way to use that in conversation today.
But really folks, sound like you got it figured out. It could still be more than just the chip amp but probally not. They are usually held on to the heat sink with a screw and have some white heat sink compound between the tab and the heatsink. You can re-use the compound if you dident wipe it off, but you need something to help with heat transfer. Is there still some white goop you can re-use?
But really folks, sound like you got it figured out. It could still be more than just the chip amp but probally not. They are usually held on to the heat sink with a screw and have some white heat sink compound between the tab and the heatsink. You can re-use the compound if you dident wipe it off, but you need something to help with heat transfer. Is there still some white goop you can re-use?
Have changed the TDA2030 but the power fuse blew. Hmmm... -Yes, it also hums from the speaker unit - raw mains-type hum. I shall carry on testing and replacing components where I can... This amp PCB has F/W rectifier on board and a couple of diodes next to the TDA2030. I think I shall start with the F/W rect. Cct and change the Radial 'smoothing' Caps first.
Michael UK
Michael UK
Thanks, GoranB. I am attempting to isolate this apparent power leak to the output Cct. I can only check through removal of components to isolate parts of the PCB. The smoothing Caps seemed a good point at which to continue. The four Diodes of the rectifier check out OK. Watch this space! Michaek UK
Thanks Firechief - it did already cause the fuse to blow! Pooof! - Being a chap of resource and not having a replacement fuse, I heated up the fuse at each end causing the metal caps to come off, then inserted some old-fashioned fuse wire and clamped it in with those end caps. I was just about to go ahead and blow the whole thing up by plugging it in when I saw your message! Michael UK
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.