Micorina, You should check and replace all distroyed electronic parts before You want to run the amp. If its possible, buy an TDA 2030 in your local electronic store. ( I dont know if You already did that). Make some pictures of amplifier PCB and send them here , so we can see what we have to deal with.
I use a 'Variac' on low voltage as supply during tests. The speaker unit is connected to show if this horrid hum stops. With supply volts at 100v. and having replaced the two smoothing caps the hum is there. An earlier multimeter check with the rectifier Cct diodes disconnected showed there to be current in only one direction on all four. So I guess they're OK. Next horrid test imminent. Michael UK
Two warnings. First, if using a split supply, the heat sink of the TDA2030 is at minus supply voltage - requires isolation from the heatsink, which would normally be grounded. Requires an insulator and heat sink grease. Test with multimeter before powering up. If amp is cap coupled and single supply, then case is at ground and not an issue. The second is about that hi tech silver goop - they put silver in it and it probably conducts. For isolated heat sinks need the ordinary white heat sink grease. Again, check with meter for short from case of output IC to ground. Good luck with it.
Thanks GoranB. I have already replaced the TDA2030 with no improvement. I had to get it on Ebay. As to 'destroyed' components I find, so far, that the two smoothing caps removed so far seem still to be OK. Photo... Yes, well I shall need to find out how to post/attach a photo - there's probably an indication on this site which describes 'How to do this'. Michael
Thanks Steve, I have downloaded the Data sheet on the TDA2030 and it mentions the option of a split supply. All I can say is - I 'think' it has. The secondary of the power Xfmr has a centre tap -well, I think that's what it is as it comes out of the Xfmr between the two leads which connect to the amp. The two leads on the other side of the Xfmr are definitely connected to the mains power supply, one via the on/off switch. Re: the fixing of the TDA2030 I have been most unobservant! And 'yes' in the original fixing there was indeed a thin layer - a piece of non-conducting material between the TDA and the heatsink. Also they had provided a poly washer which goes through the mounting hole thus insulating the metal of the TDA from the chassis. All of which means I may have B...d up my new TDA. It's possible the original TDA is OK and can therefore be re-inserted and carefully attached to the heatsink in the original manner. So it must be a split supply... Michael UK
OK. I have remounted the TDA chip using the isolating membrane and grey paste. Checking with my Multimeter I find 'diminishing' contact between Gnd and the metal of the TDA. Diminishing because I think there must be a capacitor across these two points and what I am seeing is typical of that. There's also an issue with the soldering between the legs of the TDA and the PCB. In inserting the membrane I found a dry joint. I am using Lead-Free Silver Solder. It doesn't say whether there's any flux in it, but it's not keen to make good contact with the PCB etchings. Any advice on this? Michael
If I understand you well...you cant solder the one of the pins of TDA2030? If that is a case, first clean that contact you want to solder, You can use a small screwdriver to scratch it. Also some soldering past, but not too much.
When you will be rady to turn on the amp a good protection will be if you can solder the 2 resistors of 10 ohms in series with power supply rails, in case the PS is symetrical you have to use one ressitor per rail.
When you will be rady to turn on the amp a good protection will be if you can solder the 2 resistors of 10 ohms in series with power supply rails, in case the PS is symetrical you have to use one ressitor per rail.
hat is correct. When I followed Steve's excellent advice regarding the isolating membrane on this split power supply, I moved the TDA in order to free it from the heat sink. It was then I noticed one of its pins moving through the hole in the PCB. On attempting to re-solder it I found the etched Cct would not accept the solder. I have cleaned up the area and tried to solder it once more. Now it does 'seem' OK.. Let me now check for two 10 Ohm resistors in my stock for a protection as you say. This means I must remove the two secondary connections to the PCB and connect them through one 10 Ohm resisitor for each rail. (or bus!). Interesting! Yes, I'm sure, from the isolating membrane I have found beneath the TDA that the powere supply is symetrical - or (as it says in the Data to the TDA2030) split. I used to have Lead Multicore Solder - but I have used it all. Now this Lead Free Silver Solder does not leave a shiny surface but almost looks like a dry-solder joint. I must see if I can source some Lead Multicore!! Michael
Yes, you have to remove as you said, the two secondary connections from PCB, if the voltage is symetrical there should be + rail, - rail and the ground connection, it means 3 connections. Solder the first ressistor in series with + rail before the fuse, and the second one in series with - rail before the fuse. Ground should stay like it is. This will protect your amp nad PS if something is still bad. The resistors will start to smoke, but everything else will ..survive 
. If you noticed that resistors are heating too much and there is a smoke, unplugged the amp, and look for a mistake again.
. If you noticed that resistors are heating too much and there is a smoke, unplugged the amp, and look for a mistake again.
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Good suggestion, check the speaker with an OHM meter, the resistance should be arround 4-6 Ohm's, if its 0 ohm's replace it before you want to turn on the amp.
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