A friend of mine has a valvestate amp that has let out the magic smoke. He said he was in the middel of playing Smoke on the water, so he was clearly asking for it. 🙂
It is this specific model : https://schematicheaven.net/marshallamps/vs230r_2x30w_stereochorusrev.pdf
R18 has clearly burnt, everything else looks Oke. Can anyone shed some light on the possible cause? I’ve measured sec. on the transformer which seems to be oke at 17,5 volt.
Also ordered 2 new TDA2050 as they are dirt-cheap. But before I replace them, what should I check?
It is this specific model : https://schematicheaven.net/marshallamps/vs230r_2x30w_stereochorusrev.pdf
R18 has clearly burnt, everything else looks Oke. Can anyone shed some light on the possible cause? I’ve measured sec. on the transformer which seems to be oke at 17,5 volt.
Also ordered 2 new TDA2050 as they are dirt-cheap. But before I replace them, what should I check?
Sadly NO real TDA2050 available for over 5 years now, ALL are FAKE, doubly so if "dirt cheap".
Try to get LM1875 from a respected supplier, such as Mouser, Digikey or Farnell which buy them straight from Texas Instruments or whoever makes them.
Not even your "trusted" local supplier can be trusted on them.
Suggest you build a series lamp bulb limiter with a 25W lamp (incandescent, not LED or CFL, you need a white hot wire inside) and plug amp there first, to avoid blowing a ton of fuses and your new chipamps.
An externally hosted image should be here but it was not working when we last tested it.
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oke, thanks for the info.
In the mean time I've removed the original 2050. How can I check to see if it's faulty?
I ordered the TDA2050 at reichtert, a german company. Security Check
Seemed legit, but if what you say is true. Is the replacement you suggest pin-compatible?
In the mean time I've removed the original 2050. How can I check to see if it's faulty?
I ordered the TDA2050 at reichtert, a german company. Security Check
Seemed legit, but if what you say is true. Is the replacement you suggest pin-compatible?
Yes, pin compatible,of course.
his is the real one and what everybody is using today as replacement:
https://www.mouser.com/Texas-Instru...ers/LM1875-Series/_/N-4gxtf?P=1yxyxasZ1z0zls6
you might find a Mouser distributor in Europe or perhaps Farnell.
Oriental ones (such as the ones you found) are *probably* relabelled TDA2030, I got stuck with a lot of them, work fine under TDA2030 conditions (+/- 14V supplies) but overheat and die if used as TDA2050 (+/-22 to 24V)
Farnell which is a serious supplier shows TDA2050 as "not availble - no longer manufactured" ..... since 2015!!!!!
https://ie.farnell.com/stmicroelect...o-25w-2050-pentawatt-5/dp/1094345?ost=tda2050
Notice they do not even offer a "second source" option such as an Oriental one.
Counterfeit vs Authentic TDA2050 audio amplifier IC test - YouTube
Just try 1875 from a reputable supplier which buys *direct* from TI
PS: the only practical way to test them is in-circuit, they either work or not.
That´s why I suggested the bulb limiter and with a smallish 25W lamp.
If hard to find, you can get small ones (say 15-2 -25W) for use in sewing machines, bar displays, fridges, etc. , they need small sockets too.
Remember, you need a white hot metallic wire filament inside, not LEDs.
his is the real one and what everybody is using today as replacement:
https://www.mouser.com/Texas-Instru...ers/LM1875-Series/_/N-4gxtf?P=1yxyxasZ1z0zls6
you might find a Mouser distributor in Europe or perhaps Farnell.
Oriental ones (such as the ones you found) are *probably* relabelled TDA2030, I got stuck with a lot of them, work fine under TDA2030 conditions (+/- 14V supplies) but overheat and die if used as TDA2050 (+/-22 to 24V)
Farnell which is a serious supplier shows TDA2050 as "not availble - no longer manufactured" ..... since 2015!!!!!
https://ie.farnell.com/stmicroelect...o-25w-2050-pentawatt-5/dp/1094345?ost=tda2050
Notice they do not even offer a "second source" option such as an Oriental one.
Counterfeit vs Authentic TDA2050 audio amplifier IC test - YouTube
Just try 1875 from a reputable supplier which buys *direct* from TI
PS: the only practical way to test them is in-circuit, they either work or not.
That´s why I suggested the bulb limiter and with a smallish 25W lamp.
If hard to find, you can get small ones (say 15-2 -25W) for use in sewing machines, bar displays, fridges, etc. , they need small sockets too.
Remember, you need a white hot metallic wire filament inside, not LEDs.
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Thanks again. I’m old enough to remember lightbulbs 🙂 still have some left for who knows when. Seems like tomorrow might be a good time for “when”.
Can you also help me check the 2050 I just desoldered? What to look for in a failed one?
Can you also help me check the 2050 I just desoldered? What to look for in a failed one?
Not "outside"
Still in circuit, I turn amp on (using bulb limiter) , no speaker connected, and measure pin voltages, only 5 of them and 2 are a given: +V and -V.
So check you have about 0V DC at +IN, -IN and OUT.
Not much more to do.
Still in circuit, I turn amp on (using bulb limiter) , no speaker connected, and measure pin voltages, only 5 of them and 2 are a given: +V and -V.
So check you have about 0V DC at +IN, -IN and OUT.
Not much more to do.
So, I've managed to fix the amp using the "TDA2050's" I ordered. Did check voltage and use the bulb limiter, and no problems arose. So, thanks again.
If the new "2050's" die I will change them for 1875's
If the new "2050's" die I will change them for 1875's
You are probably right, but as the amp is only worth €100 and I had these fake 2050 on hand, I saw no problem trying them. And so far so good. Would not do this if it was my stage or recording amp.