I would appreciate any advice repairing Solid State Pyle-pro PVAMP30 30-watt Guitar Amp after a short circuit--The amp only hums & the pilot lite comes on.
I needed to demo a Denon AVR-4800 home theater amp [250 watts per channel] for a buyer,but I had no speaker available.
In a hurry, I connected the Denon amp speaker outputs to the Pyle guitar speaker input clips,
but did not disconnect the spade end plugs that lead from the Pyle guitar amp section to the guitar speaker input clips.
And I accidentally powered on the Pyle guitar amp.
Increasing the volume at the Denon amp I finally heard a screech & maybe a pop.
Now the Pyle guitar amp only hums,& there's no amplification--the pilot lite comes on [so the fuse is still good].
I opened up Pyle guitar amp section [I WAS careful to unplug the power cable first & not to touch the capacitors.]
I don't see or smell any damage & I don't see a 2nd fuse.
Haven't been able to find a schematic after a bit of searching.
Should I send photos of the circuit board?
You will have blown the power amplifier by connecting the external amplifier. It will be an IC or discrete transistor device. A photo will show which. If an IC it will probably easier to replace if you are competant to do that - can solder properly etc. A Transistor amp will be more complicated. If you are not sure it would be better to take it to a tech.
Here's pic's. I guess it's a discrete transistor device. Is the power amplifier a set of components? & will they all need to be replaced or I must diagnose faulty components? Note: made in 2008. I have experience soldering.
How long might this take & how expensive?
The hum you hear is DC voltage on the speaker and that is bad for the speaker, so disconnect the speaker when powering up the amp. At this point I would guess the IC chip is probably a TDA2030 or something similar. The other thread you started on the MEF website had G1 asking you to measure DC voltage at the speaker connection. Do this but remove the speaker first since it probably has DC volts and it's not worth leaving connected at this point. So start by identifying the IC chip in there connected to that heat sink. Look at the top body of the component for a part ID.
P.S. Not sure but that D6 Diode looks like the top leg got smoked a bit?? Please confirm...
IC Chip says: TDA2030A Do you need the rest?
D6 Diode: the top leg is burnt a bit!
Will measure DC voltage at the speaker connection [w speaker disconnected]: with amp powered on?
Yeah look at the picture here and I circled the output IC chip. It is bolted down to what we refer to as a heat sink, which helps the component expel heat through the metal. Look on that chip that is bolted down and try to read what it says. The diode is in question too if it is burnt as well as the trace of copper on the board that it connects to.
Edit and ADD... The IC power opamp should look identical or similar to this...
IC Chip says: TDA2030A . Thanks so much! This is exciting for me!
https://www.wikihow.com/Measure-DC-Offset
I will measure DC voltage at the speaker connection using a VOM [is this similar to DC-Offset measurement in link above as described above?],& with amp on ---correct?
I no longer know the polarity of the red & blue speaker wires coming from the amp to the speaker.
Can I damage the VOM by connecting the positive probe of the VOM to the negative speaker wire, or vice versa?
What do think of a $1 TDA2030 IC Chip from China?
Probably fake. A TDA2040 or 2050 would also work. And an LM1875 would also drop in.
Where would you suggest I buy the chip?
Typically we say don't buy it on eBay since there are so many fakes there... However, I have personally bought from this seller before and feel okay recommending him to others. You can search mouser.com or digikey.com for the LM1875 IC chip but you won't find brand new manufactured TDA2030, TDA2040 or TDA2050. So that is why we go to eBay to find them and buyer beware of fakes. I still feel safe buying this particular chip from the seller I listed though.
https://www.ebay.com/itm/1-x-TDA2050-32W-Hi-Fi-Amplifier-IC-USA-SELLER-FAST-FREE-USA-SHIPPING/301246868204?hash=item4623b66aec:g:uV4AAOxy69JTGjHO (https://www.ebay.com/itm/1-x-TDA2050-32W-Hi-Fi-Amplifier-IC-USA-SELLER-FAST-FREE-USA-SHIPPING/301246868204?hash=item4623b66aec:g:uV4AAOxy69JTGjHO)
Quote from: Roark on August 21, 2018, 05:21:23 PM
I will measure DC voltage at the speaker connection using a VOM [is this similar to DC-Offset measurement in link above as described above?],& with amp on ---correct?
I no longer know the polarity of the red & blue speaker wires coming from the amp to the speaker.
Can I damage the VOM by connecting the positive probe of the VOM to the negative speaker wire, or vice versa?
You probably already figured this out but Yes with the amp on.
Also if you don't remember the polarity of the speaker wires you can use your DVM to figure it out. When doing resistance checks always turn off the amp and even unplug it for added safety. Measure blue wire with Red probe and place the black probe to the chassis, and do the same with the blue wire. Blue is probably negative and red is probably positive. The negative terminal will be grounded to the chassis and will read near 0 ohms resistance. The Positive will terminal will have a bit of resistance relative to ground. This method should work for this amp.
When you measure to check for DC voltage at the speaker leads it will not damage your DVM having Red probe on negative or vice versa. Black lead to negative and Red lead to positive terminal. As example you might see 20V that way and when you reverse the meter leads it will then display -20V. So it just changes the reference point of ground.
Using the DC Voltage meter, set to the 200mV range, I get a reading of exactly negative 1 when I touch the red probe to the red speaker lead [or a reading of positive 1 when reversing the probes].
This never fluctuates when slightly adjusting the contact with the probes, so I don't know if I trust the reading .
I also smell a burnt/burning smell when I turn the amp on, on so I don't leave the amp on long. [I don't allow the amp to warm up for 10 min, as suggested in the guide.]
Well if set to max range of 200mv the meter would not be able to read +/- 1. What you are measuring is simply an out of range symbol for the meter. Do you have 200mv, 2v, 20v, 200v, 700v as the range selections? Try putting the meter on 200v setting and then what does it say?
Edit: Also the burning smell is probably that diode leg cooking so yes don't keep the amp on very long at all. Just take measurement to confirm DC on the output.
Mouser has stock on the LM1875.
I found TDA2040 at bdent.com, a company that has never sent me a bogus part in several decades.
OK-will correct that! Now with meter set to the 200V range, I get a reading of -5V [DC]
[touching red probe to red speaker lead, or +5V when reversing the probes].
Also with meter is set 20V I get the same readings.
What does -5V DC [offset?] mean?
It means the amplifier chip is putting out DC, it is defective. it doesn't matter that it is positive or negative.
It is possible the input is skewed. Remove the power amp IC, then meter the input pins to see if it was being fed DC. Unlikely though.
I'm about to remove the failed TDA2030 IC Chip.
Are any other tests,etc you think I should do first?
Can I use a screwdriver to discharge the 2 Large Capacitors : 2200 microfarads,25V or is it better to use a resistor? .
Other Capacitors are much smaller: 100 microfarads or less.
Do you suggest discharging them all 30-40 of them?
I would just replace the chip as it is most probably bad.
You can measure those two bigger filter caps with your DVM to see if they are holding a charge. Chances are the caps discharge rather quickly and probably only millivolts will be stored. Still just put your meter across each one and check the voltage so you know. You don't have to discharge any of the other smaller caps.
Quote from: DrGonz78 on August 23, 2018, 04:14:12 PM
You can measure those two bigger filter caps with your DVM to see if they are holding a charge. Chances are the caps discharge rather quickly and probably only millivolts will be stored. Still just put your meter across each one and check the voltage so you know. You don't have to discharge any of the other smaller caps.
Measurement of capacitor residual voltage:
1]Measurement on the DC voltage scale?
2]With power cable disconnected?
3]This won't discharge the capacitor?
4] or damage my simple meter?
1. DC is what they store.
2. yes, disconnect the amp from the wall outlet, after all the whole reason you were measuring the voltage was to see if it was still charged up. If it is powered, then of course it is powered up and charged.
3. Not likely to discharge the cap much, but even if it did, isn;t that the point? get the cap discharged?
4. A meter measures voltage. VOltage is present or not. The meter has no way of knowing if the circuit is live or off but still charged. All teh meter knows is voltage.
OK,Thanks,Enzo! I ask some [maybe obvious] questions just to be sure I understand the theory,which helps prevent mistakes in general!
With the 2 biggest capacitors measured at 0 volts & drained:
I'm Checking the D6 Diode [the Diode with the slightly burnt upper leg], in circuit,using the Diode function of the VMM.
1] I consistently get a reading of 37 Volts, using the probes forward-biased & reverse-biased
Question: Shouldn't the meter say: .37 Volts?---ie: 10x less voltage & with a decimal place?
2] The resistance test gives 37.0 Ohms [with a decimal place!] using the probes, forward-based & reverse-biased, & on 3 different scales, so I tend to trust it.
So,with your experience, do you suggest I get a new diode? ---or is there more to consider?
______________________________________________________________
PS: I ordered the TDA2050 chip [but it hasn't arrived yet.]
Thanks,DrGonz78 for that suggestion!
& I really appreciate all the help from Enzo! [& tonyharker]
Yes, right away. In my shop I have to ask myself, how much labor time should I use up testing a 5 cent part?
Do you have a good diode of any type sitting around? measure it with your meter, presuming it is good. How does that compare to these readings? 37 ohms across a diode is not good, unless the diode has parallel resistance in teh circuit. SO unsolder one end of the diode and lift it up from the board, now measure it right on its end wires. Still 37 ohms?
Does your meter explicitly mention volts somewhere when using diode test?
I'm thinking it is probably millivolts instead. Check a good diode and it will probably give you something in the 500 to 700 range when the diode is forward biased.
So your 37 reading is probably .037V on diode test.
Quote from: g1 on August 27, 2018, 09:57:53 PM
Does your meter explicitly mention volts somewhere when using diode test?
I'm thinking it is probably millivolts instead. Check a good diode and it will probably give you something in the 500 to 700 range when the diode is forward biased.
So your 37 reading is probably .037V on diode test.
My manual does say that the diode test reading is in millivolts, so the reading is .037V , as you said.
I'm now measuring all the other Diodes on the board, to compare/check my D6 result:
ALL Measurements are in MILLIVOLTS:
D7: 005 in both directions [this diode is right next to D6]
--------------------------
D8: 37 in both directions [this is a group of 4 diodes right next to each other]
D9: 38 in both directions
D10: 007 in both directions
D11: 007 in both directions
----------------------------------------------
D2: 1078 in both directions [this is a group of 2 diodes right next to each other]
D1: 1079 in both directions
---------------------------------------------
D5: 656 in both directions [this diode is by itself]
__________________________________________________________
For each diode, I get the same reading forward-biased & reverse-biased!; just as I did for D6.
Which supposedly indicates a shorted diode.But I doubt that all the diodes are shorted.
So maybe my meter is wrong [I will borrow another]; or there may be no problem with the D6 diode?
I will also find another diode, not in circuit,to test with my meter.
I now suspect 6 diodes [D6 thru D11] may be shorted [partly based on a borrowed Analog voltmeter with no diode function, resistance tests only, in circuit.]
These 6 diodes are all labelled 4007. Anybody know where to get these? & do I need further identification?
_____________________________________________________________________
That is a most common diode.
You must place a 1N in front of it.
1N4007.
Quote from: Jazz P Bass on August 30, 2018, 01:55:06 AM
That is a most common diode.
You must place a 1N in front of it.
1N4007.
Have you used this seller?:
hstbeto Bellflower,CA https://feedback.ebay.com/ws/eBayISAPI.dll?ViewFeedback2&userid=hstbeto&&rt=nc&ftab=AllFeedback
-- who has many xlnt reviews for:10pcs 1N4007 Rectifier Diode 1A 1000V - $1.60- US Seller - Free Shipping,
listed as MIC Brand,apparently made by: https://mklec.com , in Ohio
or who do you recommend?
Did you look at Mouser? 100% solid trusted seller, as they sell real name brand parts.
https://www.mouser.com/ProductDetail/ON-Semiconductor/1N4007FFG?qs=sGAEpiMZZMtbRapU8LlZD9Yt6EMzPspSFAiKlqofgxo%3d
Those are $1.64 for 10. Or $5.80 for 100. And those are from ON Semiconductor, as solid a company as there is making parts. Looking at the other Mouser offerings in 1N4007, there are some as low as 90 cents for 10. $3.50 for 100.
Mouser charges for shipping, but if I recall, if you prepay, they don't, is that correct?
MKLEC doesn't make parts, they are a store selling parts. I also note at the top of their web page it says they are going out of business in the next few weeks.
Quote from: Enzo on August 30, 2018, 05:47:46 PM
Mouser charges for shipping, but if I recall, if you prepay, they don't, is that correct?
Thanks for all the info,Enzo! But Mouser DOES charge for shipping: prepaid it's $9.60,total, for 10 diodes.
Question for DrGonz78 & others : Have you bought 1N4007 Diodes from jlassen36wy?,[EBay company you suggested for the TDA2050 chip]
PS:MIC Brand is Chinese.
To replace my TDA2030 chip I bought a TDA2050 from jlassen36wy = Amp Repair Houston, EBay, :
I just noticed this today on the webpage:
"NOTE: Placing this TDA2050 32watt integrated circuit chip into a 20watt circuit (i.e. replacing a TDA2040) will not increase the power output of your device and may cause instability especially with a 4ohm load."
But my speaker is 4 Ohms. Is this a problem?
MAY cause...
Find out.
Correct me if I'm way off but I'd hazard a guess that IN4007 is waaaaaay overkill for a circuit that runs at 35Volts???
1N4007 is a 1,000Volt device.
1N4004 (400V) would likely be cheaper and do the same job. :-\
Maybe the factory had no 1N4004's in stock and just used the higher rated devices.
But I could be wrong, lol.
Phil.
The price difference is negligible, in fact at Mouser, buy one and the 1N4004 cost more. But they all sell for like 4 to 6 cents each in 100 lot. Only want 10? a penny more then.
Since 1000v 1N4007 works everywhere a 1N4001,2,3,4,5,6 works, there is no point in stocking them all. I have been buying only 1N4007 for decades. WHy tie up inventory space? I don't know if Pyle did it that way, but wouldn't surprise me.
Yep fair point but the stores I frequent the stock is often 100pack of 1N4004 and not much else. :'(
Phil.
Well, sure, if that is what is available and suits the need, then of course use it.
To replace my TDA30 chip I bought a TDA2050 from jlassen36wy = Amp Repair Houston, EBay.
After ordering I noticed the TDA2050 webpage says:
"NOTE: Placing this TDA2050 32 watt integrated circuit chip into a 20 watt circuit (i.e. replacing a TDA2040) will not increase the power output of your device and may cause instability especially with a 4 Ohm load."
I'm worried I got the wrong chip because My speaker is 4 Ohms!
But My amp is a 30 watt amp & has "Rated Power: 45 watts Peak".
So maybe this chip is OK?
What I don't know is : How many watts is my original TDA2030 chip?..... & Is my circuit 30 watts?
[TDA2050 is a 32watt chip ; TDA2040 is apparently 20watts? ]
Putting a "50 watt" IC in the circuit doesn;t make the circuit 50 watts. It just has heftier parts inside.
45 watts peak is marketing rubbish, a meaningless spec.
With the TDA2030A chip running 36v power supply or rather a -/+18v supply it will be max rated at 20 watts as per data sheet. So now you will have the TDA2050 in place that can handle 32 watts at 8 ohms or the claimed 50 watts with 4 ohm load. In those examples though it is with a power supply capable of delivering 50v or -/+25v from the power transformer. Your amp will still have the -/+18v power supply and will have a new chip that is highly overrated to your amp's power supply. Honestly looking at the TDA2030 data sheet I think it's really only putting out 14 watts RMS with a 4 ohm load. I would be surprised if the 4 ohm speaker caused any trouble for TDA2050 chip.
Thanks for the analysis,DrGonz78! ---That's a relief for me!
I was going to follow these instructions:
"Turn the amp on for about 2 seconds then off again. Then put your finger on the plastic part of the chip amp see if it has heated up really quickly. If it is ok for 2 seconds double the time and try again - repeat until you have reached 1 min." "[Amps usually recover if they are load unstable but they will run much hotter than they should so watch for this when you start using the amplifer.]"
Quote from: DrGonz78 on September 03, 2018, 12:45:19 AM
With the TDA2030A chip running 36v power supply or rather a -/+18v supply it will be max rated at 20 watts as per data sheet. So now you will have the TDA2050 in place that can handle 32 watts at 8 ohms or the claimed 50 watts with 4 ohm load. In those examples though it is with a power supply capable of delivering 50v or -/+25v from the power transformer. Your amp will still have the -/+18v power supply and will have a new chip that is highly overrated to your amp's power supply. Honestly looking at the TDA2030 data sheet I think it's really only putting out 14 watts RMS with a 4 ohm load. I would be surprised if the 4 ohm speaker caused any trouble for TDA2050 chip.
Here's what jlassen36wy [EBay seller] said:
"The limitation is the power supply circuit.
As far as thecircuit becoming unstable at 4 ohms, that depends on the circuit design.
The TDA2050does not begin to taper off power at 18 watts.
So, the power supply may become loaded down trying to feed the chip.
It is a design issue, and I have used TDA2050s in all sorts
of TDA2030 and TDA2040 circuits successfully,but I can't guarantee it as a substitute.
[PS: TDA2030 is 18 watts into 4 ohms. TDA2050 is 32 watts into 4 ohms]"
Does that agree with DrGonz78 said above?
DrGonz78 seems to have more information [that I have a -/+18v power supply] & sees no instability problem.
Quote from: Roark on September 04, 2018, 05:15:41 PMDrGonz78 seems to have more information [that I have a -/+18v power supply] & sees no instability problem.
Look and read this little tidbit... Note the statement on this page "If you have low impedance speakers use +/-18V supply." This was mentioned as way of saying if you running lower than 8 ohms then... do it this way.
http://www.youritronics.com/audio-amplifier-with-tda2050/ (http://www.youritronics.com/audio-amplifier-with-tda2050/)
It is saying that if you run the chip at max power supply -/+25v supply that it will only be stable with an 8 ohm load. Now typically an amp designed with a 2050 chip the power supply will be run around -/+22vdc. So the power transformer will be a 32vac supply but with a split power supply that will be -/+16vac .
16 * 1.41 = 22.56vdc >>> We multiply the voltage by 1.41 as to figure out the added voltage when the AC is rectified to DC. So most amps I have come across running tda2050 chip will have very similar set up as what I have mentioned.
You can actually confirm your voltage on your amp with the chip disconnected. I would be guessing that the power transformer is 24vac w/ center tap and it results to a split power supply of -/+12vac. 12 * 1.41 =
16.92vdc. Check out your voltages on your amp to be sure. :dbtu:
Note that when I say that a 2030 chip puts outs only 14 watts that is at 0.5% THD. It will dissipate up to 20 watts but at the expense of increased harmonic distortion. This is with a -/+18vdc power supply.
"Thanks to its high power capability the TDA2050
is able to provide up to
35 W true RMS power into
a 4 ohm load at THD = 0%, V S = ±18 V, f = 1 kHzand up to 32 W into an 8 ohm load at THD = 10%,
V S = ±22 V, f = 1 kHz."
That is from the data sheet and it even implies that running it at 4 ohm load that you should use -/+18vdc supply. Makes sense to me more each time I think about it. Now confirm your power supply voltages to make sure. Which if a 2030 chip suggests -/+18vdc supply then I would think its very close to that indeed.
+1 what DrGonz said.
It's x2 current at 4 Ohms and that tiny little metal tab has to pass ALL that extra heat across to the heat sink. Not possible :lmao:, the chip would need a larger surface area. Tiss a bit like adding a V8 engine to a mini minor while still relying on the tiny mini minor radiator to dissipate the extra heat. Yes the engine will run and as long as you don't press the pedal it may idle and stay cool but no chance if you crank up the engine on a long drive. :duh :duh
Same for that Chip,, safe at lower supply voltage but not capable of dissipating the extra heat at full supply.
If your next Q is; Why can't I just use a bigger heat sink?
Because the surface area can't pass enough heat to the larger heat sink,, false economy.
The laws of fizzy stuff don't change no matter what the data sheet claims.
Phil.
Quote from: DrGonz78 on September 05, 2018, 02:40:06 AMI would be guessing that the power transformer is 24vac w/ center tap and it results to a split power supply of -/+12vac. 12 * 1.41 = 16.92vdc. Check out your voltages on your amp to be sure.....
Now confirm your power supply voltages to make sure. Which if a 2030 chip suggests -/+18vdc supply then I would think its very close to that indeed.
-------------------------------------------------------------------
The label on the
Transformer says:
"TDB-15L-1,
OUT: 12VX2,
ACIN: 120V"
Is this the
"split power supply of -/+12vac" that DrGonz78 guessed? [so I don't need to measure the Transformer voltage]?
----------------
Many Thanks to DrGonz78, again, for that detailed analysis!!
Yes that is the 12V Dr.Gonz meant, I think you should be fine.
I'm not really in agreement with what the seller said anyway, at least not for this application:
"The TDA2050does not begin to taper off power at 18 watts.
So, the power supply may become loaded down trying to feed the chip."
Reading between the lines, he seems to be implying the original 2030 would have been limiting at 18W. I think in a guitar amp, it would have just been clipping, (not tapering off) so any power supply limitation (causing instability) should have also been evident with the original chip.
In any case, worst case scenario is the chip burns up when pushed to hard into clipping, which is what we would expect happened to the original chip anyway. ;)