SpiderII 15 Watt Amp IC question

[pudge211]

Hello...First Post...
   

I have a Line 6 SpiderII that quit working and started to smoke. upon opening the back of the amp up I plugged it back in and when I flip the power switch, the amp IC turns red hot and starts to burn. I have searched the net to find info about it but don't find much. I can make out TDA20 and the rest is burned off. I found a replacement TDA2050 at www.fullcompass.com but I Think the power is too high for a 15 watt amp. can anyone shed some light on if it is a TDA2050 or TDA2030 in there?

Thanks

[DrGonz78]

Welcome to the place!! Well first off a TDA 2050 in an amp that runs a TDA2030 chip will not draw more power. In fact, it will be just an overrated part and that just means it can take higher power rails. A TDA2030 in an amp that asks for a TDA2050 chip is a bad idea as it will probably blow out the chip. In this case your amp does take a TDA2050 chip as per schematic posted. Still it being only a 15 watt amp I would think they used the 2050 just to have it overrated, but I could be wrong. So the TDA2050 is the right part indeed.

Proceed with caution after just replacing the chip... There is always the possibility that the chip blew out for other reasons than just a common failure. Meaning those chips do just fail, but there might be something that caused it to fail somewhere else in the amp. So when you power it up for the first time with the new chip you will need a light bulb limiter. Do not connect the speaker until it has been proven to have no DC voltage on the speaker output. We all here can help you along with the process as you go, if you need the help.

http://www.ssguitar.com/index.php?topic=2093.0

[pudge211]

Thank You for the reply Dr. I placed the order for the 2050 and will do the DC power check on the speakers.. I will post what I find once the part arrives and I have it installed

[pudge211]

Is there anything you would check Right now before installing the new chip? The amp was smelling hot the last two times I powered it up.

[Roly]

Hi pudge211, welcome.

when I flip the power switch, the amp IC turns red hot and starts to burn.

Eeeek!    I think we can safely jump to the conclusion that IC's a dead one.

Wot Doc said.

While you are waiting for the postman you can make up a Limiting Lamp (as above) because you are going to need it as soon as the IC is replaced to "bring the amp up".

You can also test your loudspeaker(s) for damage.  Each speaker should have a DC resistance of something around 5 to 10 ohms, and the cone should move freely without any scraping noises when pressed gently.

You can give it a functional test by wiring it up to some external signal source; the headphone output of most gizmos (e.g. radio, cassette player or x-Pod) should produce clean sound, not loud, but clean at low levels.  If you have another guitar amp, perhaps with an external speaker socket you can use that, otherwise you are going to have to busk it.  Just be careful not to short any outputs in the process.


Live test (chip out, via limiting lamp), check power supply DC voltages are correct.

[pudge211]

ok cuurent status.... I removed the burnt Amp IC and plugged it in via the test lamp. It looks like the voltage at the test point is 3.3v DC as it is suppose to be. 

[Roly]

ok cuurent status.... I removed the burnt Amp IC and plugged it in via the test lamp. It looks like the voltage at the test point is 3.3v DC as it is suppose to be.

Well that's the supply for your digital Fx board.

We also need to know the voltages at "+HI", "-HI", "+VL", "+VA", and "-VA" (schem pdf p4).

[pudge211]

This is what I've come up with and let me know if I don't have some thing right

H1+ as marked on board = 20.2

H2- as marked on board = 20.3

VA is the voltage @ audio out connection?? If so VA+ = 3.7

                                                        VA- = .1

And VL is line voltage from transformer?? Which is 3.0

Thank You Again for all the help!!! I work with high voltage at my day job and am fumbling thru this Low voltage stuff I guess so any help is appreciated. Sorry if I have something wrong but if so just let me know where to test and I will get it done.

[Roly]

On page 4 of the pdf you will find the circuit of the power supply, and the termination points as marked "+HI", "-HI", "+VL", "+VA", and "-VA".

We need you to measure the actual voltage on those points and post them.  As the signs indicate they should be +ve and -ve w.r.t. ground.

[pudge211]

I'm not too good with reading schematics and I only see H1- and H1+ marked on the board. If VA and Ve are referring to where the chip I removed is connected those voltages are 20.3, 20.3, 5.2, 4.5 and 0.1 the H1- and H1+ voltages are 20.3 respectively. All voltages phase to ground

[Roly]

the H1- and H1+ voltages are 20.3 respectively

Plus 20.5V at both H1- and H1+?  Not minus20.5 and plus20.5V? (the polarity/sign is critical).


Okay, try and locate C35 and C36, large cans 2200uF/25V, near the transformer and rectifier diodes.  You should get +20-odd volts from the +ve end of C36 to ground, and a similar negative voltage on the -ve end of C35.  This is the spilt supply for the output/power amp.

Somewhere nearby you should find C32 and C31, smaller 10uF caps.  C32 should have around +9V on its +ve end, and and C31 should have -9V on its negative end.  This is the split supply for the preamp.

Confirm?

We need to be sure these are right before we commit fresh silicon.  If there is a problem with the power supply we need to fix that first.

(You have already found the +3.3V supply for the Fx module.)


Also please carry out the speaker tests and post results; we need to be sure the speaker isn't damaged, either as the cause or result of the amp fault.

I work with high voltage at my day job and am fumbling thru this Low voltage stuff

We'll get you onto a 100 watt valve amp with 700V HT next, and you'll feel right at home. 

We shouldn't need to pound you about safety.  It's all just the same voltage and currents, just a lot smaller than you are used to; chin up, you're well ahead of most at this point.


{In a previous life I designed and repaired VS drives up to 100HP, six SCR's as big as beer cans direct on 415V 3 phase 50Hz, 3ph theater lighting desks, live board work, 100kV X-Ray machines, and such, so I know of which you speak.  :duh right?  :lmao: }

[J M Fahey]

Don't worry, you can always wear your rubber sole boots which will protect you .

..................

..................

Will they?

[pudge211]

the H1- and H1+ voltages are 20.3 respectively

Plus 20.5V at both H1- and H1+?  Not minus20.5 and plus20.5V? (the polarity/sign is critical).

HI+ is 20.3+
HI- is 20.3-

Okay, try and locate C35 and C36, large cans 2200uF/25V, near the transformer and rectifier diodes.  You should get +20-odd volts from the +ve end of C36 to ground, and a similar negative voltage on the -ve end of C35.  This is the spilt supply for the output/power amp.

C35 is 20.3+ (you say this should be - but nowhere I test gives me -20.3 except for the point where the amp
                       IC gets connected to the board)
C36 is 20.3+

Somewhere nearby you should find C32 and C31, smaller 10uF caps.  C32 should have around +9V on its +ve end, and and C31 should have -9V on its negative end.  This is the split supply for the preamp.

C32 is 9.4+
C31 is 9.4-


Also please carry out the speaker tests and post results; we need to be sure the speaker isn't damaged, either as the cause or result of the amp fault.

Speaker Test complete and its junk. No scratchy noise, shows OL on meter and has no sound when hooked up to stereo. Ordered a new speaker today too.



We'll get you onto a 100 watt valve amp with 700V HT next, and you'll feel right at home. 

That's sounds interesting

[g1]

the H1- and H1+ voltages are 20.3 respectively

Please measure with your black probe connected to ground, use red probe to connect to H1-
Be sure your meter is set to DC volts.
Specify whether your reading shows negative (-) or positive (+)

[Roly]

Don't worry, you can always wear your rubber sole boots which will protect you .

One day while installing a guard on a press while standing on a plastic milk crate, I managed to contact two different 415V phases of the mains with each hand.  For three days afterwards I felt like I had been kicked in the chest by a horse, and no amount of off-ground insulation would have saved me.

C36 is 20.3+

I can't see it now, but somewhere I thought you posted that you also had measured 40-odd volts between supply rails, clearly implying that one of them is minus20V w.r.t. ground.

What is important here is that we have get these details right, specifically and accurately confirmed, before we can proceed.  If you are using a DMM with the black probe to ground then the display should be showing minus20V, but if you are using an analogue meter and reversing the probes then you must remember that this also reverses the polarity of the DC voltage you are measuring.

I'm being a bit pedantic because the power supply has been called on to actually light up the original IC and may have been damaged in that process.  Things could get rapidly confusing if we don't get these things clear now.