2150sx component location

[Clipped]

im going to try to attempt to give this 2150 sx a rebirth, it doesnt look pretty...

if possible can someone verify the location of these components?

i picked this amp up from a friend and its been from repairman, to repairman, to technician, to god knows who....its been through alot , and it still doesnt work and i feel sorry for it.

i removed most of the caps to replace them, but i want to be sure whoever took it apart previously put the components in the right place....

how do you check the 317/337/L7815 regulators?

at first i thought the fen/p 30 rectifiers on the back of the board were bad because the legs were melted off....but after soldering the legs back together im getting identical mirror image readings for both of them...

while in the board. .632 or with the leads reversed for each diode .380...on diode check.

good lord, where do i start with this amp?

btw...the supposed demise of this amp was a 2 ohm mono load for about 30 seconds (i know the minimum is 4 ohms mono, but shouldnt it atleast be able to hold out longer without blowing?)

[Perry Babin]

The components on top of the board are correct. I'm not sure about the two on the bottom but you can follow the center leads to the rail caps to see which goes to the positive rail caps and which goes to the negative rail caps.

Why do you suspect the regs?

What happens if you power it up? You should install at least one positive and one negative rail cap before powering it up.

[Clipped]

ive checked all the fets and transistors and replaced defective ones and it doesnt power up. ive checked and replaced the a56/06 and relative diodes also.

i guess im just being suspicious of the regs because , its the grey area i dont know how to check.

but let me put everything back together again and see what happens as this amp has been sitting for a while...and i may have forgotten something.

how do the readings for diodes look on the back? or do i have to pull them to get better readings? they look beat to heck, but seem to measure while 'in board'...just weird that they measure at all if i reverse the leads.

ill get back to this tomoorrow, im beat to heck right now, installed 6 speakers...made a ported box for 2-10's , hooked up 3 amps from battery...made an amprack....and wired an oem hu via loc to a pre-amp today...

and soldered everything....

[Perry Babin]

With the amp powered up, measure and post a list of the DC voltages on the TL594 IC. Black meter lead on the ground wire of the amp.

[Clipped]

put the caps back in today and powered it up...

when i power it up the ammeter needle stays pegged to 100 amps...100 amps is the maximum value on the ammeter.

i took the secondary windings out of the board and powered up again...but left those two wires in that go between the primary and secondary

the ammeter goes to 10 amps, then there is a 5 second delay then the needle goes to 35 amps very slowly, and stays there.

still want me to mesure the TL494? (this one doesnt use the 594)

[Clipped]

with the secondaries legs out of the board.

the initial voltage the amp draws from my power supply/battery charger is 15.69 vdc (10 amps)

then it rest at 14.65 vdc (10 amps) for a few seconds, then it drops down to 11.43vdc...as the ammeter starts to rise to 35 amps, and stays there.

with the secondary legs out...and measured at 11.43 vdc, here are the mesurements for the TL494

1 = -0.003
2 = 0.032
3 = 0.032
4 = 0.048
5 = 1.568
6 = 3.516
7 = 0.002
8 = 11.74

9 = 0.002
10= 0.033
11= 5.022
12= 5.022
13= 11.96
14= 11.78
15= 4.91-98
16= 4.91-98

or should i measure while the secondaries are in? its drawing alot of current with them in and im afraid something is going to fry if i leave it powered up too long.

[Perry Babin]

Did you use the old rail caps? Is it possible that you installed one backwards or that one is shorted?

You need to use a current limiter like a 1-2 ohm high power resistor or an automotive head lamp in the B+ line to prevent excessive current draw. It's unbelievable that the amp's power supply drew 100 amps from the 12v supply without failing. It won't be able to do that too many times without failing.

If the caps aren't the problem, the current limiter will make troubleshooting easier.

The voltage on the 494 looks OK. Look up the datasheet. You have the pin numbering backwards on the top row.

[Whortless]

Dear Clipped,

I think your TL494 voltages are wrong. I suggest you to pull the FEP16 rectifier diodes to repair your PS instead of the complete amplifier. Check your TL494 at first or regulation lines for it. Because pin8&11 or pin9&10 should have same voltage readings. I suggest you to check, if pin9&10 is going to GND (or pin7). If so, then you can check mosfets. But, I wonder if you are reading 11V for either pin 8 or 11 one of your switching mosfet is burned. Also it can damage TL494 . I think it is easy to check the current with an ammeter by pulling up the TL494. If the circuit still needs more current higher from 1A, you should check the mosfets at first. Please, turn back with your results.

Regards

[Clipped]

yes i listed the pins backwards...right when i did, my ISP cut me off and have been trying to correct it for 24 hours, the whole time thinking 'what an idiot i was'...

btw pin#1 is not negative...i think its time to change the battery in this meter...

man really sorry for posting wrong stuff.

i used new rail caps i just purchased yesterday 50v 1000uf
all put in correctly, and i checked each and everyone before putting them in to make sure there would be no question about them.


but the sideways caps (old ones) act funny, sometimes they say 'disc' and sometimes they meter.

there is one problem area on this board where it has cracked across a few traces...on the other side is an A56

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so should i get some current limiting resistors , put the secondaries back in and remeasure the TL494 ?
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[Clipped]

for sake of ease


1 = 0.003
2 = 0.032
3 = 0.032
4 = 0.048
5 = 1.568
6 = 3.516
7 = 0.002
8 = 11.74

9 = 4.91-98
10= 4.91-98
11= 11.78
12= 11.96
13= 5.022
14= 5.022
15= 0.033
16= 0.002

whortless i dont know whether you are referring to my backwards pins or the correct ordered pins, my fault.