0-5a 0-30v psu blowup

[p.larner]

I built a chinese 0-5amp 0-30v psu kit,it was fine until i hooked it up backwards to a 12v car battery,i have changed the opamps,tip41 driver +the pass transistor emiter resitors,its still totaly dead,any idea where to go next?,schematic attatched,its the same but the except the zenners,they are now 79/9 regulators.

[tggzzz]

I built a chinese 0-5amp 0-30v psu kit,it was fine until i hooked it up backwards to a 12v car battery,i have changed the opamps,tip41 driver +the pass transistor emiter resitors,its still totaly dead,any idea where to go next?,schematic attatched,its the same but the except the zenners,they are now 79/9 regulators.

Where to go next? The rubbish tip, unless it would be collected from the kerbside.

Afterwards, sit down on your hands.

[Andy Watson]

...  i hooked it up backwards to a 12v car battery ...

Any other details are moot!

... any idea where to go next?

Start again - from the very start - bin the ashes

[floobydust]

Uh that PSU schematic has an auxiliary (floating) +/-12V rails for the control op-amps, how does that work off a car battery? 

edit: The 0-30V 2mA-3A PSU boards do not work with DC input (of the correct polarity). They have a -ve rail generator that needs AC to make the -5.1V and shutoff the transistor that shorts the op-amp output during power-up/down. In other words AC yes, DC no.

[pqass]

Did you connect the battery to the transformer (L1 and L2) primary windings inputs?   
Or to the output terminals; OUT+ and GND?

If the former, the transformers are likely destroyed (unless there was a fuse in series); replace fuse and check the primary windings resistance to confirm. If open, yer SOL.

If the latter, powerup (transformer primaries with mains AC) without anything at the output terminals and verify voltages from the transformer secondaries onward.  That is, on the upper L1 part, check if there is +15 and -6.2 across either zeners (center tap being neg. of your multimeter).  Check if there +2.5V across the TL431.  On the lower L2 parts, check across C16 to give the rectified, filtered, unreg. voltage before the series pass transistors.  On the bottom LM7812 regulator section (used for L2 tap switching), check if there is +12V across output and GND.

[p.larner]

just to clear things the output of the psu was hooked up to the car battery with the polarity reversed.

[floobydust]

hmmm big smokum from 1N5404.

[xavier60]

That's a Harrison type design. Except for there being a diode across the output, the design can briefly tolerate applied reverse polarity until the output transistors overheat and fail short. Had the output transistors actually failed?

[p.larner]

its been a while but if i remember the pass transistors shorted in every direction,also the 5w emitter resistors went open,all those components were renewed.

[xavier60]

Confirm that the control supply ground is connected to the PSU's + output terminal. The junction of D9 and D10 is ground for the control supply rails.
Then measure the voltage on all pins of U1 WRT the + output terminal.

[factory]

why not tri the skytrronic psu? i'm sure it wass highy reckomended bye m3vuv for charging classic kar batery

[Jwillis]

I built a chinese 0-5amp 0-30v psu kit,it was fine until i hooked it up backwards to a 12v car battery,i have changed the opamps,tip41 driver +the pass transistor emiter resitors,its still totaly dead,any idea where to go next?,schematic attatched,its the same but the except the zenners,they are now 79/9 regulators.

Check the all polarized capacitors specifically C12, 13, 14,16, Output Capacitor and C1 and C2. Polarized electrolytic capacitors don't always explode when put into reverse polarity but can be servery damaged.