Two red wires to the + of one, two orange wires to the + of the other and the white goes to the - of one, the black to the - to the other and both - are joined with one black wire. This was exactly how it was when I got it BUT it was broken when I got it, with one cap failing. I do think a mistake here would be more catastrophic.
Pioneer SA-7500 (not mkii) won't kick relay out of protection
- Thread starter da_kube
- Start date
they are wired wrong.
the negatives should not be wired together.
i don't know the wire colors in this unit so hold tight til someone that does comes along.
They are not. They're clamped in and wired. I really can't read schematics well BUT it looks like the + of CAP 1 cap goes to pin 16 and the - of Cap 2 goes to pin 17? After that it looks like the - of cap 1 and the + of cap 2 both go to ground? If so, this would explain the third wire. The one cap is mounted backwards and the smaller wire connects both to ground.
Does that seem correct?
Attachments
my fault. i saw 'mkii' and missed the 'not'
BUT, if the negatives are wired together then they are still wired wrong
Based on this schematic, I would think two power w
Yup, I think you solved it. The Elna caps are installed the same orientation on the top and the wires is opposite on the bottom, so I have mine wired incorrectly. So it looks like two of the power wires (orange or red, I need eyes on it to
Yup, I was just replying. You cracked the case! Any guess as to how much damage this caused? I guess I really should have double checked the wiring, knowing this was bodged when I got it.
i would honestly guess that just the cap is trashed but i'd probably put a brand new pair in myself and kick myself in the ass while paying for it.
don't take it as gospel, there could still be other stuff downstream and if someone jacked up the wiring here, no telling what else was done incorrectly.
New caps and @ss kicking on order! Got off easy, only $13. I'll report back. I'm hoping not much more was done to this thing. I got the impression it broke and the dude thought the main filter caps would save the day.
don't be shy with the dim bulb
don't sweat it....i've installed caps backwards before. everybody has. once i did install a main filter cap backwards but the dim bulb let me know right away but i still replaced it even tho it was only powered up for a second. i think that single cap was 15ish bux
Thanks for helping out @painttoad. I think he got lucky, that the backwards cap did not quite literally blow it's top. Messy and stinky.
I don't think the outputs are shorted as it was never reported it blew the main fuse. It was powered without a DBT early on. But worth checking.
Replace the caps, leave the amplifier wires disconnected & test with DBT.
If DBT is good check for the correct voltages at the cap terminals. (leave amp wires disconnected)
If it passes the test power down, replace the regulated supply fuses and test with DBT.
If the 2nd DBT test is good check all of those regulated voltages.
If the regulated voltages are good lets have a quick go/no go check of the output transistors. Looking for Emitter to Collector short.
On the amplifier board ohm check from pin 32 to pin 3 and from pin 3 to pin 28.
Still on the amp board ohm check from pin 25 to pin 17 and from pin 17 to pin 22.
If you have no shorts move on and reconnect power to one of the amplifier channels from the filter caps. DBT check again.
If it passes this test then hook the filter cap power wires back to the other amp channel and DBT test again.
If it passes one or both of the last two tests the protection relay may close on one or both. That is a good sign.
Stop any where along the way if it results in a bright bulb, and ask for help
If you make it this far you should then check the bias while still on the DBT. Set it for 1/2 or less of the specified value. It will go up when you remove the DBT.
You can also check the DC offset on the DBT, it too will probably move a little when you come off the DBT.
Good luck fingers crossed.
Many thanks. I completed all steps and voltages on power supply are dead on using 30 watt DBT (a few high ones are a tad low, understandably.) No shorts but no relay. Also, I’m unable to bias due to lack of voltage. I assume that’s due to the relay?
Should I now probe voltages on the main amp?
The relay is strictly a protection device for the speakers/amplifiers. If the amplifiers are outputting damaging amounts of DC voltage the relay disconnects the speakers.
If the amplifier overdrive circuits are triggered by too much volume, or too low of a load impedance, including shorts. The relay again disconnects the load from the amplifier.
The relay not clicking in does not turn the bias on or off or make it non-adjustable.
Just to be clear the main filter caps are replaced and the amplifier channels have been hooked back up to the power supply?
30 watt bulb is probably voltage starving the the amplifiers. Move up the wattage scale to a 60-75 watt bulb and check the voltages on the main filter caps for the amplifiers.
Then check the DC offset of the amplifier channels, you can dial that in close while on the DBT. The see if you have any bias and if it is adjustable.
If you still don't have bias go back to post #9 https://audiokarma.org/forums/index...relay-out-of-protection.1083970/post-17735907 and check the voltages coming into the amp board.
Do you really think I'd be dumb enough to try to bias the amp without the power wires going to it?
Wait, you don't have to answer that!
Yes, new caps installed correctly and wires and fuses are all back where they should. I referred to the post and ALL circled voltages are correct on a 30w DBT. I tried bigger bulbs but it barely glows at 30. I think I found a problem. Pin 3 to ground is 30 VDC and 17 is 35 VDC on the main amp. No wonder the relay won't click.
What should I check next? Thanks!
Nope don't think that at all. Lots going on with caps, wires, parts etc. Just want to kind of reset. After a while it is easy to lose track of what is where without reviewing the whole thread.
OK so it appears we now have a working power supply
And it also appears we have problems in the amp channels. DC on the outputs.
I think it is best to confirm the driver and output transistors are good. Check the emitter resistors for the outputs.
Do I measure voltage to ground on each side, or across the output resistors? Or do I pull a leg and check values? Thanks!Nope don't think that at all. Lots going on with caps, wires, parts etc. Just want to kind of reset. After a while it is easy to lose track of what is where without reviewing the whole thread.
OK so it appears we now have a working power supply
And it also appears we have problems in the amp channels. DC on the outputs.
I think it is best to confirm the driver and output transistors are good. Check the emitter resistors for the outputs.
All tests are with power off! You can measure across them in circuit, they are very low value, so you may not get an exact matching reading. The primary concern is that they are not open.
They’re all around .7-.8 ohm in circuit.