Bose 1800 series VI Pro amplifier not turning on & Peavey PVi 3000 no output

[StewartH83]

Hello all,

This Bose didn't turn on one day when I come to use it. It was working fine the time before so no sudden shut down. I've finally got it out of the cupboard to have a look at it.

It still don't power up so checked the plug fuse, that has continuaty and I have continuaty from internal fuse to switch and from the switch to the board it goes to so presume they are fine.

From what I can see there's no burnt components and no bulging caps.

I wanted to know if you guys know of any prone problems with these amps and before taking it apart further to check buried boards if I should check anything else out. I understand those 22,000uF caps won't mess about in killing me so Im carefully respecting that.

Any ideas will be greatly appreciated as usual.

Also got a Peavey PVi 3000 of my brothers that turns on but no output, it was repaired at one time beforehand and has a suspicious dent on top from the inside going out, like a caps blown upwards ha. Lent him my Crown amp for now.

Thanks

[amplidude]

Did you check if the dc voltage on the big capacitors..? Check soft start circuit for damaged relay, and burned power resistor.

[amplidude]

Forget soft start part, primary side of trafo is triac driven,

[StewartH83]

Thanks for your advice and info. I didn't check those caps for DC earlier. 0.0 DC on the two I could reach

[amplidude]

It's late and have to get up early, but I leave the service manual here.
Will take a look at it tomorrow.

[StewartH83]

Can't thank you enough sir.

Hope you get some good rest.

Just a quick update: I have signal passing through the silver box but not tested much more as I cleaned all connectors, cleaned the dust out and looked at the Peavey. That just needs the sockets and pots soaking with contact cleaner by the sound of it.

[StewartH83]

I'm currently working on the Peavey (Really I should of done separate posts) and I get music through it but very distorted, only very low volume it's 90% OK, moving the pot up anyway sounds terrible. I've blasted the pots and sockets with Deoxit, slightly better sound. I took the pots out, outside contacts & solder joints are clean but when moving the pot it seems like the wiper is grinding very hard, could it be the problem? Im considering taking the pot apart before I order some better ALPS pots or something.

It also seems like the guy who serviced it previously did a great job of cleaning but I feel he may of used a poor contact cleaner as all the connectors, speaker binding posts and input Jack's I'm using are effecting the sound, the Jack's sockets can turn the sound off completely, this could be why my brother got no output at all, twisting the Jack's gets a signal.

I've blasted the sockets with Servisol Super 10 but still not sorted the jack problem, I'll take the board out and clean them better and check the solder joints.

I'll take some pictures too, not sure if this glue is the conductive type too.

[StewartH83]

Further troubleshooting on the Peavey. I removed the input board with the Jack's & speaker connection and cleaned all the pots and switches with Servisol, reflowed all the Jack's and speaker connectors solder joints only because they were thin, one of XLR joints had a hole in yet I wasn't using them inputs earlier. Seem to go no better, worse if anything, really struggling on the bass mainly.

I noticed a quiet hum coming from the transformer even when the socket had power but no switch on, I'm thinking that is suspect and needs looking at, although I've tighten the bolt but it didn't move.

I did poke about abit while it was playing music through one channel and notice the component on the heatsink in the middle, never seen one before, when wriggling the wires it had quite a bit of change, never went better yet was going worse. The connections don't look the best.

Any ideas will be greatly appreciated

[turk 182]

if you've never seen a thermal cutoff before i guess you don't know that it's there to remove the supply line to the output stage in case of a thermal fault condition, and if it does have bad connections then wiggling them will have an audible consequence your changing the supply voltage!


please tell me your doing this "testing" under current limited conditions a la Dim bulb tester!?

[amplidude]

Could be thermal cutoff, but I've done some reading and found out that bose/Carver amp are weak at triac and opto coupler, but yes do use a series connected bulb when testing, on both, that's all for now, having a busy day doing boring stuff.