Amplifier burned, please help to ID parts

[Keks]

This little unit in my amplifier burned, I would like to try and fix it myself, but not sure what these little blue guys are. I thought they are caps but not sure what kind and what to replace them with. Any help would be greatly appreciated

 

[davenn]

Hi Keks
welcome to EP

This little unit in my amplifier burned, I would like to try and fix it myself, but not sure what these little blue guys are. I thought they are caps but not sure what kind and what to replace them with. Any help would be greatly appreciated

yes they are 0.1uF caps probably rated at ~ 100V

the bridge rectifier behind them could be suspect as well

Dave

 

[Keks]

Thank you, Dave.
Would you know if they are polarised? Or does it matter at all? That little arrow confuses me.
I well check the rectifier as well, thanks again.

 

[davenn]

Would you know if they are polarised? Or does it matter at all? That little arrow confuses me.

no, they wont be polarised

 

[73's de Edd]

Sir Keks . . . . . . . .

As Davenn said . . . . that FULL WAVE RECTIFIER BLOCK should be bad.

that set of ceramic capacitors are as badly burnt as I have seen.

The way they vaporized I would be wanting to use a much higher rating than 100V . . . . .more likely some X2 or Y2 ceramic units that are voltage rated well-well-well above 100V.

That left corner seems to have a heat shrinked, hidden connector . . . . is that 230 AC in ?
What I am seeing is that you are from Ireland and that would be 230-40 AC power

The center rear board seems to have two pairs of 5 way binding posts on it SPEAKER OUTPUT CONNECTORS ?
Plus it seems like some HUGE power connectors beside them.

Is this possibly a unit that can be both AC line powered or 12 VDC powered.

A cursory look tends to suggest a linear power supply using that toroid . . .but things MIGHT be different, if this unit also works with 12VC in .

What are the voltage spec and capacitance ratings on those centrally located two large, black canned electrolytics.

All that I can see are two POWER semiconductors . . . . . that are using that HUGE heat sink . . . . are any units mounted on its other / unviewable end ?

What is the BRAND and model of this unit . . . . . and it probably will torn out be one that we can find no info on ?

73s de Edd

 

[davenn]

The way they vaporized I would be wanting to use a much higher rating than 100V . . . . .more likely some X2 or Y2 ceramic units that are voltage rated well-well-well above 100V.

depends on why they failed .... seeing the type of failure, it is most likely due to a large power line spike rather than from normal operation at the standard circuit voltage

 

[davenn]

Is this possibly a unit that can be both AC line powered or 12 VDC powered.

I see no sign of any DC input

@Keks can you please take a photo of the front panel of the amp

 

[Keks]

Here are more photos, I could not find any schematics for this online. Maybe you will be more lucky)

 

[davenn]

Here are more photos, I could not find any schematics for this online. Maybe you will be more lucky)

Awesome, thanks .... confirms my thoughts that there is no DC input. I was quite familiar with that with the professional amplifiers I used to install/repair
As they were often in public areas eg shopping centres, they supplied not only background music but also paging, and evacuation alert sounds.
As a result they had to be able to run off battery in case the mains power failed

OK you need to replace those 4 caps and bridge rectifier for a start and then we can go from there

Ohhh ... you haven't answered Edd's question about what all is bolted to that big heatsink ?

 

[duke37]

What is the black grot on the transformer. If it is some pitch droped on the winding, then OK. Of it is a due to a shorted turn, then you will need a new transformer.
Disconnect the transformer output connections and check for power.

 

[davenn]

What is the black grot on the transformer. If it is some pitch droped on the winding, then OK

Look at the earlier pic of the whole transformer .... does look like it was filled with some sort of resin and that on the outside
edge is just a few spill drops

 

[Keks]

Sir Keks . . . . . . . .



All that I can see are two POWER semiconductors . . . . . that are using that HUGE heat sink . . . . are any units mounted on its other / unviewable end ?


73s de Edd

Hi, Edd.

You were right, there are more of them on the other side.

 

[Keks]

What is the black grot on the transformer. If it is some pitch droped on the winding, then OK. Of it is a due to a shorted turn, then you will need a new transformer.
Disconnect the transformer output connections and check for power.

I was looking at that as well, it is some resin spilled, just like Davenn thought.

 

[Keks]

OK you need to replace those 4 caps and bridge rectifier for a start and then we can go from there

Will I use .1uf caps or bigger ones will be better? Any suggestions on bridge rectifier specs?
Sorry I am verry new to this and need to ask the things that might be obvious.

 

[davenn]

Will I use .1uf caps or bigger ones will be better?

no, just 0.1 uF. the size of them and their colour indicate that they may be rated at 1kV ( this is much higher than they would be running at) but that is OK

Any suggestions on bridge rectifier specs?

an educated guess, probably going top be rated at around 45 Amps ( more info on the circuit would help with that)

a schematic or service manual would be extremely helpful

 

[73's de Edd]

Sir Keks . . . . . .

I now see that the principal power transistotrs* / or / FETS * are merely those two transistors per channel, that are mounted on the bottom of the heat sink . . . . with a couple of ancillary heat sensors also being thermally tied in.

Pass us the numbers on them* so that we can see just how much OOOOMPH that they are capable of . . .just in case the end result is that they were also affected.
Somewhere on that Full wave bridge housing, I would expect some ID numbers on it also.
As Davenn said ... your photo also revealed that the unit is solely AC line powered and that the end lowered supply voltages are being 44VAC centertapped and 68VAC centertapped..

Have you either diode mode tested or ohmmed out the four power diode junctions within the FWB to see how many sections are dead shorted ?
Also was the AC line fuse badly blackened within its envelope ?
Your photo of the LARGE main supply electrolytics failed to show their Capacitance and Voltage specs
The visible M0003 numbering does not fly.
Also I might just barely see one end cap of what possibly might be the line fuse . . . . . unless it has been replaced, it seems to be a clean slow/delay rated unit.

73s de Edd

 

[Keks]

I found some schematics. Hope this will help.
If i am reading it right large caps are 10 000/50, Diodes on bridge rectifier are IN4004.
AC fuses were not affected.
I did not test diodes. I will will do a little search on how to do it and will give it a try. Bridge rectifier is a solid unit, I think it can not be fixed and will have to be replaced. Please correct me if i am wrong.

 

[davenn]

I found some schematics. Hope this will help.
If i am reading it right large caps are 10 000/50, Diodes on bridge rectifier are IN4004.
AC fuses were not affected.
I did not test diodes. I will will do a little search on how to do it and will give it a try. Bridge rectifier is a solid unit, I think it can not be fixed and will have to be replaced. Please correct me if i am wrong.

Ok that is a great help

unfortunately tho, your parts list didn't include the capacitors use ..... the schematic is only showing 2 of the 4 blue caps that is in your pic


there are 2 bridge rectifiers .... a low current one using 4 separate 1N4004 's .... this IS NOT the one in your pic with the cooked caps
the single item bridge rectifier in that pic of yours in the upper of the 2 in the schematic ... the KBPC804 ... it's an 8 Amp 400V rated diode

looks like this amplifier has no way of generating 2000 W (that rating is just a joke) with only 4 output transistors and an 8 amp rectifier

 

[Keks]

Thank you for the help guys, it is great to have support. I ordered 50amp bridge rectifier and .1uf 1kv caps. Will post an update when get them in. Nice weekend to everyone.

 

[davenn]

Thank you for the help guys, it is great to have support. I ordered 50amp bridge rectifier and .1uf 1kv caps. Will post an update when get them in. Nice weekend to everyone.

look forward to seeing how you get on
just be aware that what ever blew those caps ( a big power surge maybe) may have done other damage

I would power up the PSU section on its own for a start ... that is, have the rest of the main amp board disconnected