Axiom EP 350 Powered Sub

[landyboy]

I recently got a sub off of a friend and am attempting to repair for him. I do not have much experience with these at all. Symptoms were no power on. When I first took it apart 3 of the capacitors where obviously bulged so I though here is the problem. Replaced all three and it still will not power on. I did check the main fuse its good. It appears to have voltage going into the large transformer but I can not detect DC voltage anywhere on the board. Any ideas where to start?

[clearchris]

Re: Axiom EP 350 Powered Sub

A quick check of the pots (knobs) is always in order. If one of those pots gets jammed, the sub wont work. Its happened to me more than once because of shipping.

[budm]

Re: Axiom EP 350 Powered Sub

Are you getting any AC on the secondary winding of the transformer? The secondary side has two grey wires and the center tap white wire.

[landyboy]

Re: Axiom EP 350 Powered Sub

budm sorry I missed you post I will test those points. Upon another look at the psu board I found what looks like a blown out cap. I attached a picture of the same type of cap that is blown out. It is a polyester type. Can I substitute a diff cap with the same values? 0.1uf 100v

[landyboy]

Re: Axiom EP 350 Powered Sub

budm, Yes I am testing 44vac on all three leads of the connector circled. changed the additional bad cap and it still does not power on.

[budm]

Re: Axiom EP 350 Powered Sub

44VAC between grey and white wire? if that is the case, the transformer is 88VAC with center tap, so the DC voltage of each one of those two big filter caps should be around 60VDC.
Can we also see the bottom side of that power supply/power amp board so we can see the bridge rectifier that is fed by the transformer.

[landyboy]

Re: Axiom EP 350 Powered Sub

Here you go

[landyboy]

Re: Axiom EP 350 Powered Sub

I may have been testing incorrectly. If I test for Ac voltage at the connector on the power board from grey to white there is no voltage present. In the earlier test I was using the white lead where the AC comes from the power cord as the other side.

[budm]

Re: Axiom EP 350 Powered Sub

'If I test for Ac voltage at the connector on the power board from grey to white there is no voltage present" Ok, so we need to find out if the 120VAC is being applied to the primary winding then.
I see that the primary side has BLACK, WHITE, ORANGE, BLUE, and BROWN wires
So for 120V operation, the Black wire and Brown wire will be tied together, the White wire and Blue wire will be tied together, not sure about the orange wire.

If the primary side windings are not open, you should be able to see low Ohm reading on the AC INLET connector on the white an black wire. You can insert the power cable and take the resistance reading between to two flat pins of the plug, it should show low Ohms, power switch must be in the ON position.
OK, the fuse is under the cover on where the AC INLET is.

[landyboy]

Re: Axiom EP 350 Powered Sub

using the chassis ground i test at the transformer:
White 44VAC
BK 44
Orange 44
Blue 60
Brown 44

[landyboy]

Re: Axiom EP 350 Powered Sub

More pics

[budm]

Re: Axiom EP 350 Powered Sub

See post 9 for the main AC fuse location.
The AC readings on post 10 are not right at all.

[landyboy]

Re: Axiom EP 350 Powered Sub

OK tested fuse first its good. I then used the power cord with switch on between the flat leads it appears open 30meg ohms.

[budm]

Re: Axiom EP 350 Powered Sub

That means we have open primary windings which I do not believe it is since it has dual 120V windings connected in parallel for 120V input. Need to trace out the resistance from the AC input jack to the primary windings to see where the open circuit is, also make sure the power switch is OK.
I wonder if they are willing to provide any info: It is not cheap sub woofer.
http://www.axiomaudio.com/ep-350-subwoofer#t-3
http://www.axiomaudio.com/corp