Ampeg SVT-ii Pro No output w/EQ on

[g1]

2 and II refer to the same model amp. On multi-page schematics, down in the lower right it will usually say which circuit is shown. So when I mentioned pg.4 of schematic, it says that is for the power amp board. That is where the +/- 15V supplies come from. If they are good there, then we can move on and find out if they are not getting to the EQ.

Your D6 and D11 on the EQ board both have 470ohm resistors in parallel with them, so it makes sense that on diode range your meter would show .25 reading.

[ca7922303]

2 and II refer to the same model amp. On multi-page schematics, down in the lower right it will usually say which circuit is shown. So when I mentioned pg.4 of schematic, it says that is for the power amp board. That is where the +/- 15V supplies come from. If they are good there, then we can move on and find out if they are not getting to the EQ.

Your D6 and D11 on the EQ board both have 470ohm resistors in parallel with them, so it makes sense that on diode range your meter would show .25 reading.

Here's main board

[ca7922303]

Here's main board

[ca7922303]

Dont see a r60/61. Also, D40 on main board is reading(0.0/0.0) diode test.

[ca7922303]

2 and II refer to the same model amp. On multi-page schematics, down in the lower right it will usually say which circuit is shown. So when I mentioned pg.4 of schematic, it says that is for the power amp board. That is where the +/- 15V supplies come from. If they are good there, then we can move on and find out if they are not getting to the EQ.

Your D6 and D11 on the EQ board both have 470ohm resistors in parallel with them, so it makes sense that on diode range your meter would show .25 reading.

Pulled one leg of D40, still reading (0.00) diode test.

[ca7922303]

2 and II refer to the same model amp. On multi-page schematics, down in the lower right it will usually say which circuit is shown. So when I mentioned pg.4 of schematic, it says that is for the power amp board. That is where the +/- 15V supplies come from. If they are good there, then we can move on and find out if they are not getting to the EQ.

Your D6 and D11 on the EQ board both have 470ohm resistors in parallel with them, so it makes sense that on diode range your meter would show .25 reading.

Installed spare diode @ D40, now D39,40,41,29,31 all read(.017/.017). D30 reads(.004/.004) diode test in circuit.

[ca7922303]

2 and II refer to the same model amp. On multi-page schematics, down in the lower right it will usually say which circuit is shown. So when I mentioned pg.4 of schematic, it says that is for the power amp board. That is where the +/- 15V supplies come from. If they are good there, then we can move on and find out if they are not getting to the EQ.

Your D6 and D11 on the EQ board both have 470ohm resistors in parallel with them, so it makes sense that on diode range your meter would show .25 reading.

Found the +15/-15v from main board to EQ. Replacing D40 got it working. Appreciate the help. Thanks.

[g1]

D40 and those other diodes have to do with the bias indicator lights. D30 should have read the same as D31, etc. Did you replace D30?
Was there a bad connection or something related to getting the EQ working? I don't think any of those diodes would have stopped the EQ from working.
If you did not repair a bad connection, the EQ fault may come back.

[ca7922303]

D40 and those other diodes have to do with the bias indicator lights. D30 should have read the same as D31, etc. Did you replace D30?
Was there a bad connection or something related to getting the EQ working? I don't think any of those diodes would have stopped the EQ from working.
If you did not repair a bad connection, the EQ fault may come back.

I guess maybe a loose or dirty connection caused it then. I didn't replace R30 but I guess I better if it should be reading same as the others. Thanks again.

[Enzo]

I can see R60/61 with ease from here. Your photo is upside down compared to the layout drawing I posted, So look at the photo, along the bottom edge are two white plastic connectors with 5 wires each. The one to the right has two rectangular cement resistors right by it. Those are R60/61. I appreciate you already got it working, but in general you really do need to learn to identify parts on the board, especially with layout drawings available.

[g1]

I didn't replace R30 but I guess I better if it should be reading same as the others.

D30, not R30.
Also check all the 2W 10R resistors on the power amp board (R35 thru R40).
On the power tube board, check all the 22R resistors and all the diodes.
These are all parts that can fail with power tube problems and I believe you did replace a power tube.

[ca7922303]

D30, not R30.
Also check all the 2W 10R resistors on the power amp board (R35 thru R40).
On the power tube board, check all the 22R resistors and all the diodes.
These are all parts that can fail with power tube problems and I believe you did replace a power tube.

Right D30 not R. I'll check everything you mentioned while I'm in there this evening after work. Thanks again for the help. Appreciate it.

[ca7922303]

D30, not R30.
Also check all the 2W 10R resistors on the power amp board (R35 thru R40).
On the power tube board, check all the 22R resistors and all the diodes.
These are all parts that can fail with power tube problems and I believe you did replace a power tube.

R60(32 ohms)
R61(30 ohms)
R35-R40(10 ohms)
replaced D30, now D29,30,31,39,40 read(.47) diode test. Post power tube board readings shortly.

[ca7922303]

D30, not R30.
Also check all the 2W 10R resistors on the power amp board (R35 thru R40).
On the power tube board, check all the 22R resistors and all the diodes.
These are all parts that can fail with power tube problems and I believe you did replace a power tube.

Now no bias lights and no output, so I guess I'll put the .004 diode back in and see if I get lights and output?

[g1]

Now no bias lights and no output, so I guess I'll put the .004 diode back in and see if I get lights and output?

No, the diode itself could not do that. Make sure it was put in the right way and no solder bridges were introduced in replacement. Something related to the repair procedure caused your new problem, like a connector issue or broken wire or something.