Ampeg SVT-6 Pro No Output

[nevetslab]

I understand....nice to have work with overtime these days! We're all here as needed. I haven't gotten back to my Servicing Ampeg SVTx-Pro amps and Servicing Ampeg SVT-CL/AV/VR Amps project. I have hundreds of pages from all of my posted threads as well as all my maintenance at CenterStaging on the Ampeg amps since March 2009, so that project is behind schedule. There is a wealth of knowledge in the MEF archives under any of those models....though not much on SVT8-Pro nor SVT7-Pro...both different animals.

[ca7922303]

I understand....nice to have work with overtime these days! We're all here as needed. I haven't gotten back to my Servicing Ampeg SVTx-Pro amps and Servicing Ampeg SVT-CL/AV/VR Amps project. I have hundreds of pages from all of my posted threads as well as all my maintenance at CenterStaging on the Ampeg amps since March 2009, so that project is behind schedule. There is a wealth of knowledge in the MEF archives under any of those models....though not much on SVT8-Pro nor SVT7-Pro...both different animals.

Do you think it's possible that R147 and C50 could be only issue causing no output?

[nevetslab]

In a word....NO

[ca7922303]

In a word....NO

Im finally back on this one, trying to get it set up to test. Wondering how to get all the wires connected back to the board. Several don't reach. Photos attached

[Enzo]

OMG, no drawing of wires before disassembly? And I see a ton of little metal flat washers for jack snouts. Please don't forget them.

[ca7922303]

OMG, no drawing of wires before disassembly? And I see a ton of little metal flat washers for jack snouts. Please don't forget them.

Took photos before disconnecting. Question is how did nevetslab make connections that don't reach or which ones was he able to leave disconnected and still able to test.

[nevetslab]

I'm not sure if you have the service manual doc's, so I'm posting them here:

Final Assembly Drawings and Parts List Bass Amplifier (00-541-XX_5).pdf
Parts List Bass Amplifier (00-541-PL_5).pdf
Parts List Bass Head (699PL_D).pdf
Parts List Bass Preamp (793PL_0).pdf
Parts List Preamp (115PL_A).pdf
Power Amp PCB Schematics (699SCH_A).pdf
Power Amplifier Pictorial and Parts List (699PWA_B).pdf
Preamp PCB Schematics (115SCH_A).pdf
Preamp PCB Schematics (793SCH_0).pdf
PWA 1000 Watt Bass Amplifier PCB Layout (699PWA_B).pdf
PWA Bass Preamp PCB Layout (115PWA_A).pdf
PWA Bass Preamp PCB Layout (793PWA_0).pdf
SVT-6PRO Owner's Manual.pdf
SVT-6PROa Parts List.pdf
SVT-6PROb Parts List.pdf

The Power Amp PCB Schematic shows both the two output stage amplifier assemblies, as well as the AC Mains connection to the main power amp PCB assy, with wire colors and designation numbers. When I disassemble these and any like it, where there are quick disconnects and PCB designation numbers, I write those onto the connectors with a Sharpie so I don't loose track of where stuff goes. I see you did take photos, which is always wise! I looked at the photos I posted of both the SVT5-Pro and SVT6-Pro thread I had posted previously, and while I didn't see using any extender wires, I made myself a collection of male-female insulated 1/4" quick disconnects for when I need to remove, say, an SVT4-Pro from the chassis, where there, the power xfmr and mains wiring is NOT long enough to reach in my setup, I gain the distance using those. I'd have to go back to my service notes from when I took those photos to get further details. As I recall, the problem was associated with the power amp section, so I didn't need the preamp, apart from it needing to be powered. I inserted signal thru the Power Amp Input jack, which is on the rear panel, joined with the Preamp Output jack, and that gets disconnected when you patch into the power amp input jack.

[Tom Phillips]

I'm not sure if you have the service manual doc's, so I'm posting them here:...

Thanks for posting such a complete set of service info. I hope I never need to use it.

[g1]

Thanks for posting such a complete set of service info. I hope I never need to use it.

A guy from Poland with ten feet comes to mind.

[ca7922303]

I'm not sure if you have the service manual doc's, so I'm posting them here:

[ATTACH]n947590[/ATTACH]
[ATTACH]n947591[/ATTACH]
[ATTACH]n947592[/ATTACH]
[ATTACH]n947593[/ATTACH]
[ATTACH]n947594[/ATTACH]
[ATTACH]n947595[/ATTACH]
[ATTACH]n947596[/ATTACH]
[ATTACH]n947597[/ATTACH]
[ATTACH]n947598[/ATTACH]
[ATTACH]n947599[/ATTACH]
[ATTACH]n947600[/ATTACH]
[ATTACH]n947601[/ATTACH]
[ATTACH]n947602[/ATTACH]
[ATTACH]n947603[/ATTACH]
[ATTACH]n947604[/ATTACH]

The Power Amp PCB Schematic shows both the two output stage amplifier assemblies, as well as the AC Mains connection to the main power amp PCB assy, with wire colors and designation numbers. When I disassemble these and any like it, where there are quick disconnects and PCB designation numbers, I write those onto the connectors with a Sharpie so I don't loose track of where stuff goes. I see you did take photos, which is always wise! I looked at the photos I posted of both the SVT5-Pro and SVT6-Pro thread I had posted previously, and while I didn't see using any extender wires, I made myself a collection of male-female insulated 1/4" quick disconnects for when I need to remove, say, an SVT4-Pro from the chassis, where there, the power xfmr and mains wiring is NOT long enough to reach in my setup, I gain the distance using those. I'd have to go back to my service notes from when I took those photos to get further details. As I recall, the problem was associated with the power amp section, so I didn't need the preamp, apart from it needing to be powered. I inserted signal thru the Power Amp Input jack, which is on the rear panel, joined with the Preamp Output jack, and that gets disconnected when you patch into the power amp input jack.

Thanks for all the info and I apologize for not getting back on this. Trying to get some other things out of the way before I take on this one. Back on it shortly.

[ca7922303]

Need some help locating the following components that were listed previously to test. Are any of these on a different board than the main power board? I see a D6, D7 on the preamp board and Q3,D4 on control board(installed board). Can't find5,33,34,38,41, Q4,23,24. Thanks

[ca7922303]

Need some help locating the following components that were listed previously to test. Are any of these on a different board than the main power board? I see a D6, D7 on the preamp board and Q3,D4 on control board(installed board). Can't find5,33,34,38,41, Q4,23,24. Thanks

Found some, here's some readings:. Q3(0.6)(0.9)(0.6)(OL)
Q4 (0.6)(0.9)(0.6)(OL)
Q18(0.6)(0.9)(0.6)(0.8)
Q19(0.6)(0.9)(0.5)(0.98)
Q5(0.8)(0.8)(OL)(OL)
Q6(0.6)(0.8)(0.6)(0.8)
Q15(0.6)(0.5)(0.6)(OL)
Q17(0.6)(0.5)(0.6)(OL)

Q5 has a leg broken loose so I know it needs replaced.

[ca7922303]

Found some, here's some readings:. Q3(0.6)(0.9)(0.6)(OL)
Q4 (0.6)(0.9)(0.6)(OL)
Q18(0.6)(0.9)(0.6)(0.8)
Q19(0.6)(0.9)(0.5)(0.98)
Q5(0.8)(0.8)(OL)(OL)
Q6(0.6)(0.8)(0.6)(0.8)
Q15(0.6)(0.5)(0.6)(OL)
Q17(0.6)(0.5)(0.6)(OL)

Q5 has a leg broken loose so I know it needs replaced.

Can't find D5,33,34,38,41.

[ca7922303]

I'm not sure if you have the service manual doc's, so I'm posting them here:

[ATTACH]n947590[/ATTACH]
[ATTACH]n947591[/ATTACH]
[ATTACH]n947592[/ATTACH]
[ATTACH]n947593[/ATTACH]
[ATTACH]n947594[/ATTACH]
[ATTACH]n947595[/ATTACH]
[ATTACH]n947596[/ATTACH]
[ATTACH]n947597[/ATTACH]
[ATTACH]n947598[/ATTACH]
[ATTACH]n947599[/ATTACH]
[ATTACH]n947600[/ATTACH]
[ATTACH]n947601[/ATTACH]
[ATTACH]n947602[/ATTACH]
[ATTACH]n947603[/ATTACH]
[ATTACH]n947604[/ATTACH]

The Power Amp PCB Schematic shows both the two output stage amplifier assemblies, as well as the AC Mains connection to the main power amp PCB assy, with wire colors and designation numbers. When I disassemble these and any like it, where there are quick disconnects and PCB designation numbers, I write those onto the connectors with a Sharpie so I don't loose track of where stuff goes. I see you did take photos, which is always wise! I looked at the photos I posted of both the SVT5-Pro and SVT6-Pro thread I had posted previously, and while I didn't see using any extender wires, I made myself a collection of male-female insulated 1/4" quick disconnects for when I need to remove, say, an SVT4-Pro from the chassis, where there, the power xfmr and mains wiring is NOT long enough to reach in my setup, I gain the distance using those. I'd have to go back to my service notes from when I took those photos to get further details. As I recall, the problem was associated with the power amp section, so I didn't need the preamp, apart from it needing to be powered. I inserted signal thru the Power Amp Input jack, which is on the rear panel, joined with the Preamp Output jack, and that gets disconnected when you patch into the power amp input jack.

D6(0.5m/6m ohms), (0.5v/OL diode test)
D7(0.5m/16m ohms), (0.5v/OL diode test)
D28(170k/OL ohms), (0.5v/OL diode test)

[ca7922303]

D6(0.5m/6m ohms), (0.5v/OL diode test)
D7(0.5m/16m ohms), (0.5v/OL diode test)
D28(170k/OL ohms), (0.5v/OL diode test)

D6, D7 are on preamp board.