Summit EQF-100 schematic?

[chops]

I know Summit are secretive about their schematics, but thought I'd see if anyone has one?
My EQF-100 is suddenly outputting 24VDC at the audio output! I'm guessing PSU recap is a place to start, but does anyone have any other ideas?

 

[pucho812]

Check with jmp in Orange County California

they own summit these days.

 

[radardoug]

I know Summit are secretive about their schematics, but thought I'd see if anyone has one?
My EQF-100 is suddenly outputting 24VDC at the audio output! I'm guessing PSU recap is a place to start, but does anyone have any other ideas?

Sounds more like an opamp has died, not uncommon on Summit stuff.

 

[chops]

Sounds more like an opamp has died, not uncommon on Summit stuff.

Thanks radardoug. Yeah, there are three 990's in here. I have a spare 990 but I'm a little afraid to start swapping them out...

 

[chops]

OK, so I probed around a bit. I'm measuring 3VDC at the audio input pin on two of the 990's. So, coupling caps?

 

[radardoug]

If the 990 is faulty, it may reflect dc back to the input. Better to put in a new one and see if it fixes the problem. Summit used very cheap and crappy 990s.

 

[chops]

If the 990 is faulty, it may reflect dc back to the input. Better to put in a new one and see if it fixes the problem. Summit used very cheap and crappy 990s.

ok thanks again. I guess if I pull one, I could check for DC at the input terminal on the PCB before installing the replacement It's weird that two of the three 990's are measuring 3VDC at the audio input. (All three 990's are showing correct power supply voltage on the V+ and V- pins...) Swap em both I guess?

 

[radardoug]

Are they both offset on the output? They used two to do a balanced output drive, so one may be upsetting the other. Pull them one at a time and measure.

 

[kags]

If the 990 is faulty, it may reflect dc back to the input. Better to put in a new one and see if it fixes the problem. Summit used very cheap and crappy 990s.

I agree that changing out the 990s is a good idea! Steve Firlotte replaced the 990s in my Summit DCL-200 with his Inward Connections VF-600 (I think) opamps about 10 years ago. Those gave the compressor a much wider sound field and a more open bottom end.

 

[chops]

OK. Getting weirder... I've removed all 3 990's and I'm still reading 2VDC at the audio INPUT to the unit...

 

[chops]

Update. F3 was open.. Replaced it and no more DC at the input. Reinstalling 990's now...

 

[chops]

Unbelievable. Working great again. After replacing fuse, I put the same three 990's back in. Sounds great. So how can a blown fuse put 24VDC on the output? (It blew up a channel on my A/D converters...) That can't be by design?

 

[radardoug]

Unbelievable. Working great again. After replacing fuse, I put the same three 990's back in. Sounds great. So how can a blown fuse put 24VDC on the output? (It blew up a channel on my A/D converters...) That can't be by design?

There is no protection in there to stop that happening. There are speaker protection boards on Ebay that you could use.

 

[chops]

Thanks Doug.