As far as obvious things to check that is, i'll trace signal from the front end's when i dive back in.
intermittent switches or pots, maybe an intermittent connection between the main and preamp board. Lift and re-seat the preamp board.
Lol yup.. spent way too much time on that one. Intermittent switches it was.
Labeled COMAX.
Any ideas? May replace the pots while I'm at it, bourns?
Ty sir
Labeled COMAX.
Any ideas? May replace the pots while I'm at it, bourns?
Ty sir
Search the forum for comax. I think another forum member found suitable replacements.
It's very rare that you cannot clean the pots or switches.
It's very rare that you cannot clean the pots or switches.
True enough, I have some contact renew and lube.. But i'd rather replace, gives me an excuse to get the 2907A's too since shipping was the only reason I didn't pick them up already.
Found some:
Electronic Components and Parts Search | DigiKey Electronics
and
Electronic Components and Parts Search | DigiKey Electronics
Hoping they aren't crap..
Found some:
Electronic Components and Parts Search | DigiKey Electronics
and
Electronic Components and Parts Search | DigiKey Electronics
Hoping they aren't crap..
I did, but didn't find the correct switch.
Found Eg2319 and Eg2319 on digikey. They are made by E-switch. Dimensions are the same.
I assume they'll work.
Found Eg2319 and Eg2319 on digikey. They are made by E-switch. Dimensions are the same.
I assume they'll work.
Yeah, they are. Hopefully a decent enough brand. Not going to bother with the pots.. seems like more trouble than it would be worth. They work, and once set that's it anyway..
One more time out of the chassis, then I'll have a solid back-up 6 channel. 🙂
One more time out of the chassis, then I'll have a solid back-up 6 channel. 🙂
I had prism sound dscope home from work for a night the other week. Had to take it to the other office. God, what I'd do to have one... Anyway.
Hooked up all my amps and found this guy still isn't right. Ch1-3 perform well, mid gain 2dbu in 7out wirh comparable thd. Ch 4 is at 15v, ch5 at 10v and ch6 at 14v.
Gain min and 8dbu in, ch1-3 are 8dbu out. 4 is at 21 ch5 is at 18 and 6 is at 21.
Don't really recal fft differences, but kinda moot atm since gain is screwy.
Pots? Bias v?
I set them all by hand again after fixing it to a similar level, thought it was 6 or 7 mv. That said, I don't have a real understanding of what that affects at this point..
Thx
Hooked up all my amps and found this guy still isn't right. Ch1-3 perform well, mid gain 2dbu in 7out wirh comparable thd. Ch 4 is at 15v, ch5 at 10v and ch6 at 14v.
Gain min and 8dbu in, ch1-3 are 8dbu out. 4 is at 21 ch5 is at 18 and 6 is at 21.
Don't really recal fft differences, but kinda moot atm since gain is screwy.
Pots? Bias v?
I set them all by hand again after fixing it to a similar level, thought it was 6 or 7 mv. That said, I don't have a real understanding of what that affects at this point..
Thx
I can scope it and figure out if it's the pots obviously.. 😀 more interested in whether bias could affect this?
Got my hands full with more interesting broken stuff atm, but wanted to get a bead on this guy.
Got my hands full with more interesting broken stuff atm, but wanted to get a bead on this guy.
10-4 thx, I'll come back to it another day. Probably the pots.. should have changed them with the switches.
Yeah, the ch5-6 pcb gain pot measured 100k across one of the gangs instead of 5k.
Bummer is I dont see anywhere that has a pot like this. Stubby A5k and b50k pots with 4 gangs on each.
Bummer is I dont see anywhere that has a pot like this. Stubby A5k and b50k pots with 4 gangs on each.
Gonna buy a handful of these then drill the chassis pin ends out and hope i can couple them together without anything else.. After taking apart the pot from the pcb I'm pretty optimistic.. pots we use at work are center pin driven on dual ganged pots, these are coupled with plastic on the wiper assemblies.
Spacing etc is correct..
http://www.mouser.com/ProductDetail...=sGAEpiMZZMtC25l1F4XBU1xwXnrUt/uol5Bg6gBTgqM=
Spacing etc is correct..
http://www.mouser.com/ProductDetail...=sGAEpiMZZMtC25l1F4XBU1xwXnrUt/uol5Bg6gBTgqM=
Okie dokie.. got that fixed.
In the process of getting a better test bench setup... Got a linear 30v 5a supply and plan to diy a server psu to give me 12v @ high current shortly to test amps under load (using arrays of large resistors).
Anyway... hooked this guy up to test and the pots have my levels spot on; but i noticed current climbs on the amp. Starts around 2A and slowly climbs to over 3A at 14v. Didn't let it sit more than 20min but assuming it would have kept going. Audio seems fine, but in no rush to hammer on it yet...
Thoughts?
thx
In the process of getting a better test bench setup... Got a linear 30v 5a supply and plan to diy a server psu to give me 12v @ high current shortly to test amps under load (using arrays of large resistors).
Anyway... hooked this guy up to test and the pots have my levels spot on; but i noticed current climbs on the amp. Starts around 2A and slowly climbs to over 3A at 14v. Didn't let it sit more than 20min but assuming it would have kept going. Audio seems fine, but in no rush to hammer on it yet...
Thoughts?
thx