hey everyone im new here and have a question for anyone in the know I have an old ev 7300 amp its in a rack with 3 bgw amps and I have not used it for about 7 years the bgws work fine but I have not had a need for the ev well I hooked it up the other day and it powers up but nothing is coming out with the power all the way up I hear a low sound but that's it any ideas whats wrong I moved all the cables to one of my bgws and the sound is fine what could have happened to this amp from not being used thanks for any help
It might just be bad contacts in the input jacks. I had one channel of an AB amp that didn't work because the Normally Closed contacts in a 1/4" jack were oxidized. The speaker protection relay is another possibility, though if those contacts are bad you shouldn't hear anything from the speakers (no hiss, no hum).
Filter caps in my experience only go bad if they're run at painfully high temperatures for extended periods. I'm using a power amp that has 30 year old filter caps and works fine.
Filter caps in my experience only go bad if they're run at painfully high temperatures for extended periods. I'm using a power amp that has 30 year old filter caps and works fine.
The filter caps are probably not the problem as they are fairly reliable. Small value coupling capacitors go leaky and the line in/out sockets have issues.
I had a client with a Crown VZ5000 with a dead channel, (protection was activated). He took it away with out a repair, powered it up with no speakers for a few hours and the capacitors reformed. Lucky or what!
I had a client with a Crown VZ5000 with a dead channel, (protection was activated). He took it away with out a repair, powered it up with no speakers for a few hours and the capacitors reformed. Lucky or what!
I have a bunch of those old 7300's.
They all have an intermittant somewhere on the circuit board.
If I bang on the amp the sound comes back proper but then eventually fade-crackles back to the lower level.
Try banging on the amp while it's running -and by banging I don't mean to beat the **** out of it, but gentle taps by a rubber mallet on the front panel while in a rack.
I've since narrowed them all down to one spot on the Ch2 circuit board -and since they are near sequential in serial number, it might have been just a glitch in soldering the day they were made.
(It's not like they've run flawless for 20 years before developing the problem -I "rescued" them at the point where the fans had stalled due to excessive dust pile-up so they were definitely heat-stressed for the last few years of their duty!
Hi Tamaman,
That Ev amp is identical to an Altec 9444B and a QSC1400 (QSC made both amps for Altec and EV). The problem areas in those amps were always bad (cold, or cracked solder joints). De-case the amp, flip the board over and look at the solder mask under a magnifier, You should easily be able to see which joints are bad (especially around the driver and output transistors, emitter resistors, and the main electrolytics). Also, clean and burnish the contacts on the protection relay (another weak spot on these amps). Otherwise these are great-sounding old workhorses!
That Ev amp is identical to an Altec 9444B and a QSC1400 (QSC made both amps for Altec and EV). The problem areas in those amps were always bad (cold, or cracked solder joints). De-case the amp, flip the board over and look at the solder mask under a magnifier, You should easily be able to see which joints are bad (especially around the driver and output transistors, emitter resistors, and the main electrolytics). Also, clean and burnish the contacts on the protection relay (another weak spot on these amps). Otherwise these are great-sounding old workhorses!
tamaman,
I'm thinking the speaker relay contacts have gone bad. If you're lucky they're in sockets and you could try pulling them out, removing the cover and clean the contacts with a burnishing tool. If that fixes the problem, I recommend replacing the relays if reliability is important.
Mike
I'm thinking the speaker relay contacts have gone bad. If you're lucky they're in sockets and you could try pulling them out, removing the cover and clean the contacts with a burnishing tool. If that fixes the problem, I recommend replacing the relays if reliability is important.
Mike
Totally different amps, I think you're confusing the QSC model number.
EV 7300 looks just like this except level controls on front:
An externally hosted image should be here but it was not working when we last tested it.
QSC 1400 looks just like this:
An externally hosted image should be here but it was not working when we last tested it.
thanks for the imput guys ill check it out and ndcraig my 7300 looks different than the one you pictured mine has two big blue capactiors inside and the imput jacks connect to a circuit board it looks like new inside as it has never been out of the rack since the day it was brand new I did notice when I checked the xlr in jacks that all three pins have continuity between them I don't think they should im thinking the input board may be the problem I will try and post some pictures soon
thanks for all the help I found the problem the xlr inputs are shorted to ground I was using the amp mono 1/4 in then jumping xlr channel 1 to 1/4 channel 2 then both channels out if I use both 1/4 in and leave the xlrs out of the mix the amp works fine I don't know what happened as I used it xlr to 1/4 for years with no problem all I can think is the board shorted any way thanks guys this is a great forum
It looks like mine is actually a 7300"A" - a later model, and last version of the amp. It seems to have the same specs for output, so don't know what the differences are.
I have had both versions and never really noticed any differences in the performance.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.