Hello Friends,
I've got an old Deton Max Power 1000 that has developed a curious 'death rattle': When turning power off, there is a sound like a relay is rattling for about 2 seconds. Another way to describe this would be a buzzing sound, but it is defintielty mechanical and it definitely comes from one of the blue output relays. I've not been able to determine which one though.
Another symptom is that when powering the amp on, channel A comes out of protect mode earlier than channel B. This sometimes happens fast enough that Channel A speakers get the switch-on-thump.
Pictures attached to this post, and a video here: Amplifier Death Rattle.... - YouTube
I've had the amp apart, replaced the filters, cleaned all the contacts, connectors and switches, and done a thorough visual inspection but couldn't find any obvious culprit. That said, after pulling apart and putting together, on initial couple turn-ons the issue didn't happen, but it soon reoccurred.
Apart from these two issues, the amp still works fine and sounds great. I'm just afraid that it will blow if this is not taken care of.
Hoping the knowledgebase of this wonderful forum can help!
Thanks!!!
I've got an old Deton Max Power 1000 that has developed a curious 'death rattle': When turning power off, there is a sound like a relay is rattling for about 2 seconds. Another way to describe this would be a buzzing sound, but it is defintielty mechanical and it definitely comes from one of the blue output relays. I've not been able to determine which one though.
Another symptom is that when powering the amp on, channel A comes out of protect mode earlier than channel B. This sometimes happens fast enough that Channel A speakers get the switch-on-thump.
Pictures attached to this post, and a video here: Amplifier Death Rattle.... - YouTube
I've had the amp apart, replaced the filters, cleaned all the contacts, connectors and switches, and done a thorough visual inspection but couldn't find any obvious culprit. That said, after pulling apart and putting together, on initial couple turn-ons the issue didn't happen, but it soon reoccurred.
Apart from these two issues, the amp still works fine and sounds great. I'm just afraid that it will blow if this is not taken care of.
Hoping the knowledgebase of this wonderful forum can help!
Thanks!!!
Attachments
If only one of the speaker relays chatters like that, the fault is likely isolated to its individual channel fault sense and relay drive circuits - possibly a local power supply capacitor issue. We need to know the design details of what you are looking at and how it works to offer assistance but this alleged US brand pro. amp doesn't seem to be widely known, though it may be similar to some SMRT branded pro. amps in Europe and possibly elsewhere. It seems the common factor is they were sold via Ebay and of course, no local service or technical support is available.
The supplier seems a bit dodgy and their website is identified as risky - perhaps no longer in business? Otherwise, the product looks to be in very good, clean condition so it can't have seen much use in pro. work. Do you have access to a schematic that shows us the circuit details?
The supplier seems a bit dodgy and their website is identified as risky - perhaps no longer in business? Otherwise, the product looks to be in very good, clean condition so it can't have seen much use in pro. work. Do you have access to a schematic that shows us the circuit details?
It sounds a bit like there is a protection circuit being triggered. I would put a voltmeter across the output before the protection relay and watch at power on and off.
Compare channels.
See if this enlightens you.
Compare channels.
See if this enlightens you.
Thanks for the replies!
Googlyone, how do you suggest I check the 'voltage before the protection circuit'?
Ian, I don't have schematics or any documentation whatsoever. I did contact Deton but haven't heard back. I also cleaned the amp before photos, it was truly filthy inside. 😱
I pulled out the board with the power caps on and cleaned that up good too. My gut feel is that there's something wrong here, because it seems the caps unload causing the relay to buzz. Is there an easy way to test this without unsoldering all the caps?
Googlyone, how do you suggest I check the 'voltage before the protection circuit'?
Ian, I don't have schematics or any documentation whatsoever. I did contact Deton but haven't heard back. I also cleaned the amp before photos, it was truly filthy inside. 😱
I pulled out the board with the power caps on and cleaned that up good too. My gut feel is that there's something wrong here, because it seems the caps unload causing the relay to buzz. Is there an easy way to test this without unsoldering all the caps?
Attachments
Ah pah - I give up! I've listed it on Ebay - anyone want to give it a shot repairing - pick up in Hawthorn East / Melbourne.
Just don't have the wherewithal to start messing with it right now.
Thanks anyway for the ideas!
Just don't have the wherewithal to start messing with it right now.
Thanks anyway for the ideas!
A reasonable start if you don't have schematics would be to replace all of the small-value electrolytics. I've seen this sort of thing happen before. Either they short, the ESR goes through the roof or they stop being a capacitor. More often than not it seems to be open or high ESR with the little ones. Sometimes it leads to instability (bypass caps), low output (coupling caps) or bizarre issues like what you're describing if it's in the protection circuit.
You can try to troubleshoot it one-by-one, but you're in the dark without a schematic and the cost of caps has gotten to the point where it isn't a huge deal.
You can try to troubleshoot it one-by-one, but you're in the dark without a schematic and the cost of caps has gotten to the point where it isn't a huge deal.
I’ve not got the time now to start long troubleshooting process, was hoping it was something obvious 😉 I’ve put it up for sale if anyone else feels confident in fixing it. On the other hand since the issue only appears at shutdown and it works perfectly in all other respects I’ve put it back into the stereo setup as sub amp.