Hello... I bought an amp from the flea bay advertised as "goes into protect mode when powered up" I bought it dirt cheap and thought a lil fix "might"sort it out... Did a bit of testing, transistors seem to be "ok" and so does the thermostat... However, when I disconnected the left and right speaker terminals that lead from the amp board to the power board (where the connectors are based for the rear speaker terminals, it no longer goes into protect mode (it does for 1 second) on power up, but so I read online most "standard power amps" do this. Also it powers up ok, the fan switches on, only once on switching it on it actually switched on and I could hear the speaker relay switch click, then a minute later back to protect mode 🙁
So, what could be the issue? I thought about a DC drop off? But again, no clue what to look for 🙁
I also checked caps and resistors, all seem good except a few with odd readings, with a capacitor multimeter they seemed to go over the values stated on them.
So, what could be the issue? I thought about a DC drop off? But again, no clue what to look for 🙁
I also checked caps and resistors, all seem good except a few with odd readings, with a capacitor multimeter they seemed to go over the values stated on them.
Attachments
Can you put a multimeter on the speaker outputs directly on the amp board (i.e. before the relays). Do you measure any DC voltage?
Do I understand? The amp powers up and leaves protect mode IF you disconnect the line from the amp circuit to the rear panel?
Can this be narrowed down to just one of the channels?
Perhaps the speaker relay has contacts welded shut, or if there is a crowbar circuit on the output that might be shorted. Either way, from the speaker jack side, like from outside the amp, measure resistance across the output of each channel. Is there a dead short across either channel?
And what atom94 said, look for unwanted DC voltage on the amp output.
Can this be narrowed down to just one of the channels?
Perhaps the speaker relay has contacts welded shut, or if there is a crowbar circuit on the output that might be shorted. Either way, from the speaker jack side, like from outside the amp, measure resistance across the output of each channel. Is there a dead short across either channel?
And what atom94 said, look for unwanted DC voltage on the amp output.
Yes Enzo, very odd, all the caps and resistors seem all ok...
When powered up with internal speaker leads disconnected you can hear the second click of the relay, but with them leads connected there is no second relay click...
I'll report back, but, me being a bit dumb, do I just attach both red and black leads to the internal amps leads? As there is only one lead, 1 connecter for each channel...
When powered up with internal speaker leads disconnected you can hear the second click of the relay, but with them leads connected there is no second relay click...
I'll report back, but, me being a bit dumb, do I just attach both red and black leads to the internal amps leads? As there is only one lead, 1 connecter for each channel...
Right, with NO internal speaker connections connected, there is no DC voltage at either channels (connected via outside terminals) no DC voltage either when the internal leads are connected back to the power board, absolute NO resistance readings also, but the weird thing was, when I was checking for the resistance on both the rear terminals, it made the protective circuit come back on without either of the internal leads connected...
- Status
- Not open for further replies.