Hello all...
I need some advices
I picked up this rare and early Marantz 30, but this amp. has a small default
when I switch on the tone command, the relay switch off and come back on and I loose one channel, when the tone is off the amp. works well...I have no schematics I think the problem in on the pré board what do you think about that...
If someone has the marantz 30 service manual it will be great... Thanks for your help!
Dominic
I need some advices
I picked up this rare and early Marantz 30, but this amp. has a small default
when I switch on the tone command, the relay switch off and come back on and I loose one channel, when the tone is off the amp. works well...I have no schematics I think the problem in on the pré board what do you think about that...
If someone has the marantz 30 service manual it will be great... Thanks for your help!
Dominic
Attachments
All of those blue axial electrolytics need to be replaced for a start. Many 70s amplifiers used those caps and trust me they need to go. May or may not be causing this particular problem. I recently repaired an old Acoustic guitar amplifier, replaced close to fifty of those caps and it worked fine after that.
Craig
Craig
Is the tone control "defeat" (think that's what you mean) done via switches or does it use a relay for signal switching ?
Relays can go faulty... dirty contacts.
Which relay do you mean clicks off ?
Do you mean the protection relay and the speakers are being disconnected ?
Need a bit more info
Relays can go faulty... dirty contacts.
Which relay do you mean clicks off ?
Do you mean the protection relay and the speakers are being disconnected ?
Need a bit more info
Hi,
I would check first the selector switch itself. Are you sure it's making a good contact when you switch it to tone control, and that it is disconnecting properly from the "direct" position? ... That's easy to check first.
In my opinion you may have an open when you turn the switch to tone control. May be this switch is in the feedback path of some IC ot transistor (I'm not familiar with this amp) and this creates a DC voltage at the output, which turns on the protection....
If the switch is fine, then you should find the tone control circuit and check the components. You might have a faulty transistor/IC, shorted diode or capacitor, causing bias problems ... It could be practically anything, causing a short DC discharge, enough to activate the protection for awhile.
I would check first the selector switch itself. Are you sure it's making a good contact when you switch it to tone control, and that it is disconnecting properly from the "direct" position? ... That's easy to check first.
In my opinion you may have an open when you turn the switch to tone control. May be this switch is in the feedback path of some IC ot transistor (I'm not familiar with this amp) and this creates a DC voltage at the output, which turns on the protection....
If the switch is fine, then you should find the tone control circuit and check the components. You might have a faulty transistor/IC, shorted diode or capacitor, causing bias problems ... It could be practically anything, causing a short DC discharge, enough to activate the protection for awhile.
most of these axial electrolytic caps are history .... they were rubish on the first place any way ....
you might think of a complete recaping of your amplifier combine this with a good cleaning may be a relay change and a few other things and then you are really going to have a very nice amp
here is some extra help http://www.diyaudio.com/forums/solid-state/136261-vintage-amplifier-repair-upgrade-manual.html
you might think of a complete recaping of your amplifier combine this with a good cleaning may be a relay change and a few other things and then you are really going to have a very nice amp
here is some extra help http://www.diyaudio.com/forums/solid-state/136261-vintage-amplifier-repair-upgrade-manual.html
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