Maranz ein kanal defekt

Hi,

In one channel the output-transistors are most likely shorted. Don't turn-on the amplifier until it is repaired; you may do more damage to your amplifier and your speakers.
The cause of this problem can be many. Here are a few:

1)
In old amplifiers are old electrolytic capacitors. They dry out and loose their capacity making the amplifier-circuit un-stable. Self-oscillation may occur and the output-transistors are damaged.

2)
There is a BIAS-circuit in most amplifiers. Bias is adjusted to a value that will make the amplifier run safely and produce the least distortion. Unfortunately in this amplifier, this circuit is constructed in a bad way. When the potentiometer, used for adjusting the Bias, becomes corroded/dirty and looses contact, the Bias is increases beyond this safety-setting and the amplifier runs hot and may easily be destroyed.

3)
You have a defective speaker. A shorted/burned tweeter-unit may be seen from the amplifier as a short when you turn-up the volume. The current in the output-transistors may exceed the safety-value and they are destroyed. Of course it doesn't have to be inside the speaker you may have a short. The speaker-cable may also be shorted in either end.

These are the 3 most common causes of defective amplifiers in my opinion. Not that it will make your amplifier run again, but it may explain what went wrong. A repair is for the professionel and what he will charge you is upon him and what is really defective inside your amplifier. After all you can't call the garage and expect the mechanic to say what a repairs will cost when you only tell him the car wont start

mfg,

/tri-comp

PS, when you find the pro that will repair your amp., I may be able to help with schematics/manuals.

Ruf' mal bei Forumsmitglied 'ruesselschorf' (Helmut Thomas)an - der repariert/überholt solche Klassiker - gerade alte Marantz. Tel.: 09776/7632

BG
Bernhard