Marantz 2230 problem

vrobec

Active Member
Greetings!

Noticed a strange thing. Sometimes. randomly the 2230 is sounding saturated, then randomly weak, and after a few seconds it came back to normal. I can describe this like switching the loudness button on and off. What this could be, and what causing it?

The potmeters, switches were deoxited yesterday.
 
Could be tired coupling cap or even a bad solder connection. More info required.
- does it occur on both channels (suggest power supply issue)
- does it occur on all inputs, AUX, Tuner,,,. Best to try AUX to eliminate tuner and phono stages
- would be nice to localise to pre/power amp but didn't see any jumpers
 
- would be nice to localise to pre/power amp but didn't see any jumpers
Amp does have pre out/main in, suggest try connecting a different pre (ipod/iphone or whatever) to determine
if pre or power problem.
 
Could be tired coupling cap or even a bad solder connection. More info required.
- does it occur on both channels (suggest power supply issue)
- does it occur on all inputs, AUX, Tuner,,,. Best to try AUX to eliminate tuner and phono stages
- would be nice to localise to pre/power amp but didn't see any jumpers

It occurs on AUX, as I heard it's on both channels.

Amp does have pre out/main in, suggest try connecting a different pre (ipod/iphone or whatever) to determine if pre or power problem.

I have two 2230's, so I will use one of them as preamp, but what do you suggest which one?
 
I have two 2230's, so I will use one of them as preamp, but what do you suggest which one?
Point to the test is to localize the problem a bit as either a pre or power issue, Test can be done as follows.
Using "faulty" unit, connect source to AUX. Connect RCA cables from pre out faulty unit to main in, "working" unit. Connect speakers to working unit.
Test using tone/volume controls on the faulty unit. Is fault still present?

Regardless if fault present, perform the opposite test, ie, Source connected to AUX of working unit, connect RCA cables from pre-out working unit
to main-in faulty unit, speakers also connected to faulty unit. Fault still present.

Hopefully the fault will only be present for one configuration but...
 
Point to the test is to localize the problem a bit as either a pre or power issue, Test can be done as follows.
Using "faulty" unit, connect source to AUX. Connect RCA cables from pre out faulty unit to main in, "working" unit. Connect speakers to working unit.
Test using tone/volume controls on the faulty unit. Is fault still present?

Regardless if fault present, perform the opposite test, ie, Source connected to AUX of working unit, connect RCA cables from pre-out working unit
to main-in faulty unit, speakers also connected to faulty unit. Fault still present.

Hopefully the fault will only be present for one configuration but...

I found out the preamp is causing it. The poweramp section is working ok with my another Marantz configured as preamp.
Please let me know where to start with component replacement? Capacitors or something else?
 
Will take a look at the service manual, as a guess I'd lean towards power supply to the preamp since both channels affected.
Will try and come up with a list of candidates.
 
I think this is a long shot but since both pre channels affected
you should check out the pre power supply. Monitor the supply voltage at
pin J808 (nominally +35.6Vdc). Certainly play music and listen for
the disturbance and note any change in the voltage. There should be slight
changes due to mains drift etc. I would certainly clean all controls especially
volume pot.

Is the problem also noticeable through headphones?

The sm has preamp transistors H401,2,5,6 as 2SC1000. These have some
history of going noisy, replace with KSC1815 however they are unlikely
to cause this problem. Same applies to caps C403,404,407,408,410,411,414,
415. Would need 2 faulty parts since both channels affected.

upload_2018-9-17_6-49-37.png
 
I think this is a long shot but since both pre channels affected
you should check out the pre power supply. Monitor the supply voltage at
pin J808 (nominally +35.6Vdc). Certainly play music and listen for
the disturbance and note any change in the voltage. There should be slight
changes due to mains drift etc. I would certainly clean all controls especially
volume pot.

Is the problem also noticeable through headphones?

The sm has preamp transistors H401,2,5,6 as 2SC1000. These have some
history of going noisy, replace with KSC1815 however they are unlikely
to cause this problem. Same applies to caps C403,404,407,408,410,411,414,
415. Would need 2 faulty parts since both channels affected.

View attachment 1283224

Thank you very much!
 
An additional problem. The receiver's left and right channel doesn't sound equally. Switched to mono for accurate results. The left channel is louder. Strange, this problem is present on both 2230. :( They have the same issue (louder left and weaker right channel).
Tried them with my neighbour's loudspeakers too. No changes.
 
Is your balance knob aligned correctly (the actual knob not the pot)? Not hard to put the knobs back on wrong. Can turn all the way right or left and see where it lines up...
 
Is your balance knob aligned correctly (the actual knob not the pot)? Not hard to put the knobs back on wrong. Can turn all the way right or left and see where it lines up...

The balance knob is aligned correctly. Strange that some CD's sounding balanced, some having louder left channel. I'm confused. :(
 
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