Marantz 2220B needs attention...

[sbparks]

Hello Marantz Fans,

I am currently working on a 2220B receiver. Mostly in nice shape. I wish the previous owner wouldn't have allowed the chassis to become cruddy with corrosion, but the exterior is nice and *most* everything is working well.

A couple of questions... I need the procedure for adjusting the Bias and the Offset. The amplifier board has several adjustable pots that I'd like to make sure are set correctly.

Can anyone share the Service Manual or just the pages of the SM that deal with this adjustment?

One specific issue that I'll ask about here and now is that the amplifier puts out a 'hum' (both channels) that is clearly audible when no source (music) is being put through the speakers. The hum intensifies as the volume is turned up. The hum is loudest when I switch the source to 'Phono' (no input attached to the phono inputs). The hum is present with each source that is selected.

Are there any other adjustments that should be made / looked at?

Thanks for your input!

[Oerets]

Could be a cap in the power supply , or a bad ground . Have you ever done a re-cap on a power supply ?
I don't have any manuals for you model so can't help with any specifics on what parts to check .



Barney

[catrafter]

Scotto,
I would look at the P800 board capacitors first.

PM sent.

Tom

[sbparks]

I am now in the posession of a Service Manual for this receiver - Thank you very much!

I wasn't able to spend too much time last night, but I did give the manual a look through. On page 4 of the service manual (pg 6 of the PDF), there is a trouble shooting guide. Number 6, "Audio Trouble Analysis", problem number 3, "High hum and noise level". The manual states to "Check filter capacitors C002 and C004".

I could be wrong, but aren't they referring to the two large main capacitors? I think that should be C003 and C004. Not C002. Might just be a typo. Are these candidates for replacement?

Oerets and Catrafter are suggesting to look at each capacitor on the Power Supply Board (P800). I could replace all of the caps on P800, that shouldn't be too bad as there might be 6 to 8 of them. I did notice that most all of the caps are glued to the PCB. How would I release the glue?

Thanks for any ideas.

[catrafter]

Since you said the hum increases with the volume control, that should mean that the big caps are OK. The glue holding the caps on the power supply board has likely lost most of it's strength after 30 years or so. A little judicious wiggling and/or prying after removing the solder should pop them loose. I always carefully scrape all the glue away. Sometimes it becomes corrosive or conductive or both, get rid of it.

While you are in there, make sure that the screws securing the boards to the chassis are snug.

Tom

[sbparks]

Tom,

OK Thanks.

Then if the largest capacitors are OK, I'll focus on the Power Supply board caps first.