2270 no power

[Dearslayer]

Hi .... Been away for a bit working on another unit but I picked up a 2270 in Wooden case today. Seller told me it wouldn't power up and blew the fuse when plugged in and power button on. He said he had it stored away for some time and it worked before storing. This thing was so dusty inside. Must have been in a warehouse. Cosmetics are really nice overall and I had no choice but to meet the guy in the city at a gas station near his work. Like I said he already told me up front over the phone that it wasn't working and I was buying it " As Is ". Got it home and put a new fuse in the rear and put it on the DBT. Fail. Bulb glows bright, constant, so I powered it down. Dead short somewhere! So I guess I need hand holding ,and guidance on where I should start! Need help cause I'm lost as to what I should do first.

Regards.
GT.

 

[petehall347]

first suspects are output devices and rectifiers .. might even be main filter capacitors if it was really working before storage ,,

 

[Dearslayer]

I'm only taking his word about it working before storage. He also told me he knew the original owner who he got it from and said he bought it from him that way so who really knows. So is there something I can do to determine the possibilities?

 

[petehall347]

i cant remember now if the output transistors plug in or are soldered in on this one ..if plug in they should be removed and tested first ..

 

[Richs_Trains]

Dearslayer, Don't know if this will help, but I had a 4230 that was shorted also and I was able to remove the AC feed to the filter caps and the DC feeds to the power amps, I then powered it on the DBT and it passed and had dial lights. I the reconnected the filter cap feed and got a short again. I replaced the filter cap and it passed the DBT. I connected one power amp and it passed DBT, connected the second power amp and it failed. Doing this I was able to determine that the filter cap and one power amp were bad. Removing the power from the bad power amp again, I was able to power up with the 'good' channel and new filter cap and got audio. Since I am not very good at troubleshooting at the circuit level, I purchased a used power amp and now the unit is 100%. Hope this helps. Good luck Rich

 

[Dearslayer]

I'll take another look but I believe they are soldered on this unit. Hahaha was hoping to not have to take it apart right away to find the problem.

 

[Dearslayer]

Dearslayer, Don't know if this will help, but I had a 4230 that was shorted also and I was able to remove the AC feed to the filter caps and the DC feeds to the power amps, I then powered it on the DBT and it passed and had dial lights. I the reconnected the filter cap feed and got a short again. I replaced the filter cap and it passed the DBT. I connected one power amp and it passed DBT, connected the second power amp and it failed. Doing this I was able to determine that the filter cap and one power amp were bad. Removing the power from the bad power amp again, I was able to power up with the 'good' channel and new filter cap and got audio. Since I am not very good at troubleshooting at the circuit level, I purchased a used power amp and now the unit is 100%. Hope this helps. Good luck Rich[/QU


Hey Rich. Sorry to sound like a complete noob but I will have to print the SM and have a look to see of I can figure out about the AC feed and DC feeds. Remember I'm kind of a rookie. So do you mean unsolder the main wires at the filter caps at positive and negative?

 

[wlhd1610]

2270 outputs plug in.
All Marantz receivers 22xx (from 2220 up) and 23xx have plug in output transistors.
The mighty 2500/2600 are soldered.

Bob

 

[Richs_Trains]

I un-soldered at the rectifier, on the 4230, the rectifier had 4 wires, the 2 center leads went to the transformer (AC) in and the outside wires (DC+ and DC- out) went to the filter cap. I removed the DC out wires to the filter cap. As Bob pointed out you can unplug the power amps one at a time to DBT. Rich

 

[Richs_Trains]

......and on the wooden cases, I have been lightly sanding them and the applying 'Tung Oil' which brings out the grain and seals, but does not add gloss. I usually apply one treatment of tung oil, let it sit awhlie, wipe it down with a clean towel and the repeat the process and then let it sit overnight. I tried stain and finish and felt it was much too glossy, even when I used low gloss polyurethane.

 

[Richs_Trains]

rectifier on 4230, outside wires feed filter caps.

 

[Dearslayer]

Been looking on the schematic to see where the rectifier is on this thing, and I feel so stupid not being able to find it! Maybe I'm in over my head on this one. The other units I've worked on were at least all working units.

 

[rBuckner]

It's on the bottom side, a cubic dark green block with 4 fat wires going to it. It's about 2-3cm on each side. I've never seen a bad one. First I'd unscrew the outputs (after taking notes as to what number part goes where) and test for shorts, especially collector to emitter.

 

[Dearslayer]

thanks so much. I took some pictures of that this morning before I left for work and thought it might be it but I will follow the advise of checking the outputs first.

 

[Dearslayer]

Pulled the output transistors on the RS power amp and tested. The bottom one( SJ2518) tested ok at .523. The top one SJ2517 got no reading. Left the top one out and put the unit on the DBT and bulb dimmed and I got power to the dial face which is a good sign. Turned it off and hooked speakers to the unit to see if I would get sound from the left side ( still on the DBT ). Turned it on and no sound and smelled a foul burning smell and saw a little wisk of smoke so shut it off immediately. Waited a few minutes and just quickly powered it on to see if dial face was still lit and it was but I shut it down again right away in case of damage. So bottom line is it does get power without that transistor. Gonna test the two on the other side to see if they are toast and report back shortly. The wisk of smoke and burning smell has me very worried that there may be more wrong.

 

[petehall347]

if you run speakers with no outputs you did a bad thing to the drivers . maybe burned a collector resistor and a driver . if no resistor in the circuit to burn you maybe burned a driver or 2 .
i am going of general topology here i haven't looked at the schematic yet .. but driving speakers with the outputs missing will cook the driver transistors in a few seconds if not quicker .. this is why i install powerful drivers if permissible but that is another story ..

 

[Dearslayer]

Ok sorry please excuse my ignorance but what are the drivers ? I checked the outputs on the other side and they both have a reading. Bottom being .504 and top being .462. Here's the other thing ... Shouldn't the part numbers for outputs be a mirror image the R/S top is SJ2518 /7413 bottom SJ2517/7426. L/S top is SJ 2517/7426 bottom SJ2518/7426. Also the top L/S is NPN whereas the other two were PNP. Ok so bottom line is how much damage did I do and considering I want to do a complete restoration will that fix any damage done or is it beyond that ?

 

[petehall347]

everything is repairable .. it is my bedtime right now so i will let someone else chime in . then catch up in waking hours .

 

[Dearslayer]

Ok thanks so much for the help so far.

 

[Dearslayer]

Planning a full resto of this unit and will place an order with Mouser soon. A couple questions first if I could. I will follow a cap list that was recommended on AK. Would it be a wise choice ( considering the one output transistor is pooched ) to include all four " new outputs" as a preventive measure and if so can someone recommend the Mouser part numbers for such to ensure I get the correct ones. Also given the fact that I perhaps ( most likely) did more damage as Pete suggest ( and I respect his expertise and knowledge) what really should be my next step considering the wisp of smoke and burning smell. Are there more measures I should take before ordering anything? I did start out feeling good about the small success of discovering the bad output and getting it to power up at least ( I am very inexperienced with diagnostics as opposed to remove and reinstall ) only to end up feeling stupid about the whole speaker hook up without the output and doing more damage. So much for a small victory I guess.