Marantz 2230 Blowing Fuse

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Bootz

New Member
Trying to fix my Pops Marantz 2230 which is blowing the fuse when powered on. I bought a full restore kit and with my limited knowledge of these things got to work.

First thing I did was recap the power supply and replace the two diodes and transistor. I pulled all 4 output transistors (2SD217's) and tested them in diode mode against the new ones I received and all 4 tested good as far as I can tell.

I was doing some reading on here before posting and looks like ill need to build a dim light tester which I should be able to get the parts for and build tomorrow.

stumbling across some tips from other posts I measured resistance between pins J757+J759 and get .5ohms

Only strange things I thought I found was a resistance reading of 6ohms between the black and yellow wires on the Power Supply, and the middle pins on the rectifier appear short in circuit, not sure if that is normal.

Need some help! TIA
 

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Welcome to Audiokarma, Bootz!

Where did you buy the kit?
By "new" 2SD217s do you mean Onsemi modern subs?

Check your PS cap polarities, do not power it up again until you have a DBT to protect it.

Dim Bulb Tester – Geek-Tips.com

www.geek-tips.com www.geek-tips.com

You can just use a polarized two prong plug, skinny=hot fat=return, make sure hot goes through the switch/bulb first.
60 or 100 watt incandescent bulb (incandescent only)
It's saved my bacon many times (like today when I inadvertently bent a cap enough to short the lead against a resistor lead...took me a while to find it.
 
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Thanks Milo, I got the kit from a seller on eBay, the replacements for the 2SD217 are the MJ transistors.

Thanks for the DBT tips! Hoping to have one made in a few hours
 
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Bootz said:
Thanks Milo, I got the kit from a seller on eBay, the replacements for the 2SD217 are the MJ transistors.

Thanks for the DBT tips! Hoping to have one made in a few hours
Click to expand...
Was it blowing the fuse before you started working on it?
If your original 2SD217s are good leave them in, new mica insulators and Dow 340 nonconductive heat paste (or the T03 silpads).
 
Yes it was blowing fuses before working on it. I am on a two week vacation from California to Maryland to visit my parents, not sure ill have time to order the mica/dow340. The original mica seems pretty intact, no wear as far as I can tell, I also brought some Arctic MX-4 thermal paste hopefully that will work instead of the DOW. I'll clean the mica and metal off and use some of that if we can get it up and running. Bought everything for the DBT today should be able to use it soon as well.
 
Bootz said:
Yes it was blowing fuses before working on it. I am on a two week vacation from California to Maryland to visit my parents, not sure ill have time to order the mica/dow340. The original mica seems pretty intact, no wear as far as I can tell, I also brought some Arctic MX-4 thermal paste hopefully that will work instead of the DOW. I'll clean the mica and metal off and use some of that if we can get it up and running. Bought everything for the DBT today should be able to use it soon as well.
Click to expand...

If the MX-4 thermal paste you're talking about is intended for CPU heatsinks, it's most likely electrically conductive - not what you want for this application. The mica sheets are electrical insulators, but thermal conductors.
 
MX-4 is not electrically conductive, however, I typically use GC Type Z9 Silicone Heat Sink Compound white paste or Dow.

1690329350124.png
 
Yea. I used to use (I think it was MX-5, or Arctic Silver) for CPU heatsinks.
That had silver particles in the paste so you needed to make sure that it did not come in contact with the CPU BGA pins. ;)
 
yeah MX-4 will work just fine, the mica is still in good shape so I plan on reusing them and cleaning them good with alcohol and applying new thermal compound between both layers id assume it needs to be between the mica and heatsink and also the mica and transistor?

Got all the parts for the DBT today but didn't have a chance to build it, hopefully tomorrow and then back to work on the unit.

While I am here I might as well ask again, there are three wires (x2 yellow and x1 black) coming from the transformer to the power supply which I assume is power? Why would it measure 6ohms resistance between the yellow/black wires, to me that is almost a full short, is that a normal reading for that area? Will report back tomorrow when I have the DBT build.. I also have a discord server I can go live with the repairs if anyone wants to take a stab at helping live :-) Let me know and I'll post the link for my discord server as long as that is allowed on this forum.
 
Yes, on the both sides question. Use as thin of a layer that coats each. I find it easier to apply the grease first to the transistor, slip on the mica and then coat that. A toothpick, layed way over when working is my favorite applicator tool and oh so cheap. Make sure the pins are at a right angle to the body in all planes and parallel to make plugging it back in possible.

That's a very reasonable resistance for a transformer secondary. The primary side is quite a bit lower. Bothe sides are a wound single piece of wire AKA a short circuit in short lengths. The wire guage and length along with the iron core determine the output voltage and current capability.
 
Alright, is there a way I can disconnect certain boards and power on safely with DBT to see where the short is? I am not sure where to go from here. Going to build the DBT shortly and I’ll be ready to continue.
 
IMG_1518.jpegWell I got the DBT built and we already knew it was blowing fuses so of course the light is bright, I have no idea other than to continue replacing all parts from the rebuild kit so I’ll start with the amp boards, any more advice?
 
Looks like my bridge rectifier is blown, removed it from circuit and from negative to AC I am getting a short with diode reading in both directions, all other diode readings are .5v drop. The rebuild kit I bought was pretty darn expensive but lo and behold it did not come with a BR :p

Also plugging it into the DBT without the BR and no more light.

Can I use this as the listing states?

www.ebay.com

Replacement 5B2 Bridge Diode Marantz 1060 Sansui QRX 6500 AU-999 4000 | eBay

Find many great new & used options and get the best deals for Replacement 5B2 Bridge Diode Marantz 1060 Sansui QRX 6500 AU-999 4000 at the best online prices at eBay! Free shipping for many products!
www.ebay.com
 
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Ok so I got the new Bridge Rectifier and that solved the no power issues so I recapped the remaining boards minus the Tuner Boards since we wont be using the Tuner.

The issue I am having now is that the left channel is extremely low volume but can be heard when turned up, no distortion.

I've checked the voltages on the amp boards and they match, I've also cleaned out the volume/balance pots to no avail.

The mono button doesn't do anything, still low audio on left channel, and headphones also have very low audio on left side.

Where should I be looking?

Appreciate any help. Some pics of the new lamps installed below
 

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You said the new rectifier fixed the power issues. Did you check the unit to see if it was working correctly before recapping other boards?

Which boards did you work on after putting in the new rectifier? When rebuilding/recapping boards they should be replaced and tested to be sure that board is good before moving on to others. Now you don't know which board is the problem.

Go back over your work to find the problem.
 
Well to be honest I checked for power after working on every board, but did not hook up speakers to test the sound.

The unit powered up correctly after each board was recapped/transistors replaced. I recapped the preamp/phono boards after I replaced the rectifier and left the tuner boards alone.

I looked over both the preamp/phono boards and did not see any issues. I will take a look tomorrow, thanks for the help.
 
1) I cleaned the volume/balance pots out with alcohol as I don't have deoxit

2) I plugged Preout L into Main R
Preout R into Main L and the problem stayed on left channel low, which I was told points to an Amp board problem and not the preamp.

3) Took a look at BOTH amp boards since I recapped/replaced transistors on both and measured all the resistors comparing the two sides and all readings matched.

4) Noticed the Left side Amp board had a cracked diode so I swapped the one from the R board to the L board and in the process the L side diode fell apart. With the working diode from the R side Amp board in the left side amp board and NO diode installed in the R side amp board the unit STILL functions the same, the R side (confusingly) is still working strong, and the left side is still low.

5) I checked diode readings for the transistors and Jumper pins on the ends of the amp boards and both match.

I have absolutely no clue what is going on.
 
BTW, the preferred chemical for pots is Caig Fader F5. For your issue, it may be time for you to find a tech. Add your location before asking around for one.
 
I’ve got a week left visiting here to troubleshoot, after that my Dad would need a tech near queenstown Maryland
 
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