Jumped in BIG....found a Marantz 2500.

mech986.......thanks for the amazing pictures. Your 2500 is gorgeous!

Well....it pretty much confirms it.........although, I have found a picture or 2 of units that dont have the 'bits' there.....like mine.

Now the big question is....what do i do? Do I install the bits OR just leave it?????

I will take a voltage reading at pin 4...................
 
I just measured voltages on all 9 pins on jx05

Pin1=0.0v
Pin2=0.13v(ground pin?)
Pin3=83.3v
Pin4=0.34v(should be 41v)
Pin5=66.2v(should be 52v)
Pin6/7/8=83.4v
Pin9=0.01v.


Pin4 is directly connected to the aforementioned area with the missing 'bits'. Also voltage on pin5 seems a little high. The other voltages check out pretty good.

Any suggestions?
 
If its all functioning correctly, I would just leave it Anders, you could be opening up a Pandora box of trouble.....there could be other things different about the circuit which may not be obvious until you fill the board up...then you could be taking a step backwards........

Looks like a mammoth of a receiver!!

Good work getting it going though..........:thmbsp:
 
Hey fellas...check this picture link: http://www.canuckaudiomart.com/image.php?image=2232830&is_user=0

This unit does not have the 'bits' on the peak board..............like mine.

Strange this.

Anyway....my unit is working again....and all seems normal.

I do still have the slight hum....which I now know is from one of the main caps. I got some Panasonic 8200uf/100v caps from DK......I am tempted to try matthewk's procedure again, as I think one of my former caps was defective.
 
Since I still have the slight hum(which I have identified as the right big cap's fault)...even after changing to brand new diode bridges.....the hum is still there. Also the 61v voltage on the 3 mounting screws on the amp board is still there. I think the right big cap is dragging down the voltage.....please(guru/tech) confirm this....thanks.

Below is pictures of the NEW DK caps.......wired as per matthewk procedure. If anyone sees something not correct...please, please tell me. Thanks.

I have NOT soldered any wires into place yet........

The RED wire goes to the A terminal.
The BLACK wire goes to the B terminal(ground)
The WHITE wire goes to the '-' terminal.

I am trying to recreate the A-//-B-//- symbol on the old cap.
 
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Red should go the positive of one cap. The negative on that cap should go to the positive of the other cap, and these two terminals comprise the 'common'. The white should go to the negative of the second cap.

That's it.
 
Hey EW.......ok.....please look at my excellent-e photos.......I think I have it correct.
I know it is simple........but, I just don't want another BANG!...........
 
hey skibjr/EW/kevzep/mech986/others................ok ok.......I am travelling at the moment.......I'll be back at the bench in 4-5 days........patience. patience.:thmbsp:

This second 'matthewk'-procedure better work.........or I'll be officially depressed. I just need to fix the slight hum...........can it be something else than the big caps? On the driver board maybe.......any suggestions or info is good...I'll check on it all.:thmbsp:
 
hey skibjr/EW/kevzep/mech986/others................ok ok.......I am travelling at the moment.......I'll be back at the bench in 4-5 days........patience. patience.:thmbsp:

This second 'matthewk'-procedure better work.........or I'll be officially depressed. I just need to fix the slight hum...........can it be something else than the big caps? On the driver board maybe.......any suggestions or info is good...I'll check on it all.:thmbsp:

Roger that, until then.....:thmbsp:
 
hey skibjr.......right on! check my dbt thread........built one an'all....have tested the 2500 already...................................................standby for 'matthewk-cap-procedure-dbt-test'! Spock.......calibrate and engage!
 
Hello forum......back with the 2500.....rigged up the new caps(only on the right channel)..........checked everything.......DBT in line.......and turned ON......bulb went bright and then dim......all seems ok I guess. The protection relay did come on, although it took a longer time.....I am thinking this is due to the DBT...(engaging voltage lower?).....am I right?

I measured the voltage on the amp board mounting screws.....and they all(both amp boards/12 screws in all) measured about 56.8v.......the low voltage is due to the DBT........am I right about this?

The matthewk procedure seems to work fine..........after a bit more testing...I will gut the big caps and put the new caps inside 'em and make it all look nice.
 
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Just tested at FULL voltage.........all ok and NO hum from the right channel. YEY!

I have been trying friggin-frantically to empty out the old cap..........this is damn hard work..........is there an easier way to empty the old cap??? I want to do this because, I want to put the new caps inside the old caps housing.

The reason for the hum was quite self-evident once I sawed the cap open ......the 'B' connector was completely burned and disconnected from the inside. So the big caps have to go..............................but, HOW do you empty them easy?????

Great.....
 
Hello forum......I have been doing hard work the last 2 days. The cap-transformation worked great, but, boy, was it HARD work. After taking out the original caps, cutting them open and TRYING to empty them........this was just not possible. I ended using the the bottom part of both caps...........for the top part, I used some ex-sx1250 caps that I had lying around from an earlier fix-operation(they were leaky anyway). These caps came apart nicely and were easy to gut.

So, the new caps went in the ex-sx1250 cans and the original bottom ends closed them up. The new caps were secured inside the cans with some nicely cut flamingo. They are nice and secure.

I took some photos........the wiring somehow looks messier in the photos.....in real life it looks pretty good.........all was assembled and I dbt'ed........FANTASTIC.....bulb went bright and then dim.......tried with normal power.......all clicked and tested as it should..the HUM is gone!! YEY! Now I will clean'n oil...........connect them to my JBL L50's and play for a few hours................tuner works fine.
 
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And a few more......unit ON and playing stereo......Radio India in Singapore...NICE.:thmbsp:

The unit caps look decent..........just need to put some Marantz stickers on them.:banana:
 
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Nice work and happy for you that its working well. At the risk of raining on your parade, seems little effect on your operation without those parts that supply the soft start (?) to the 1st part of the 700 amp boards. I'm not familiar with that part of the circuit as I mentioned above so maybe Glenn or Skibjr could guide us through what that does and why yours works even without it?

I'm thinking it ramps up the voltage to the input differential pair, but maybe you're getting faster or immediate voltage but its being masked because the speaker relays are kicking in slower.
 
mech986....no worries......there are units out there that don't have the parts on the peak board.....just like mine. i have seen a few photos.

At this time, I will not be putting those 'missing' parts on the board......I think it is original. On the back side of the board the holes are 'blocked'...and the 'blocking' looks original......I have seen this on other units.

The unit is working fine......best of all, the HUM is completely gone.
 
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