Maranz 2500, 2600 Transformer Design

[ccheath]

Thank you JuanPabloCue for taking the time to measure the transformer. I do see that all your wire colors are all the same as what I have and I do notice that they are radically different location. Now THAT'S confusing. To add further confusion, I question the reading on the "AMP 1 RED-BLACK-RED" being different by almost 9 volts while the "AMP 2" being different by a little over 2 volts and appears to be low on voltage but the voltage you listed as "Red2-Black" seems about right. I've tested numerous transformers that feeds the main amp and I've seen a tiny difference between the two halves by a volt or two but never saw the 1st half winding being different by 9 volts than the 2nd half winding. Your J802 measurement is very confusing. I wonder if your Audio Power Plant Premier is fudging up the reading by making the transformer behave funny? I'm not saying your line conditioner is bad but rather but might be getting undesired result from the "unloaded" transformer during testing. I don't know if that's really the case since I never owned such line conditioner. If your outlet is within +/- a few volts around 120vac, then I'd try hooking your transformer to the outlet rather than the conditioner when doing the measurement. State your line voltage just like you did with your line conditioner's output voltage.

Both of your boards seem to be "essentially" the same. The transformer voltages at J802 shouldn't be any different.

P800-J801
green-green = 0.535mH - 00.6ohm = 7.2vac
blue-blue = 00.6ohm - 0.582mH = 9.3vac

I assumed that you measured the two above which is not respect to ground but directly hooking one probe to green and another probe to the other green (same apply for blue) on J801 correct? If that's the case, thank you. That's what I'm looking for. You might want to try remeasure again though while the transformer is hooked to the AC outlet.

Now for J802 which the wiring is RADICALLY different even though there are all the same colors there but different location. Since YELLOW is the ONLY color being in the same pin as mine, let's try this (Please make sure your meter is set at AC):

Measure YELLOW - GREEN << (Mine is Purple and expecting around 430vac)
Measure YELLOW - PURPLE << (Mine is Brown and expecting around 160vac)
Measure YELLOW - GREY << (Mine is Blue and expecting around 160vac)
Measure YELLOW - BROWN << (Mine is Grey and expecting around 30vac)
Measure YELLOW - BLUE << (Mine is Green and expecting around 30vac)

There may be variation of a few volts than what I stated.

 

[JuanPabloCue]

Thank you JuanPabloCue for taking the time to measure the transformer. I do see that all your wire colors are all the same as what I have and I do notice that they are radically different location. Now THAT'S confusing. To add further confusion, I question the reading on the "AMP 1 RED-BLACK-RED" being different by almost 9 volts while the "AMP 2" being different by a little over 2 volts and appears to be low on voltage but the voltage you listed as "Red2-Black" seems about right. I've tested numerous transformers that feeds the main amp and I've seen a tiny difference between the two halves by a volt or two but never saw the 1st half winding being different by 9 volts than the 2nd half winding. Your J802 measurement is very confusing. I wonder if your Audio Power Plant Premier is fudging up the reading by making the transformer behave funny? I'm not saying your line conditioner is bad but rather but might be getting undesired result from the "unloaded" transformer during testing. I don't know if that's really the case since I never owned such line conditioner. If your outlet is within +/- a few volts around 120vac, then I'd try hooking your transformer to the outlet rather than the conditioner when doing the measurement. State your line voltage just like you did with your line conditioner's output voltage.

Both of your boards seem to be "essentially" the same. The transformer voltages at J802 shouldn't be any different.



I assumed that you measured the two above which is not respect to ground but directly hooking one probe to green and another probe to the other green (same apply for blue) on J801 correct? If that's the case, thank you. That's what I'm looking for. You might want to try remeasure again though while the transformer is hooked to the AC outlet.

Now for J802 which the wiring is RADICALLY different even though there are all the same colors there but different location. Since YELLOW is the ONLY color being in the same pin as mine, let's try this (Please make sure your meter is set at AC):

Measure YELLOW - GREEN << (Mine is Purple and expecting around 430vac)
Measure YELLOW - PURPLE << (Mine is Brown and expecting around 160vac)
Measure YELLOW - GREY << (Mine is Blue and expecting around 160vac)
Measure YELLOW - BROWN << (Mine is Grey and expecting around 30vac)
Measure YELLOW - BLUE << (Mine is Green and expecting around 30vac)

There may be variation of a few volts than what I stated.

will test directly to the wall tomorrow.
120.4v~120.5v AC ,
************************
************************
P800-J802
Purple-Green

6.Blue-Purple 15ohm - 0.55H~0.61H
6.Blue-Brown 12.25mH - 1.8ohm
6.Blue-Gray = 1.8ohm - 13.45mH
6.Blue-Yellow = 43.7mH - 3.5ohm
6.Blue-Green = 14.8ohm - 0.55H
***
6.Blue-2.Yellow-5.Brown. = P400
blue-yellow = 58.2vac
brown-yellow = 29.1vac
***
4.Gray-2.Yellow-3.Purple =

[2.Yellow-1.Green = 322vac = 1.66H = 18ohm]
[4.Gray-3.Purple = 335vac = ]
[6.Blue-5.Brown = 29.1vac = ]

2.Yellow-1.Green = 322vac = 1.7H = 18ohms
2.Yellow-3.Purple = 247vac = 0.98H = 13.9ohm
2.Yellow-4.Grey = 89vac = 128.5mH = 5.1ohm
2.Yellow-5.Brown = 29.1vac = 15.mH = 2.ohm
2.Yellow-6.Blue = 58.3vac = 56.H = 3.5ohm

1.Green-2.Yellow = 322vac = 1.7H = 18ohms
1.Green-3.Purple = 569vac = 5.17H = 31.8ohms
1.Green-4.Gray = 233vac = 0.88H = 13ohms
1.Green-5.Brown = 293vac = 1.37H = 16.3ohms
1.Green-6.Blue = 263vac = 1.1H = 14.7ohms

xBlue-Green = 263vac

 

[ccheath]

Thank you again for taking your time to measure. I could not make head to tails on what's going on in your transformer.

I added up the voltage that I was able to figure out as 430+160=590 but the highest you get was 569. So basically I was close by about 20 volts total voltage for that multitapped secondary. After careful study, I was able to come up with multitap being as 430-160-30-GND-30-160 and I was able to power up my receiver very well using that configuration.

Seeing that you have blue-yellow-brown is showing blu-yel=58.2vac and brn-yel=29.1vac but you get blu-brn=29.1 and that makes brown look like a center tap and should be grounded but Yellow is grounded on your connector. That got me stumped.

Looking at your measurement makes Brown a center tap at least for the 29-GND-29 but your picture showing the connector shows otherwise. Try Brown being the "Ground" with your meter. Don't change any wiring on the connector. Just leave one probe on BROWN and measure the rest with the other probe on J802 connector.

Was your Marantz working when you got it? Were those wires like that when you got it? Did it look like it had been altered?

 

[JuanPabloCue]

120.4v~120.5v AC

1.Green-2.Yellow = 321.5vac = H = ohm
1.Green-3.Purple = 569vac

1.Green-4.Grey = 232.5vac
1.Green-5.Brown = 292vac
1.Green-6.Blue = 263vac

2.Yellow-1.Green = 321.5vac
2.Yellow-3.Purple = 246vac
2.Yellow-4.Grey = 88.9vac
2.Yellow-5.Brown = 29.1vac
2.Yellow-6.Blue = 58.3vac

3.Purple-1.Green = 569vac = H = 32ohms

3.Purple-2.Yellow = 246.5vac = H = 13.9ohms.
3.Purple-4.Gray = 335.5vac = H = 18.8ohms.

3.Purple-5.Brown = 276vac = H = 15.9ohms.
3.Purple-6.Blue = 305vac = H = 17.2ohms.

4.Gray-1.Green = 233vac = H = ohms.
4.Gray-2.Yellow = 88.9vac = H = ohms.
4.Gray-3.Purple = 335.5vac = H = ohms.

4.Gray-5.Brown = 59.7vac = H = ohms.
4.Gray-6.Blue = 30.5vac = H = ohms.

5.Brown-1.Green = 292.5vac = H = ohms.
5.Brown-2.Yellow = 29.1vac = H = ohms.
5.Brown-3.Purple = 276vac = H = ohms.
5.Brown-4.Gray = 59.7vac = H = ohms.
5.Brown-6.Blue = 29.1vac = H = ohms.

6.Blue-1.Green = 263.5vac = H = ohms.
6.Blue-2.Yellow = 58.3vac = H = ohms.

6.Blue-3.Purple = 305vac = H = ohms.
6.Blue-4.Gray = 30.5vac = H = ohms.
6.Blue-5.Brown = 29.1vac = H = ohms.

 

[JuanPabloCue]

Transformer seems factory Glued...
but... very strange.
Red-Black(18AWG 80°C)-Red wires are smaller AWG than Orange-Black(18AWG 90°C)-Orange(22AWG) ?

Blue1-Blue2 & Green1-Green2 seem same 22AWG / AWM 1015.

Primary AWG18,
Yellow,Grey,Green,Brown,Blue & Purple AWG22.

Incredible, not even Yellow!

 

[ccheath]

I'm curious. Was your Marantz working before you pulled out the power supply?

Could you post the picture of your transformer where the wires are coming out at?

 

[JuanPabloCue]

I'm curious.
Could you post the picture of your transformer where the wires are coming out at?

from left to right in pairs:
Top/Left Side:
Blakc-Red-Red .../... Orange-Black-Orange .../... Green-Green...Blue-Blue.

Bottom:
Purple-Yellow....Brown-Blue....Grey-Green .../... Primary: Blue/Red-Dark
:thmbsp:

 

[ccheath]

Thank you again Juan. I didn't say take it apart. At least now I know what it looks like inside. I was expecting to see the potted material inside. The transformer inside doesn't look burn't. I don't know if you have been using your scope to test or how you hooked up your scope. Maybe we can give it one more try. Do you have a regular multimeter similar shown like here (picture as reference)?

I looked at your voltage posting starting with Green and was able to put it out like this:

GRN-GRY-BLU-BRN-YEL-PUP

What I was able to find so far is going from GRN-PUP is 569. Sounds right.
Second is going from GRN-YEL will give me 322. That is the total I'm looking for.
Third is going from YEL-PUP will give me 247. That's also what I'm looking for.



I think your wiring is WAY out of wack at the connector. That probably explain why one of your trace pad on the board is burnt at where the diode resides. For starter, PUP should be in place of GRN (don't change anything). Here's why:

1. There are group of voltages you measured that is within 322 range going from GRN to YEL.
2. That gives (or should give) 160-30-0-30-160. That is 160 + 160 = 320v (322v you measured).
3. Going from YEL to PUP will give you 247v. So if I half what you measured 322v into 161v then add 247v, I will get 408 volts.
4. Those voltages 322v, 247v, 408v and 569v is getting me somewhere figuring this out.
5. There's a possibility that on your transformer, BLU is the center of 322 volt. It should be yellow but doesn't look like it. I can't really confirm yet.

I don't know why your wires are reconfigured. So, don't change any wires around until it is confirmed wrongly wired.

Keep your transformer disconnected from the power supply board. Use a multimeter similar in the picture. If you have 750 or 1000 volts AC setting, set it there. Do the measurements keeping one probe on GRN while measuring the other colors with another probe again. If BLU looks like it's the "center" of 322 (GRN-YEL), measure keeping one probe there on BLU while the other probe on other colors and post back.

WARNING: I forgot to say this before. Do NOT leave your meter hooked to the transformer while powering up or powering off the transformer. Transformer generates HUGH spike while hooking up to and disconnecting from AC outlet. I've damaged my nice DMM that way awhile back. My DMM still works but is flaky in the AC setting after the incident. After powering on, then you can start your measurement but disconnect your meter before powering off.

 

[ccheath]

JuanPabloCue, I was looking at your post #64.

Are those measurements done with your oscilloscope or with your DMM meter?

Did you test those voltage when the transformer is disconnected from the regulator board?

 

[JuanPabloCue]

Thank you again Juan. I didn't say take it apart. At least now I know what it looks like inside. I was expecting to see the potted material inside. The transformer inside doesn't look burn't. I don't know if you have been using your scope to test or how you hooked up your scope. Maybe we can give it one more try. Do you have a regular multimeter similar shown like here (picture as reference)?

I looked at your voltage posting starting with Green and was able to put it out like this:

GRN-GRY-BLU-BRN-YEL-PUP

What I was able to find so far is going from GRN-PUP is 569. Sounds right.
Second is going from GRN-YEL will give me 322. That is the total I'm looking for.
Third is going from YEL-PUP will give me 247. That's also what I'm looking for.



I think your wiring is WAY out of wack at the connector. That probably explain why one of your trace pad on the board is burnt at where the diode resides. For starter, PUP should be in place of GRN (don't change anything). Here's why:

1. There are group of voltages you measured that is within 322 range going from GRN to YEL.
2. That gives (or should give) 160-30-0-30-160. That is 160 + 160 = 320v (322v you measured).
3. Going from YEL to PUP will give you 247v. So if I half what you measured 322v into 161v then add 247v, I will get 408 volts.
4. Those voltages 322v, 247v, 408v and 569v is getting me somewhere figuring this out.
5. There's a possibility that on your transformer, BLU is the center of 322 volt. It should be yellow but doesn't look like it. I can't really confirm yet.

I don't know why your wires are reconfigured. So, don't change any wires around until it is confirmed wrongly wired.

Keep your transformer disconnected from the power supply board. Use a multimeter similar in the picture. If you have 750 or 1000 volts AC setting, set it there. Do the measurements keeping one probe on GRN while measuring the other colors with another probe again. If BLU looks like it's the "center" of 322 (GRN-YEL), measure keeping one probe there on BLU while the other probe on other colors and post back.

WARNING: I forgot to say this before. Do NOT leave your meter hooked to the transformer while powering up or powering off the transformer. Transformer generates HUGH spike while hooking up to and disconnecting from AC outlet. I've damaged my nice DMM that way awhile back. My DMM still works but is flaky in the AC setting after the incident. After powering on, then you can start your measurement but disconnect your meter before powering off.

http://www.uni-trend.com/ut70a.html

No spike here.

Anyway...

I think: (1. near J801 "Top-to-Bottom")
1. Green 284.5vac.
2. Brown Center.
3. Purple 284.5vac.
4. Grey :scratch2:
5. Yellow 29.15vac.
6. Blue 29.15vac.

Green & Purple here definetively are secondary ends... 4.722:1
Yellow & Blue seem a different secondary winding, 0.5:1 & Brown defenetively seems center tap for that winding.
but if it's the same Winding (like schematics say), Brown here should be Center Tap for all other.

The only problem i see is that J801 4.Green2 is connected to J802 2.Grey.

found something strange...
J801 Green1-Green2 both have same Phase.
also both Blue, same Phase.
J801 does not seem to be a dedicated winding like the Schematics say, because both Green should be out of phase.


Plan A, change only 1 wire.
Plan B, change 5.

 

[ccheath]

Did you disconnect the plugs from the regulator board? I think that's tying up one of your green wire to other secondary. PUP is the high voltage that is supposed to feed 410v and one side of the green is linked to -576v rectified from 410v (according to the schematic). If you haven't done so, disconnect both plugs (J801 and J802) from the regulator board.

If you did disconnect, you might be experiencing capacitance between windings. In order to tell whether the blue pair and green pair are part of the other secondary or not is to disconnect power and use an ohm meter to check for continuity on those secondaries. If there's no continuity then you might be experiencing capacitance which is normal. There shouldn't be any connection between those 2 secondaries and the multitap secondary that we're trying to figure out. I figured that capacitance issue out on my Pioneer SX-1980's transformer awhile back.

 

[JuanPabloCue]

Did you disconnect the plugs from the regulator board? I think that's tying up one of your green wire to other secondary. PUP is the high voltage that is supposed to feed 410v and one side of the green is linked to -576v rectified from 410v (according to the schematic). If you haven't done so, disconnect both plugs (J801 and J802) from the regulator board.

If you did disconnect, you might be experiencing capacitance between windings. In order to tell whether the blue pair and green pair are part of the other secondary or not is to disconnect power and use an ohm meter to check for continuity on those secondaries. If there's no continuity then you might be experiencing capacitance which is normal. There shouldn't be any connection between those 2 secondaries and the multitap secondary that we're trying to figure out. I figured that capacitance issue out on my Pioneer SX-1980's transformer awhile back.

J801 Green1-Green2 = Continuity True.
J801 Blue1-Blue2 = Continuity True.
J801 Green1&2-Blue1&2 = Continuity False.
J801-J802 = Continuity False.
J802-1-2-3-4-5&6 = Continuity True.
Red1-Black-Red2-Orange1-Black-Orange2 = Continuity False.
Red1-Black-Red2 = Continuity True.
Orange1-Black-Orange2 = Continuity True.

Marantz schematics error:
J804-J914 wiring
C812 P800 schematic.
I doubt the -570vdc possible, P800 has 250v fuses, ¿could it be -470vdc?

anyway, i swapped the Brown-Yellow(brown->center), and the Green-Purple.
worked, but -15vdc became -13vdc. j804.1.2

did a crazy thing, swapping the J801-4.Green2<-->J802-Green0
leaving J801-4.Green0 & J802-1.Purple for +569vac.

the C811 +350v cappacitors exploded!, older cappacitors are very dangerous!.
they do not have the (X) or (+) or (Y) or (|) ding on the Top, when they explode... the aluminium shell acts like a proyectile, cappacitor hit me in the arm like a mule kick.
in the eye would be fatal.
smell also very toxic.

What bugs me is that the J804-6 (CW, L--to-->R) should be +13vac, but also has -433vdc.

could you measure your J805, J804, J803, "J802&J801" for AC & DC?

 

[ccheath]

......................
GRN-GRY-BLU-BRN-YEL-PUP

What I was able to find so far is going from GRN-PUP is 569. Sounds right.
Second is going from GRN-YEL will give me 322. That is the total I'm looking for.
Third is going from YEL-PUP will give me 247. That's also what I'm looking for.



I think your wiring is WAY out of wack at the connector. That probably explain why one of your trace pad on the board is burnt at where the diode resides. For starter, PUP should be in place of GRN (don't change anything). Here's why:

1. There are group of voltages you measured that is within 322 range going from GRN to YEL.
2. That gives (or should give) 160-30-0-30-160. That is 160 + 160 = 320v (322v you measured).
3. Going from YEL to PUP will give you 247v. So if I half what you measured 322v into 161v then add 247v, I will get 408 volts.
4. Those voltages 322v, 247v, 408v and 569v is getting me somewhere figuring this out.
5. There's a possibility that on your transformer, BLU is the center of 322 volt. It should be yellow but doesn't look like it. I can't really confirm yet.

I don't know why your wires are reconfigured. So, don't change any wires around until it is confirmed wrongly wired.................

This is why I say above (Highlighted). We haven't gotten to a point to say it is safe to put this to that yet. So far, I was able to find that Purple is supposed to go in place of Green. BUT without sorting out and changing other wires to a proper slot, catastrophe happens as you just experienced.

J801 Green1-Green2 = Continuity True.
J801 Blue1-Blue2 = Continuity True.
J801 Green1&2-Blue1&2 = Continuity False.
J801-J802 = Continuity False.

Marantz schematics error:
J804-J914 wiring
C812 P800 schematic.
I doubt the -570vdc possible, P800 has 250v fuses.

Schematic is correct on those plugs. And I recall those voltages listed are correct.

Fuse may be stamped with 250v but they'll handle 600volts without problems if you don't put too much current through them. But the current going through that fuse is so tiny that the fuse won't break a sweat.

What is INCORRECT is they forgot to add in the schematic C811 in series with C812 to handle -576volts DC.

Also the way the multitap secondary wirings in schematic was incorrect. If you see my Post #2 again on the 3rd picture of the schematic that I modified. I had to reroute the wirings according to my board wiring that the previous owner cut off and threw away the transformer. Everything just fell in place and made sense. Quoted from Post #2 pic 4 shows:

Since then I was able to come up with the voltages.
The only AC voltage needed to produce 180vdc is 160vac following the dropping resistor (R801 4.7k 1/2w on P800).
So looking at the picture above, just substitute both words (AC Unknown) with (AC 160v)

anyway, i swapped the Brown-Yellow(brown->center), and the Green-Purple.
worked,
but did a crazy thing, swapping the J801-Green2<-->J802-Green0
leaving J801-4.Green0 & J802-1.Purple for +569vac.

the C811 +350v cappacitors exploded!, older cappacitors are very dangerous!.
they do not have the (X) or (+) or (Y) or (|) ding on the Top, when they explode... the aluminium shell acts like a proyectile, cappacitor hit me in the arm like a mule kick.
in the eye would be fatal.

:nono:

I hope you didn't fry your scope tube filament. That tube is hard to come by.
J801 Green pairs and Blue pairs are in the right place. They should be left alone.
Wires swapped between two different plugs should never be done unless they were tampered with and proven that they were swapped and needed to be swapped back. In your case, J801 is correct.
J802 is the only one having problem as we know.
Purple should be in PIN 1 of J802.
The center I'm seeing in your measurement is BLUE not BROWN. GROUND is supposed to be in center of 322 volts, not the entire winding.
The problem of putting BLUE in GROUND is it is way off center of 322 volts.
1. One side of BLUE is showing 263v between BLU and GRN.
2. Other side of BLUE is showing 59v between BLU and YEL.
3. BLU is way off center by 102v.
4. Further problem is PUP will not achieve 408v needed to generate -576 volts whether you made BLU or BRN "center". You'll experience voltage being too low.

I think your transformer probably died and had been rewound but incorrectly tapped sometime in the past. There's no potting material inside. Granted, I've never seen inside 2500's transformer but I have seen inside of 2385's transformer. The 2385 has the potting material inside that well cover the transformer core where you can't see it but you'll see wires coming out. I can't imagine Marantz pass it through production and out the door like that. GRN and YEL are useless because they are not the same voltage needed to go together to generate 180v. PUP is useless because it will not produce 408v needed. You'll get either 336 if GRY is ground which is too low or 569vac if GRN is ground which is dangerously too high because it'll generate -805vdc, exploding capacitors.

You can probably just use that transformer to make your PREAMP AND MAIN AMP part of the receiver work. The tuner would work too since it feeds off of the Preamp part of the power supply. It can be done by using either BLU or BRN "center" but not both and make sure the other two wires are from the center reads 30vac or close. Say if you decide BRN to be center and hook it to PIN 2 of J802 and hook BLU to PIN 5 and YEL to PIN 6, then disconnect and cap off PUP, GRY, and GRN and don't use them. Then remove connector from J804 that goes to the scope off the power supply. You'll just lose the scope that way. You can't use the scope until the transformer is correctly wound and tapped. You'll also have AMP 2 having ORANGE-about 14vdc below the listed voltage in the schematic and AMP 1 may show the rated voltage but the transformer has offset center on the RED-BLACK-RED. It'll work but you will not get optimal performance on either channel.

What bugs me is that the J804 .6 (CW, L--to-->R) should be +13vac, but also has -433vdc.

could you measure your J805, J804, J803 AC & DC?

I can't do the measurement because all the transformers I used to power up that receiver had been put away. I will have to hook all 4 transformers and 3 variacs in order to power it up to do the testing. Currently I'm repairing my Marantz 2385. Marantz 2500 is next on the bench after I finish my 2385. 2385 won't be finished for awhile.

But, I recall that the schematic showing voltages through J804 and J805 are correct. But J803 is for the lights and that's easy to determine. It should be close around 8vac. I also recall Pin 5 and 6 (one probe on 5 and another on 6) on J804 should be about 7vac but pin 5 is tapped to -576vdc in the circuit board so be careful. All the rest of the pins on J804 and J805 are listed in the schematic. But they are measured in DC not AC. Exception of J803 and Pin 5 and 6 of J804 which is measured across in AC but pin 5 is measured DC from GND.

 

[ccheath]

JuanPabloCue, I'll tell you what. I know the schematic is correct on the voltage coming from P800. If you still insist on me rehooking up my receiver and actually measure from those connectors (J803, J804, and J805), I'll do it for you. Because you spent painstaking time doing several measurements from the transformer for me to be able to confirm the voltages on my finding is correct and I thank you for that. In return, I will check the voltages on mine if you still want me to. If you do, then give me about a day or two to rehook it all up and get everything set up. There's several transformers and variacs , alot of wiring and minor mod involved to make it work.

 

[JuanPabloCue]

all the transformers I used to power up that receiver had been put away. I will have to hook all 4 transformers and 3 variacs in order to power it up to do the testing.

There's several transformers and variacs , alot of wiring and minor mod involved to make it work.

can you tell me more about the transfomers you used?

 

[ccheath]

1. To power the main amplifier both left and right, I used Pioneer SX-1980 transformer full power with two secondaries both having 65v-0v-65v (each per channel)

2. To power the Preamp circuit, I used Pioneer SX-980 with variac to power up 30v-0v-30v

3. To power 180 volt circuit, I used Pioneer SX-1980 (same one as #1) transformer's multitap secondary end to end with rectifier and dropping resistor to bring it down to 160v.

4. To power the -576 volt circuit, I used one of my EL84 tube amplifier's transformer 600v secondary with variac to power up to 430vac. Although 408vac would be sufficient.

5. To power the scope tube's filament, I used a 6.3v transformer with variac to keep it at 7vac.

6. To power the dial lights and LEDs, I used Pioneer SX-980 (same one as #2) 8v secondary.

Pioneer SX-1980
Pioneer SX-980
Tube amp transformer 300-0-300 (600vct)
6.3vac standalone transformer
3 variacs
1 fullwave rectifier
1 dropping resistor

The original transformer for my receiver is missing. I bought the 2500 on ebay as a fixer upper price. The previous owner had already cut the wires off the transformer and THREW AWAY the transformer before I was able to ask him for it. So, it's LOOOONG GONE!! That is why I started this thread. I plan hopefully to have funds by the end of this year to have one company to customize the transformer for my 2500. Fortunately in the meantime, I powered it up and EVERYTHING works except the first horizontal half of the scope. But that can be fixed.


Here's a couple pics from Post #48 on this thread:

 

[JuanPabloCue]

Well,

i think im gonna build an external PSU,
with multi-pin neutric or similar concert type connectors.

seems to me that original toroidal transformer is underpowered,
& it was too complex for a small box, could be thats why the high fail rate.

seems that multi-tap toroidal transformers, do not output a symetric waveform, one of the sides seems saturated with more THD.
could be good or could be bad, but other Marantz square EI transformers ive measured; 2265B for example, have perfect symetrc output waveforms. with dual secondary, exept lamp.
with a multi-tap toroid the + or the - will sound different.
and that seems contradictory when i remember the M2500 brochure about perfect symetry amplifier circuits.

¿could it be that the amplifier circuit is so symetric that does not care if the transformer is symetric or not?

the good thing is that all that empty space can be used...
i want to change the Tunnel Forced Air-Cooling with a 100% Passive Cooling.
or Water Cooling.

the easy way i think will be to use 8x or more: Wakefield 423A heatsinks or 3x or 4x Walefield 490-12K or 6K or 3.5K, need to measure.
http://masterdistributors.com/products/490-12k
http://www.onlinecomponents.com/wakefield_490-12k.html?p=12788037

the 423A will dissipate 50w at 47°C each, and the 490-12K can dissipate 200w each, but price&size becomes a barrier.
with IC Diamond thermal paste, for maximum heat transfer.

Watercooling would be more complex and still needs fans, but cooling performance should be way better than air-cooling, increasing transistor life at full load.
it would be the world first watercooled TO-3.

Anyway, will not be all-in-one-box, but will improove in some areas.

 

[ccheath]

That will be an interesting project. External PSU gives you more options. It can get bulkier though. I'm curious, do you have two Marantz 2500? Does the transformer work inside the other?

The brochure is more likely talking about the amplifier circuits being symmetrical not the transformer. The transformer's output would be rectified and filtered before it reaches the main amps. But BOTH secondaries for the main amplifier should have the same or very close voltage give or take a couple volts and that's it. My SX-1980 transformer shows about identical is it can be on both main amp secondaries. Your transformer seems to be lopsided. I'm willing to bet it was rewound some time. And whoever did the rewinding job didn't do a good job. There is NO WAY Marantz would have certified it as working and ship it out the door unless the employee gone berzerk. Even if they did, that would have been corrected YEARS ago.

You're right. I see alot of comments on the Marantz 2500 and 2600 transformers failing alot. My theory is they love to drive into 4 ohms load. 4 ohm load puts heavy strain on the transformer which probably is sized for 8 ohm load with (a ballpark figure) 50% duty cycle. That's just my theory so just take it with a grain of salt. That's why I'm taking this into account when I get new transformer made for my receiver in the future.

Passive heatsink is in my opinion looks cool. Have you seen a 2385 heatsink? It nearly fill the whole side right up to where the power transformer platform. When I removed it from my 2385, it was the biggest I've ever seen from a receiver. Here's my >>2385 top pic<<. It would have been cool for 2500 to have larger passive heatsink. But I do notice the advantage of having fan forced is the whole inside of the receiver is running cool while the 2385 runs hotter inside.


Thought you might like to check out Anderslober's thread for the 2500: Jumped in BIG....found a Marantz 2500.

I plan to get my 2500 restored but will do some modification to the transformer and main cap section. The size of the transformer will be larger and beefier. In fact, I'm considering bringing it to 2600 level (larger if possible). I also plan to chuck those Dual-C's and have NO plan to restuff them. I am considering stacking individual capacitors. I'm also considering modifying the main amp to put as much power as the 2600 or higher. I think it'll be nice to have 2500 with 2600's power. :yes: Haven't fully decided yet. But it will still be all in one box.

 

[JuanPabloCue]

Thinking outloud, LOL,

Original Transformer is aprox 5.25" high x 5.5" Diameter...
to replace the Amp1 & Amp2, there is many options available.

One option is to connect a Bi-Polar DC power directly to P700, no Diodes no cappacitors.
A regulated DC power supply,

Instek SPD-3606
gives +/-60vdc "120v" @ 3A. / 6Kg. / $845usd.
http://www.gwinstek.com/en/product/productdetail.aspx?pid=38&mid=76&id=177

or...
GPC-6030 +/-60vdc "120v" @ 3A / 18kg. / $360usd.
http://www.gwinstek.com/en/product/productdetail.aspx?pid=38&mid=53&id=158

120v*3a = 360watts, 3A per amp could work, depending on amplifier efficiency.

Advantages: Super Regulated very low Noise.
more can be used in Parallel. SPD should be the best sound with lowest weight.
Dissadvantages: Precision comes with a Price.
*****************
Option B.
to use standard Rectifiers & cappacitor bank.
there is also several options:

1) Buy/Get a vintage Transformer from other amp.
2) Buy a New EI
3) Buy a New Toroidal.

made by Hammondmfg.com look interesting.
Part numbers:
182N60 / 4.17A / $130usd. / 3.81Kg. / 5.50" x 2.21"
182P60 / 5.21A / $187usd. / 4.67Kg. / 6.10" x 3.10"
182Q60 / 6.25A / $194usd. / 6.1Kg. / 6.40" x 3.10"
182R60 / 8.3A / $216usd. / 7.44Kg. / 6.50" x 3.50"
182T60 / 12.5A / $340usd. / 11.25Kg. / 7.20" x 3.50"

http://www.partsconnexion.com/hammond_toroid.html
http://mx.mouser.com/Hammond/Power/...xZ1z0j5qx&Ns=ManufacturerPartNumber|1&FS=True
http://www.digikey.com/product-search/en/transformers/power/786735?k=182 60
http://www.digikey.com/product-search/en/transformers/power/786735?k=182 60

Advantage: Low Price.
some models have overbuilt cappacity.
Dissadvantages: Big & Heavy.
Unknown symmetry, center tap precision.
No Regulation, Higher noise, no meters.
Possible Hum or Audible transformer Hum noise, probably a DC blocker is needed, PS Audio Humbuster 3.

other option would be to buy a compatible transformer from another amplifier company, like:
Crest Audio, Crown Audio, QSC.
http://yhst-93643794936312.stores.yahoo.net/xf00201000.html
http://www.qscaudio.com/support/library/schems/Discontinued/MXa Series/MX2000a.pdf
has +/-110v and +/-58v ct.

Toroids have more options:
Purchasing any Balanced Power Transformer, +/-60vac CT.
from Furman IT-20 II, P-2400 IT, BPT, Equitech, tortech, atlascables, toroid.com, Monster, thecableco.com

Equitech son of Q Jr.1 - $1200usd. each / 28Kg.
Furman IT $1700~$2500 / 36Kg~41Kg.
B-P-T $
Toroid BT1000X $ / 9Kg.
Transend $550usd. / $12Kg.
Plitron $ / Kg

Advantages: Higher precision center tap, Lower Hum, EMI & RF, Lower Weight than EI, Big Transformers can be used for both Amps.
"Equi=Tech uses a patented "bifilar" AC power transformer winding method which balances it's two output coils like identical twins. By maintaining near perfect phase accuracy."
http://www.google.com/patents?id=LwoEAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false

Dissadvantages: Precision comes with a Higher Price. More Power = More Weight = More Price. Bigger Transformer = Better Sound.

 

[ccheath]

For starter, you WANT raw DC rectified, filtered, and unregulated going to AMP1 and AMP2 individually. The regulator may get too slow to respond to fast changing pace of the main amplifier. A good main amplifier would have some level of PSRR (Power Supply Rejection Ratio) that keeps the hum down very well. Maybe use a 750va toroid dual 125vct secondaries [for mine, I'm thinking 1000va with dual 133vct secondaries], two 25A 400v bridge, and capacitor banks with capacitors with plenty of capacity and capable of high current but I wouldn't go too high on the capacity. That should be plenty for 250wpc. The center taps of those secondaries are normally centered. If they are off, it's usually around a volt or two. That will not be an issue but never 10v offset for this application.

For the preamp power, use a 60vct 1.5a (90va). Remember, the tuner will sap power from that circuit so don't go too low on the current. You can have that secondary added to the same toroid for the main amps but the total VA must go up. Ex. 750va + 90va = 840va output. Or just have individual transformers.

I am curious, is your scope tube filament okay? When you swapped those green wires, you could have fried it.

- - - - - - - - -

My thoughts for mine is:

1000va toroid with dual 133vct secondaries.

Another toroid with the following:

7.2v 2a (lights)
7v 1a with enough dielectric strength to handle over 600v (tube filament)
160-30-0-30-160-410 multitap secondary. I haven't decided on the current on this yet. (tuner, pre, scope)

Those two donuts will be stacked inside my receiver.
Spec on paper seem like it will be plenty of height and width room to accommodate two stacked toroids inside the receiver.
That's my thoughts so far.