Marantz SR5004 with missing IC 51

[Crystaleyes]

Hi all.

Was given a clean, but very dead, Marantz home-theatre, all-in-one, type of thing which a friend bought for peanuts of off one of the homeless street sellers, so I have no idea as to it's history.

Anyway, the power switching board had a blown fuse and burnt out a trace, so I figured that may well be all that was needed, but alas, no.

Here in Brazil we often get power surges which frazzle the power supplies, but this one remained totally dead.
Looking through the service manual, there are a few suggestions for dead units, so I checked some diodes, the transformer and then where it said to check IC51... It was just not there!

Attached below is some photos and the part info from the manual, however I can't seem to find any IC with these numbers, so if anyone has any idea of which IC number it is, or even a Marantz they can look into, it would be well appreciated.

[budwich]

Re: Marantz SR5004 with missing IC 51

locate CN85 (pin 20) and trace the tracks along towards any next device.

[Crystaleyes]

Re: Marantz SR5004 with missing IC 51

locate CN85 (pin 20) and trace the tracks along towards any next device.

Sorry, why would I do that? I think before anything the missing IC needs to be replaced, no?

[R_J]

Re: Marantz SR5004 with missing IC 51

ic51 and all the support components are not installed on this model. If you look there is a lot more missing on that board.
See Page 91,92

SR5004 : Not use parts without specific marking

IC51 etc. is used in the SR6004 only

You need to provide more information... which fuse was blown? Do you have ANY voltages on the regulator board connectors BN20, BN22?

[Crystaleyes]

Re: Marantz SR5004 with missing IC 51

ic51 and all the support components are not installed on this model. If you look there is a lot more missing on that board.
See Page 91,92
IC51 etc. is used in the SR6004 only

You need to provide more information... which fuse was blown? Do you have ANY voltages on the regulator board connectors BN20, BN22?

Aha!

Good to know. Thanks. Although I am a bit confused as to why IC51 would be listed in the service manual which is specific to the S5004 model if it is not used? IGoing by the state of the solder on the traces, it does appear to me that a chip was removed at some point.

Anyway, the blown fuse was F200, a T5A on the regulator board, and there are NO voltages on the regulator board bridge rectifiers, nor is there any AC from the transformer, although I do get around 0.5v on a couple of pins of the other end of the ribbons connected to BN20 and BN22.
There is also 5v to gnd on the CN85 connector.

I already removed the front panel and verified that the main switch is working and that the cables and connectors were seated or soldered properly.

One thing that I need to look into more is that on the main board, where the mains AC is connected, there is a 2 wire transformer connection which is separated from the mains via a relay (see below). With the transformer connected, the connector pins register the mains voltage, however once the transformer is connected, it reads zero.
The thing that confuses me here, is that on the PCB below this connector is written, 'From Transformer', yet surely this is where the mains 'goes to' the transformer?

Can't remember the axact readings on the trafo but there were no open nor shorts.

[R_J]

Re: Marantz SR5004 with missing IC 51

You need to have A/C voltage to the primary of T600 standby transformer, If you do you should have +5VL, and also about +12v across C655 to supply the relay etc. CN64 connects TO the main transformer and the relay contacts supply A/C to the main transformer.
This manual covers two models, but it does not list it on the front page for some reason.
Does your version have a MOMS switch across BN61?

All the component locations on that board were pre soldered, but not all components were installed for the SR5004, the SR6004 has more hdmi jacks etc.

[Crystaleyes]

Re: Marantz SR5004 with missing IC 51

You need to have A/C voltage to the primary of T600 standby transformer, If you do you should have +5VL, and also about +12v across C655 to supply the relay etc.

As mentioned, there 'is' +5VL on CN85...

I can't access C655 without taking the whole thing apart again so I may just put AC across the transformer and then take readings, just to 100% confirm that is not the problem.

Does your version have a MOMS switch across BN61?

No.

[budwich]

Re: Marantz SR5004 with missing IC 51

Sorry, why would I do that? I think before anything the missing IC needs to be replaced, no?

well... IF the pin on cn85 is supposed to have 5vl on it... that has to come from somewhere... and if that somewhere may be the "missing ic"... so if you follow along the trace you should either come across the "missing ic" or another one that you can determine what its doing with not having 5v out of it (ie. a regulator or converter maybe).

I haven't looked thru the service manual (only what you have posted) but other posts have so hopefully your "lost ic" will reconciled one way or the other.

[R_J]

Re: Marantz SR5004 with missing IC 51

As mentioned, there 'is' +5VL on CN85...

I can't access C655 without taking the whole thing apart again so I may just put AC across the transformer and then take readings, just to 100% confirm that is not the problem.



No.

I missed that you had standby voltage, Does the voltage change on BN82 pin 8 change when you press the power button?
The signal to turn on the relay is STANDBY_RL This signal is sent by the main cpu

[Crystaleyes]

Re: Marantz SR5004 with missing IC 51

well... IF the pin on cn85 is supposed to have 5vl on it... that has to come from somewhere... and if that somewhere may be the "missing ic"... so if you follow along the trace you should either come across the "missing ic" or another one that you can determine what its doing with not having 5v out of it (ie. a regulator or converter maybe).

I haven't looked thru the service manual (only what you have posted) but other posts have so hopefully your "lost ic" will reconciled one way or the other.

I understand now. Thanks for the suggestion.

Been juggling between working, cooking, cleaning and doing this amp, so please excuse the disjointed replies

[Crystaleyes]

Re: Marantz SR5004 with missing IC 51

I missed that you had standby voltage, Does the voltage change on BN82 pin 8 change when you press the power button?
The signal to turn on the relay is STANDBY_RL This signal is sent by the main cpu

Pin 8 changes from around +1v to +5v when the power button is pressed.

Another thing that I've noticed is that on BN22, the first 4 pins are supposed to be -12v, gnd, gnd, +12v, whereas... They measure +7v, gnd, gnd, and +39v.

The rest of the +5v and +8v are all well under...

(Not quite sure why there is an AGND, DGND and VGND, but sure that will become clear)

[R_J]

Re: Marantz SR5004 with missing IC 51

What do you measure if you use AGND, do you then have -12v, G, G, +12v If it is still wrong, check that R217 and R218 (fuse resistors) are ok and that one is not open.

[Crystaleyes]

Re: Marantz SR5004 with missing IC 51

What do you measure if you use AGND, do you then have -12v, G, G, +12v If it is still wrong, check that R217 and R218 (fuse resistors) are ok and that one is not open.

It is still wrong, so shall check those resistors. Thanks.

EDIT: The resistors are ok.


Can't really take any more readings at the moment as have pulled the various LM and KIA voltage regulators.
Some of them have failed so I'll get to the shops and report back once they've been replaced... Should have checked them before. Doh!

[Crystaleyes]

Re: Marantz SR5004 with missing IC 51

just a quick update..

Couldn't find the KIA578R05 nor KIA278R00 regulators in the local shops, so shall get back once I have sourced them...

[Crystaleyes]

Re: Marantz SR5004 with missing IC 51

Update:

After replacing the voltage regulators, there is no longer any voltages at all on the BN22 connector so it is looking like the whole unit needs to be disassembled again.

I say this, because the connector CN64 where the AC leaves the main board for the transformer, has 127v across it until I connect the trafo, at which point it drops to zero across it, although I can get 127v from the connector - to ground.
As it isn't blowing any fuses, I'm ruling out the transformer being shorted, so shall look to see if something on the main board is failing under the load of the transformer?

Any suggestions would be welcomed at this point

[petehall347]

Re: Marantz SR5004 with missing IC 51

bad neutral connection if its mains grounded .

[Crystaleyes]

Re: Marantz SR5004 with missing IC 51

bad neutral connection if its mains grounded .

It's not mains grounded and neither is the building AC supply, although I 'was' standing barefoot on a stone floor and touching the chassis whilst taking the measurements.

This is something I can check though, when I get back on the unit tomorrow.

[R_J]

Re: Marantz SR5004 with missing IC 51

Update:

After replacing the voltage regulators, there is no longer any voltages at all on the BN22 connector so it is looking like the whole unit needs to be disassembled again.

I say this, because the connector CN64 where the AC leaves the main board for the transformer, has 127v across it until I connect the trafo, at which point it drops to zero across it, although I can get 127v from the connector - to ground.
As it isn't blowing any fuses, I'm ruling out the transformer being shorted, so shall look to see if something on the main board is failing under the load of the transformer?

Any suggestions would be welcomed at this point

The reason you measure ac voltage across CN64 is due to C632 across the relay contacts, that is conducting the voltage but at almost no current, as soon as you connect the transformer that phantom voltage disappears.
You need to trace the standby line which turns on the RY62 relay.

[Crystaleyes]

Re: Marantz SR5004 with missing IC 51

The reason you measure ac voltage across CN64 is due to C632 across the relay contacts, that is conducting the voltage but at almost no current, as soon as you connect the transformer that phantom voltage disappears.
You need to trace the standby line which turns on the RY62 relay.

Thank you. I'll do that and see what turns up

[Crystaleyes]

Re: Marantz SR5004 with missing IC 51

From what I can understand (and I could be completely wrong) after looking at page 97 of the service manual (attached below), the standby relay is activated via pin 136 of IC105, however pin 136 has zero volts output when the on/off switch is pressed.

The 'Wake Up' signal from the switch is present at pin 8 of IC105.

As I said, not sure if I have completely overlooked something obvious, nor do I know how to test a 144 pin IC.
The VCC and VSS1 pins have +5v across them.

I'm wondering about bridging the RY62 relay to see if the rest of the unit switches on when connected to the mains?