Marantz 2215 hiss and hum

[bdondo]

Ugh., I just realized the "75" watt bulbs that arrive today are actually "75W equivalent" and are really just 53W. I never imagined buying a light bulb would get so difficult.

 

[bdondo]

I can' tell from the photo, but did you verify that the replacement transistors are installed with the correct leads connected. Some look like they are twisted to install. Please list the H# and replacement transistor for each that you changed. I apologize if you already listed it earlier in the thread.
View attachment 2985798

Here are the parts I used:

Part ID	Service Manual	Replacement Value	Replacement Brand	Replacement PN	Mouser Link
H701-H702	2SC945	KSC945	ON-Semi	KSC945YBU	KSC945YBU
H703-H704	2SC853	BD139	ON-Semi	BD139	BD13910STU

 

[bdondo]

Photos of the transistors on the power amp board attached.

 

[dankik]

Looks like parts were installed correctly from what I can see in the photos. Could have ordered the C suffix to get the matching ECB pin out. Thanks.

 

[bdondo]

Looks like parts were installed correctly from what I can see in the photos. Could have ordered the C suffix to get the matching ECB pin out. Thanks.

Oh.. I didn't even think about the suffix when ordering. Thanks!

 

[bdondo]

If this receiver's specs say it consumes 29W of power at idle (no volume), then is a 60W bulb in my DBT sufficient? I.e., if a 60W bulb is glowing pretty bright and the receiver lights turn off, is that a strong indication of a short?

 

[dankik]

When I recapped my receiver (52W), I started testing using a 40W bulb then went to a 60W bulb, so a 60W should be fine. Normally, it should glow bright for the first 3-4 seconds then dim down to a low glow. So, to answer your question, YES... you probably have a short somewhere.

 

[bdondo]

When I recapped my receiver (52W), I started testing using a 40W bulb then went to a 60W bulb, so a 60W should be fine. Normally, it should glow bright for the first 3-4 seconds then dim down to a low glow. So, to answer your question, YES... you probably have a short somewhere.

Thanks! I guess I'm not sure what the next step is. Maybe I need to assume I broke something in another part of the receiver while working on the power amp board.

 

[dankik]

Was the P700 power amp board the only one that you recapped? And, before you recapped it did the receiver work OK?

 

[bdondo]

I also recapped the P800 power supply board. After I did that, it powered on fine with the DBT (I didn't test audio, etc. though). Before I recapped the power supply board, audio worked fine other than some hiss. That's the only other board I (intentionally) messed with.

 

[bdondo]

After applying power with the DBT in place, the C703 and C704 caps have a charge. They're the only ones I tested because they're the only ones I can easily reach without disconnecting the board from the heat sink. This seems to imply that the short is somewhere past this point in the circuit, but I'm not sure about that.

 

[dankik]

Can you verify the installed polarity of caps C711, C712. (See diagram below) i don't know if it's your particular board or not, but the SM of C712 shows + 'UP' on the diagram and your photo seems to have a + on the silk screen towards the bottom. C711 & C712 seem to be oriented 90 deg different than the diagram? The schematic shows that the (-) should be connected to the base of H703/H704.

 

[bdondo]

Yeah, these ones are odd. The positive mark on the board wraps around.

 

[bdondo]

I've been assuming that the side with the black arrows pointing down on the old Elna caps is the negative, right? The other side has small "-" marks, so maybe I screwed that up
..

[Edit: I don't think I screwed this up]

 

[bdondo]

Can you verify the installed polarity of caps C711, C712. (See diagram below) i don't know if it's your particular board or not, but the SM of C712 shows + 'UP' on the diagram and your photo seems to have a + on the silk screen towards the bottom. C711 & C712 seem to be oriented 90 deg different than the diagram? The schematic shows that the (-) should be connected to the base of H703/H704.

I verified with a DMM that the negative side of the C711/C712 caps are connected to the bases of H703/H704.

 

[bdondo]

I also turned on the power with the DBT in place very briefly, and then measured DC voltage from each J pin to ground. The only ones that were essentially 0V were:
- J701, 702, 703, 704 (J701 and J702 have 0.47uF caps between them and ground, and 702/704 are ground)
- and J719, 720, 721, 722, 723, 724, 725, and 726 (723-726 are ground, 721 and 722 have no capacitors between them and ground, and 719/720 have 0.1uF caps between them and ground).
I'm not sure why J717 and J718 would have a voltage reading (about 2.1 V immediately after turning off the power).

 

[bdondo]

Well, I just made a dumb mistake that might actually help troubleshoot this. I accidentally plugged the receiver into the wall outlet directly, thinking it was my de-soldering iron (d'oh). I didn't notice for about 20 seconds. Nothing smoked or exploded, but the heat sink did get pretty hot in that amount of time.

Maybe that's a clue..

 

[dankik]

Maybe this will help. It's the P700 schematic from a 2220. It looks the same as yours but it lists voltages for all of the transistors. You can check yours to see if you find something amiss.

 

[bdondo]

Thanks @dankik -- I'm hesitant to take measurements with power supplied, but maybe I don't have much choice other than de-soldering and re-soldering everything.

How quickly should a heat sink get hot? It wasn't too hot to touch after 20 seconds, but it was pretty hot.

 

[dankik]

At idle with volume down to 0 and no input it should not get hot at all. Pretty much cool to the touch. If your DC offset voltage is off, then it might get warm. Maybe one of your output transistors H001-H004 is shorted?