• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Marantz 2220: Need help troubleshooting hiss

Aaron99

Aaron99

Active Member
I have been working on restoring a Marantz 2220. AK link to restore.


Overall it sounds pretty good. I notice that there is more hiss (than my other Marantz units) when the volume is all the way down. It does not matter which input selection it is on (AM/FM/PHONO/AUX) the hiss is there at 0 volume. It is even there with the headphones. I am guessing it is somewhere on the P500 board. Its not horrible, just there in the background like white noise. When there is any music playing I can not hear the hiss.

Any hints how to track it down? I do have an oscilloscope and a multimeter....
 
Register to hide this ad
txturbo said:
Is the hiss on both the left and right?
Click to expand...
The hiss (like white noise) is in both left and right channel. It is present using the headphones and speakers when volume turned down. It doesn't matter which input is selected. It doesn't matter if the main/remote speaker button it on or off. The only thing that suppresses the hiss is the Hi Filter button. That removes the hiss, but also takes out the top end when playing music.
 
Last edited:
If the unit is in Aux with no input and you just crack the volume pot off of minimum does the level go down? Same setup, does the hiss get louder when the volume control is turned up?
 
Aaron99 said:
The hiss (like white noise) is in both left and right channel. It is present using the headphones and speakers when volume turned down. It doesn't matter which input is selected. It doesn't matter if the main/remote speaker button it on or off. The only thing that suppresses the hiss is the Hi Filter button. That removes the hiss, but also takes out the top end when playing music.
Click to expand...
I don't know if you fixed this problem yet but I'm also working on a 2220 and have the same issue you have. I've only restored the P-800 board so far, up next I guess will be the P-500. I ordered some 2SC2240 Transistors already to replace the 2SC458LGA ones.
 
Thanks I'll keep you posted if I can solve my issue, I've got 3 other Marantz units a 1040,2240B and 2215B, this is the first with this type of problem, I'm in various resto stages with the others but no real issues, I have become a Marantz junkie! of late.
 
Outside chance it's a dc offset issue.Measure the dc voltage at the Speaker A left then right
speaker terminals, speaker selector set to A, volume to minimum. Input selector set to AUX with
nothing plugged into AUX. Expect 0-20mV. >50mV is high and >100mV way too high.

Probably some of the low noise caps (the orange ones) are loosing their edge. Certainly
the 2SC458 nust be replaced, they have a bad history of going noisy.
 
I had an experience with an amp hissing on both sides after accidentally installing a 10,000pf orange drop "pp" in place of a 1000pf ceramic in the same location of both amp boards of a 2325 once.
I had the caps misidentified.
 
New update on hiss, on the P-500 board I replaced the 6 2SC458LGA with 2SC2240 transistors and the hiss has vanished, so this problem seemed to be from these type transistors, in my case anyway. I have 2 of these transistors to replace in the phono board which will be my next upgrade. The 2220 is laid out very nice so working on the boards is fairly easy.
 
Last edited:
Andy Hi-Fi said:
New update on hiss, on the P-500 board I replaced the 6 2SC458LGA with 2SC2240 transistors and the hiss has vanished, so this problem seemed to be from these type transistors, in my case anyway. I have 2 of these transistors to replace in the phono board which will be my next upgrade. The 2220 is laid out very nice so working on the boards is fairly easy.
Click to expand...
Thats great. I will take a look and see if that is my issue as well.
 
The 2SC458LG's should be pre-emtively replaced, KSC1845FTA are suitable.
KSC1815 is the lower voltage version, these will also be ok in this amp
with 34V rails.

Since you have a scope, some test points would be,
PREAMP (P500)
- J501,2 (input)
- J504,5
- J507,8
- J511,2

POWER AMP
J701,2
J715,6 (23Vdc)

Set scope to AC.

This is "top down/left to right" so once you encounter the hiss there is no
point going further foward. Go to previous measurement point and confirm no hiss.
 
So I put the 2220 back on the bench tonight. Trying to see if I can get rid of the 'snow' hiss.
One other symptom. When volume is all the way off, switching to FM there is a slight click sound in both headphones and speakers. Raising the volume does not increase the volume of the click.

Anyway. I think I have isolated the problem to the P500/P650 board.

When I ground J512 and J511, the 'snow' hiss goes away. The click disappears when switching to FM.

When I test grounding further upstream on J501 and J502 there is no change (snow/hiss still there)

Replaced:
C501/C502 witth WIMA Film 0.22uF
C503/C504 with 4.7uF 50V Electrolytic
C505/C506 with Wima Film 1uF
C513/C514 with Wima Film 0.47uF
C515 with 100uF 63V Electrolytic
H501-H506 with KSC1845FTA.

Checked the grounding of P500 by using clips to make secondary ground connection from J503 to chassis.

Things I've noticed:
J510 is 39.4V instead of 34V.

Measurements:
Transistor Voltages (E C B): (E C B) spec
H501: 5.4, 26.8, 6 (measured): 4.3, 22.6, -?- (Spec)
H502: 5.4, 26.8, 6 (measured) :4.3, 22.6, -?- (Spec)
H503: 0.039, 1.25, 0.56 (measured): 0.043, 1.3, 0.58 (Spec)
H504: 0.043, 1.26, 0.58 (measured): 0.043, 1.3, 0.58 (Spec)
H505: 0.59, 14.48, 0.64 (measured): 0.68, 10, 1.3 (Spec)
H506: 0.63, 14.76, 1.26 (measured): 0.68, 10, 1.3 (Spec)

Any pointers where to look next would be appreciated.
 
mbz said:
The 2SC458LG's should be pre-emtively replaced, KSC1845FTA are suitable.
KSC1815 is the lower voltage version, these will also be ok in this amp
with 34V rails.

Since you have a scope, some test points would be,
PREAMP (P500)
- J501,2 (input)
- J504,5
- J507,8
- J511,2

POWER AMP
J701,2
J715,6 (23Vdc)

Set scope to AC.

This is "top down/left to right" so once you encounter the hiss there is no
point going further foward. Go to previous measurement point and confirm no hiss.
Click to expand...


I did try to visualize the hiss/snow. I can't seem to 'see' anything on the scope. I get a straight line, I have adjusted to the smallest volt/div and can possibly see a little fuzzy line, but nothing that would show me the problem. I can see the audio waveforms on the scope when looking at points specified when turning up the volume.
 
You can usually hear just a mV or so of hiss with phones or even putting your ear next to speakers. Most scopes don't have enough gain to see it at all points in the circuit. That's the main reason I use an ancient boat-anchor scope, because it can take a high gain vertical plug-in. IMO, all the 458 transistors ever made should be placed in an ICBM and launched to the moon. Actually, the low gain group ones seem a bit better, but I wouldn't trust them. If you have a click on switching, there's probably a slight DC difference between the things you're switching. It may be normal, but look at cap leakage. Once again, the levels might be far too low to see on the scope. Not sure about the "snow" hiss, but even the best circuits will have some trace of noise.
 
ConradH said:
Not sure about the "snow" hiss, but even the best circuits will have some trace of noise.
Click to expand...
Certainly agree with ConradH, in vintage gear expect some hiss, especially noticable through headphones and sensitive spkrs however should not be audible
when music playing. It's up to you to decide if excessive. J511,2 is the audio path so grounding them will kill all audio. The high filter will reduce the hiss confirming
it's coming from the preamp. If you are real keen you can buy/build an audio probe, it's just a battery powered chip amp from china for $2-$5 then probe various
test points listening for hiss. If both channels are affected then maybe look at using a bypass cap on the main filter, might help.
 
Thanks for you reply....

There is much more noise that usual. I have 15 other 22xx series and this one is at least 3 or 4 times as noisy.

So I did another test.
I removed the wire attached to J512. (Disconnect preamp output) The left channel now has the normal amount of noise from the downstream amplifier board.
I placed a 1k hz signal at 0.005v on the wire attached to J512 to test the signal downstream and it sounds good. Much reduced hiss, no click when switching to FM.

More testing to come.... Think I might watch a game....
 
Last edited:
@Aaron99 I'm curious if you ever figured your hiss problem out.

I have a 2220 that I've replaced all the ecaps with quality ecap replacements or film caps on the p800, p500, p900, and main ripple filter. I've also replaced the 6 2sc458 transistors on p500 and 2 on p900.

I've had the same hiss symptom as you, although curiously, I also can't seem to visualize it on my scope's fft. It's possible the white noise is uniform enough that it's just the noise floor without any peaks.

I hear the hiss through phones and speakers, even when the volume knob is at zero. To prove to myself it's p500, I added preamp outputs tapped off of the output of p500 and I hear the hiss on a totally different amp.

I've paused my recap work while I dig into this issue. At this point, I only have p700 and the DC coupling caps left to rework.
 
You must log in or register to reply here.
Back
Top Bottom