2220B - yet another tuner issue

Discussion in 'Marantz Audio' started by Uncle Bambi, Dec 26, 2017.

  1. Uncle Bambi

    Uncle Bambi Funky Tut

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    OK - two Marantz receivers in a row have been on my bench, and both have tuner issues. :( On the previous 2216B I recapped the tuner and caused my own problem. On this 2220B I HAVE NOT touched the tuner at all.

    This issue is a "no stereo light" in FM mode. The Stereo light illuminates when I switch the selector to AUX, so the bulb is good. I get good reception and what seems like a strong signal, but no Stereo light. Depressing and releasing the Mono button does not give me an audible difference is signal sound. I checked Pin 6 on IC H301 via TP J305, and there is 10v present (schematic says 9.7) so that's good.

    So what am I left with? The only components I see between that 10v on pin 6 and the light are the selector switch and the FM muting switch. I've De-Oxit'ed both, but maybe they need some more?

    I went ahead and recapped and overhauled the receiver, and it sounds great. But I'd like to square the tuner away, as I plan on gifting this to a friend for his garage stereo.

    I do not have an oscilloscope or frequency generator..... are there any simple checks, tweaks, or troubleshooting that I can do in the hopes of getting the tuner to work properly?
     
    Last edited: Dec 26, 2017

     

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  2. catrafter

    catrafter Marantz Specialist Subscriber

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    Pin 6 of the HA1156 chip (H301) should go near ground to turn the lamp on.
    H302 is to prevent the FM VCO from interfering with AM. If H302 is ON, it will kill the VCO and you will have no stereo.
    H303 is to prevent stereo operation if the signal is too weak. If it is ON then the HA1156 is forced to mono operation.

    HA1156 operation, selector switch in FM, mono switches not pressed:
    Pin 1, power, ˜13VDC
    Pin 2, signal input, ˜560mVACRMS signal(max), ˜3VDC
    Pin 3, preamp output, ˜5.3VDC
    Pin 4, left audio output, ˜300mVACRMS, ˜10.4VDC
    Pin 5, right audio output, ˜300mVACRMS, ˜10.4VDC
    Pin 6, Lamp driver output, ˜1VDC=stereo
    Pin 7, chassis ground
    Pin 8, Phase comp out and stereo lamp LPF in, ˜0VDC= force mono operation, ˜2.3VDC stereo operation
    Pin 9, lamp driver input, ˜2.5VDC
    Pin 10, VCO monitor test point, 19KHZ ˜2VACRMS, ˜1.8VDC
    Pin 11, phase comparator input, ˜5.3VDC
    Pin 12, Phase comp output to VCO LPF input, ˜2.5VDC
    Pin 13, VCO error voltage, VCO LPF out, ˜2.5VDC
    Pin 14, VCO adjust, ˜3.4VDC
    The HA1156 datasheet tells the story...

    Tom
     
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  3. Dingman

    Dingman Do you know where your towel is? Subscriber

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    Ya, I've had multiple Marantz with that exact issue - just won't break into stereo. I haven't addressed this yet, but I will using the excellent check-list catrafter has posted - I've seen it in several posts, and will certainly use it.
     
  4. Uncle Bambi

    Uncle Bambi Funky Tut

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    Tom,

    Thanks for the detailed and informative response. I went and checked the pin outputs on the HA1156, and compared them to your list. My actual readings are bolded:

    HA1156 operation, selector switch in FM, mono switches not pressed:
    Pin 1, power, ˜13VDC 11.1v
    Pin 2, signal input, ˜560mVACRMS signal(max), ˜3VDC 3.1v
    Pin 3, preamp output, ˜5.3VDC 5.2v
    Pin 4, left audio output, ˜300mVACRMS, ˜10.4VDC 8.2v
    Pin 5, right audio output, ˜300mVACRMS, ˜10.4VDC 8.3v
    Pin 6, Lamp driver output, ˜1VDC=stereo 10v
    Pin 7, chassis ground 0v
    Pin 8, Phase comp out and stereo lamp LPF in, ˜0VDC= force mono operation, ˜2.3VDC stereo operation 0v
    Pin 9, lamp driver input, ˜2.5VDC 2.3v
    Pin 10, VCO monitor test point, 19KHZ ˜2VACRMS, ˜1.8VDC 1.56v
    Pin 11, phase comparator input, ˜5.3VDC 2.20v
    Pin 12, Phase comp output to VCO LPF input, ˜2.5VDC 2.37v
    Pin 13, VCO error voltage, VCO LPF out, ˜2.5VDC 2.37v
    Pin 14, VCO adjust, ˜3.4VDC 3.29V

    H302 has 0v at the base, as measured at TP J303 and J304. H303 has 0.6v at the base, as measured at TP J306

    Right off, I see that pin 6 voltage is too high and pin 8 is too low according to your post. I'm confused because the schematic shows pin 6 at 9.7v and pin 8 at .3v, which is essentially the opposite. Any idea what could be causing the problem?

    I see that pin 8 and pin 9 are tied together via a tantalum .22uf capacitor and then feed the collector of H303, and pin 6 goes straight to the mono and selector switches. I'm not really sure how this circuit works and would be grateful for some insight. Could the Mono switch be the culprit?
     
    Last edited: Dec 28, 2017
  5. SoCal Sam

    SoCal Sam Lunatic Member

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    Catrafter is the man. Back in my flipper days when BOTL and MOTL receivers fetched under a hundred, there was no money in them for tuner service. I found that cleaning the oscillator trimmer on the tuning gang cleared about 3 out of 4 "no stereo". Almost all vintage receivers and tuners came in with no stereo condition and this cleaning trick saved my bacon many times. It works on TOTL receivers as well, my ex-Rotel RX-1603 just got the osc. trimmer cleaning.
     
  6. Uncle Bambi

    Uncle Bambi Funky Tut

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    Can you guide me in how to clean the oscillator trimmer on the tuning gang? I'd really love to get this working properly, but I don't want to go banging on it willy-nilly if I can help it. Any advice/guidance/instruction would be very gratefully received!

    Here's a pic of my tuning gang.... can you tell me where the oscillator trimmer is and how to clean it? Is it the screw I have marked?

    upload_2017-12-28_13-28-48.png
     

    Attached Files:

    Last edited: Dec 28, 2017

     

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  7. Steven Tate

    Steven Tate AK Subscriber Subscriber

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  8. Uncle Bambi

    Uncle Bambi Funky Tut

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    Thanks for the link, I'll go over the information carefully and see if anything there can help me.

    As an aside, the tuner pulls in signals nice and strong. I just cannot get the "stereo" lamp to light.
     
  9. SoCal Sam

    SoCal Sam Lunatic Member

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    Again, catrafter is the pro here. I am strictly amateur. I will always recommend seeing a tuner tech but if you are in a flip situation... Yes, the trimmer you indicate is the oscillator trimmer. Spray with residue free contact cleaner, turn trimmer to work the contacts and return to original position. Sometimes the trimmer will be soldered into position, its ok to break the joint. This trimmer is the one to use when centering a station to the dial pointer.
     
  10. Uncle Bambi

    Uncle Bambi Funky Tut

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    If you're an amateur, you're one pay grade above me..... I'm a hack. :) Not a flip situation, but giving it ti a friend for his garage.

    Thanks for the info so far, and for confirming the location of the trimmer. I'll get some residue free contact cleaner and give it a try..... although I'm pessimistic about the outcome because the signal is strong, just no stereo light.
     
  11. Uncle Bambi

    Uncle Bambi Funky Tut

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    So, I cleaned the trimmer with CRC QD Contact Cleaner (non-residue), with no change in symptoms. I've located the muting threshold trimmer at R253, but am reluctant to start tweaking on it unless someone more knowledgeable than me thinks it is a good idea. The unit is pulling strong signals, but still no stereo light. If I set the selector switch to a different output (AUX, for example), I can toggle the light on and off with the mute switch.... so the switch appears functional. I even tried replacing the small BP capacitor between pin 8 and 9 of H301, but that did not change anything so I put the original back.

    I'm at a loss - hopefully someone here has some ideas on what to look at or try next......
     

     

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  12. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    It seems the question is why does pin 6 have 10V when tuned to a stereo station? Have you checked H302 and H303 that Tom mentioned? Maybe some of the passive components in their circuit? Just spit balling here.
    Steve
     
  13. rBuckner

    rBuckner Luv 2 Restore Subscriber

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    I'd be looking into why pin 8 is wrong, pin 6 is just reacting to that I'd think as it's the lamp driver and is a symptom and not a cause.

    To be accurate, the trimmer cap for the oscillator is to set the frequency more at the "108" end. There is an adjustable inductor for the low end that requires the proper plastic tuning tool to attempt to turn. Do not be tempted to use a standard steel allen wrench! I don't think front end sensitivity is your issue here either anyway.

    I have seen the muting control set to the wrong end before causing issues with the stereo operation. Just pot a small felt pen dot at the top and try turning it to either extreme to see if that's it. If not, return it to where it was.
     
  14. catrafter

    catrafter Marantz Specialist Subscriber

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    A check of the DC voltage at J208 will tell us if the detected IF signal strength is high enough to trigger stereo operation.

    Tune in a strong station that should be in Stereo, set meter to read DC volts, black lead to chassis, red lead to J208. Look for something very close to zero volts for Stereo Ops. This is affected by R253 the 'muting threshold'. Randy is correct, mark it's location before tweaking it.
    If you look at the service manual the voltages in parentheses are when strong stereo station is tuned in.

    Tom
     
  15. Uncle Bambi

    Uncle Bambi Funky Tut

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    OK - I tuned to a strong station, set the meter up as directed, and measured at TP J208. I get 0.625vdc. I marked the trim pot R253 and swept it through its arc with no change. Voltage at the TP stays steady, and the stereo light does not come on. I tried moving across the dial to try other stations, with no effect. According to the schematic, I should be seeing either 0.06v with a strong signal, or else 7.4v...... correct?

    Could R253 be bad?
     
    Last edited: Dec 29, 2017
  16. Beamer302

    Beamer302 AK Subscriber Subscriber

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    You also might want to check the voltages on H209,H208 and H207. While you are at it , the other ones on that board as well. In the service manual it talks about which transistors trigger each other . Your voltages should change when tuning in and out of a "stereo" signal. If the circuit is working. The voltages are on the schematic. You might find a bad transistor.
     
    Last edited: Dec 29, 2017

     

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  17. Uncle Bambi

    Uncle Bambi Funky Tut

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    Good idea...........I will measure them all. Maybe something will jump out.....Also - I pulled R253 and checked it out. 0 - 90k ohms through the sweep, so it looks good.

    H201
    E - 2.78v
    C - 8.73v Looks like all the right voltages here
    B - 3.31v

    H202
    E - 2.67v
    C - 7.69v Looks like all the right voltages here
    B - 3.39v

    H203
    E - 2.78v
    C - 8.73v Looks like all the right voltages here
    B - 3.10v

    H204
    E - 1.94v
    C - 9.21v Looks like all the right voltage at the collector and base, emitter maybe a bit low low?
    B - 3.24v

    H205
    E - 1.55v
    C - 13.3v Looks like all the right voltage at the collector, others look low?
    B - 1.88v

    H206
    E - 2.7v
    C - 12.17v Looks like all the right voltages here
    B - 3.49v

    H207

    E - 0.03v
    C - 13.7v Mono voltages present
    B - 0v

    H208
    E - 0v
    C - 0.14v Mono voltages present
    B - 0.034v

    H209
    E - 0v
    C - 7.13v Mono voltages present
    B - 0v

    It would appear that all the collector voltages are at the value specified for mono operation - the VDC value not in parenthesis. H206 seems to have the values as specified in the schematics, as do the others, more or less. Does this tell me anything useful?
     
    Last edited: Dec 29, 2017
  18. rBuckner

    rBuckner Luv 2 Restore Subscriber

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    I just printed out a blow up of the 2220B P300 board schematic. I'll write in the measured voltages and see what jumps out. Recovering from a nice strong large margarita from the local Mexican restaurant I just had at dinner - not that I mind the effect!!

    P.S. It seems I should have printed out the P200 schematic chunk! Yo boy!!!
     
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  19. Uncle Bambi

    Uncle Bambi Funky Tut

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    AWESOME - thanks!!!
     
  20. rBuckner

    rBuckner Luv 2 Restore Subscriber

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