1980 FM tuner dead

Discussion in 'Pioneer Audio' started by jtee1340, Feb 18, 2017.

  1. rcs16

    rcs16 Super Member

    Messages:
    3,184
    Location:
    Baldwin, Ontario, Canada
    I think it would be very difficult to find a PA3001, unless you scavenge one out of a old unit. Even then, you would want to know if it was working okay to begin with, as you have experienced already.
    If you plan on trying a HA11225, try these guys. $1.67 is pretty cheap, $4 post delivery is more.
    https://www.utsource.net/ic-datashe...m1ED2gjQlpzjzkU8vV3h1Z50u-dP9d-lfoaAgTs8P8HAQ
    I have heard good and bad, but mostly good.
     
    Last edited: Mar 2, 2017
  2. zebulon1

    zebulon1 Getting behind on work. I need help? Subscriber

    Messages:
    4,257
    Location:
    Las Vegas Nevada
    I've bought from those China sellers and had good luck. I'll order as many as seems fit in anticipation of a bad one.
    The op-amps in many of the Phono EQ's circuits like the HA1457's, I'll buy 10 to maybe find five that will work. If they work they will last.
    Sounds like a gamble and it is but on the whole it's worked for me.
     
  3. jtee1340

    jtee1340 AK Subscriber Subscriber

    Messages:
    509
    Location:
    Tampa Florida
    Well I took your advise Zeb. I also ordered a HA11225 from B&D. I want to try it. If it works cool.
    We shall see. I got a couple 16 pin sockets to be able to swap out chips as I troubleshoot.
    I'll be back when the parts get here.
    Thanks for all the help!:thumbsup:
    J.T.
     
  4. zebulon1

    zebulon1 Getting behind on work. I need help? Subscriber

    Messages:
    4,257
    Location:
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    BDent?
    Good, wonderful people, Matt is very helpful.
     
  5. jtee1340

    jtee1340 AK Subscriber Subscriber

    Messages:
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    Location:
    Tampa Florida
    I also ordered a few PA3001a from China just in case HA11225 doesn't do it.
    J.T.
     
    rcs16 likes this.
  6. clh69

    clh69 Active Member

    Messages:
    150
    Location:
    Columbus Indiana
    I recently had fm problem with a SX 1080, and i thought it was the the 3001, All the voltages didnt look right... turns out
    , it was the HA chip was the problem.. All is good now.
     
  7. jtee1340

    jtee1340 AK Subscriber Subscriber

    Messages:
    509
    Location:
    Tampa Florida
    Thanks for the input clh69. I am sure I am not through troubleshooting this tuner even if I get the meters to work ok with the 3001 chip. I know the 3001 has an issue since swapping it out with another chip, (even though I didn't know it's condition) did help get the signal strength meter working.
    I am taking one step at a time and will certainly look forward to getting this tuner working to specs.
    Thanks again, and stay tuned.
    J.T.
     
  8. txturbo

    txturbo AK Subscriber Subscriber

    Messages:
    827
    Location:
    Austin, TX
    I bet the PA3001a is just a rebadged HA11225. When I look inside the SX-1250 the tuner board has the IC's labeled Pioneer with the Hitachi part number below it. In the receiver wars it was common to put nudity in advertisements, especially touting tuners and such. Not so good to have your top receiver running Hitachi IC's at it's core so why not just stamp your own part number on it.

    Just a theroy....
     
  9. jtee1340

    jtee1340 AK Subscriber Subscriber

    Messages:
    509
    Location:
    Tampa Florida
    Well, I installed the HA11225 in a socket and the tuner acts the same as it did with the second Pa3001 from the parts unit. So it looks like the PA3001 I pulled out could be a good chip.
    The signal strength meter works good, but the tuning meter still goes about half way to the left between center and full scale left.
    If I turn the tuning knob, it changes about 4mv up and down. Not a lot of voltage swing to move the meter.
    I still adjusted the lower coil, and it does adjust the voltage about 20mv, but not enough to bring it to center whem tuned to a strong station.
    So, I am a little further along, but the new chip didn't do anything except point to something else causing the low voltage swing as you turn the tuning knob.
    I may have a bad component in the area of the Pa3001 chip.
    I guess this is why most people leave the tuner board alone, even in a recap. Pretty complicated circuit.
    Thanks for any help on where to look.
    Should I take voltage measurments on all the pins to compare what I had with the old chip?
    J.T.
     
  10. txturbo

    txturbo AK Subscriber Subscriber

    Messages:
    827
    Location:
    Austin, TX
    So just as a recap what else is working or not?

    FM reception?
    Signal strength?
    Stereo?
    Quartz lock?
    Fine tune?
    All power supply voltages good?
    AM?
    What happens when you push the multipath button?
    What adjustments have you made?
    What parts have you replaced?
    Do all other functions on the reciever work?
     
  11. rcs16

    rcs16 Super Member

    Messages:
    3,184
    Location:
    Baldwin, Ontario, Canada
    Well now, the mystery continues. These can be a challenge to trouble shoot and isolate the problem.
    Like I said earlier, I am not 100% certain that a HA11225 is a proper sub, it is very similar but exact, yet to be proven. The quad transformers are designed specific to the device. Also isolate and measure the surrounding comps, R19(16K), R20(4k7),L5(22uH)
    It is possible that there is something wrong with the quad transformer, there are capacitors in their on both sided of the transformer, they can go faulty. Requires surgery.
    You could test/measure the quad transformer outside the circuit, measure the coils inductances, inject and sweep a 10.7MHz signal and measure its response.

    I also suggested/recommended earlier, to fire up the other 1980 tuner pcb on your work bench and see if you can get its quad coil to center the tuning meter/afc ckt.
    All you need to do is wire it up, the supply +13.5VDC(terminal 6,7) and grounds(terminals 2,10, 35,40,42) connect up the tuning meter(terminal 30,31). Ground terminal 34 (IF i/p) to 35(GND). If you do not have a separate DC supply, you could get it from the 1980's supply.
    If the above works, you could then further the test and connect the RF FE, to the IF i/p(the one on the bench) ( use a piece of coax) and test its operation, monitor the composite audio at the o/p of the birdie filter, C23,R25, use a small cap 1uF to block DC (it is at +10.4VDC) to couple the signal into the tape monitor play jack and see if you get any audio when tuned to a station.

    It really comes down to method of elimination and faulty component isolation. easier said than done however.
    Once again, changing ecaps in this tuner will not take it out of alignment.

    Good Luck JT
    Rick
     
  12. jtee1340

    jtee1340 AK Subscriber Subscriber

    Messages:
    509
    Location:
    Tampa Florida
    FM reception?
    Seems pretty good. It will pull in most stations.

    Signal strength?
    The signal strength goes up to nearly full scale on the station that is normally the strongest.

    Stereo?
    Nope, does not work

    Quartz lock?
    Nada, does not come on.

    Fine tune?
    No, none of the three lights work in that set.

    All power supply voltages good?
    All power supply voltages are good.

    AM?
    AM seems to be working ok.

    What happens when you push the multipath button?
    I will try that tonight.

    What adjustments have you made?
    Only adjustment I have made is to the lower coil on the quad coil.
    Like I said, it does change the voltage level about 20 mv, but the meter swing is small with about 4mv change when tuner is turned off strong station.

    What parts have you replaced?
    In the tuner, nothing other than Pa3001 chip with HA11225.

    Do all other functions on the reciever work?
    Yes, the receiver seems to work in all functions.

    I have the equipment needed to do the test bed with the other tuner board. I will work on that this weekend.
    I have not pulled out the quad transformer to test it. I will do that this weekend also.
    I have always changed caps in the tuners on Pioneers that I have worked on in the past 2 -1280s 1 -1250 1 -1010. You are right, they never had issue after recap. Thing is, they worked before I started heheh.
    B & D said the HA11225 was a sub and so did the Pioneer site. It seems to be working as good as the PA3001a I pulled, so.....:dunno:

    Thanks for the input guys, I appreciate you coming back to this mess!
    I will post finds tonight.
    J.T.
     
  13. rcs16

    rcs16 Super Member

    Messages:
    3,184
    Location:
    Baldwin, Ontario, Canada
    Do this first before you mess with the quad transformer. I am sure you want to know the op. condition of this spare pcb. I hope you put a ic socket in the spare as well for the PA3001 chip.
     
  14. jtee1340

    jtee1340 AK Subscriber Subscriber

    Messages:
    509
    Location:
    Tampa Florida
    I have not installed a socket yet.
    I have one and will install it.
    Probably won't be able to set it up till this weekend.
    J.T.
     
  15. txturbo

    txturbo AK Subscriber Subscriber

    Messages:
    827
    Location:
    Austin, TX
    Any update on this?
     
  16. jtee1340

    jtee1340 AK Subscriber Subscriber

    Messages:
    509
    Location:
    Tampa Florida
    I can't say there has at the moment. I have the test board out of the parts unit and I have been slammed with work. Co-worker had a stroke and is out for a while it seems. When there are only two of you in the department, it gets crazy. Broken A/C units at my and my son's house.
    Plan to try to get back to it this weekend.
    Took forever to get the Pa3001a chips from China. I want to try one just to see.
    Thanks for asking.
     
    Last edited: Mar 28, 2017
  17. txturbo

    txturbo AK Subscriber Subscriber

    Messages:
    827
    Location:
    Austin, TX
    A local AKer has a 1980 with what appears to be similar to the problem described above. The tuner would play FM but no qtz lock, fine tune or stereo and the tuning meter was slammed to the left.

    Taking the easy path we tried replacing the PA3001 with the HA11225, the problem still existed.

    Since the problem is not just the tuning meter we decided to try and inject signals into the board to simulate RF, IF and MPX with a Sencore SG80. No joy.

    Next we started looking at what else was not working. We discovered that the touch lock sensor ckt was inoperable. This can be verified by measuring pin 13 to ground on the tuner board. Pin 13 should read aprox .62V when the tuning knob is touched and aprox 9V when not touched, this was verified on a known good receiver. On the receiver with the problem pin 13 was always at 12.3v. The 12.3V is coming from the reed relay coil on the APC board. One side of the coil is connected to 12.5V and the other side is driven by Q27 on the tuner board to ground, activating the relay.

    On the tuner board we removed Q27 to isolate the circuit and grounded PIN 4 of the APC board, activating the relay and driving the tuning meter to the center. Once we removed the ground the tuning meter was working almost normally again, it was still off center to the left but appeared to move left and right with tuning.

    With the tuner tuned to a station until the peak tuning was indicated on the signal strength meter the lower slug of the discriminator was adjusted until the center tune was centered. This allowed the stereo lamp and fine tuning lamp to work again. We could now tune stations again in stereo with the fine tune working.

    Checking the touch sensor ckt Q26 appeared to be open however when the transistor was removed from the circuit it appeared to work on the bench.

    Cycling the power to the receiver brought the problem back, this time with the meter slammed to the right so it was shut down. The meter was momentarily stuck to the right with the power off, may have been residual voltage? Powered up again and repeated the pin 4 grounding of the APC board and the unit was working again. At this point we stopped for the evening.

    So.... I am thinking that the circuit utilizes some kind of latch on power up. If the relay is not closed momentarily it will drive the meter to the left or right of center. You can sort of see this when a working unit is powered up. There is a moment of stabilization then everything works properly. As I read through pages 17-19 of the service manual I think this is the timing trigger working at power up. If the relay does not close the VCO will slam the IF high or low of 10.7 MHZ as indicated on the center tune meter.

    The next step will be to fix the touch circuit, this should restore the qtz lock.. hopefully :) The relay on the APC board appears to be driven by touch and the QTZ lock circuit.

    One other note... The receiver we were working on did not have a switch in the back for touch sensitivity. Looking through the service manual we discovered a service bulletin that describes retrofitting the receiver with the switch, adding a couple of resistors and changing components in the circuit. So I wonder if the OP's receiver has the switch or not? Could receivers without this switch be susceptible to a problem like this?
     
    native likes this.
  18. txturbo

    txturbo AK Subscriber Subscriber

    Messages:
    827
    Location:
    Austin, TX
    Tuner is working again...

    The APC relay drive transistors Q26, Q27 (2SC1914) were replaced with KSC2383YTA. This restored the touch and quartz lock function.
    The original PA3001 was reinstalled and is working fine. The tuner was cleaned and aligned.

    To the OP... Check your relay drive CKT...
     
    hrballenger likes this.
  19. jtee1340

    jtee1340 AK Subscriber Subscriber

    Messages:
    509
    Location:
    Tampa Florida
    Thanks for the update txturbo.
    I will do this for sure. Glad to hear this tuner is working good.
    J.T.
     
  20. txturbo

    txturbo AK Subscriber Subscriber

    Messages:
    827
    Location:
    Austin, TX
    Did you ever solve this problem?

    The receiver that I was working on last year is back with the same issue again. :yikes:
     

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