Pioneer CT-F1000 Low sound output both channels

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Hey all,

I had a question regarding the ct-f1000. I've combed the forums and couldn't find anybody else with this issue, if this has been brought up before, please fwd me to that page.

I ended up getting this deck off craigslist. Guy wanted 100, got it for 50. Seeing how these sell for insane prices on ebay, didn't think that was a bad buy. This deck has been sitting for some time though, wasn't in the best of shape.

I tore it apart, ended up recapping the entire thing with a cap list I found on here, even replaced the 3 switches on top. This deck also had no FF or RW, come to find out the clutch had the infamous crack. I sent the clutch to Mark and he did a great job fixing it (Thanks again Mark), I also got the belt kit from WJoe and replaced everything. So the whole tape section is working fine now, like new actually.

I got to put a tape in and I have very little sound output, I have to turn the output pot all the way up and the VU meters correspond with the little output. The most they go is 2-3db if that. I also hooked up an input and got the same deal. I have to turn the input pot all the way up and the VU meters go to 2-3db. This is also with my amps volume knob about 50% in order to hear something in the speakers.

I checked the obvious, solder connections are good, no broken wires, fuses are good, I pulled the service manual and checked voltages here and there and all seem ok. Power supply is outputting the right voltages, the IC's on the IC amp boards (L&R) all have the proper voltages. I used some D5 deoxit and cleaned all the switches and stuff.

I'm still going through it, trying to see what could be the issue, but I just wanted to ask somebody on here if maybe I missed something or if somebody could point me into the right direction on what to look for as to what's causing the very low output on both input and output. I thought maybe a bad head, but I didn't see any visible damage and the factory glue on the screws are still intact, but the issue is also on the input side as well.

Any help is appreciated. Thanks,Frank.
 
First, and foremost, recapping the deck before assessing its function, and before getting it fully functional, was a grave error. Recapping should be the very last thing, other than calibration, that should be done. Also, each board should be recapped individually, and function should be checked after each board, so, if there is a problem, it can be easily narrowed down to affected boards and circuits. Now, you do not know if the deck acted in any certain way before the recap. Therefore, you do not know if you made some kind of error in the recapping. Errors made during recapping can be among the hardest to narrow down to cause.

From what you are describing, the signal reduction is common to both sides, as well as common to monitoring the tape, as well as the source. Also, the signal reduction is common to the output amp and meter amp. This would be a difficult problem to have. Since the signal has no common circuits between line out, the meters, and tape and source monitoring, except right at the output side of the tape/source switch, before the buffer and headphone amps see it. The error must be the same for both channels, and result in a signal reduction. Otherwise, source / tape commonality is found in the fact that both record and both playback Dolby boards are the same, and an error would have to be common to all 4 boards, such that the signal is reduced the same way for tape or source. Finally, there may be one or more low power supply voltages that are common to source and tape monitoring circuits, but low voltages usually show some distortion, in addition to signal reduction.

Good luck,
Rich P
 
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Hi Rich,

Yea, I realized that was prob a mistake. Prob was alot of the caps that were in this unit were leaking and had crowning going on. The tape mechanics were also bad, so I opted to just recap first and go from there. I did go board by board, all have been checked for right polarity and right capacitance. But I don't know if this was working prior or to the recap, I'm guessing no. So it's been recapped and the tape section is back to working.. now I just have to figure out why this has a signal reduction. I have not touched any of the transistors in this unit.

Is there any one area to check first/rule out? I checked the voltages on the power supply. They all seem to be correct.
 
Please read my previous post carefully. It tells you where to look, as far as I can surmise from here.

If you are going for correct polarity of installation of caps by marks on the board, it is rare with Pioneer, but possible, that marks can be wrong, that is why you install by what was the original orientation, part by part. Recapping board by board has little value, beyond organization, if you do not check for affects of the recap of each board, after recapping each board. If something worked before the board was recapped, and does not work after, you know where to start looking.

Correcting your problem will not likely be a DIY operation, unless you are an experienced tech, with a service manual and schematic. Please note that recapping will cause a need for a Record/Play/Dolby Calibration/Alignment, which is definitely not a DIY operation, without the requisite and specialized test tapes and test equipment. Some of the caps just replaced are part of tuned circuits, which will require re-tuning with new caps, or other components.
Good luck,
Rich P
 
what does it do with the test tone?
have you tried recording, and them monitoring the source?

The line out is fed from the source/tape monitor switch, as is the headphone jack and meters ON A SEPARATE CIRCUIT.

Look carefully IF there is a difference between the meter / headphones (TRY THE HEADPHONES) on one circuit and the line out on another, because the line out has a muting circuit, and that muting circuit is a point of commonality between the channels.
 
I will have to test out the headphones when I get home from work. I have not tried recording yet either. I was messing around with it late last night, when I engage the test tone, the needles come up to where it maxes out when I play a tape or have a line input. It is acting like the muting circuit is engaged. I read through the service manual and seen on the potentiometer board transistor Q405? (I don't have the manual in front of me at the moment) is part of that muting circuit and I'm not getting the right voltages on that. The center pin has 23V or so, nothing on the other 2 pins and if your looking down at that board, the left 3? transistors(again I'm at work and I'm just going by memory) don't have any voltages at all. Is it possible the transistor for the muting circuit went bad?

I was looking at some "similar" sound issue threads that people have with this unit and have read that some of the C711 transistors do go bad.

But I will try out the headphones when I get home from work later, but its acting like the muting circuit is engaged as the tape, line input and test tone all have the same kind of outputs..
 
Ok.. The headphones are playing fine, output pot is controlling the sound to the headphones as it should, but the meters dont match that output, it's still about 2-3db if that. I also had the line out going as well and it was silent to the speakers
 
we have narrowed it down considerably, line out muting is engaged somehow.

meters can be calibrated. muting circuit q1513, q1514 2sc711, npn small signal transistors (on the main board), the base signal (the emitter is grounded) controls the line out muting when the base is +0.6v or greater. These transistors can be safely removed for testing, they have multiple inputs contributing to their bases, so sorting THEM out will be a challenge.

but muting is common to both channels, so that does remove the possibility of a double error.
 
I was just about to ask.. Late last night I had pulled out the control board as I found another thread with somebody who had a muting issue with pause and it came back to this board. My plan tonight when I get home is to pull those C711s and test them.

The other thing I noticed, this deck is an older one. The service manual I have and a thread I found, mentions several updates(11 components I believe) that should have been done to this board. I checked my board vs the service manual updates and this is not an updated board. So I don't know if that's part of my problem here or not. Sort of what Rich was mentioning, I did the recap job, but I based it off of a list somebody had done. I want to say the list that was compiled was most likely an updated(current) list and seeing how my board is an older non updated one, maybe this is part of my problem here.

Think were narrowing it down. I'm going to test those C711s tonight, but should I also update the components as mentioned in the service manual?

I appreciate the help thus far!
 
Let's not complicate it now...
Recap means one by one replacing e-caps, LOOKING at each one for capacitance and voltage, paying CLOSE attention to polarity when removing original cap.

There have been instances of boards being mis-marked for polarity.

The LIST is just a convenience in having all the needed values present when the work is done, and THAT means a 100% VISUAL VERIFICATION of the unit, using the recap list BEFORE ordering the caps.
Had you done that, this update question would have come to light, and been extensively explored.

I strongly suspect the muting transistors are working correctly, but are being INCORRECTLY told to do the wrong thing - mute.
And there are multiple "inputs" to the bases of the muting transistors to be explored as to whom is wrong.

My statement "removed for testing", should have been more exact - my fault...
I should have said "removed from the board, and audio levels output at the line out output plug checked for full volume".
WHEN in circuit, with their emitters grounded, their bases will be at or slightly above +0.6v, which is all that's needed to cause muting. Anything over about 5v at the base will DESTROY the transistor - this is the resistor's function, to tame the mute signal voltage and prevent too much current flow that would destroy that transistor

I will need more time to research the "inputs" (which are resistors)

hey, this is my 20,000th post...
 
we have narrowed it down considerably, line out muting is engaged somehow.

meters can be calibrated. muting circuit q1513, q1514 2sc711, npn small signal transistors (on the main board), the base signal (the emitter is grounded) controls the line out muting when the base is +0.6v or greater. These transistors can be safely removed for testing, they have multiple inputs contributing to their bases, so sorting THEM out will be a challenge.

but muting is common to both channels, so that does remove the possibility of a double error.
There are, then, multiple problems. The headphone amp feeds the meter amp. If the headphones work correctly, or apparently so, then the "Line Out" could indeed be affected by the "Line Out Muting," which would account for the source and tape monitoring attenuation. However, the meters are not affected by "Line Out Muting," so the meters must either be maladjusted, or the meter amp must have some sort of problem (also common to both sides).

Multiple problems do complicate diagnosis. In such a case, chasing one down, at a time, is the best medicine, now that it looks like it has to be more than one.

Also, it is pretty much necessary now, to determine the skill level of the OP. Are you a technician? If so, what kind of experience do you have? What test equipment do you have available? If not a technician, how would you estimate your level of expertise? It will not help those rendering assistance, if incorrect assumptions on these topics are taken.

Enjoy,
Rich P
 
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First of all, I am a tech. If were going by day job, I am a technician/machinist.. If were talking tech from an electronics stand point, I have my AAS degree in electronic technology. This stuff, is rainy day/fun side projects for me. I like working on old stereo equipment, sometimes though.. errors happen like craigslist buys that don't work. What do I have on hand? I have a scope, and a volt meter, if I need other equipment I can easily get it. As for what I've worked on? or rather restored? I've done the KR-9600, done the SX-1250, done turntables, expanders, the KR-4070, a couple sansui's, dynaco 400, ect ect.. So i'm capable of tackling this beast.

Now that's out of the way.. project at hand.. I picked up this tape player from a craigslist ad. Guy wanted 100, I gave him 50. Ironically, my dad used to have one of these units and unfortunately sold it. Wish I still had that deck, because it was mint. So I am familiar with it's functionality. This unit, was in trashed condition. I was UNABLE to test it out due to the fact that most of the caps had leakage going on, the tape side was completely non functional and it had 2 blown fuses. I replaced the fuses, that solved that problem. I recapped this unit and let me clarify my definition of recap. I didn't just desolder something without even looking at the polarity or farad rating. Trust me, I have a number of recap jobs under my belt. I used the cap list that was on this site to aid me in a general "what to order" so to speak. I followed the service manual and went 1 by 1. My error in this.. was the fact that I didn't test it out as I went, again.. unable to do so. I usually do the board by board method on amps. What can I say, I went for the initial recap as that's usually not been a problem with working stuff, however..

So I got the unit fully recapped, I had Mark fix the clutch and got the belts from WJOE and that had fixed the tape section. and then here we are..

So for all I know this unit was non functional to begin with, being a craigslist buy n all. Prob is, I now have a recapped deck with a like new tape drive and a muted output. I've been burned on CL buys before because there is no return policy. Though, the $50 spent on this is not bad. I would get that back and then some if I listed this on ebay as is, but my intent is to fix her up and use it.

I should have called this thread, bad craigslist buy, now how do I fix it? lol.. I digress..
 
OK. Here is what I am able to glean:
  • You have a decent multi-meter with leads (pointy probes and clip-ons)
  • You have a decent scope with leads
  • You have a decent set of tools, suitable for electronic work
  • You have decent skills with a soldering iron, and have a decent one
  • You know how to read a schematic
  • You know how to test semi-conductors (diodes, transistors,etc.) with your meter
  • You have a service manual and schematic
For future projects, especially involving tape decks...
  • Blown fuses should trigger a bit of checking out (visual inspection, etc.) before installing new ones
  • Unless there is evidence of dangerous circuitry issues (blown fuses, toasted parts, etc.), transport functionality should be first to restore. Then, functional testing, up to the next issue to be solved, starting with playback, outputs, meters, record operation, etc.
  • Most of what folks think is leaking capacitors is actually glue, holding larger caps down, to pass vibration testing. Not all, but most.
  • Reasonable, full functionality should be present before recap, and I suggest a pre-recap calibration attempt, for pre- and post- comparison and potential future diagnostics
  • Boards should be recapped, one at a time, and after each board is recapped, functionality should be revisited, in case recapping caused a problem (solder bridges, cold joints, reversed parts, broken wires...we all have done it, and it is easier to find if you keep touched areas small and limited)
  • Recapping triggers a need for calibration, which requires suitable tools, equipment, and test tapes, specific to the job (a list can be posted if required). See here to count the cost before attempting to build the tower: http://audiokarma.org/forums/index....r-ct-f900-transport.67191/page-4#post-9925883
I have stacks of these high end decks around the place, and this is the procedure and ideas that I have learned to be governed by.

Now that we have this information, folks providing guidance know who we are talking to and at what level we need to talk.

Enjoy,
Rich P
 
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This is not a simple circuit set (lots of possibilities), so it might take Mark a bit to decipher. Mark has long been the resident remote diagnostician. I don't have much time for it anymore. Here is a set of hints, while we are waiting for Mark to pick the reins back up...

OK, analysis of potential causes of muting:
  • Both "Line Out" muting transistors are bad - not likely
  • Both "Line Out" muting transistors are being told to turn on - most likely
  • Mode-related muting activities, via Q220, are prevented if the "Source/Tape" switch is in "Source" position - errant muting action is active in "Source" position, so not likely
  • Power-related muting activities, from Q305, via D1503, have no intervening switch - most likely
Proof, I would expect positive voltage on the anode of D1503 is causing the dictation of muting via Q1503 & Q1504. Likely coming from Q305.

Likely causes, in order of likelihood:
  • Q305 is bad, E-C conducting when being dictated off
  • Q304 is bad, C-E conducting when being dictated off
  • C314 is leaking DC current, beyond what would be needed to charge it (about 3 secs) - Possibly installed backwards (+ lead should be approx. +24v)
  • Analogous circuit issue (solder bridge, lifted trace, bad joint, etc.), in the area of Q304 & Q305
Q305 is used to drive muting in power-related ways: initial power application, or power off (to prevent related popping out the "Line Out" connections)

You are a tech. This should be enough hints for you to find it. If the anode of D1503 is not being driven significantly positive, post what you do have. Point of interest: what is the voltage on the base of Q1513 (L-channel muting transistor)?

Enjoy,
Rich P
 
I appreciate the information. When I get home later this evening I will check out those components you mentioned and report back with my findings. Thank you.
 
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Alright. C314 was installed correctly. had 23.8v on the positive. I pulled out the Q305 and Q304 transistors and they tested bad on my meter. One of my meters has a port where you plug in the transistor, pnp or npn and it'll test it. I had some spare KSC1845's and KSA1013YTAs from an old project laying around, popped them in and SUCCESS! 1845 for 711 and 1013 for A628. I now have full output to the amp. Line in also is now working as is the test tone. So issue one is fixed. THANK YOU!

Issue 2: the meters are still dead. The right one flickers a little bit and left one is stationary. They both bounce a little when the deck is initially turned on but that's about it. I'm assuming the little silver "lever" that moves the needle is the calibration. But no matter where the needle goes, it's still not really working. I focused on the meter amp, checked the 3 wires on top, all good. I rechecked the caps(again they were installed as the old ones were removed). All the right farads. I also painstaking removed each transistor one by one and tested them, all test good. Any tips on what to look for regarding this meter issue?
 
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Whoah! You cannot use the KSC1845 in a position that requires a PNP transistor (Q305, 2SA628), and I'm not sure that the KSC1845 is a good replacement for Q304 (2SC711). Proper substitution research is required. Unpredictable operation, and possibly damage may be possible as currently installed.

markthefixer, if you are watching, maybe you could pull up the proper subs from your database...

Rich P
 
I edited my previous post. Im a tad over tired and got a little over happy that it's working. Sorry for the confusion.

I used KSA1845 for the 711 and used ksa1013yta for the a628.
 
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The best I can tell, at the moment, is that Q905 and Q906 keep the meters from pegging on power-up, acting as a meter mute. C915 & C916 turn on those transistors, one per side, for a brief period at power-up, until they charge up. The caps could be backwards, or the transistors could be bad. Otherwise, the meter amps, or related circuitry could be bad: Q901/Q903 and Q902/Q904.

Mechanical meter adjustments are not the issue here. VR901 and VR902 are meter adjustment pots.

Enjoy,
Rich P
 
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