Hello My D6C has a strange issue where I am playing a cassette and it sounds great but after a few minutes it starts to sound distorted and fuzzy and progressively gets worse the longer I listen. I tried different cassette, changing the battery, Plunging in to the wall Adjusting the head. nothing helped. I also took it apart and looked at the belt seemed ok.
Have you had a look at the head after it starts to sound fuzzy? Is the cassette chemically breaking down and depositing white gunk on the head? The white gunk is quite easy to clean off the head but if you have a cassette with sticky shed syndrome (rare with cassettes) then you get a brown "cement" on the heads which takes about 20 minutes to clean off.
If the head is OK then the next thing to check is the mute module (CP301) if it is an earlier version of the D6C. The mute modules aren't fitted to the later "surface mount" versions. I have had several of these fail, especially on the older D6s. They normally fail gradually, distorting at first and then failing intermittantly before you lose the sound altogether. There are a couple of ways you can test for this. Firstly if you freeze the mute module, the sound may come back and sound quite normal for a few seconds until the module warms up again. Another way to test is to remove the module altogether. If the module is faulty then the walkman will play without it. The problem with running a D6 or D6C without a muting module is that the unit produces loud "thump" sounds when starting and stopping, which are a problem, especially when playing through and amplifier and speakers. The mute module momentarily attenuates the signal by about 44dB when starting and stopping to prevent these thumps. Since I value my speakers and eardrums, I decided to get some replacement modules made up which I now have for sale on Ebay. There is more information on my listing, including photos. I hope this helps.
Its happens on all cassettes and the head is clean. Do you have a picture of the module so i know what it looks like?
Thank You for Your post. I desoldered the mute module and now my D6 lives again. I also ordered new modules from You. I have a question about my other D6c where the problem is bad sound on recording. My radiodealer says it depends on broken IC and he could not find that part. It was a couple of years ago. I wonder if You can tell which IC he ment cos I never asked and what the number for this part is.
Thanks for the order. I'll get them posted to you later today. When you say bad sound on recording, in what way does it sound bad? If you get no sound at all with the recording level low - then as you increase the level you get broken bits of sound on the peaks - as you increase the recording level further you get more sound but it's still very broken and distorted - then you have no bias. In this case start by checking the screened wire which connects the erase head to the main PCB. I had the screen on the erase head wire desolder on a D6 a while ago and it stopped the bias / erase oscillator with the results I've described above. Once I'd resoldered the screen it was fine. Another possibility is that one or both of the EQ switching modules has failed. I have not had any experience of this myself so can't describe the symptoms, however a customer in France has had this so I am getting some replacement modules made up. I am waiting for the PCBs to arrive from China; once they're here I'll get them made up and listed on Ebay.
Thanks for Your respond. I Think it is the first alternative but Í will check later after work and respond.
Strange things happen. When I recorded through Line In there was no distorsion but through Mic In. I´m sure there was on both for a couple of months ago. Only thing I´ve done since that is sprayed som Contact spray on sthe rec lever Control when I thougth there was corrosion on it. Now when You try to rec through Mc In there is distortion in all levels and from the rec level controller. Could it be the Rec Jack that is the problem? I have even changed the belts rubber tyres.
What type of signal are you recording from? Is it from a microphone, a line out from another peice of equipment or a headphone output?
I have recorded via mic and from a portable cd-players headphone output. It is only problem with mic recording.
I think the problem may be that you are trying to record from a high signel level output into a mic input. A mic level signal is very low level (typically between 0.001V and 0.01V) and so the D6C has a mic amplifier to boost the weak microphone signal to a higher "line" level. The mic amp will try to boost the, already high level, signal beyond the maximum voltage which the amplifier can produce (the power rails) and cause the signal to clip or distort badly. If you want to record from a CD player, the best way is to take the signal from the "Line Out" jack, if the CD player has one, and feed it into the "Line In" jack on the D6C. If you don't have a "Line Out" jack on your CD player, can you please try recording from the "Line Out" jack of your other D6C into the "Line In" jack of your suspect D6C and let me know how you get on.
Ok,sorry there is a Little missunderstandig about the issue. I have no problem with Line in recording from different source but recording with a mic to mic input. There is lots of "scratch" when I move the mic in the mic in jack and when I turn the rec level Control. Nothing of this when Line In from for example a cd player.
A couple of questions for you both. I'm trying to work out what's going on by eliminating various bits. Firstly, do you get any scratch when you turn the recording level pot when you are recording using the line in jack? Or does the record level pot appear to work normally? Secondly, does your microphone work OK in other equipment, such as your other D6C? I've just been having a look at the D6C service manual and there appears to be some sort of switch built into the mic socket, which automatically switches the feeds into the record level pot from the line in jack to the boosted mic signals (L&R) automatically when you plug a jack into the microphone socket. If these switch contacts have become oxidised or dirty then I think it could produce the symptoms which you are describing. I'll have a look at my scrap D6C tomorrow and see if I can find anything out further.
I had a look at the Mic socket from my scrap D6C and it does have a 2 pole changeover slide switch built into it. The switch is in a separate module which can be removed and taken apart. The switch changes the inputs into the record level potentiometer from the Line In socket to the outputs from the Mic Pre Amp when a jack plug is inserted into the Mic socket. Here are some photographs. You will need to be very careful removing the switch module from the red plastic Mic socket casing, which is very brittle and will break easily - mine did. WM-D6C schematic showing the Mic socket and Line / Mic automatic switching. Position of the Mic and switch connections on the PCB. The Mic socket with switch module. Take care not to break the red socket when removing the switch module - it's brittle. The switch module. Remove the spring - be careful doing this. Lift out the wipers. They will lift out easily. The switch module disassembled.
Hello again. Back from Christmas. I have tested both Line recording and my microphone and there is no problem with these. I even sprayed contact spray in thef mic jack but it didn´t help. So You don´t think the problem depends on a dead IC as the radiodealer assumed?
Hello. I hope you had a good Christmas. It is difficult for me to tell where your fault is without your D6C on the bench in front of me. Do you get any distortion or scratching when you move the record level control when recording through Line In? Or does the scratching and distortion only happen when recording through the Mic jack? Do you get any distortion on playback is it only happening when recording? Also, is the distortion happening on both Left and Right channels, or on one channel only? If the problem is only happening with the Mic input and not with the line input then I do not think it is a dead IC as there are no ICs in the Mic pre amp stage.
Thank You! Hope You had a nice Christmas too! Yes, there is distorsion only when recording with a mic and then in both channels.
