|
Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
|
Thread Tools |
24th Mar 2020, 3:47 pm | #1 |
Diode
Join Date: Mar 2020
Location: Milan, Italy
Posts: 4
|
Sony WM-D6C Hi-freq sound of motor heard recorded on tape
Hi. In order to repair my Sony WM-D6C I have found that during normal playback the player acts as well.
Otherwise during recording either from mic or line-in the tape gets recorded with a high-frequency sound of the motor spinning superimposed (maybe it is the sound of the brushes inside the motor). This can be clearly heard during the following playback. The sound can be heard also using batteries. Any hints? Best regards and thanks Steve |
24th Mar 2020, 9:32 pm | #2 |
Octode
Join Date: Jul 2014
Location: Petersfield, Hampshire, UK.
Posts: 1,043
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
I would check the routing of the two wires connecting the motor to the circuit board .
Especially if it has been repaired.If they are near the preamp it could cause the fault. If you take the bottom off the unit you can see these wires . Also check the earthing of the circuit board to the main frame .This is archived with screws holding the board . Be very careful with the wires connected to the board,they have a habit of falling off ! Try playing back a known good tape and move the wires to see if it cures the problem Cheers, Pete |
25th Mar 2020, 7:54 am | #3 |
Octode
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,965
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
Also, generally, a motor which is labouring under excessive load (although perhaps still maintaining correct speed) can transmit increased interference through modulation of the power supply rail and even interference through sparking at the brushes and commutator.
Good service manuals sometimes quote an acceptable motor current draw figure in normal conditions. |
25th Mar 2020, 7:48 pm | #4 |
Octode
Join Date: Jul 2014
Location: Petersfield, Hampshire, UK.
Posts: 1,043
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
Good point about motor loading.
There is a nylon bearing at the bottom of the capstan which is adjustable with a screwdriver Check to see if it's too tight ! |
26th Mar 2020, 9:09 am | #5 |
Heptode
Join Date: Oct 2007
Location: Birmingham, West Midlands, UK.
Posts: 615
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
The manual is readily available, I've got pdf if you need it. Is the motor running at the correct speed and steady?
|
26th Mar 2020, 10:41 am | #6 |
Diode
Join Date: Mar 2020
Location: Milan, Italy
Posts: 4
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
Hi. Thank You all for your quick reply. I really appreciate it. Apparently the motor does not have any issue, it is running at correct speed and stable. I have not yet measured current consumption. The strange fact is that this behavior appears only during recording on tape. With empty slot or even a blank cassette playback and also during cueing through headphones the recording the problems does not occur.
So it has to be in the recording chain. Maybe the erase head is injecting on tape the noise? I have a 49 pages long service manual. Does not know if it exist a detailed one. Thank you all again |
26th Mar 2020, 11:27 am | #7 |
Tetrode
Join Date: Jul 2016
Location: Renfrew, Renfrewshire, UK.
Posts: 93
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
Hi Steve, the Sony WM-D6C uses a servo chip to drive the motor but if speed is OK its probablly working. To prove it try slowing the motor slightly by hand to see if the interference pitch changes. Sony use an inverter from the batteries to derive about 50v or so for the record circuit. This is housed in a small square can about 20mm sq. If the output filtering is bad this could give noise only on record. Beware that Sony used neg centre pin on the power input and there is no protection diode. One I repaired had an OC resistor inside this can so I know Its easy to open. Superb machines, and I usually hate cassettes !
Peter |
26th Mar 2020, 11:32 am | #8 |
Diode
Join Date: Mar 2020
Location: Milan, Italy
Posts: 4
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
Here you can find the sound that was recorded without any input. The noise is clearly heard and superimposed on the tape during only recording. I have to check the erase head.
Thank you all |
26th Mar 2020, 3:03 pm | #9 | |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,587
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
Quote:
Unlikely to be of any help to your issue. Update - I now see that these 2 supplements are actually incorporated into the 49 page manual, in addition to a couple of other supplements. Last edited by DMcMahon; 26th Mar 2020 at 3:19 pm. Reason: Update |
|
26th Mar 2020, 4:05 pm | #10 |
Tetrode
Join Date: Jul 2016
Location: Renfrew, Renfrewshire, UK.
Posts: 93
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
Hi Steve, that sounds very like motor noise but does it record audio from, for example a line input. What does that audio sound like?
Peter |
27th Mar 2020, 6:33 pm | #11 |
Diode
Join Date: Mar 2020
Location: Milan, Italy
Posts: 4
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
Hey! Culprit found!
It was a ground wire that was not properly soldered, but only few copper whiskers!! It was under a tape so apparently unseen at first sight!!! Problem solved!!! After desoldering it, the noise disappeared. Thank You all, forum |
27th Mar 2020, 9:19 pm | #12 |
Octode
Join Date: Jul 2014
Location: Petersfield, Hampshire, UK.
Posts: 1,043
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
Well done .
These are notorious for the thin wires falling off ! |
27th Mar 2020, 10:42 pm | #13 | |
Nonode
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,669
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
Quote:
I'm glad to hear the OP found the source of the noise problem. Chris
__________________
What's going on in the workshop? http://martin-jones.com/ |
|
28th Mar 2020, 9:04 am | #14 | |
Heptode
Join Date: Oct 2007
Location: Birmingham, West Midlands, UK.
Posts: 615
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
The dc to dc converter converts 6v ro 12v for the audio circuits. It's worth doing a few voltage checks just in case something is haywire, maybe isolate stages of the record amp to see where noise is creeping in,assuming it's some sort of pick up? Decoupling capacitors on power rails? 0v track not broken anywhere?
Quote:
|
|
28th Mar 2020, 9:07 am | #15 |
Heptode
Join Date: Oct 2007
Location: Birmingham, West Midlands, UK.
Posts: 615
|
Re: Sony WM-D6C Hi-freq sound of motor heard recorded on tape
Sorry I hadn't read the entire thread when I wrote the above! Well found and you have a superb machine there!
|