Philips (Black Tulip) N5748 HIFI Cassette Deck

De compact cassette was een schitterende uitvinding van Philips en werd een wereldwijd succes. Ook bandrecorders blijken een tijdloos populair medium.Kun jij ook geen genoeg krijgen van die sfeervol draaiende spoelen? Deel hier je magnetische passie!

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Michael 5of9
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Lid geworden op: 06 sep 2014, 11:48
Locatie: CUMBRIA in ENGLAND
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15 mei 2019, 16:03

There is a little Interference Noise from the volume control on this unit; only when it is being turned around, and in a certain position this happens, I have tried once giving it a good spray of Kontakt Chemie: Kontakt 60 and a few days later a good spray of Kontakt WL and turning the knob after each spray to move the spray around inside.
https://drive.google.com/file/d/1BjdC99 ... sp=sharing

I have uploaded a two old photos showing the rear of this control although one of them is the balance control; there is access for spraying on the side and maybe from the centre of the end and info on Kontakt Chemie.

Can you kindly advice on this; I don’t want to do anything more without further sound advice because it could also destroy the potentiometer depending on the materials in the potentiometer :think:
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Volume Control.jpg
Balance Control.jpg
Kind Regards Michael
Heating & Electrical Engineer
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Fotohuis
Berichten: 6552
Lid geworden op: 19 feb 2016, 17:37
Locatie: R'stein soms Mykolaiv
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15 mei 2019, 18:00

Ultrasonic cleaning in IPA drying and using contact grease or Brunox will be the final solution for this potentiometer problem.
http://www.svema.info
Dynavox TPR-3 6N3P-EV voorversterker, ET-100+Teufel U.20, Theater 500. N4504, N4511, N4450, N2521, N2507, (1)408, 212, 312, 222, draaitafels +GP401/412 Mk2 Sh./MC-3. CD204, CDF200. NAD C352, C422, C521BEE+FB820. 22RH743+22RH544/79R
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Michael 5of9
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Lid geworden op: 06 sep 2014, 11:48
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31 mei 2019, 13:31

There will be carbon tracks inside this control; so an IPA is not recommended for this at all, it would washout any lubrication that is already there, the IPA will only destroy the carbon.
The KONTAKT 61 is a cleaner with a lubricant; which I already have, I have tried injecting a small spray amount through the side access entry as well as from the end of this control then turn the knob fully both ways for several times to move the spray around inside, then apply a little push pressure on the knob whilst turning followed be a little pull pressure.

I fitted a piece of paper towel around the control to catch any over-spray and used an absorbent clean cloth to remove excess spray from the external parts; I left it for an hour before switching on the unit to test.

Doing this hasn’t made any difference at all, apart from, when I turn the volume knob it feels more firm, less looseness, so on that side there is an improvement.

Please can you give further suggestions, thank you.

https://music-electronics-forum.com/sho ... hp?t=27696

https://forums.tomsguide.com/threads/cl ... fo.232603/

https://audiokarma.org/forums/index.php ... rol.13152/
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Looking cleaner
Looking cleaner
Looking cleaner
Looking cleaner
Kind Regards Michael
Heating & Electrical Engineer
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Fotohuis
Berichten: 6552
Lid geworden op: 19 feb 2016, 17:37
Locatie: R'stein soms Mykolaiv
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31 mei 2019, 13:45

FullSizeRender.jpg

IPA (Iso Propyl Alcohol) won't destruct carbon at all. It is a neutral de-greaser and used in all semi-conductor industry.

After it you have to dry and use or (RS-) Contact Grease or e.g. Brunox Turbo spray as lubricant.
http://www.svema.info
Dynavox TPR-3 6N3P-EV voorversterker, ET-100+Teufel U.20, Theater 500. N4504, N4511, N4450, N2521, N2507, (1)408, 212, 312, 222, draaitafels +GP401/412 Mk2 Sh./MC-3. CD204, CDF200. NAD C352, C422, C521BEE+FB820. 22RH743+22RH544/79R
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Michael 5of9
Berichten: 47
Lid geworden op: 06 sep 2014, 11:48
Locatie: CUMBRIA in ENGLAND
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09 jul 2019, 14:32

Philips Service Manual; gives reference points for voltage readings shown on the Main board U405 drawing and the schematic diagram (bottom right). Note some of these references are quite precise to the point of a volt, giving the impression that they are important!

Shown below; readings in red are the reference voltage followed with the actual voltage in black.

B -12v -11.98v (Under)
B2 -5v -4.83v (Under)
A1+15v +15.15v
A2 +12v +12.04v
A3 +12v +12.15v
A4 +14.5v +14.63v (Over)
A5 +11.5v +12.06v (Over)
A6 +9v +9.03v via D457/R596 diagram (via R589 +8.42 shown on the drawing. Under)
Cr -4v (+15v) +15.13v (via C796/R600)

Recording Amplifier Board U406 Power Supply
Pin 2 +15v +15.13v
Pin 7 -12v -11.96v

Zener Single Diodes voltage regulators
Have now replaced all Zener voltage regulators on this unit the readings are set out in the usual way below, first reading across, second readings to ground, anode (A) side first followed with cathode.

Main Board U405:
D457 BZX79C9V1

Across -9.01v
A. +8.2mv
C. +9.02v

D458 BZX79C5V1
Across -4.84v (Note this reading; it is under?)
A. -4.83v
C. +5.4mv

Motor Control Board U302:
D467-C4v7

Across -4.73v
A -11.89v
C -7.16v

D477-C9v1
Across -9.0v
A -11.89v
C -2.91v

D476-C7v5
Across -7.52v
A -11.0v
C -3.54v
Kind Regards Michael
Heating & Electrical Engineer
mae
Berichten: 4323
Lid geworden op: 17 nov 2013, 02:42
Locatie: Randstad

09 jul 2019, 15:23

Is there a reason (symptoms, performance) to suspect the voltages are too far out?
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Michael 5of9
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09 jul 2019, 15:47

Is there a reason (symptoms, performance) to suspect the voltages are too far out?
No symptoms or performance issues; just wondered if these voltages are acceptable :think:
The new 12 volt regulator IC431 on board U402 power supply may not be an exact 12v?
Kind Regards Michael
Heating & Electrical Engineer
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Michael 5of9
Berichten: 47
Lid geworden op: 06 sep 2014, 11:48
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16 aug 2019, 13:59

There is a Word document (this allows you to edit) and a PDF both having the same contents that anyone wishes to have a copy; they list all the Electrolytic Capacitors and Transistors.

This is the link to the folder https://drive.google.com/drive/folders/ ... sp=sharing

This link you can see the cassette player playing; the recording on this cassette was re- recorded in the 1980’s hence the second recording did not fully overwrite the first recording, I think this was done because the recording was a little poor.

To get the optimum recording; preparation is required by making sure the tape heads are clean hand wind the tape forward to clear the transparent tape, insert and press only the REC button, set the player going with the LP or CD that you are going to take a recording of and make sure that the monitor switch is set to position “Source”;

Then bring up both recording level controls so that the peak indicator +4dB is just starting to blink; both meters should just reach the red areas of the scale. (if you look at my left channel of the recording in this post the level meter it is a little lower than the right, the left level should have been a little higher, so it is better to have both levels reaching the same).
Some tracks when played workup to a grand finale which is higher/louder in this case it is better to play the track through, this gives a chance to alter the level controls, we call this setting up, to achieve clarity on the recording, after you are happy with the levels, then start your recording from the beginning.

https://drive.google.com/file/d/1Ajcya4 ... sp=sharing
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Badge Identity
Badge Identity
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Philips N5748.jpg
Laatst gewijzigd door Michael 5of9 op 20 aug 2019, 09:08, 3 keer totaal gewijzigd.
Kind Regards Michael
Heating & Electrical Engineer
Karsten
Berichten: 6044
Lid geworden op: 17 sep 2012, 14:07
Locatie: Bakermatregio van ons geliefde merk.

16 aug 2019, 15:22

Nice result, Michael! :handgestures-thumbup:
Meten is weten en weten wat je meet.
Hoewie Loewie
Berichten: 8362
Lid geworden op: 10 okt 2014, 14:12
Locatie: Veghel
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16 aug 2019, 17:45

:text-bravo:
Erres SX6290 SX6393 SX6194 SR3390 Aristona AR8530 SG1408 CD1202 Philips GF403 GA202 GA212 RH423 RH426 RH532MFB CD104 CD303 CD950 N2221 en veul Superscope. :D www.superscopeaudio.nl
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Michael 5of9
Berichten: 47
Lid geworden op: 06 sep 2014, 11:48
Locatie: CUMBRIA in ENGLAND
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20 aug 2019, 13:47

Cleaning the tape heads; you will need methylated spirits (meth’s), I have a nice smallish glass bottle to store mine, cotton buds 3" inch (75mm) long or longer would be better because access is limited due to the cassette holder being partly in the way and if you have large hands, even more so and kindly ask for a pair of your wife’s white cotton which is usually lint free pants all very important.

Using one cotton bud dip on end in the meth’s and gently polish/wet all of the top of the 2 heads (2 heads in 1 = 3 heads in total) the right-hand head has a depression near where the two heads meet, clean this part also going inline, on this part for about 20 seconds in total; then use the wet end of the bud and place it centrally inside the gusset of the pants, keeping it quite tight, gathering all the loose material and holding it with your last 3 three fingers in your palm leaving your thumb and index finger to hold the covered bud which should be wet from the remaining meth’s and be very gentle, polish up the heads again for 20/30 seconds in total.

Use the other end of the cotton bud which is dry and place it centrally inside the gusset of the pants over a dry area not soaked in meth’s and holding it as before, polish up the heads again for 10 seconds in total. If you then avoid placing a cassette in for 5 minutes, to be sure the heads are completely dry.

Note; if you play a cassette for a few seconds and mentally listen before cleaning you might be very surprised at the results of the cleaning, even if the heads look clean.
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Twin Tape Head; as this is a magnified view, one might think something is wrong here?
Twin Tape Head; as this is a magnified view, one might think something is wrong here?
Tape Heads.jpg
Holding Position.jpg
Kind Regards Michael
Heating & Electrical Engineer
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