Electronics, Flea Markets

Philips AG-4000 Turntable – Maintenance

Found this cute Philips AG-4000 turntable at a local flea market and decided to buy it since I could not believe the price.

The unit seems to run only on battery power (no plug for AC) and it seemed rather beaten down. The main label was missing, some of the plastic was melted by a hot wire and I saw some white corrosion:

Upon powering up, the platter would not turn. I figured that the belts were bad – and before starting working on the turntable, I had already ordered some spare belts.

To lift the platter, the little hook has to be pushed just a little to the side, while lifting the platter by the spindle (which is attached to the platter):

To be able to lift the platter – the little hook needs to be pushed to the side

Inside it looked rather messy. The main belt was loose, the smaller belt glued itself to the turning wheels – and there was a lot of black powder around the belt area:

Philips AG-4000 – Bad belts

After replacing the belts and cleanup, the platter would still not turn! The problem seemed that the idler wheel was not touching the inside of the platter – and after some poking around, I discovered that the grease at the pivot where the idler wheel attaches to was too stiff. The idler wheel would touch the spindle but would not move outwards to touch the platter.

Dried up grease / Idler wheel doesn’t get pushed towards the platter

Although I could have taken the swiveling mechanism apart and thoroughly clean the dry grease, I decided to first try to soften it with some sewing machine oil. And it worked – the idle wheel now also slides towards where the platter inner wall would be:

Idler wheel is now pushed towards the platter

I then proceeded to clean up all the remaining grease and apply silicone grease:

To clean up the white corrosion I used some vinegar on the metallic parts and just soap and water on the underside of the rubber mat:

I also applied some sewing machine oil onto the bronze bushings as well as on the motor axle – as the motor was rather noisy:

Few more words.

The smaller belt is actually too tight. The current consumption increases with about 40mA when I attach it and this takes the consumption to about 100mA (manufacturer says maximum 70mA). I think this may have a detrimental effect on the bronze bushings, thus, I will not use the turntable for long with them – and I will store the turntable without them installed anyway.

The AG3306 crystal cartridge is in fact rather dull and muted even with a new stylus. I have ordered a 22GP204 ceramic cartridge which sounds much better:

The turntable was also lacking the 45 rpm adapter. Some online photos shows it as having a white adapter. As luck would have it, in the same flea market maybe a week or two later, I found a black Philips 45 RPM adapter from a more modern turntable that looked identical to the white one I saw online. So I bought it to at least have a reference – and decided to design and 3D print a replacement:

3D printing it was not easy due to the needed supports and my printer started chewing on the filament due to many small retractions as it got closer to the inclined top. Thus, I had to print with retractions disabled, which produces small visual artifacts.

The electronic parts are working properly, although there are discrepancies between the board and the few online schematics that I found. For example, my board contains an AC125 transistor which doesn’t appear in any of the schematics online. One schematic shows two resistors for each of the final output transistors, but mine only has one, R14, but it is installed in the place of R15 that appears in some other schematics. A 200uF capacitor seems to be 2 capacitors in parallel sandwiched on my board. Thus, they took some liberty in putting the board together as the design was revised here and there.

Similar to the video of Shango066 – where he fixes the same turntable (sold under the name of Philips Mercury), the 33 RPM speed is almost there, but it accelerates and decelerates during the rotation:

Philips AG-4000 – 33 RPM speed

The 45 RPM speed was slower and the 78 RPM was faster, with the 33 RPM being the closest to stable. Since speed adjustment seems to be mechanical (once the motor lid is taken apart), and since the smaller belt feels too tight, I decided not to bother adjusting the speed.

I decided to buy one more on ebay since I saw an announcement that had a decent price and that one came with the sticker / label “Philips All Transistors” which. Thus, when I’ll find a shop that can print on a thin Aluminium board, I may order a replacement label too:

Thus, an easy to maintain turntable but not very fulfilling since speed is wobbly. I guess, as a colleague was mentioning, these type of turntables were targeted for the youth (to be taken to the park for music) and were made cheap so that the youth could afford them.

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