With a slight rewiring the riaa to the 2nd central earth created by the big caps. I think has a minor improvement.
Plus using microphonie reducing rubber on the tubes. (Plan to change to long ecc83)
My in May
Category Uncategorized
An AG9018 restaruation
https://sonocite.wixsite.com/marantz-collector/rest-philips: Google translate: “I have been looking for a long time for this Philips chain, consisting of the AG9018 amplifier, the A6X38AT tuner, and the AG2230 record player for two reasons: the first is that we had this chain at home in the 60s, the second is that these devices were a “hinge” in Philips production: the amplifier is the latest Hi-Fi tube amplifier, and the tuner, the first “all transistor” manufactured by the brand. As for the record player, it was their first real P.U. high fidelity, as evidenced by its high manufacturing quality.
These devices were built with good quality components, in any case much better apparently than today …:
The amplifier, equipped with 11 tubes (4 x EL86 output – derived from the famous EL84), gives a nice impression of robustness, and is of a flattering aesthetic (let’s not forget that we are in 1964).
No gadgets, only the necessary: two groups of selectors, PU – tape – tuner, mono-stereo, classic tone controls, volume and balance controls, and finally the Power switch “and its beautiful green light. It has the distinction of having two groups of HP outputs, either 8 or 16 ohms selectable by bridging inside the device, or 800 ohms (direct output without output transformer), suitable for the AD5055 baffles that were part The power of 2 x 15 watts (800 ohms) or 2 x 10 watts / real 12 watts / music (8 ohms) is sufficient with baffles with an output of 90 dB / 1W / 1M.
The retro-looking tuner has some very interesting features: FM band from 88 to 108 MHz, MW, LW and 4 short wave ranges! We even managed to pick up the radio signals (safety beacons to inform the boats). The FM part is very sensitive, and the stereo decoding easy. A mechanical clutch system selects one or the other hand depending on whether you are in AM or FM.
The turntable, developed at the same time, had to ideally complement this beautiful set. The general aspect exudes quality, is endowed with a special drive (however without fine adjustment of the speed) and is in agreement with the look of the amp and the tuner, by sporting the same materials and colors, teak, brushed aluminum and gray lacquer.
The AG9018 amplifier:
It comes from France; found by classified ad, it’s always a little bit quit or double: we see a camera on a photo but we don’t know what we will receive!
But here, no disappointment, the device arrived well packaged, in one piece, here it is as is (this is the photo of the ad):
As soon as received, immediately disassembled to test it, and there, surprise: no trace of previous repair, no component with questionable appearance, the measurements join the characteristics of the time, the power is there, the background noise very low , no sign of notorious snoring !!! Only the wooden case, the appearance of the grilles, and the interior dust betrays its advanced age. Not bad for a 49 spring device, the current manufacturers would do well to take the seed !!! but then pure profit was secondary. We did not put 1/8 th watt resistors, most of the non-polarized capacitors were of the “mustard” type.
So let’s go for a deep cleaning, direction the “bathroom”: degreasing and dusting.
It is not very dirty, despite all the years:
All the parts that can be dismantled are, for cleaning or deoxidation, or even repainting:
I repaint with a gun with a beautiful gray of my composition, presenting better than the sad gray – medium – original khaki, then drying at good temperature:
The fabric covering the front grille falling to shreds, I replace it with a piece of mosquito net: it will allow better ventilation than original. A small polishing of the shields of the preamp tubes and the aluminum plate is essential:
Here it is, all beautiful, very clean, being reassembled, above and below:
I clean and glue the acronym in the right place:
The real teak wood case is carefully sanded to 400:
After revarnishing in a shade a little warmer than the original (Philips had fairly dull woodwork tones at the time), complete reassembly after having replaced the outlet tubes with Sylvania Black Plate, which gives more richness sound, and here it is again, I hope, for another half a century!
The A6X38AT Tuner:
Also found through a p.a. of 2èmemain.be, it presented much less well …
No doubt he stayed in an attic, or worse, a cellar. The wooden box is very damaged, and has a depression on the top. The plating is to be repaired at this place, fortunately, the defective solid-state amplifier which is part of the sale will give the piece for”
Repair
I try to list failures which I saw with the AG9015 and explain my way of resolving these.
In general it is a good idea to replace electrolytes. Also, the carbon (brown small) resistors are a source of issues (always replace Replace R26, R30, R126, R130). Avoid heat stress on the small caps as these tend to get noisy with the repair. Swap things in pair and measure if both matching in value! Philips Mustard caps do not like heat, else they work forever, they are teh best.
Symptom: One channel has much stronger sound
Solution: Seeing the stronger 1kHz signal on scope on the 800Ohm output, became clear, that the stronger channel is wobling. As signal was fed in on C21, the end amp was clearly the suspect for issue. Checking resistances (especial the brown carbon one’s) became clear that R30 gone into the MOhm range and is not fulfilling any negative feedback(normal value is 120kOhm). Carbon resistors have perfect sound, but can easier fail. Please replace both channel with carbon resistor at the same time. This is the most common part which fails.
Symptom: hissing noise in one of the channel.
Solution: Remove one leg of C21 to separate circuit for end and pre amplifier. In my case issue remained (so end amplifier.) Such noise can be generated by a cap, so hard to think it is caused by an resistor. Through a high voltage, smaller cap try to short audio signal of the end amp. In my case in area of B3, B3′ was canceling the noise. After unsoldering C23, noise disappeared. As previously the area had several resistor exchanges the cap became damaged with heat of my solder iron.
Symptom: No sound, R38 burned down.
Replace resistor(both channel, take care on power rating), check tubes, avoid short circuit at the output
Symptom: No sound, R1, R2, R3 burned down
Replace resistors (take care on power rating), check tubes, avoid short circuit at the output . Please do not use bigger fuses then 125mA for the anodes.
Symptom: hissing noise in one of the channel
Similar hiss noise in the upper region, but noise is more white and is hard to hear (I realized it only with the 800Ohm speakers)
Solution: The 820Ohm carbon resistor became noisy. Replace it. (R26, R126)
Ticking noise (see video:)
https://www.facebook.com/groups/elektroncsoveserositok/permalink/670649066708000
Replace R26, R30, R126, R130, the NFB is cuasing as it becames positive.
Potentiometers
Poorman 5min solution is WD40 for contact. I am sometimes satisfied with the result. Better is:
You may use a 3 step spray solution: Kontakt 60 for cleaning, Kontakt WL wash , finally Kontakt 61. KONTAKT 60 removes oxidations, dist, grease. Keep it on for some seconds. (if you can’t rub, keep it on for 15 min), KONTAKT WL washes away residues of the previous process, KONTAKT 61 protects, helps is contact.
You may try to gently disassembly with bending back the metal tips (can easily break!), clean with isopropyl alcohol, clean with fiber scratch pen or with rubber (of a pen!) the surfaces. You will need a copper rivet as the inner potentiometr will be not accessible.
The original potentiometers could have issues with synchronous running… If you can’t fix it the replacement possibility for volume is:
ALPS RK27
These are the BLUE cubes. There is dozen of fake, so please take care what you source.
In short words, you need an stereo 500K volume potentiometer with long flat shaft.
For volume, you will need the dual unit for vol (12A)
Shaft type: flat – F
You will need the longer shaft – 25mm, but note, that the original shaft length is 30mm so you will need to do some magic here.
You will need no detent – C0
Resistance path 15A – A
Resistance 500K – 504
That is then RK27112A-F30-C0-A504
Unfortunately even that is too short and hard to get…, so
What really worked for me is an 500K Alps Blue potentiometer, with an round uncut shaft with a coupling, which I cut to size in a drill and shortened also. I also cu teh ALPS potentiometer in length + add a washer to minimize length on counterside. See pics:
For Balance:
I have no solution for you. You may skip the balance as is and use just the volume potentiometer. It is very interesting that the original balance control at the 2 paths has 0Ohm till the half path… In reality it works not good. I plan to disassemble and try to match them in the middle position where both are shorted… And also, well the short is somehow just 10kOhm… (oxide?)
AVC Volume control
Elma type 04 switch
04-2133 3 R(-) 00 000 (or longer with 15mm ) 00 0
32mm diameter , 45mm long, need shorter version
Small electrolytic caps 100uF/25V, 4V
The original caps are for sure to be replaced! These were all axials. 4V for the pre-preamp/riaa, 25V was for the end amplifier driver preamp.
Luckily you have lot of choice. I wish not to list up here all of them, just some of the better options. Please take something known brand and not the cheapest chinese something.
Black Gate FK 100uF 25V
My recommendation is clear on this after I saw 3.5 times better results compared to a new Sprague atom…
Sprague Atom 100uF/25V, axial electrolytic capacitor, TVA1207
Bought these, but not that satisfied as I have hoping it.
Elna Silmic II
Clearly better on measured paramaters then Sprague Atom
Nichicon Muse UKZ
Bought the KZ, but the results really satisfying. My recomendation, after BG.
Jensen,
Comparison:
(scroll for more values)
| Capacity(100Hz) (higher better) | Capacity(1kHz) (higher better) | Capacity(10kHz) (higher better) | ESR(100Hz) (lower better) | ESR (1kHZ) (lower better) | ESR (10kHZ) (lower better) | Q(100Hz) (higher better) | Q(1kHz) (higher better) | Q(10kHz) (higher better) | Teta (100Hz) (-90 is the ideal ) | Teta (1kHz) (-90 is the ideal ) | Teta (10kHz) (-90 is the ideal ) | |
| Philips 100uF 25V | 111.26 | 108.2uF | 106.1uF | 0.3Ohm | 0.12Ohm | 0.09Ohm | 37.6 | 11.39 | 1.539 | -88.4 | -84.9 | -56.9 |
| Philips 100uF 4V | 165.97 | 156.76uF | 125.7uF | 0.6Ohm | 0.36Ohm | 0.3Ohm | 15.13 | 2.8 | 0.415 | -86.1 | -70.3 | -22.5 |
| Elna Silmic II 100uF 25V | 99.37uF | 94.94uF | 88.7uF | 0.6Ohm | 0.23Ohm | 0.19Ohm | 24.3 | 7.04 | 0.93 | -87.6 | -81.9 | -42.8 |
| Sprague Atom 100uF | 92.05uF | 89.17uF | 83.8uF | 0.6Ohm | 0.31Ohm | 0.26Ohm | 28.3 | 5.75 | 0.712 | -87.9 | -80 | -35.4 |
| Black Gate FK | 89.86 | 18.77 | ||||||||||
| Noname 100uF 35V | 89.24 | 83.01 | 69.4 | 1.3Ohm | 0.75Ohm | 0.64Ohm | 12.78 | 2.52 | 0.353 | -85.5 | -68.3 | -19.4 |
| Nichicon Muse KZ | 99.7uF | 96.57uF | 91.1uF | 0.4Ohm | 0.15Ohm | 0.12Ohm | 32.3 | 10.53 | 1.444 | -88.1 | -84.5 | -55.2 |
Electrolytic capacitor 8+8uF 350V-400V
Originaly there is 3 type of caps used to smothen the preamp tube voltages (2 cap/chanel in one product)
-8uF+8uF 350V isolated (in every type), 18mmx34mm
-8uF+8uF 350V not isolated (older ones), 18mmx34mm
-8uF+8uF 400V not isolated (newer ones), 18mmx50mm
F&T:
The best one to one replacement is F&T 8+8uF 450V.
I measured really nice ESR values on 100Hz, so really a lovely cap (and ugly drop on higher frequencies…) Is a little bigger, then the Philips was but you can bend the original holders to accomodate.
Sprague Atom:
8uF(single) 450V. 12.3mm*44mm
They are only fine if you use it purely for the end amplifier, so a pair of such gives one capacitor. So If you remove riaa/pre-pre amplifier, then this is a good solution. Objective measurements shows that these caps do not perform really well…
Ruby GOLD
8+8uF/500V. Is to big, 34mm in diameter, else it would be fine.
AN Kaisei
CAP-100-R-10U-350V AN-KAISEI 10uF 350V ELECTROLYTIC RADIAL CAPACITOR 12.5mm X 20mm £4.95
If you have the model with 350V caps, this may be fine.
CAP-100-R-22U-500V AN-KAISEI 22uF 500V ELECTROLYTIC SNAP-IN CAPACITOR £30.36 AN is very “strong” on specifications for thsi amoutn of money… Even the size is hidden.
Comparison
| Capacity(100Hz) (higher better) | Capacity(1kHz) (higher better) | Capacity(10kHz) (higher better) | ESR(100Hz) (lower better) | ESR (1kHZ) (lower better) | ESR (10kHZ) (lower better) | Q(100Hz) (higher better) | Q(1kHz) (higher better) | Q(10kHz) (higher better) | Teta (100Hz) (-90 is the ideal ) | Teta (1kHz) (-90 is the ideal ) | Teta (10kHz) (-90 is the ideal ) | Leakage (uA)(lower is better) | |
| Philips 8+8uF 350V | 9.143uF | 8.912uF | 8.509uF | 3.4Ohm | 1.05Ohm | 0.71Ohm | 49.8 | 16.87 | 2.6 | -88.8 | -86.5 | -69 | |
| Philips 8+8uF 400V | 8.764uF | 8.46uF | 7.929uF | 4.3Ohm | 1.11Ohm | 0.59Ohm | 42 | 16.93 | 3.39 | -88.6 | -86.5 | -73.5 | |
| F&T 8+8uF 450V | 8.438 uF | 8.305uF | 7.958uF | 3.3Ohm | 1.44Ohm | 1.21Ohm | 56.3 | 13.19 | 1.643 | -88.9 | -85.6 | -58.6 | |
| Sprague Atom 8uF | 7.585uF | 7.438uF | 6.779uF | 6.3Ohm | 3.78Ohm | 3.38Ohm | 33 | 5.66 | 0.694 | -88.2 | -79.9 | -34.7 | |
| Kaisei 10uF 350V |
Resistors
The designers of the Philips AG9015 were aware which type of resistors where to use. Unfortunatley at repairs the carbons typically are never replaced with carbons…
Recommend for replacement: Takman, Kiwame or Riken ohm for carbon. I actually test/use Xicon, for now they are OK. Alen Bradley tend to degragade over the years, so not recommendable. (even if soldering with caution)
List what and where to use:
Carbon composite
If you see “brown” resistors, these are the carbon composite resistors. All in the audio path should be such! The disadvantage of the component is the high tolerance and the original ones really tend to fail. Example: I had to replace R30 and R130 in nearly all amp I saw and many other carbon resistor were source of mysterious noise… . I used 1/2W Xicon resistors. In the original schematic these are the carbon composites: R154,R5, R6, R7, R105,R106, R107, R53,R153, R49,R149, R22, R122, R23, R123, R14, R15, R114, R115, R18, R19, R20, R21 , R118, R119, R120, R121, R29, R129, R24, R26, R30, R124, R126, R130, R34, R134, R31, R32, R131, R132, R44, R16, R116, R42, R142.
1/2W is fine for these. Carbon composite rare to find in bigger heat dissipation.
Carbon film:
You will not find such in the AG9015. I personally find these less good then the carbon composite.
Metal film:
You will find a lot of such in the Ag9015 power circuit. and also in the audio circuits.
R2(2W),R3,R4(2W),R13, R55, R155, R8, R108, R43, R143, R45, R145, R9, R109, R17, R117, R10,R11,R12, R110,R111,R112, R27, R28, R127, R128, R25,R36(2W), R125, R136(2W),R33, R35, R133, R135, R37(2W), R137(2W), R38 (5W) , R138 (5W)
Where not marked, the resistor has 1W dissipation capability. They look much bigger as resistors from nowadays, so you may buy 2W to keep the look.
Metal oxide composite:
Good for power supply applications, but you will not find such in the AG9015
Metal wire:
These are one of the best for power supply applications. R1 (4W) is such.
Level X – soft start
Aim is to avoid the very short overcurrent of the tube filaments. The flash like glow up is not good for the tubes.
(Because somebody in a Forum said: This glow up has been planned in by the clever Philips engineers. SURE they have! But they never planned with tubes which lasts forever. Just think about why tube tester tests first for shorts at the filament…)
The circuit is an easy turn on delay, where an 330Ohm 8W (self-extinguishing) resistor is blocking overcurrent for 3secunds till the 6.3V AC filament power supply (actually is -4V with the 330Ohm resistor ) is loading the 47uF capacitor via the 120Ohm to turn the solid state relay on, to power up fully the amp.
The SSR I used (RP1A23D5):
Note: On the pics I connected the cable after the fuse. This is incorrect! Bears the risk that if the filament blows the fuse, the resistor gets too hot. So as wrote above connect directly on the transformer, maybe use an small fuse(less than 100 mA) to be really safe.
And finally the glow up of Miniwatt tubes:
1959 – long plate (17mm)
Code: mC6 Δ9X
Identified by:
– straight D-getter with flat
cross bar
– stapled plates
Philips AG9015 
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