Revox B226-S transport problem

Hi,

just got one and there is some part missing, between the puck and the arm that presses it onto the CD.
Anybody knows how it looks like ?

The problem is that the arm touches the puck directly and the arm does not lift the puck entirely when opening the disc tray.

By the way, CDM1mkII and single crown S1 chip.

And it uses AD7528 dual multiplying D/A converter as attenuator for the variable output.

Is this a good idea ?
 
Bernhard said:
just got one and there is some part missing, between the puck and the arm that presses it onto the CD.
Anybody knows how it looks like ?
You can find the service manual here
Probably the nylon sleeve on the driving pin is missing or severely worn. A complete and well aligned tray has to load very, very smoothly!

Bernhard said:
By the way, CDM1mkII
Are you sure it's not CDM1?

Lourens
 
Thanks for the link, here is a pic of the transport.

It is CDM1 mkII like in Philips CD880. It made me wonder too, I also expected CDM1 :cannotbe:

There is another problems, the backlight of the LCD is very very dark and the loading tray was totally blocked first.

Parallel to the belt there is a slot (?) where a pin with white plastic moves. Around the pin was a worn out black rubber.
This slot is wide where the pin is when tray is open, it becomes more narrow in the middle and widens again to the end, but not as wide as on the beginning. The white plastic is just to big to fit except on the beginning.
Now I replaced the white plastic with something else and it works so war except there is still a little resistance when closing the tray and it starts moving back and forward in circles until I push it a little to close. I don't believe there is a mechanical damage to that slot :confused:


[IMGDEAD]http://www.beautyphoto.de/b226sdrawer.jpg[/IMGDEAD]
 
Bernhard said:
It is CDM1 mkII like in Philips CD880. It made me wonder too, I also expected
IMHO this it not original. This could very well explain the loading problems because the distance between puck and top plate (or rather: the spindle plateau) is very critical.

There is another problems, the backlight of the LCD is very very dark
A very common problem on Revox cdp's. On eBay you will find the necessary replacement bulbs.

and the loading tray was totally blocked first.
Parallel to the belt there is a slot (?) where a pin with white plastic moves. Around the pin was a worn out black rubber.
This slot is wide where the pin is when tray is open, it becomes more narrow in the middle and widens again to the end, but not as wide as on the beginning. The white plastic is just to big to fit except on the beginning.
Now I replaced the white plastic with something else and it works so war except there is still a little resistance when closing the tray and it starts moving back and forward in circles until I push it a little to close. I don't believe there is a mechanical damage to that slot :confused:
This 'white plastic' should to be the nylon sleeve i mentioned. Normally it's fitted with a black rubber O-ring and is the bearing on the driver pin of the selenoid lifter which engages exactly into the guiding groove of the cd drawer*. Just replacing it 'with something else' will not do, i'm afraid. This self lubricating precision nylon sleeve is responsible for the smooth ride your Revox deserves. Find a new one or make one yourself. I used a rather similar sleeve used in the ordinary (slow!) cdm1 drawer mechanisms you will find in nearly all first generation cdp's with Philips inside. It's outer diameter too big, so you have to carefully machine it to the exact size.
This all has no relation at all with the red arrow in your picture!

*in German: "Nylon-Hülse am Mitnehemerstift des Magnethebers in die Führungsnut de CD-Schublade".

Good luck!

groeten
Lourens
 
The transport works.
Backlight is FL and should have 110Vac.
But it is not very bright.
When I increase voltage to 150V, yes there is a pot :xeye: , it gets better but for short time only, the voltage starts to drop over a few minutes and the display gets dark.
On the primary there is an op amp coupled by a cap.
I already changed the cap and the AC voltage on the op amp output is stable.
The step up transformer gets hot.
Can it be the FL is dead and starts making a short after warm up ? There are no other parts.
 
Bernhard said:
It is original CDM1 mkII, CDM1 could never fit there.


Yes it will. Your B226 is just an beefed up (S1) and externally restyled 226 (black facia and wooden side boards) using the same chassis as all first and second generation Studer/Revox cdp's like B126, A725 and A727. All are fitted with cdm1, so i still think the mkII is a modification. Compare yours with this standard B226:
 

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Yes it looks the same except the prozessor pcb is a little bit different.
I downloaded the sevice manual and that is also for B226 & S.
And guess what, the inverter ( for backlight ) section was missing.

Does standard B226 also have 1541A S1 chip ?

Maybe they changed CDM1 to mkII later on in production, the base where the mkII is mounted looks original and will not fit for CDM1, same with servo board.

Any idea where to get that backlight foil ?
I adjusted to 112Vac and it is stable but not very bright, is that normal ?
 
Yes it looks the same except the prozessor pcb is a little bit different.
Like this ?
In that case the 226S looks more like a beefed up B126...

Does standard B226 also have 1541A S1 chip ?
No.

Maybe they changed CDM1 to mkII later on in production, the base where the mkII is mounted looks original and will not fit for CDM1, same with servo board.
:confused:

Any idea where to get that backlight foil ?
Search the web or eBay (past biddings), sometimes look alike FL's were offered there, my Studer A727 does not need one yet, and i did not bookmark the website of the maker.

I adjusted to 112Vac and it is stable but not very bright, is that normal ?
Yes, diying backlits are very common, also with FL -- replace it.

Lourens
 
Yes it is exactly like the B226s on that picture and got single crown chip.
Also in Philips players some used CDM0 other CDM1, maybe REVOX ran out of CDM1, the player is from '89.
I have 3 single crowns and two of them are very good on left channel and the other on right channel.
Now I think about building a DAC with 2 chips and only use one channel of each chip.
Same with 6 another single crowns, some have also only been good on one channel but never on both.
 
The display is a LCD, the EL is a 0.5mm thin illuminating foil that needs 110 Vac to light up.
I removed the old foil between LCD and PCB, bought a blue one from Conrad Electronik here in Munich and cut it to size. After that put some transparent film around the foil for isolation. They also have red, green and white.
It is a little bit tricky to get the two leads through the holes in the pcb you will see when you try :D

off topic: The display looks a little blurred in the photo, this is because I used studio-flash with 1/15s exposure time to make the display visible.

http://kaufen.conrad.de/leuchtfolie_blau_138x34.asp
 
Hi friends, I got a used B226s and have the same problem: the CD clamp arm would press on the CD. However, someone uses a very tiny spring to lift the arm and the other side of the spring is hooked on the side frame! Also, I found a small plastic tube and a rubber O ring on it, it looks like some shaft loses its shoe, and work around by a spring... I have to take the player apart to find out more mechanical problems, if there are any.

I am planning to mod it as following:

1. change all LM317, 337 to LT1085 and LT1033
2. all 22 coupling caps (originals are all ROE) replaced by Panasonic FM
3. the 10000 uF 16V cap: change to BC component one

But what are good choices for the other 3 "FRACO" caps and those blue Philips elco 100 uF, 25V ones? Any suggestions?
 

poynton

Member
2005-03-10 11:57 pm
UK
The first thing about the power supply is the standby arrangement...any mods must not interfere with it or the player will not work.

personnally, I would forget about changing all the caps, other than the PSU caps, and concentrate on other improvements.

New clock

Definitely give the SAA7220 its own supply, well filtered etc.

individual supplies for the DAC +-5v and -12v

replace the opamps

enlarge the holes in the back panel to take proper phono leads
replace the RCA sockets

Whatever you do, remember the golden rule...

one upgrade at a time and check it is working in between mods !!

Andy
 
Thanks Andy. I definitely will not touch those WIMA, PHILIPS MKP caps, just swapping out elco power supply caps and coupling caps (with the same value, of course).

But before doing those things, I need to find a CD tray mechanical drawing to figure out where the extra small plastic tube with rubber O ring comes from. Align or lub all the mechanical parts. Then, will I started to consider modding the DAC board, new LCD back light film.

Yes, golden rule like what I told my students: one thing at a time. This is the really fun part of DIY. :clown:
 

poynton

Member
2005-03-10 11:57 pm
UK
Nornally I would recommend looking at the service manual..
but...
I have just looked at my copy and it has no information or pictures about the mechanism. In fact it says do not dismantle.
So no help there !!

I am not at home for the next few weeks otherwise I would look at mine and post pictures.

Andy
 
i have not even started modding yet! now my player's the clamp arm presses on the cd and create some noise sometimes even stopped the motor, and the transport i found in it is a CDM1 Mk-II! Exactly the same problem that Bernard had!

Even worse, I got a cheap 126, and it was working when I received it, but it quit the second day, when I open the lid: it is not original, some one obviously burned the ZTX651 and BD126 on the power supply chain and replaced by something else (BD126 replaced by BD140, that is OK, but ZTX651 should be replaced by ZTX651/3, but it was not replaced by proper transistors and it burned!).

When I started to mod, I will do that.
 
But before doing those things, I need to find a CD tray mechanical drawing to figure out where the extra small plastic tube with rubber O ring comes from.

This is just a quick freehand sketch. (see post AFTEr this one for picture)
You need to remove this entire grey plastic piece with the disc clamp to put the nylon bush and O-ring back.
See the two little plastic protrusions at the back - the pins it hinges on (pivoting pins).... they are slightly springy, you can squeeze then inward with a screwdriver, and the whole clamp and lifter pops out.
Then, you need to replace te nylon bush - grease the plastic pin it goes on, or the bush will keep falling off while you work.
Put the lifting arm back in, guiding the bush-and-o-ring back into the long groove along the left-hand side of the tray. Then click in the springly plastic pivoting pins.
It's a very tricky manoevre! The drawer must be in the half-open position.

After it's back together, you need to adjust it for correct height. Otherwise it will
(a) not lift the magnetic puck clear of the drawer when opening, or
(b) the lifter will rest on the puck and scrape while playing.

You do the adjustment by bending (VERY small amounts) the bit of metal arrowed in my picture below.

HINT: The O-rings that the drawer slides on are bigger than the one that goes on the nylon bush referred to above.
Get an extra ONE of the larger O rings, and push it into the hole in the centre of the metal disc turntable (puck needs to be out of the way to get access). Push it deep into the hole.
This trick stops the magnetic clamp sticking really strongly to the turntable *when there is NO disc in the machine*. When this happens the drawer cannot open, and it is incredibly sensitive to the adjustment I described above. With the o-ring in the turntable hole, it isn't too touchy about adjustments.
 

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