Author Topic: Fixing a CVP-85 Piano: Unknown schematic symbols  (Read 6990 times)

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Offline gameaddict20

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Fixing a CVP-85 Piano: Unknown schematic symbols
« on: March 21, 2015, 10:36:12 pm »
Hi all,
I'm in the process of repairing my beloved piano. The problem is that almost all of the surface mount capacitors have burst and leaked, they were the round ones which I could easily decode the value from the marking and have no problem replacing. However I also need to replace 2-3 very small 0805 (2012 metric) package capacitors that are on the other side of the board so I was very kindly given a schematic by Yamaha but I am having trouble decoding what the symbols mean on the capacitor values.

The particular symbol that is causing me the most trouble is what I can only describe as a cross between a 't' and a 'z' that is contained in brackets, I have attached an example of what I mean to this post. I trying to find out what C53's capacitance is. I tried searching the internet first but as I can't type the symbol it proved difficult and I got nowhere. It has 0.01 written next to the symbol so I'm guessing the cap is 0.1pF but I would still like to know what the symbol means

Also on the same board I need to replace a capacitor that has 22P printed next to it on the schematic (Upper case P, not lower case p). Would I be right in thinking that this is a 22pF cap with tolerance +100,-0%? (Source: http://www.sentex.ca/~mec1995/gadgets/caps/caps.html)

Thanks for any and all help
And I look forward to hopefully being able to carry on my repair work :)


 

Offline Seekonk

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #1 on: March 21, 2015, 10:45:00 pm »
Since it is used as a supply bypass cap, I would assume it is .01uF.
 

Offline eejake52

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #2 on: March 21, 2015, 10:50:21 pm »
C53 is definitely 0.01uF (not .1pF). Since it is connected to Vcc and GND near an IC, it is likely a bypass capacitor. You can probably find a 0.01uF, 16V ceramic cap from lots of old discarded electronic boards.

I can't give a good answer for 22P. Perhaps show us a picture, or the excerpt from the schematic.

Jake


 

Offline tautech

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #3 on: March 21, 2015, 10:52:59 pm »
Yep, decoupling cap 0.01 uF, ordinary ceramic 0805, just be sure to get at least 50 V rated.
Tolerance won't be an issue in this application.

22 pF, if part of an oscillator should be an NPO type.

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Offline gameaddict20

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #4 on: March 21, 2015, 11:08:25 pm »
Thanks for the help folks :)

Attached is the caps I'm trying to replace with 22P written next to them. The diagram doesn't give much away but where it says PN2 -CN2 it is I believe going to the circuit board used to control the lights and character LCD on the front of the piano as that is called PN2. I can provide more of the circuit diagram if needed but I'm not sure whether I'm allowed to distribute it so I'd rather just upload small snippets. I'm guessing as most of the values in the schematic are in uF, that the P next to 22 means pF right?

Also I'm still very curious as to what that funny symbol in the first diagram means if anyone knows?
 

Offline tautech

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #5 on: March 21, 2015, 11:30:36 pm »

Attached is the caps I'm trying to replace with 22P written next to them.

Also I'm still very curious as to what that funny symbol in the first diagram means if anyone knows?
The 22pF look like debounce caps, are you sure they are on the LCD connections?
Quote
I'm guessing as most of the values in the schematic are in uF, that the P next to 22 means pF right?
Right.  :-+ this is quite normal in schematics

The tz will likely be a tolerance spec which really is of little concern for a supply decoupling cap in this application. You could even use 0.1 uf if that is all you have.
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Offline Alex Eisenhut

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #6 on: March 21, 2015, 11:42:41 pm »
It's kanji for the first sound for the Japanese word for ceramic.

I think.

?
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Offline gameaddict20

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #7 on: March 21, 2015, 11:54:35 pm »
It's kanji for the first sound for the Japanese word for ceramic.

I think.

?

Ah that is quite interesting, and yes that is correct doing a google translate of the word ceramic brings up that tz as the first symbol (https://translate.google.com/#auto/ja/ceramic)

I've attached more details about the 22P caps
It seems that the connector does go to the character display/lights board on the front of the piano (PN2) but the wires seem to be used on the button switches and not the LEDs/Character display. As you can see in the first attachment the pins are given labels of P60-P67 and in the second image you can see those labels used again on specifically the switch bits.

As for where the wires go in the opposite direction to the connector in 'circuit_extract_3.png' they go directly to pins on the yamaha CPU.

So I know it needs to be a 22pF cap but does it need to be any special type or just a bog standard ceramic cap?
« Last Edit: March 21, 2015, 11:56:57 pm by gameaddict20 »
 

Offline tautech

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #8 on: March 22, 2015, 12:43:58 am »
Bog std will be fine, just whatever you can easily get or have on hand.  ;)
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Offline gameaddict20

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #9 on: April 06, 2015, 10:03:34 pm »
I have been asked via pm how to fix the CVP-85 so I will post here for any wayward internet travellers. Note it is a similar process to fix the CVP-87.

After months of working on my piano(yes it really does take quite a long time to repair these but you learn a lot along the way so its very useful) I put it back together a few days ago and it now plays beautifully. The left pedal still doesn't work because I think I damaged the multiplexer when I removed it to clean under it but I am not too bothered as the rest of the piano works very well and I am very happy it is working again!

The first question I was asked is where do you get the service manual from?
Answer: You can use google fu to find a website that might have it for download or much easier is the method I took of contacting Yamaha and asking for the manual, they were reluctant but eventually gave in and sent me a copy. And no I won't give you a copy if you PM me, they sent it to me under the condition that I don't distribute it and I intend to keep that condition.

Sources of information:
The most information that I used came from this website but unfortunately it seems to be down at the moment: http://bradfordmusicstore.com/repair-blog/2014/6/7/yamaha-cvp87-dm-board-repair-also-appplies-to-cvp85-and-cvp83
There is more useful information here: https://drewforchione.wordpress.com/portfolio/yamaha-cvp-87a-repair/.
(Yes it details how to fix CVP-87 but the 85 and 87 are pretty much identical except the CVP-87 has more components mounted onto the board)

The Repair:
Firstly you need to remove ALL (yes ALL) the metal can surface mount capacitors (list below). I highly recommend that you remove them using a hot air rework station, there is other ways to remove them but if you want to do the least damage to the board I would use hot air. (Remember if you screw up your board there is no chance of you getting a replacement!)
Secondly you need to clean, clean and clean. I used acetone for this, a Stanley knife and a brass wire pen/brush. Using the knife and brass wire I scratched off any black(electrolyte fluid) I could find. You will most likely scratch down to the copper traces, you want to remove ALL the black you can find as it slowly corrodes away the copper traces and any black left will cause you problems in the future.
After you have removed all the black you will have quite a lot of bare copper. You need to plate this copper with solder. I used the brass wire to make the copper shine first then cleaned with acetone then applied flux and finally used a soldering iron to cover the copper with solder.
Now you need to repair broken traces, get a multimeter and check all the traces near each affected area. For any broken traces reroute them using bus wire. (I used an old IDE cable). Its important you inspect the board thoroughly. I didn't do this properly and missed a very small black spot that corroded a trace and broke the connection so when I first put the piano back together all the switches on the front panel did not work.
Finally you will need to solder on replacement capacitors. I recommend not using surface mount caps again.
Put the piano back together and hopefully you have fixed it.

Good Luck!

CVP-85 Replacement capacitor list:
Identifier - Value - Writing on Cap
C95 - 1uf 50V - (D3/1/50V)
C94 - 1uf 50V - (D3/1/50V)
C98 - 100uf 6V - (G2/100/6V)
C96 - 100uf 6V - (G2/100/6V)
C109 - 100uf 6V - (G2/100/6V)
C105 - 100uf 6V - (G2/100/6V)
C97 - 100uf 6V - (G2/100/6V)
C101 - 100uf 6V - (G2/100/6V)
C93 - 1uf 50V - (D3/1/50V)
C90 - 1uf 50V - (D3/1/50V)
C92 - 1uf 50V - (D3/1/50V)
C89 - 1uf 50V - (D3/1/50V)
C88 - 1uf 50V - (D3/1/50V)
C91 - 1uf 50V - (D3/1/50V)
C100 - 100uf 6V - (G2/100/6V)
C99 - 47uf 16V - (G2/47/16V)
C275 - 47uf 16V - (G2/47/16V)

C87 - 100uf 6V - (G2/100/6V)
C104 - 10uf 16V - (F3/10/16V)
C114 - 330uf 6.3V - (330uf 6.3v)
C115 - 330uf 6.3V - (330uf 6.3v)
C272 - 330uf 6.3V - (330uf 6.3v)
C289 - 10uf 16V - (F3/10/16V)
C288 - 10uf 16V - (F3/10/16V)
C113 - 100uf 16V - (100uf 16V)
C112 - 100uf 16V - (100uf 16V)

C290 - 4.7uf 25V - (4.7/25A/34G)
C295 - 4.7uf 25V - (4.7/25A/34G)
C296 - 22uf 16V - (A4/22/16V)
C294 - 100uf 6V - (G2/100/6V)
C298 - 47uf 16V - (G2/47/16V)
C297 - 4.7uf 25V - (4.7/25A/34G)
C292 - 4.7uf 25V - (4.7/25A/34G)

C283 - 4.7uf 25V - (4.7/25A/34G)
C285 - 4.7uf 25V - (4.7/25A/34G)
C287 - 22uf 16V - (A4/22/16V)
C286 - 100uf 6V - (G2/100/6V)
C291 - 47uf 16V - (G2/47/16V)
C293 - 4.7uf 25V - (4.7/25A/34G)
C284 - 4.7uf 25V - (4.7/25A/34G)

CG1 - 4.7uf 50V - (c3/4.7/50V)
CG2 - 4.7uf 50V - (c3/4.7/50V)
(2 Generic Capacitors, next to CN5)
 
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Offline tautech

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #10 on: April 06, 2015, 10:08:14 pm »
Well done.
Thanks for sharing.  :-+
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Offline yosiamir

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #11 on: April 07, 2015, 06:29:11 pm »
Thanks for sharing this important data , I guess that several of CVP-85 will back to life again.

 

Offline Hideki

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #12 on: April 07, 2015, 10:12:10 pm »
It's kanji for the first sound for the Japanese word for ceramic.

I think.

?

Close. It's the katakana symbol for the sound "se" in the word "seramikku".
 

Online blueskull

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Re: Fixing a CVP-85 Piano: Unknown schematic symbols
« Reply #13 on: April 08, 2015, 06:42:36 pm »
It's kanji for the first sound for the Japanese word for ceramic.

I think.

?

Close. It's the katakana symbol for the sound "se" in the word "seramikku".

It should be. It is lame that this forum doesn't support kana character (actually all CJK).
 


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