MHZ 66一個很嚴重的問題

MHZ 66用家注意:

在CD摩機課上, 高佬有部 MHZ66.
他拿來說該機在播放時會"拍"一聲.

經檢查後發現如下:
屏壓只有 75V.
輸出波形嚴重失真
嚴重削波, 正弦波波形是圓頭的, 我也是第一次在CD機上見到
頻寬在10KHz 便 Roll Off.

由於該機拿來時侯己摩過, 並且PCB傷痕雷雷, 故此花了較長時間檢查

該屏壓(变壓器) AC = 80V, 全波整流後約113V. 但該穩壓Zener 用75V(該Zener沒有摩過, 胆的偏壓電阻沒有攪過,原廠的, 問題在於廠方落錯料, 或計錯數), 以至到頂
改变屏壓至100V (Change 75V zener to 100V), 問題全部消失

高佬, 我想你會很 high, 當你真正聽到它的音色, 我比較過, 真是不錯.
你攞部野回家先, 聽二個星期, 再找我們, 比D新造的補品你試下

Result :
輸出波形沒有失真
頻寬在18KHz 便 Roll Off, 問題在LPF的电容參數, 有得攪, 用SPICE Sim 二野便有結果

Conclusion:
你們的MHZ66 有無問題?
吾知有無輸出波形失真?
定己經用咗好多錢去摩? 最怕你有日看見波形是失真的, 那便一定要即刻 93067521(KK摩斯密碼)

教你一個方法, 量度一下屏壓, 看看是多少.
底板上有一插頭, 近住同軸輸出附近, 排列為 (6.3) (6.3) (0V) (空接) (100V)
度到100V 無事, 度到75V就或者有事,要量度一下波形, 除了波形外, 還會影响 freq. response
吾怕重, 攞上HiFiFEVER, 收你小小錢, 用我們的架生檢查及測量一下.
好吾好?
再吾係, 上門又得, 我們有 portable 示波器, 好吾好


KK.Ho
93067521

MHZS 這個牌子問題非常多!!
如果不幸買入MHZS, 搵你地幫手搞搞都係好方法

頻寬在10KHz 便 Roll Off<<< 好多人無耳仔, 聽唔出, 都唔出奇! ha ha ha ha

Pure HiFi,

You are Welcome

I am share what I found(problem) in the MHZ 66.

KK.Ho
93067521

Is the same problem occur to the MHZ CD33? they use similar circuit right?

Windwss,

Conguration!

Same.

There are some method to test it without CRO.

1. Do you have Gameboy ? It can modification as CRO
2. Do you have MD, DAT, Cassette deck, you can monitor it output 20-20KHz by them
3. Also AC voltmeter.

KK.

My God!!! my bada HD-21 using same circuit as this mhzs cd 33.
I also found got "pak sound sometimes.

The volatage acrross the 2 cap(100uF/100v) is ~ 75v, across the 47uF/160v CAP is 114.5V, then voltage supply to the 2nd board (to the 1uF/250v) cap near the tube is ~81V.
to measure輸出波, just simply use a osciloscope(20MHz) should be enough right? which point shall i put the probe to measure the wave form?

KK Sir,

Below is the voltage reading i had measure:

at A (100UF/100V ECAP) = ~79V
at B (47UF/160V ECAP) = 114.7V
at C (+75V TO GRN -word print on pcb) = 81.7V
at D (diode) = 79.7V

the supplier from point C will connect point E in the other board which consist of 6n3 tube & 1uf/250v solen cap.

at E, V=~81v

at tube (6N3) pin 2 & pin 6 , voltage -->~53v

i not yet use OSK to see the wave form. If in case it really roll off at 10kHz, what can i do?

Do u mean that change the diode at point D can solve this problem?

WindWss,

What is your model of the CDP ?

The look and components placement is not = MHZ66 from classmate.

Please take a full look picture to me.

Thanks
KK.Ho

KK Sir,

It is BADA HD-21, Is's circuit ~ 80% same as CD33 So i'm not sure it will have similar problem as cd33 or not? i still not check the wave form (waiting for the tools).

Maybe my ear not good, can't really feel roll off after 10khz....

KK sir,

我朋友有部MHZS CD66壞左, 不能讀碟
有無得救?

pure_ hire,

Ask your friend check all connection especially the ribon cable (better using multimeter because hairline break can't be detect visually.
if still not ok, then check
1) lens, see got laser output not(u should see red colour light, also see got scartches not?
2) see got unusual movemonet of the laser head or motor.
the cd66 still use KSS 213Q right?

common fault happen in this cd pickup is:

1) flat/ribbon cable defective/break
2) cable connection loose.
3) laser not output
4) in case u had adjust the white button at the back --> the control chip behind may damage & cause unsual movent/total breakdown or laser output failure

easier way is to change the whole laser pickup assembly (include motor), i think should be <hk50.
i had change my laser pickup kss-213C 2months ago.

incase u buy thr new cd pickup & install yourself, don't forget to remove the safety soldering point...

I'm very happy when I know that HIFI FEVER move to Tsuen Wan. It is much more near my home. I really want to bring my Shanling CD300 to your office to have your advice how to mod it when I is free.
Looking for meeting you.

Best regards.

Why,

I thought u already heavily mod your shanling?? still need further modification?

叫你朋友將部機掉落海 :

[quote:9355c06287="pure_hi-fi"]KK sir,

我朋友有部MHZS CD66壞左, 不能讀碟
有無得救?[/quote]

pure hi-fi

Please contact me la.

KK.Ho
93067521

Don't throw into sea

Dear KK sir,

can you draw me a correct wave form if a CDP working properly?

[quote:ebf2be316e="WINDWSS"]Why,

I thought u already heavily mod your shanling?? still need further modification?[/quote]

Windwss,
I have just replaced the output cap with Jensen copper foil. Last time, KK Sir tought how to mod the power supple, so I want to mod it. otherwise, I also want to mod the opamp etc., after have K.K Sir's advice.

KK sir,

聽聞下星二你去觀塘
約你下星期二ok??
部機放係VxxxAxxx
帶定粒SAA7824

我朋友部機就吾使掉落海 la :

[quote:d626a2ed8e="kk_ho"]pure hi-fi

Please contact me la.

KK.Ho
93067521

Don't throw into sea[/quote]

WindWss,

It is a pure Sine Wave, no need to take photo.

Why,
First checking your machine (no distortion waveform) before use the money to mod this machine.

Pure HiFi,
Please direct contact me for repair service.

KK.Ho
93067521

叫你朋友做下好心,贈給窮困難民,好讓知道CD機的奧秘

我已换佐Zener 测电子管电压为96伏
高音就几好,但太明亮,低音就很不足.
CD33E摩改如下:
胆输入电容 德国MCAP银箔油浸电容
电源电容换RIFA 2200UF 的
整流用VISHAY SF4004
胆电源滤波前用闪光灯高速电解后用B.G 220UF
胆用JAN 5670
请教各位大佬,问题出在哪里? 不胜感激!

大陆初烧友

Regulator stage have bug !!!!