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 1 
 on: Today at 01:35:54 am 
Started by Geoff Doane - Last post by MaxReedLeo07
First, the photo you want to apply must be uploaded into your pc, from your cellphone, or camera, and preferably as a jpg report, even though a gif document will paintings, too. Make sure you've got a photo report set up to upload the picture to.

 2 
 on: Yesterday at 03:48:34 pm 
Started by Dominick Costanzo - Last post by Dominick Costanzo
We've a Sony PCM-3402 machine that has a power supply failure.
A sub board in the supply, Sony part # 1-614-406-11 had 3 components fail.
One of the components, D12, exploded. It's face with the part number becoming one with the cosmos.
It is a 3 leg item, most likely a half wave rectifier.
Although I have a full service manual, the supply, Sony Model UR-08, is referred to only as a part in the manual.  No schematics or component lists are in the manual. Without a parts list I have no way to attempt repair.
A month of communication with Sony Professional Electronics have lead only to dead ends.
Sony Professional Electronics has thrown out and destroyed all spare parts, test jigs, and documents related to this machine.

 3 
 on: Yesterday at 03:35:20 pm 
Started by Dominick Costanzo - Last post by Dominick Costanzo
Does anyone have working experience in repair of Sony PCM-9000 magneto optical recorders?
I have 3 machines, all with issues.
Sony Professional Electronics has thrown away all test jigs, spare parts and documentation of these machines.
I've a full service manual but nothing else.

Dominick Costanzo

 4 
 on: September 18, 2017, 05:29:13 pm 
Started by mu90r - Last post by mu90r
I am looking for a head or capsule K47 or M7 for U47 in good condition.
The k47 capsule is vintage and still in good condition ,the best.
Any offer by private.

 5 
 on: September 18, 2017, 01:07:01 pm 
Started by Kultivator - Last post by klaus
In your opening post you reported that you have 9 Volts at the DC board's Zener. That indicates that the  amp board is healthy, and the problem must be located on the DC board which is not pumping out the required high voltages for the capsule.

Hence my advice for troubleshooting the always suspect Tantalums on the DC board.

 6 
 on: September 18, 2017, 07:17:42 am 
Started by Neutrino - Last post by Neutrino
Finally, with some help from eBay, I was able to return the PL20 for a refund. Thanks anyway to everybody for your help!

Prior to returning the PL20, I also did a simple measurement of the frequency response of both mics (PL20 and RE20) with my limited possibilities. Since I don't have an anechoic chamber, I used a calibrated measurement mic (Beyerdynamic MM1) as a reference and measured all three microphones with RoomEQ Wizard, which is normally used for room measurements. All mics were positioned at the same spot at less that 1m distance from a monitor speaker in my control room. The attached plot shows the results (green: MM1, blue: RE20, red: PL20).

Since the MM1 is supposed to be pretty flat, it only shows the influence of the speaker and the room at that position. Any deviation from this should be attributed to the microphone.

The response of the RE20 resembles the official curve published by EV: a peak around 8 kHz and a dip around 4.5 kHz. Below that frequency the curve is rather close to the measurement mic meaning a pretty flat response.

Now the PL20 shows a strong peak (~+10dB) around 3kHz, which is neither present in the measurement mic, nor the RE20. This is also in line with what we were hearing in the samples I posted initially. Whether one can conclude from this that the PL20 is defective, I don't know. But it is certainly strongly out of spec. Just thought it would be interesting to post.

 7 
 on: September 18, 2017, 03:27:38 am 
Started by Kultivator - Last post by Kultivator
Yes,IŽll try that. But first I would like to rule out the amp board, the amp board feeds the dc board with 8v when I measure black-red wire coming from the amp board to DC board and DC board disconnected. IsnŽt that low?

One strange thing is when I engage the low-cut circuit voltage rises to 10v :-\



 

 8 
 on: September 17, 2017, 12:47:38 pm 
Started by Kultivator - Last post by klaus
The fact that the voltage increased dramatically after disconnecting the DC board's electronics points to a component on the DC board, or, more likely, the 9.1V Zener on the DC board does its work, and that points even more to a shorting component on the DC board.

Methodically replace capacitors on the DC board with polarized electrolytics, particularly the 10nF and 22nF are suspect. If that does not bring up the voltage, which most likely it will, you need to check out the zeners, particularly the 9.1V.

P.S.: Leave the thin wires around the switches alone, They are not involved in this type of troubleshooting at the moment.

 9 
 on: September 17, 2017, 12:40:43 pm 
Started by mu90r - Last post by klaus
The capsule in the first two pictures is not a genuine Neumann capsule, but most likely a Thiersch Blue Line (PVC diaphragms).

It cannot be determined from the photos whether this capsule is a new M7 copy capsule manufactured entirely from scratch, or whether new diaphragms were mounted on an original Neumann M7. Thiersch offers both services.

In either case, do not expect genuine Neumann sound from such a capsule.

 10 
 on: September 17, 2017, 07:33:18 am 
Started by klaus - Last post by mu90r
I have seen the valve # 129 VF14M on this page.
Maybe, you should ask the owner where the valve came from ....
Luck!

http://www.moxtone.com/mU47_U47.html

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