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 Circuit for an HMV Monaco
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 Return to top of page · Post #: 1 · Written at 8:23:58 PM on 5 June 2016.
Scotty's Gravatar
 Location: Melbourne, VIC
 Member since 26 December 2010
 Member #: 794
 Postcount: 274

Hi, does anyone have a copy of the circuit diagram for an HMV Monaco record player. The unit I have has very low audio output and I need to fix it.

Cheers
Scott


 
 Return to top of page · Post #: 2 · Written at 8:49:23 PM on 5 June 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 5307

Model C7-8E from 1966 with these semiconductors: SE4010, AY1108, AC187, AC188, AS25.

Shown here, but alas no schematic: http://www.radiomuseum.org/r/hismasters_monaco_c7_8e.html


 
 Return to top of page · Post #: 3 · Written at 10:08:58 PM on 5 June 2016.
Scotty's Gravatar
 Location: Melbourne, VIC
 Member since 26 December 2010
 Member #: 794
 Postcount: 274

Thanks GTC, I saw that pic and yes, no schematic. As I said it works, but very low volume. You reckon it could be any of the caps - I assume the transistors are ok given there is some signal


 
 Return to top of page · Post #: 4 · Written at 11:59:08 PM on 5 June 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 5307

Any original caps, especially electrolytics, from1966 would be well past their use-by date, even though they may still appear to be be good.

Usual procedure is to check power supply voltages, then work backwards from the speaker, injecting a signal.

The cartridge may well be cactus. Might even be as simple as a bad/corroded connection. Shouldn't be too hard to find the cause of the attenuation.


 
 Return to top of page · Post #: 5 · Written at 4:53:45 AM on 6 June 2016.
MonochromeTV's avatar
 Location: Melbourne, VIC
 Member since 20 September 2011
 Member #: 1009
 Postcount: 1051

Ducon branded electolytics & Ducon Red Caps are the biggest culprits for faults in 1960's Australian made solid-state gear. All Red Caps should be replaced as a matter of course.

If that fails, I'd turn my attention to the cartridge.

HMV H5-8E, JF-8E, C7-8E, U2-8E Service Manual


 
 Return to top of page · Post #: 6 · Written at 9:57:15 AM on 6 June 2016.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 3808

There are two things in 60's sets that I am finding causing volume issues. Yes! to electrolytics these were used as coupling caps & dry out. The others are some small axial caps around 1/4" x 3/8" of similar values to the old wax paper type & are equally as reliable (not). Some of the Ceramics were also a worry and I am also finding Germanium Oscillator transistors failing.

Also check resistors and for the common dry joint (cracks on printed circuits).


 
 Return to top of page · Post #: 7 · Written at 10:51:50 AM on 6 June 2016.
Scotty's Gravatar
 Location: Melbourne, VIC
 Member since 26 December 2010
 Member #: 794
 Postcount: 274

Thanks guys, re the cartridge, when I unplug it, I get the low signal. When its re connected there is no signal at all.
Will replace the electro caps and check the rest.

Hopefully a schematic turns up to so I can at least check volts etc.

Cheers
Scott


 
 Return to top of page · Post #: 8 · Written at 7:41:00 PM on 7 June 2016.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 5574

Service manual uploaded to post #5.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 9 · Written at 4:18:34 PM on 16 June 2016.
Scotty's Gravatar
 Location: Melbourne, VIC
 Member since 26 December 2010
 Member #: 794
 Postcount: 274

Thanks guys - much appreciated.


 
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