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 Sanyo MR-999 Reel to reel problems
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 Return to top of page · Post #: 1 · Written at 10:58:57 AM on 15 January 2022.
Tyson's Gravatar
 Location: Gippsland, VIC
 Member since 2 February 2019
 Member #: 2329
 Postcount: 13

I recently brought a Sanyo MR-999 R2R tape deck online and am having issues with it. It likes to make hissing\popping noises whenever it is in play but it also happens occasionally when I put it into record mode. What could be the source of this as I am thinking its ether the original capacitors, leaky\noisy transistors somewhere in the record\play head amplifier or the record\play switches being dirty (even after giving them a good cycling through by engaging play and record a few times).

Any help is greatly appreciated


 
 Return to top of page · Post #: 2 · Written at 3:47:58 PM on 15 January 2022.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2050

More likely a noisy resistor, unless they are film types. Carbon comp parts are notorious for this.

You can track it down by clipping in a 100nF cap to ground, starting at the base of the first stage.


 
 Return to top of page · Post #: 3 · Written at 9:42:52 PM on 15 January 2022.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4602

There are also often black sometimes brown etc. plastic axials around 3/8" in diameter and 1/2" long common in car radios & lots of other stuff. These horrid little beasts can crack their jackets, burn & generally create havoc.

Keep an eye out for them; Not unusual to decorate the bin with all of them, from a set.

Marc


 
 Return to top of page · Post #: 4 · Written at 10:31:59 PM on 15 January 2022.
Tyson's Gravatar
 Location: Gippsland, VIC
 Member since 2 February 2019
 Member #: 2329
 Postcount: 13

I was planning on replacing the caps anyway as the one for the motor gets hot to the touch after its been running for around 5-10 minutes. I have managed to get my hands on a partial service manual (no schematic but it comes with a parts list and board layout as well as a troubleshooting checklist) and it appears that they are "Carbon P and Carbon L" types. Are these the same as carbon comps?


 
 Return to top of page · Post #: 5 · Written at 12:27:54 AM on 16 January 2022.
MonochromeTV's avatar
 Location: Melbourne, VIC
 Member since 20 September 2011
 Member #: 1009
 Postcount: 1140

Schematic is freely available from here: https://elektrotanya.com/sanyo_mr999.pdf/download.html


 
 Return to top of page · Post #: 6 · Written at 9:44:02 PM on 16 January 2022.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2050

Use the bypass cap method to track down where the noise is coming from rather than guessing and shotgunning the thing.


 
 Return to top of page · Post #: 7 · Written at 2:41:46 PM on 17 January 2022.
Tyson's Gravatar
 Location: Gippsland, VIC
 Member since 2 February 2019
 Member #: 2329
 Postcount: 13

I got my hands on the schematic and will definitely be using the bypass cap method to fault find. For the resistors in the service manual, they are listed as being "Carbon L and Carbon P" types. Are these the same thing as carbon composition?


 
 Return to top of page · Post #: 8 · Written at 9:50:14 PM on 17 January 2022.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2050

Don't know. The "quiet" type is normally a carbon film resistor. These normally have little bulges (end caps) where the wires are attached.


 
 Return to top of page · Post #: 9 · Written at 1:18:49 AM on 18 January 2022.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4602

There has been a variety of resistors made over the years, some more successful than others. Cracked carbon was interesting, my running gag with them was that they kept cracking & went high. As there is an erase oscillator there could be Mica caps & they often have a "hissy fit" when they die.

Early Germanium transistors had a habit of hissing, especially the output ones.

White space fixed known cause.


 
 Return to top of page · Post #: 10 · Written at 12:43:27 PM on 18 January 2022.
Robbbert's avatar
 Location: Hill Top, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1553

Hopefully someone can get of the enormous amount of white space.

Thanks.


 
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