10DC-2 Blocking Rectifier - Substitute?

jheu02

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I'm having a hard time finding any information or data sheet for these rectifier diodes from the Yamaha CA-800 and 1000. D701 and D702 are 10DC-2R and 10DC-2 respectively. Looks like I have a bad D702 and will need a replacement, but I don't even know what specs to look for.

Thanks,

John
 

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You can substitute a pair of 1N4005 or 1N4006 or 1N4007 for each one. They are very cheap, probably a dime each more or less. Just connect them as in the diagram.
 
Thanks a bunch. I did get a cross reference to a TO-220 rectifier, but since I couldn't find any specs on the original, I had no idea if it would be compatible. Where'd you find the specs so I know of other resources to search for future projects if needed?

Just so I'm sure, the 2 different links are for the 10DC-2 AND 10DC-2R correct? Also, the link to newark.com came up with heat sinks, insulators, etc. I'll assume that these are required also...it's not a complete package by itsself? The reason I ask is that the originals are snadwiched in between ceramic caps and I'm not sure how much room I'll have to play with for heat sinks, etc.

Do you think the earlier issue I was having with the Operation switch and "sizzling bacon" was a result of this rectifier going out or the other way around? Not sure if I have to troubleshoot anything further before putting the new rectifiers in. The 3.9ohm resistor connected to the one leg of the diode went up in smoke when I powered up, but that's the only thing affected afaik. The others check fine.

John
 
The 1620CT would replace D702 (the 10DC-2), and the 1620CTR would replace D701 (the 10DC-2R). These devices are capable of 16A of current. Seeing as how the circuit on the Yamaha is fused for 400mA on each rail, I'll leave it to you to ponder the necessity of heatsinks. ;)
 
Thanks a bunch. I did get a cross reference to a TO-220 rectifier, but since I couldn't find any specs on the original, I had no idea if it would be compatible. Where'd you find the specs so I know of other resources to search for future projects if needed?

Just so I'm sure, the 2 different links are for the 10DC-2 AND 10DC-2R correct? Also, the link to newark.com came up with heat sinks, insulators, etc. I'll assume that these are required also...it's not a complete package by itsself? The reason I ask is that the originals are snadwiched in between ceramic caps and I'm not sure how much room I'll have to play with for heat sinks, etc.

Do you think the earlier issue I was having with the Operation switch and "sizzling bacon" was a result of this rectifier going out or the other way around? Not sure if I have to troubleshoot anything further before putting the new rectifiers in. The 3.9ohm resistor connected to the one leg of the diode went up in smoke when I powered up, but that's the only thing affected afaik. The others check fine.

John

Are you sure those rectifiers are bad ? Did you do a diode check on them?I worked on a similar CA-800 that was popping and sizzling and it was a bad transistor in the regulator circuit.
 

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Are you sure those rectifiers are bad ? Did you do a diode check on them?I worked on a similar CA-800 that was popping and sizzling and it was a bad transistor in the regulator circuit.

I'll check those too, but look at the last post in my earlier thread. These are the measurements out of circuit using the diode test of my DMM.

http://audiokarma.org/forums/showthread.php?t=294038&page=2

On the photo, the dashes next to L and R are just that, not to signify negative voltage. Sorry if it's confusing.

Don't know if this is a related problem, but I also replaced the power indicator bulb and it didn't light. I had checked it for continuity before installing, as I had gotten a bad bulb from RS, or whatever issue the amp is having is causing such a current draw through the bulb that they're instantaneously ruined.

John
 
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OK..Must have breezed over that post,not really reading it.Yes ,those suggested dual rectifiers should work nicely.
 
No problem. I really appreciate all the help I'm getting with this amp. I do have some 1N4007's so I may try that route. The circuit board has the "directional arrows" printed right on it, but just to confirm, for D702 I'd tie the anodes together to make the center pin? And the opposite for the other if I wanted to put new diodes in for preventative mx?

As for the transistor you mentioned Dave, TR703 is a 2SC1213 NPN. Can you check my procedure to make sure I understood how to check it. Data sheet says it's ECB, so I put the + (red) probe on the 3rd pin which should be the base. Diode check voltages b,e +0.668v and b,c +0.662v

I also took out TR 702 (2SA673, PNP). - (black) probe on the base and these were what I got: b,e +0.684v and b,c +0.677v

Do these numbers sound reasonable?

If I read the datasheet correctly, looks like typical base to emitter voltage is 0.64v.

I'm learning alot about troubleshooting, and trying to figure out how to determine substitution parts for these old units, so any help in determining which figures are important to look at vs less important is great. It would be easier to just get a "here's the substitution part, it'll work" kind-of answer, but I'm trying to understand what I'm doing also and why.

Thanks again everyone who's helped.

John
 
your way of meassuring transistors seems fine - i really don't notice wether it's the black or the red on the base - i expect the reading to be app. 600 to 700millivolts , if not i flip the wires and look again ( i'm to lazy to spend time checking for npn versus pnp - i'm searching for a fault - if need be, i can dig into the polarity issue later ~ we Techs' are strange birds) besides that you have to get used to meassure CE also - a short from Collector to Emitter is a normal fault, it won't allways be revealed by meassuring Base->collector or base -> emitter

ps - try to hardwire a transistor - you'll still se a normal reading, but that thing is blown :D
 
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Spec sheet

I've used the following as replacements from Mouser:

10DC-2 512-FEP16DT
10DC-2R 512-FEP16DTA

The attached spec sheet is for the 10D, but I assume that 10DC-2 just means two diodes in common.
 

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I've used the following as replacements from Mouser:

10DC-2 512-FEP16DT
10DC-2R 512-FEP16DTA

The attached spec sheet is for the 10D, but I assume that 10DC-2 just means two diodes in common.

Thanks for the part link. Just to get things rolling, since I had the 1N4007s on hand I went ahead and wired them together, soldered, etc as shown in pic. Anodes tied for the center lead for the 10DC-2 (right, black legs), cathodes tied for the center lead as in the 2R (left, red legs) and as screened on the board. I used the insulation stipped from 14ga home wiring to both prevent unwanted contact and as a visual reminder of which original part went where. Put it on the dim bulb, initial dimming, and then back up brighter in a pulsating way. So something's still trying to draw too much current correct? :tears:

I read another thread on Spec-1 amps being mislabelled as to polarity of caps. Is this also an issue with the CA-800? I'll admit to not paying as much attention as I should have when pulling the caps during my recap, but I doublechecked inserting the new ones with the polarity as printed on the board. I'll be pulling boards and checking again, and for any solder bridges, etc, but what else should I look for? Something else on the PS board or the main filter board? Or could this still be related to the Class A switch microswitches I had to replace earlier?

John
 

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Something Still Amiss

Replaced the power switch and the 10DC2 and 2Rs, fired it up on the dim bulb, and while the bulb comes back up bright, it's no longer pulsating. So I guess that's progress. Still don't know where else I should begin looking. I did check all the caps on the function board and they are in correctly compared to the CB diagram from the service manual.

Guess I'll need to check all the other boards and recheck transistors. Argh.

John
 
Just a follow up note; whether related or not I leave to you. I am working on a Sansui 9090 with one half of D01 shorted. It too is a 10DC with a common cathode. I salvaged a C25M from a scrapped car amp and it works fine. Also rated at 16 amps forward bias, it's only on a line fused for 1 amp. I have a distinct feeling that it's going to hold up just fine...

Rob
 
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Check all the fusistors, labelled HWnnnn on the board, they have a nasty habit of changing value.

This project has, unfortunately, been put aside for the time being. I have checked and/or replaced all the fusistors on all the boards and am still having issues with the current draw as indicated by the not-so dim bulb. I may try replacing more of the regular and zener diodes, especially on the PS board, but they appear to check OK. I'm still left with the feeling that, although all the caps I've replaced are correct according to the silkscreening on the board, one or more are reversed in polarity. If anyone has high-res pics of the boards of a functioning CA-800 that not only shows the screening, but also the caps themselves (including tantalums) I would REALLY appreciate it to compare against my actual boards.

Or...I have pics of my boards I could forward to someone to compare to their functioning 800 and let me know if I've got anything in bass ackwards.

For now I've switched gears to several speaker rebuilds that I'm just about finished with. KLH-17s, Criterion 50A and Zenith Model 66s (complete gut and rebuilds). Maybe some time off from the amps and receivers will clear my head a bit.

John
 
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