[KCMike]

I found the # on the diodes it was 1s1073 NTE diode 5804 400V/3Amp is an replacement for them. I have read NTE not that good a product. I can't seem to find equivilant at mouser. Will keep looking. Hope to have order list together tomorrow.

[morzh]

Not sure of voltages but if the B+ for power amp is 65V, then 400V is plain excessive, though 3A looks plausible.

I would get a 100-120V GP rectifier diode 4A rated.

MOUSER Catalog

6A1-T
MUR410G
MUR415G

[KCMike]

Just to make sure I'm on same page with you. The 4-diodes I'm referring to are in the power supply unit. I believe it to be rectifier bridge circuit. The schem. is on the above page next to amp schem.

[morzh]

The rectifier bridge shown in the Power Supply Unit, this is what I think we are talking about.

BTW how did you find out they are bad?

[KCMike]

I checked each one with a fluke dvm (in circuit )on the diode test setting. 3 of them are reading both ways positive or neg.1 seems to test ok. but I figured replace all 4.

[BrendaAnnD]

Just inputting SRIDM into the NTE cross reference comes up with NTE116 (1A 600V) for SRIDM, SRIDM-2 and SRIDM-4.

[morzh]

Brenda


I found those up to SRIDM-4, but not 8.


PS. Just went to look at the power, it is 58W into 8 Ohm. So the top current (let's forget about current waveform etc) is 2.7A (which is close enough to initial guess of 25W into 4 Ohm which is 2.5A). Half that (bridge rect) is 1.35A and two channels make it 2.7A again. Plus this is peak power which is unlikely to be sustained. So a 4A diode would be still my choice. But not 1A.

I do not think a 1A diode will cut it here.

[KCMike]

Thank you Brenda. I checked the #'s on the diodes and they were 1S1O73. NTE shows the 5804 as the one to replace with. I had tried the SRIDM -8 as the search number because that was on the parts list with no luck.
I went ahead and ordered 4 - 5804 diodes. If you think I should not use them please let me know. I'm new to stereo and these different uses and parameters for transistors and diodes is kind of overwhelming.

[morzh]

I would use MUR.

1. You do not need 400V rating.
2. The datasheet on this diode is extremely poor. No data at all.
2. Vf instantaneous (measured at 9A) is 1.2V for NTE while 0.9V at the same current for MUR. There are no graphs for NTE to evaluate non-max value.

But...it will work.

[KCMike]

 morzh I really appreciate you helping with my ignorance about these stereo parts.
 What is a MUR? So far the hardest part for me about stereos is learning about the many combinations and trying to make sure I'm getting the correct value  substitute parts   I have not removed the amp or power unit. Thought I would wait till I have parts in hand.

[morzh]

Look at the diodes PNs I gave you before, there are some that start with MUR.

[KCMike]

I have got back to the stereo after waiting for parts to come in. Started on power board unit. I have a question about a transistor. It is the 2SC905 on schem.
I bought an replacement nte 194 NPN that is crossrefrence match.
My problem is the pin out doesn't seem to match the schem. What I mean is the new transistor PO is emitter base collector. The way I see it on the schem. the base will be in the lef hole then collector in middle then emiter on right. here is a picture of the board and schem. of power unit. Can someone please tell me if I"m right about this or missing it? Thanks
http://s1336.photobucket.com/user/220koh...9.jpg.html
http://s1336.photobucket.com/user/220koh...7.jpg.html

[morzh]

Mike


Schematic NEVER tells you pinout, the sequence on a symbol is usually tailored to best fit it into the graphic flow of the sch, has nothing to do with the real world.

From your board (the link does not work the way you posted it) it is BCE left to right.
As here:
http://english.electronica-pt.com/compon...ref=2SC905

Now your new transistor is: EBC
http://www.nteinc.com/specs/100to199/pdf/nte194.pdf

Simply match the functions: E-E, B-B, C-C

When you cross pins, use some insulating sleeves (from wire or heatshrink) to prevent shorts.

[KCMike]

Thanks morzh. The crossing of the pins was what didn't seem right. The e-b-c for new transistor I got from the front of the package. I tried to find a matching transistor with the correct pin out.

[morzh]

You don't need to. It is mere inconvenience, not a functional problem.
Another way is try to flip the transistor pins up (transistor's body down) and see if bending them downward would make crossing easier. Then pins might not be long enough.

Myself, I'd just cross'em.