Help me create an SX-727 BOM

[cuda440]

I picked up an SX-727 a couple of weeks ago and found (or didn't find) that, although some recap lists are available, there isn't a comprehensive (caps, transistors, diodes) BOM for it, or at least I couldn't locate one here, so I've started creating one. I'd like to post my findings here over the next few days in the hopes that y'all will point out the errors, necessary corrections, pointers, suggested mods, etc. and I'll edit it into a fresh BOM.

I'm limiting the parts to those most commonly replaced in a refurb. Of course, not every part on the list needs to be replaced (and some may argue that none/few of them do, especially if the unit is working), but I wanted to at least capture the list for posterity. Please indicate those parts that can typically be left alone and those that should ALWAYS be replaced.

One other note: the silicon replacements listed are based on an AK search of the original part and the most recent expert opinions on it's replacement. Since some parts came up with more than one possible substitute, it may be the case that I missed the context and chose the wrong one. Please set me straight.

A Mouser part number can be found in the last "column" (too bad we lose the formatting when pasting).

Let's start with the POWER SUPPLY AWR-011

AWR-011 C6 100 50 20 ELECTROLYTIC 100uF, 50V CEA 101P 50 647-UPW1H101MPD
AWR-011 C7 100 50 20 ELECTROLYTIC 100uF, 50V CEA 101P 50 647-UPW1H101MPD
AWR-011 C9 220 35 20 ELECTROLYTIC 220uF, 35V CEA 221P 35 647-UPW1V221MPD
AWR-011 C10 220 35 20 ELECTROLYTIC 220uF, 16V CEA 221P 16 647-UPW1V221MPD
AWR-011 C11 220 35 20 ELECTROLYTIC 220uF, 16V CEA 221P 16 647-UPW1V221MPD
AWR-011 Q1 BJT NPN 2SD313 512-KSC2073TU
AWR-011 Q2 BJT NPN 2SC373 512-KSC2383
AWR-011 Q3 BJT NPN 2SD313 512-KSC2073TU
AWR-011 D1 400V Rectifiers 400V 3A SR3AM-8 863-1N5404G
AWR-011 D2 400V Rectifiers 400V 3A SR3AM-8 863-1N5404G
AWR-011 D3 400V Rectifiers 400V 3A SR3AM-8 863-1N5404G
AWR-011 D4 400V Rectifiers 400V 3A SR3AM-8 863-1N5404G
AWR-011 D5 1S1850 2 x 625-1N4007E-E3/54*
AWR-011 D6 13V ZENER DIODE WZ-130 512-1N5243B

* a pair of diodes, nose to nose. There is a diagram from larryderouin.


-Cuda.

 

[rcs16]

Looks okay after a quick glance.

 

[cuda440]

The next installment is the power amp, but I need some advice on which variable resistors are needed. There are two pairs of 4.7k and 2.2k on this board, but I don't know what orientation, multi or single turn, etc.

 

[Watthour]

http://www.audiokarma.org/forums/in...advice-on-a-sx-727.266564/page-3#post-3314981

 

[cuda440]

That thread contains caps lists, but nothing about transistors, diodes, trimmers, etc. that I could see.

In any case, I've gotten much farther in the BOM process and will publish my findings in the next day or so, but I did run across something while trying to determine which trimmers to include for the power amp section. I could not find any procedure for setting offset/bias/etc in the service manual.

Am I just not seeing it?

And I'll repost the question about what trimmers to get - do I need to do all 4 on the amp board, just two, which two?