SA-8500II Restoration

jheu02

AK Subscriber
Subscriber
Well, it's in the mail to me, and not sure when I'm going to get the chance to do the recap/restoration, but a quick question while I get my parts order ready:

There's a couple 470uF/6V caps on the board. I'd normally go with a 10 or 16V cap, but I have some 25V caps. Too much of a voltage increase???
 
Thanks Mark. I didn't think it to be an issue 3 steps removed from design, but I certainly wouldn't want to go much higher. The amp arrived yesterday afternoon, but I was only able to do a quick check for shipping damage...passed the DBT with flying colors. Relay clicked and no shorts showing up, but didn't get a chance to hook it up to speakers and listen for the little static/crackle that was mentioned by the seller. Should be a pretty straight forward restoration.

I was looking at the parts list from this thread which brought up a couple more quick questions while I'm thinking of them:

1. The list in post #2 was from the 9500 correct? So the proper list for the 8500II was at post #15 to also include Qs. Yes?

2. Switch assembly. C22-23 CEA 220uF/50V. The schematic shows 46.5V there. I have some UHE 220/50 caps, but would it still be better to order some 63V caps for a little more buffer?

3. Other than the UKLs for CEANLs, would any of the caps outside of the power supply benefit from having audio caps vs the PW/PMs listed? I have some of the smaller values listed on the various boards (2.2, 3.3 in both FG and Silmic).

Thanks again.
 
1. yes
2. yes 63v
3. maybe, if you have a preference for silmic, I have never had proof of their superiority.
For Silmic specifically, they might be slightly more immune from microphonics, a very small effect.
I consider most expensive audio caps more marketing than physics.
 
This is the correct list : (post #15)


Control Amp (AWG-044)

AWG044 C15 4.7uF 50v CEANL 647-UKL1H4R7KDDANA 4.7uF
AWG044 C16 4.7uF 50v CEANL 647-UKL1H4R7KDDANA 4.7uF
AWG044 C17 2.2uF 50v ach-309 647-UPW1H2R2MDD 2.2uF
AWG044 C18 2.2uF 50v ach-309 647-UPW1H2R2MDD 2.2uF
AWG044 C37 4.7uF 50v CEANL 647-UKL1H4R7KDDANA 4.7uF
AWG044 C38 4.7uF 50v CEANL 647-UKL1H4R7KDDANA 4.7uF
AWG044 C39 4.7uF 50v CEANL 647-UKL1H4R7KDDANA 4.7uF
AWG044 C40 4.7uF 50v CEANL 647-UKL1H4R7KDDANA 4.7uF
AWG044 C43 100uF 16v CEANL 647-UKL1E101KPDANA 100uF
AWG044 C44 100uF 16v CEANL 647-UKL1E101KPDANA 100uF
AWG044 C45 2.2uF 50v ach-309 647-UPW1H2R2MDD 2.2uF
AWG044 C46 2.2uF 50v ach-309 647-UPW1H2R2MDD 2.2uF
AWG044 C47 100uF 25v CEA 647-UPW1E101MED 100uf
AWG044 C48 100uF 25v CEA 647-UPW1E101MED 100uf
AWG044 C49 100uF 25v CEA 647-UPW1E101MED 100uf
AWG044 C50 100uF 25v CEA 647-UPW1E101MED 100uf
AWG044 q1 2sa725 512-KSA992FBU
AWG044 q2 2sa725 512-KSA992FBU
AWG044 q3 2sa725 512-KSA992FBU
AWG044 q4 2sa725 512-KSA992FBU
AWG044 q5 2sc1919 512-KSC1845FTA
AWG044 q6 2sc1919 512-KSC1845FTA
AWG044 q7 2sc1919 512-KSC1845FTA
AWG044 q8 2sc1919 512-KSC1845FTA




Power Amp (AWH-051) times two as there
AWH051 C4 22uF 50v CEA 647-UKL1H220MEDANA 22uF
AWH051 C5 330uF 6v CEA 647-UPW1A331MPD 330uF
AWH051 C13 1uF 50v CEANL 667-ECQ-V1H105JL5 1uF
AWH051 q1 2sa798 no-substitute
AWH051 q2 2sc1885 512-KSC1845FTA
AWH051 q3 2sc1885 512-KSC1845FTA
AWH051 q4 2sa912 512-KSA1220AYS
AWH051 q5 2sd358 512-KSC2690AYS
AWH051 q6 2sb528 512-KSA1220AYS
AWH051 d1 1s2473 512-1n4148
AWH051 d2 1s2473 512-1n4148
AWH051 d3 stv-3h no-substitute
AWH051 d4 1s1885 512-uf4004
AWH051 vr1 100 ohms idle current 652-3386H-1-101LF


Switch Assembly (AWS-108) psu & prot

AWS108 C7 .68uF 35v CSZA 667-ECQ-V1H684JL .68uF
AWS108 C8 .68uF 35v CSZA 667-ECQ-V1H684JL .68uF
AWS108 C9 .22uF 10v CSSA 667-ECQ-V1H224JL2 .22uF
AWS108 C10 .22uF 10v CSSA 667-ECQ-V1H224JL2 .22uF
AWS108 C11 470uf 6v CEA 647-UPW1A471MPD 470uF
AWS108 C12 100uF 16v CEA 647-UPW1V101MPD 100uF
AWS108 C13 2.2uF 50v cea 647-UPW1H2R2MDD 2.2uF
AWS108 C20 100uF 35v CEA 647-UPW1V101MPD 100uF
AWS108 C21 100uF 35v CEA 647-UPW1V101MPD 100uF
AWS108 C22 220uF 50v CEA 647-UPW1H221MPD6 220uF
AWS108 C23 220uF 50v CEA 647-UPW1H221MPD6 220uF
AWS108 q1 2sc869 512-KSC1845FTA
AWS108 q2 2sc869 512-KSC1845FTA
AWS108 q3 2sc945 do-not-replace
AWS108 q4 2sc945 do-not-replace
AWS108 q5 2sa733 do-not-replace
AWS108 q6 2sc945 512-KSC2383YTA
AWS108 q7 2sc1384 512-KSC2690AYS
AWS108 q8 2sd381 512-KSC2073TU
AWS108 q9 2sb526 512-KSA940TU
AWS108 d1 30d2 512-1N5404
AWS108 d2 30d2 512-1N5404
AWS108 d3 30d2 512-1N5404
AWS108 d4 30d2 512-1N5404
AWS108 d5 30d2 512-1N5404
AWS108 d6 30d2 512-1N5404
AWS108 d7 30d2 512-1N5404
AWS108 d8 30d2 512-1N5404
AWS108 d9 1s1886 512-1n4004
AWS108 d10 1s1886 512-1n4004
AWS108 d11 1s1886 512-1n4004
AWS108 d12 1s1886 512-1n4004
AWS108 d13 wz-250 512-1N5253B
AWS108 d14 wz-250 512-1N5253B
AWS108 d15 1s2472 512-1n4148
AWS108 d16 1s2472 512-1n4148
AWS108 d17 1s2472 512-1n4148
AWS108 d18 1s2473 512-1n4148
AWS108 d19 1s2473 512-1n4148
AWS108 d20 1s2471 512-1n4148
AWS108 d21 1s2473 512-1n4148
AWS108 s12 asr-023 653-MY4-02DC24

Equalizer Amp (AWF-023)

AWF023 C1 1uF 50v CEANL 667-ECQ-V1H105JL5 1uF
AWF023 C2 1uF 50v CEANL 667-ECQ-V1H105JL5 1uF
AWF023 C9 470uF 6.8v CEA 647-UPW1A471MPD 470uF
AWF023 C10 470uF 6.8v CEA 647-UPW1A471MPD 470uF
AWF023 C17 3.3uF 50v CEA 647-UPW1H3R3MDD 3.3uF
AWF023 C18 3.3uF 50v CEA 647-UPW1H3R3MDD 3.3uF
AWF023 C21 4.7uF 25v Bipolar 647-UEP1V4R7MDD 4.7uF
AWF023 C22 4.7uF 25v Bipolar 647-UEP1V4R7MDD 4.7uF
AWF023 C31 47uF 35v CEA 647-UPW1V470MED 47uF
AWF023 C32 47uF 35v CEA 647-UPW1V470MED 47uF
AWF023 C35 47uF 35v CEA 647-UPW1V470MED 47uF
AWF023 q1 2sa725 512-KSA992FBU
AWF023 q2 2sa725 512-KSA992FBU
AWF023 q3 2sa725 512-KSA992FBU
AWF023 q4 2sa725 512-KSA992FBU
AWF023 q5 2sc1919 512-KSC1845FTA
AWF023 q6 2sc1919 512-KSC1845FTA
AWF023 q7 2sc1919 512-KSC1845FTA
AWF023 q8 2sc1919 512-KSC1845FTA
AWF023 q9 2sa726 512-KSA992FBU
AWF023 q10 2sa726 512-KSA992FBU

parts list:

647-UKL1H4R7KDDANA
647-UKL1H4R7KDDANA
647-UPW1H2R2MDD
647-UPW1H2R2MDD
647-UKL1H4R7KDDANA
647-UKL1H4R7KDDANA
647-UKL1H4R7KDDANA
647-UKL1H4R7KDDANA
647-UKL1E101KPDANA
647-UKL1E101KPDANA
647-UPW1H2R2MDD
647-UPW1H2R2MDD
647-UPW1E101MED
647-UPW1E101MED
647-UPW1E101MED
647-UPW1E101MED
512-KSA992FBU
512-KSA992FBU
512-KSA992FBU
512-KSA992FBU
512-KSC1845FTA
512-KSC1845FTA
512-KSC1845FTA
512-KSC1845FTA

647-UKL1H220MEDANA
647-UPW1A331MPD
667-ECQ-V1H105JL5
512-KSC1845FTA
512-KSC1845FTA
512-KSA1220AYS
512-KSC2690AYS
512-KSA1220AYS
512-1n4148
512-1n4148
512-uf4004
652-3386H-1-101LF

647-UKL1H220MEDANA
647-UPW1A331MPD
667-ECQ-V1H105JL5
512-KSC1845FTA
512-KSC1845FTA
512-KSA1220AYS
512-KSC2690AYS
512-KSA1220AYS
512-1n4148
512-1n4148
512-uf4004
652-3386H-1-101LF

667-ECQ-V1H684JL
667-ECQ-V1H684JL
667-ECQ-V1H224JL2
667-ECQ-V1H224JL2
647-UPW1A471MPD
647-UPW1V101MPD
647-UPW1H2R2MDD
647-UPW1V101MPD
647-UPW1V101MPD
647-UPW1H221MPD6
647-UPW1H221MPD6
512-KSC1845FTA
512-KSC1845FTA
512-KSC2383YTA
512-KSC2690AYS
512-KSC2073TU
512-KSA940TU
512-1N5404
512-1N5404
512-1N5404
512-1N5404
512-1N5404
512-1N5404
512-1N5404
512-1N5404
512-1n4004
512-1n4004
512-1n4004
512-1n4004
512-1N5253B
512-1N5253B
512-1n4148
512-1n4148
512-1n4148
512-1n4148
512-1n4148
512-1n4148
512-1n4148
653-MY4-02DC24

667-ECQ-V1H105JL5
667-ECQ-V1H105JL5
647-UPW1A471MPD
647-UPW1A471MPD
647-UPW1H3R3MDD
647-UPW1H3R3MDD
647-UEP1V4R7MDD
647-UEP1V4R7MDD
647-UPW1V470MED
647-UPW1V470MED
647-UPW1V470MED
512-KSA992FBU
512-KSA992FBU
512-KSA992FBU
512-KSA992FBU
512-KSC1845FTA
512-KSC1845FTA
512-KSC1845FTA
512-KSC1845FTA
512-KSA992FBU
512-KSA992FBU
 
Hi John,

I'm glad to hear it arrived safely, and is now with someone who will restore it.

I'm not sure of the physical spaces on the board of this Pioneer, but I had some excellent results replacing KL series electrolytics with WIMA film caps in the NAD 1020 preamp I hot-rodded into a 3020 integrated. I even managed the squeeze a 10uF one right in the output of the phono pre by moving a resistor to the underside of the board.

The advantages of the WIMAs are they are square and upright, rather than long and narrow. Their disadvantages are they are more expensive, plus they have very short leads leaving little room for maneuvering. I see in the cap list above some Panasonic films, these will work also, along with the Cornell Dubilier ones Mark recommends.

You can find the 1020 to 3020 thread here if you are interested :

http://www.audiokarma.org/forums/showthread.php?t=589265

Lee.
 
WIMAs are nice, but I do already have the Panasonic ECQs for the 1uF (nice little square ones with long leads). I MAY look at other films, but already having the FG and Silmics I'll probable stick with those. What I may do though is get some of the other transistors besides the 992 and 1845s since they'll probably be lower noise. I had been watching that build thread...nice work and very inventive!
 
Pre restore Photos

I finally got a chance to open it up, take some pics and do a little listening test. All the switches and knobs work properly, though there is some stiffness in turning some of the knobs. Not very much scratchiness at all in any of the pots, but in giving a listen, there is a low background hiss (as Lee described) in both channels and it is independent of the volume knob position...i.e. present with volume all the way down. It's not very noticeable while music is playing, but if I ever use phones with it I might not feel that way. So yes, probably replacement of some of the transistors will help.

Other than a bit of grime inside, and needing some casework, I'm sure it will respond well to a freshening up. A couple questions and then pics to follow to aid.

1. Anyone have a tried/true paint that approximates the off-grey of the metal case of this vintage? I'd like to keep it the same color so it will match the TX-9500II, but this one definitely needs some work.

2. It's definitely been worked on at some time in the past. Regarding the OPTs and the STV-3Hs, Mark...are these correct batwings or should I be thinking about the mods to new Qs and clamps as shown in one of the other restore threads? Please reference the photos below to see what's installed. i couldn't find a cross-reference for the ECG labeling on alltransistors.com.

3. The STV-3Hs...There's a difference between channels, so I'm not sure which is original or whether neither are and subs have been put in there at one point. Possibly the R channel is original??

4. So far, the 2W 0.5ohm Rs on the amp boards check fine, so do the other green Rs. The SM calls them Metal Film as differentiated from Metal Oxide, but they sure look like metal oxides to me. Any problem using metal oxide here if need be? They're much less $ than true metal films in that power rating (0.15 vs 1.15 ea), and offerings like that from Panasonic list Metal Film (Oxide).

Like I said, the amp works and plays music, so the parts in there are functional, just not sure whether to leave them or completely redo those two boards. Thoughts???

Now the pics:
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14814205816_1bffb84c76_o.jpg


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14834111591_d7e6e398d9_o.jpg


14650643467_50b4fbfb59_o.jpg


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14650643037_bc77c35b1c_o.jpg
 
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I bought one of these units a couple weeks ago.
Said to be recapped,sound is to my ear good but
Not great.

I was thinking about adding a power amp to the
Mix along with my SG-9500 EQ..

Rock on.
 
WOW! Now I feel bad, I thought all the outputs were originals.

Lee.

No worries. It was, after all, a fixer upper, and it's functional vs the epray unknown. After looking at pics of STV-3Hs on, I'm pretty sure the right channel one is original. The ECG OPTs I can only guess were the correct replacement at the time of the work, they just didn't show up when I input 2S... Into the alltransistor search engine. I didn't try it in reverse or do other data sheet searches.
 
Digging In

I now have some time to get into this restoration, and want to be a little more methodical with this one vs prior recaps (do some work, listen for changes, etc. vs doing it all at once). So, I started with a check of DC Offset and BIAS prior to any work. The SM states to use 5.1K resistors on the Main In RCAs, but in one of the threads MTF stated it was only necessary for other more technical tests/ratings. So, no problemo boss, except if there is one. Here's the readings I took IAW SM directions to check/set with leads connected to Pins 3(+) and 9(-), then check the balance on pins 6(+) and 12(-). Bias should be set to 30mV (3/9) and 30mV +- 10mV as checked at pins 6/12.

Checked with Pre Out / Main In jumpers installed

L Channel
3/9 --- 5.7mV
6/12 --- 12.mV

R Channel
3/9 --- 2.5mV
6/12 --- 2.4mV

So, a bit low, but somewhat balanced on each channel.

However, I wasn't sure if the jumpers should have been left in so i checked again with them out.

L Channel
no change from with the jumpers installed

R Channel
3/9 --- 0mV
6/12 --- 0mV :scratch2:

So, which reading is the "off" one? Should I not get a BIAS reading with no load at the Main-In jacks, i.e. R CH is good, L CH has issues? With this odd reading, I decided not to try and adjust the BIAS to the 30mV just yet. I'm wondering if before trying to adjust it, I should install new multi-turns preset to whatever value the old ones that come out are reading. But, I also haven't gotten to all the pots and switches yet.

Offset was OK but not great, and I don't see a way to adjust it in the SM.

L Channel --- -11.4mV
R Channel --- 29.1mV

So, there's some out of spec stuff going on that I'll need to track down, but i want to do a good switch/pot cleaning to make sure there's no issues being created that can easily be cleared up.

Are there any tricks to get at the Equalizer and Control Boards without having to desolder any wires? They all appear to be wire-wrapped at an initial glance and that would require snipping and soldering back to the pins or getting a wire wrap tool. At least the wires to the EQ board appear too tight to be able to turn the board over to get at the switches on it.

Do the amp assemblies for each channel need to be removed to make some slack?

Though it doesn't really show it in the pics, the RCA jacks and the Pre Out/Main In jumpers had a lot of oxidation on them. I may eventually replace them, but for now I used a mini wire brush on my dremel at slowest speed and some D5 to clean/shine them up and enable much better signal transfer.
 
Time to Update the Cap List

Here's a shot of the Control Board of my 8500II. The 2.2uF/50V caps are also Low Leakage even though they have an ACH...part number.

So, these caps on the Control Board (AWG044) should look like this:
AWG044 C17 2.2uF 50v ach-309 647-UKL1H2R2MDDANA 2.2uF
AWG044 C18 2.2uF 50v ach-309 647-UKL1H2R2MDDANA 2.2uF
AWG044 C45 2.2uF 50v ach-309 647-UKL1H2R2MDDANA 2.2uF
AWG044 C46 2.2uF 50v ach-309 647-UKL1H2R2MDDANA 2.2uF

Unfortunately, I already placed my order and didn't catch this before doing so. So, I'll end up using either Nichicon FG or Elna Cerafine here since I have them on hand.

14965968795_66318898cb_o.jpg
 
Here's a shot of the Control Board of my 8500II. The 2.2uF/50V caps are also Low Leakage even though they have an ACH...part number.

So, these caps on the Control Board (AWG044) should look like this:
AWG044 C17 2.2uF 50v ach-309 647-UKL1H2R2MDDANA 2.2uF
AWG044 C18 2.2uF 50v ach-309 647-UKL1H2R2MDDANA 2.2uF
AWG044 C45 2.2uF 50v ach-309 647-UKL1H2R2MDDANA 2.2uF
AWG044 C46 2.2uF 50v ach-309 647-UKL1H2R2MDDANA 2.2uF

Unfortunately, I already placed my order and didn't catch this before doing so. So, I'll end up using either Nichicon FG or Elna Cerafine here since I have them on hand.

I still feel bad you're finding things needing doing to this, although as you said, it was purchased as a fixer-upper.

I have two unused 2.2uF 50v Nichicon KLs still in their Mouser bag. I also have two of the same fitted to the power amp boards of my SA-9800 project. Since this won't be going anywhere soon, and it's been SO long since I've worked on it I probably need to order some more components anyway, I can desolder these and send them to you.

Let me know,

Lee.
 
Don't worry about it Lee. But if you do have an extra toggle-switch sleeve that helps keep dirt out that would be great. Like isaid, I have some Fine Golds and Cerafines (which I've never used but have read can compare somewhat to Black Gates).

I'm really just hoping someone has a trick to being able to work on the boards without having to snip or desolder all the wires, but I'm not seeing a way around it yet. Yes, the control board has enough slack in the wires, and I can do the switch board through the bottom access, but the EQ and main amp boards look like they'll have to be snipped to do the work.

EDIT: KLs? I read it quickly and thought you had KWs since I knew you liked using them in your builds. Yeah, I'll take 'em. Need and MF resistors in trade?
 
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Control Board

Since I was able to get at the control board without undoing the wirewraps (except one that broke and had to be soldered back onto the post) I went ahead with the recap of this board. I also replaced the 2SC1919s and 2SA725s with the recommended KSC1845s and KSA992s, being careful to ensure proper polarity when installing the new ones since the originals were BCE and the replacements are ECB. Caps used were Pana FR for the 100uF/25V general purpose caps and UKL for all the CEANL caps in the SM. As stated in a previous post, there were 4 2.2uF/50V caps in the SM listed as ACH, though the board was actually populated with the low-leak CEANL caps. Since I didn't have the UKLs in that value it was experiment time. One of these caps per channel are always in the circuit based on the position of the Tone (defeat) Switch. So, the L Channel got Cerafines, while the R Channel got Fine Golds. Once I get a chance to listen I'll see if I can tell any difference and whether the background hiss/static was cured by this board being redone. I also may go back in with UKLs for these 4 if the noise is still present, however, one of the traces lifted where one of the Cerafines now lives (Krazy Glue and a bent lead to the rescue). So, I hesitate to do any more to that one.

Just for fun, I also replaced several resistors with Dale RN60C precision Metal Films which I had on hand and matched them for each side.

Some shots:

14793832487_46961f0872_o.jpg


14793784128_e32ab91f7a_o.jpg
 
Just a quick listen after a DBT fire-up. Hiss is present still, but I did decide to separate the Preamp from power amp sections. Hiss goes away when running them separated with my Proton D940 as the pre. I did notice though that there was a.slight buzz in the R speaker in this configuration that was being masked by the hiss when running the amp by its own preamp. I forget whether there was that buzz in the L speaker also. Be more methodical John!

Anywho, i noticed some distortion in the right channel, that's the one with ~ 28mV offset at the speaker terminal, so I went to try and bias it, but the trimmer either is shot, was already maxed out, or otherwise had no effect on the biasing as I turned it. So, no more testing with power on for now. It's time to pull that amp board out and start checking components. I don't remember whether I noticed the distortion on my quick listen before or not...be more methodical John and take notes too will ya.
 
Ok, so ignoring my own desires to be more methodical, I decided to do some work on the switch board since I had the time and it was easy moving the control board out of the way. I wanted to get rid of the light blue Sanyos and the two tantalums sitting between some switches. There's also another ACH listed 2.2uF/50V cap on that board which whoever worked on this amp before had replaced. He used what I'm guessing is a low-leak cap, though it's a Matsushita I believe (has an orange sleeve but not ELNA). He'd also moved a resistor to the trace side of the board, but I don't see any reason for it (laziness?...didn't want to remove the faceplate and control board for easier access to the component side). There were no burned spots or anything.

But I now have to wonder about some of the things I'm finding...whether they were running changes, or mods/repairs that were done a long time ago.

So, the big question for now, (Mark are you out there?):

There's a jumper wire where R54 (620ohm 2W) should be, and R49 (680ohm 2W according to the schematic and parts list) is actually a 560ohm 2W. These Rs trace to Pin 45 which has a lead wire going to the Power Indicator lamp (8V 50mA according to the SM). I haven't pulled the bulb to see if it was replaced by a different value, requiring a different resistance, but that's on my list now.

However, if I wanted to change it to an LED, I guess these traces will come in handy for a tidy appearance, but I'm not sure how to do the calculations for the value of the LED and it's dropping resistor. More research....

Can anyone with an 8500II pop the top and see if yours also has a jumper vs resistor? If you look at the 7th photo in post #8 you can see R49 (red 2W resistor running vertically about the middle of the photo). R54 would be sitting in the shadow of the frame making a "T" crosspiece for R49. Should also be a red 2W.

EDIT: I think I must have the KC (Canada) version as that schematic shows the jumper and 560ohm resistor. Now to check a couple other things to confirm.

EDIT 2: I was looking at the parts list posted earlier and the following Q were listed for the Switch Board...
AWS108 q3 2sc945 do-not-replace
AWS108 q4 2sc945 do-not-replace
AWS108 q5 2sa733 do-not-replace

Why???

I happen to have both KSA733Y and KSC945Y on hand looking for a project to fit into...
 
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EQ Board

I know I'm doing things bass ackwards by recapping, etc the different boards vs getting the amp boards functioning 100%, but methodology will now be the next project. Yesterday's work was the EQ board. Easiest access was desoldering the two pins from the trace side which had brown and white wires attached. The remaining ones could stay attached as there was plenty of wire slack now. Caps used were a mixture...Cerafine for one of the 3.3uF/50V caps (FG the other to be consistent with the experiment), ELNA RBS (Silmic Bipolars), Panasonic ECQ film to replace the 1uF/50V CEANL caps, Panasonic FC (47uF/50V) and United Chemicon 470uF/25V with 0.1uF/50V ECQ bypass.

I again replaced a bunch of resistors just because I had the Dale MFs and was able to match them. The ones I din not replace were due to not having the value (or close enough) on hand.

I also replaced the Qs per the suggested ones and hfe-matched the new ones as best I could. Interestingly, Q1-Q4 (2SA725P) had orange dots on the tops, I'm assuming meaning they were either originally matched or selected for low noise (sort of like they did with certain preamp tubes that had painted tips). Here's how they measured:

Q1 - 470 Q2 - 510
Q3 - 460 Q4 - 530

I'd say the matching was OK for each pair, but nothing was done to keep each channel pretty close (like a matched quad of tubes). I don't know whether it was all that important, but I was able to get 4 KSA992Fs matched at ~ 520.

The others Q5-Q10 (Q5,7,6,8 - 2SC1919, Q9,10 - 2SA726) were all over the place:

Q5 - 755 Q6 - 644
Q9 - 420 Q10 - 323
Q7 - 630 Q8 - 550

These got replaced with KSC1845F and KSA992P. Why the different hfe groupings you ask? My 1845s, even though they were "F" (300-600 hfe) were reading <= 420 whereas my KSA992Fs were in the 500-600 range. Since the 2SA726s that were pulled measured lower than the 2SC1919s, and my "P" KSA992s measured on the high end of their 200-400 hfe range, I decided to save the higher measuring "F"s for other projects.

So, my Q5,7 and Q6,8 measured ~ 410 and Q9,10 measured ~ 385, thus keeping the KSCs with higher gain than the KSAs.

Again, for those trying this at home, make sure to insert the Q's observing proper polarity: the originals are BCE and the replacements are ECB. Also reflowed the rest of the board and added a touch of solder to all the wirewrap posts after a light Dremel wire brushing.

Some shots:

Overhead
14827644359_96585c80ab_o.jpg


Oblique
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Switch Board

Just a couple shots of the work done to the Switch Board. Caps used are Nichicon HE, FG, Panasonic FM, FR, and ECQ, and one United Chemicon KZE. Many Dale MFs, small signal diodes are now 1N4148, 10E2s are now 1N4004. I left the 3A ones as is and didn't have Zeners in the correct rating. I did change out a couple Qs, but still wonder about the 945/733 set that MTF suggests not to change. I wanted to get all this work done before starting to pull the amp boards for a complete workover. Still need to do some more cleaning of the boards as can be seen. I've been using Q-tips, an old tooth brush, and 91% Isopropyl for the most part, but they're pretty grimy. Any other suggestions for in-place cleaning that won't set p the leads or future corrosion"?

Right Side Overhead
15027316162_8592b7b0c9_o.jpg


Right Side Oblique
15004684776_3d29053277_o.jpg


Left Side Overhead
15004686016_31b3ec1f5b_o.jpg


Left Side Oblique
14841028240_cc08a196a0_o.jpg
 
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