Making a Sansui G-9000 Recap/Parts List...

[rotini]

I wasn't able to find a recap list for this receiver and thought I'd share my work in progress, and this way I can receive some feedback and direction from the more experienced.

Since I literally just started taking the receiver apart this evening, I've only had the chance to look at a few boards, and even then I'm mainly focusing on identifying electrolytic caps. I will also be in the process of identifying power resistors, transistors, and zener diodes, as applicable. I don't intend this to be at all comprehensive but hopefully might benefit a novice such as myself tackle a project such as this.

Sansui G 9000 Recap List


Doh, I just found this Sansui Common Parts List for Resistors & Capacitors Only (courtesy of AK) which I think will prove very useful:

"Most resistors & capacitors are common to Sansui models unless specified otherwise, therefore these resistors and capacitors in this list are not shown in parts lists of Service Manual".​

Comments are welcome/requested!

 

[Oerets]

I threw my back out once messing with a G-9K! Be careful that is one heavy beast.




Barney

 

[anderslober]

When you do the re-capping.......will you be doing the big caps too? There is a special procedure for this. There is a good thread about it too. I plan on doing this soon to my G9000 soon.
Also...........you MUST post pictures.......this is an AK-official-legal-A-ok-requirement!;-))

 

[kevzep]

I will be watching this one with interest, and offer advice where I can.....

G9000's arent heavy, a McIntosh MC2205 is heavy........

 

[ossodiseppia]

The Sansui published service manuals often times will have some errors in them. This also may apply to the common parts list that you pointed to. Use them only as guides. The best source for a parts list is the unit itself.

The best approach may be if you find a discrepancy, ask on the BB.

 

[rotini]

The Sansui published service manuals often times will have some errors in them. This also may apply to the common parts list that you pointed to. Use them only as guides. The best source for a parts list is the unit itself.

The best approach may be if you find a discrepancy, ask on the BB.

Thanks Osso. That's exactly what I figured and am doing - taking out the boards, recording the values on each component (electrolytics and power resistors for now), and comparing to the values listed in the Service Manual if present. So far, the only discrepancy I've noticed is in the AF Power Supply and Protector Circuit Board, where it has two C37's printed on the board, while the Service Manual has one of the C37's as C39 (likely correct).

If anyone is interested in evaluating my list to provide suggestions/advice (looking at you Kevzep!), so far I've completed (see link in OP):

F-2810 RF Power Supply Circuit Board
F-2801 Tone SW Circuit Board
F-2799 Flat Amp Board
F-2809 AF Power Supply and Protector Circuit Board

The questions I have are:

1. Should I replace the "MICRON 70", white rectangular prism resistors all throughout the receiver? Some of these, particularly on the power supply board, get quite hot.
2. Should I replace the gray/blue resistors? Some are larger than others, and some are much hotter than others. I know that modern-day replacements will likely be much smaller. Since resistors dissipate heat, should I be concerned that the new, smaller resistors will have a higher temperature due to their smaller surface areas limiting their heat dissipation?
3. Do you guys recommend replacing the trimpots, such as the ones on the power supply board? I know things like corrosion can cause disaster for the amp when adjusting the bias (momentary shorts), but the innards of this receiver are pristine and look like new. Safe to leave the trimpots as-is?
4. On the power supply board, a few components next to the transistor heatsinks and power resistors look like they might be exposed to heat long-term. Examples are TR01, TR02, TR03, TR04. Does anyone recommend replacing these (i.e. are they more failure-prone)?

Next I'll be finishing my lists for the L and R power supply and driver amp boards. I might be leaving alone some of the other boards for now as I'm more concerned with the amplifier/power sections.

 

[kevzep]

Should I replace the "MICRON 70", white rectangular prism resistors all throughout the receiver? Some of these, particularly on the power supply board, get quite hot.

Not necessary unless you want to, the regulated supplies are not under as much stress as say their Pioneer counterparts.
Unless those resistors measure out of spec and have visual signs on heat stress (which I have not seen in these Sansui's), I wouldnt worry about it.

Should I replace the gray/blue resistors? Some are larger than others, and some are much hotter than others. I know that modern-day replacements will likely be much smaller. Since resistors dissipate heat, should I be concerned that the new, smaller resistors will have a higher temperature due to their smaller surface areas limiting their heat dissipation?

Same rule applies here really. I replaced all mine, but there was some misunderstanding on my part as I thought they were all fusible resistors....they are not...Non Inductance Resistors.
If I had done the research I may have just left them...
I think you had looked at my thread regarding this topic....
But however, I felt there was some improvement, this was possibly because I used all 1% tolerance metal films.....The improvement was a consistency improvement between the two channels, or so I thought/believed.....
But I am a little skeptical, typically when one modifies or replaces something along this order, think you expect to hear something, and its easy to convince yourself you have heard something when in fact it is the same.....
This is the Audio Engineer in me coming through......I critically listen for a living....

Do you guys recommend replacing the trimpots, such as the ones on the power supply board? I know things like corrosion can cause disaster for the amp when adjusting the bias (momentary shorts), but the innards of this receiver are pristine and look like new. Safe to leave the trimpots as-is?

I would replace the DC offset and Bias trimmers, I wouldnt do the other ones unless they have a real problem, just a dab of deoxit will be enough....

I didnt replace any trimmers on my G9000, they are fine, and I had no reason to suspect they were about to fail, just gave them a dab of deoxit and all is well...

On the power supply board, a few components next to the transistor heatsinks and power resistors look like they might be exposed to heat long-term. Examples are TR01, TR02, TR03, TR04. Does anyone recommend replacing these (i.e. are they more failure-prone)?

I have never found any problems in this area, the supplies in these amps arent under the huge stress like some of the Pioneer amps for example...

Those transistors are not in my experience prone to failure....

Do not rely on the schematics and service manual, Sansui manuals are notoriously incorrect, as are some of the silk screenings on the PCBs.
Do not assume the amp is wrong and the manual is correct....

Replace caps one at a time, observe orientation of the component in the amp, take pictures to reference....
As I said, DO NOT reply on the silk screening or manual....

 

[rotini]

Thanks for the response. As much fun as it is restoring these old units, the less work is always better :thmbsp: I did indeed look across your threads which was why I was thinking those N.I.R. ought to be replaced. Although upgrading to 1% wouldn't be a bad idea, I might just skip this since the work and time really adds up. I'm also anxious to slap the faceplate back on so I can sit back and enjoy it.

You are right about these units not displaying signs of heat stress anywhere near those of the Pioneer's. I'll leave those transistors alone unless I have a reason to mess with them.

 

[kevzep]

Thanks for the response. As much fun as it is restoring these old units, the less work is always better :thmbsp: I did indeed look across your threads which was why I was thinking those N.I.R. ought to be replaced. Although upgrading to 1% wouldn't be a bad idea, I might just skip this since the work and time really adds up. I'm also anxious to slap the faceplate back on so I can sit back and enjoy it.

You are right about these units not displaying signs of heat stress anywhere near those of the Pioneer's. I'll leave those transistors alone unless I have a reason to mess with them.

Well for me I always rather fancied the Pioneers over Big G's when I was a young teenager, but I had advertisements for both on my wall in my bedroom....
Fast forward to a few years ago, and I quickly learned by studying the circuits and reading on the forum, that the Sansui GX000 series including the G22/33000 seemed to be easier to work on, far more reliable, and just seemed to age better than the Pioneers....
Although, I still like Pioneers real wood veneer cabinets, I dont think it would have hurt Sansui to "finish the job" rather than using the cheap vinyl veneer...

I had an SX980 which I thought was pretty cool, but then I heard a G....I have never looked back....

Re the resistors, I would definitely replace R17 and R20 on the F2806 driver board, they are fusible resistors and do go hiZ with age, and when they do, you get no bias current....the amp will still work, but you wont be able to wind in any quiescent current....

Once you do start using it you wont want to turn it off.......:thmbsp:

 

[rotini]

Re the resistors, I would definitely replace R17 and R20 on the F2806 driver board, they are fusible resistors and do go hiZ with age, and when they do, you get no bias current....the amp will still work, but you wont be able to wind in any quiescent current....

Once you do start using it you wont want to turn it off.......:thmbsp:

I measured the voltage related to bias current, and both channels are reading ~4mV, far below the manual recommended of 16mV. I think you may be right that those resistors have gone hiZ. Could I go ahead and try to attain 16mV anyway using the bias pot, or would this be a bad idea? I'm tempted but I have a feeling this would be "artificially" raising the bias and could stress the other components.

How about adjusting the DC offset? Could I go ahead and do that, or is it related enough to the bias that I should leave it alone for now?

 

[kevzep]

I measured the voltage related to bias current, and both channels are reading ~4mV, far below the manual recommended of 16mV. I think you may be right that those resistors have gone hiZ. Could I go ahead and try to attain 16mV anyway using the bias pot, or would this be a bad idea? I'm tempted but I have a feeling this would be "artificially" raising the bias and could stress the other components.

How about adjusting the DC offset? Could I go ahead and do that, or is it related enough to the bias that I should leave it alone for now?

Its not unusual to find the bias way off if it has not been adjusted for a while.....
But I would just put you meter on those resistors R17/20 and make sure they are 150Ω, you can measure them in circuit, you dont have to take them out...
You will need to remove the driver board to get at them.....
Be VERY CAREFUL plugging the driver board back in that you dont get it one pin out, make sure you line it up right.....You can just see the molex if you are on the right angle......

Once you have done that then, yes adjust the Bias and DC offset, they are two independent adjustments, one wont affect the other.....

Let us know how you get on......

 

[rotini]

Thanks - was just about to post when I saw your response. R17 and R20's both read ~150 ohm (+- a couple), and you're right about not having to take them out of circuit.

Since both driver boards have the same bias voltage, I'm just going to go ahead and adjust both channels and not check R17/R20 on the second driver board. It' s a real PITA to take them out without the proper screwdriver (mine's barely long enough), and another risk of not aligning those molex connectors up right.. There's also nothing to suspect that something is seriously out of spec save for the stable 4mv bias voltage. Worlds apart from the condition I got my Pioneer SX in..

I'm very impressed with the build quality. The way the boards are connected with molex connectors and all the black aluminum plates/holders reminds me of a modern-day PC. Nicely packed together albeit requiring more disassembly steps vs a Pioneer SX X50.

 

[kevzep]

Thanks - was just about to post when I saw your response. R17 and R20's both read ~150 ohm (+- a couple), and you're right about not having to take them out of circuit.

Since both driver boards have the same bias voltage, I'm just going to go ahead and adjust both channels and not check R17/R20 on the second driver board. It' s a real PITA to take them out without the proper screwdriver (mine's barely long enough), and another risk of not aligning those molex connectors up right.. There's also nothing to suspect that something is seriously out of spec save for the stable 4mv bias voltage. Worlds apart from the condition I got my Pioneer SX in..

I'm very impressed with the build quality. The way the boards are connected with molex connectors and all the black aluminum plates/holders reminds me of a modern-day PC. Nicely packed together albeit requiring more disassembly steps vs a Pioneer SX X50.

Yes, they have a very high build quality and they also very easy to work on....
You will be fine adjusting it up, wont be a problem......

Let us know what you think of the sound.....I'm interested to see how it goes against the Pioneer.....

 

[Golanr]

Did you manage to update the excel? I'm starting to do the same on mine and I see that many capacitors are missing from your list. Thank you

 

[Hyperion]

Did you manage to update the excel? I'm starting to do the same on mine and I see that many capacitors are missing from your list. Thank you

No posts in this thread for 5½ years, and the OP was last seen here 2½ years ago, I think you are on your own.

However, you should really audit your own unit, as production changes may mean that you have somewhat different values for some components compared to the OP's unit. Also, I think you may be aware that you should not rely entirely on the schematic and SM for component values, use it as a guide only.

 

[Golanr]

Thank you, I did, parts were ordered and the Flat & Tone amps as well as the EQ Amp Capacitors have been replaced