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9090 F-2436 Driver Board Bulletin

R

rredfern

New Member
Hi, I understand there may be a service bulletin available for the driver board F-2436 for my Sansui 9090. I have searched but the links seem to have expired. If anybody has a copy they could send to me, or point me in the right direction, that would be much appreciated.

I'm new to this vintage audio thing and the technical content on this site is amazing! My 9090 is getting a revamp- some questionable looking components replaced, and a bit of a face lift with a new case veneer. I've spent hours reading tons of great posts! Thanks!
 
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Hi, I was able to get the service manual from there but couldn't find the driver board bulletin. I've seen reference to a bulletin for this board which apparently contains some mods/updates in a few other posts. Thanks!
 
Yes, seems to be referred to several times, but I've had no luck actually finding it. I have found that there does seem to be earlier and later versions of the F-2436 board. The later ones seem to have two fuses added, obviously for protection of some type, which is never a bad thing. I was hoping to find some info that would tell me how to convert my early style board to the later style and thought this bulletin may be what I need. I'll keep searching, thanks!
 
rredfern said:
Yes, seems to be referred to several times, but I've had no luck actually finding it. I have found that there does seem to be earlier and later versions of the F-2436 board. The later ones seem to have two fuses added, obviously for protection of some type, which is never a bad thing. I was hoping to find some info that would tell me how to convert my early style board to the later style and thought this bulletin may be what I need. I'll keep searching, thanks!
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Would a close up of a board with the fuses help you out ? Viewing the connection points maybe ? I have one on my bench right now 10 feet away.
 
The OBSINC site, that used to sell pdf copies of all kinds of Sansui literature, including service bulletins, service manuals and sales brochures has closed down. I contact the guy that operated it and he said it wasn't generating enough revenue to cover the cost of maintaining the site. If you click on the OBSINC link in this post, it will take you to the main page of the former site. There is an email address on that page. Try asking him directly for the bulletin.

I had a pdf copy of the bulletin but I can't find it. Sorry. I'm sure I stashed it someplace "safe."

- Pete
 
rredfern said:
That would be great if you could! Thanks!
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Here are a few pics. Labeled A and B to correspond to each side. "A" set has connections I marked 1 and 2 while the "B" set connections are labeled 3 and 4. Wife phone pics and Im not too hot with it. Not sure if these help I don't have a schematic for this gen of board. All I have is the service manual which references the older boards.

A - Back.jpg A - Front.jpg B - back.JPG B - Front.JPG
 
Thanks for the pics! Can you tell me what the value of the resistor is that I've done a stellar job of circling in this pic? I can't quite make out the color code.

LBPete- thanks for the link. I'll try emailing him directly.

Capture.JPG
 
rredfern said:
Thanks for the pics! Can you tell me what the value of the resistor is that I've done a stellar job of circling in this pic? I can't quite make out the color code.

LBPete- thanks for the link. I'll try emailing him directly.

View attachment 688437
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Ha ha, paint is always challenging. I measured 22 ohm while still in circuit. Same with the opposite side same resistor. Here is a high res pic so that you can see theto see the color code.Resistor.JPG
 
If anyone needs bulletins or prints I likely have them "if they were worth having", let me know what the number is in question. Smile on the last but there were a lot of bulletins that really didn't mean a whole lot for reworking a board 30-40 years later. It's been a while since I've been around but happy to help out if I can.

Ron
 
Hi, Ron - I have 9090, with the blinking red light of death, it has the F-2436-1 driver board - I could use the service bulletin for this board - also a better copy service manual for 9090, the one I have you can not read the "parts list" Thanks Stumpper
 
The service bulletin in question does not address protection issues. It covers modifications that were made fairly early in production. Most 9090s already have those modifications.

If the Red LED is flashing you need measure DC offset at a point before the protection relay. If the fuse resistors haven't been changed out that's a good place to start. The fuse resistors are light grey in color and will be raised slightly above the board. They are not hard to find.

The two sides of the driver board are a mirror image of each other. Compare the resistance values from the left to right sides of the board. If the resistance values don't match left and right, replace both resistors.

- Pete
 
The board is from a 9090 (non-DB) board model F-2436-1
Pete - The board looks untouched accept for a replaced fuse, replaced (not be me) with a 7A/250V fuse
These are the resistors to replace (my takeaway) to start with:
R19/R20 (8.2K-1W) - Digi key part No. PPC8.2W-1CT-ND (Metal Film)
R29/R30 (390-1/4W) - Digi key part No. S390CACT-ND (Metal Film)
R43/R44 (22-1/4W) - Digi key part No. S22CACT-ND (Metal Film)
R45/R46 (150-1/4W) - Digi key part No. RNF14FTD150RCT-ND (Metal Film)
R47/R48, R49/R50 (4.7-1/4W) - Digi key part No. S4.7OCT-ND (Carbon Film)
Could not find a Metal Film on Digi Key for the last one
Pete let me know what you think - Thank you for the help, Ron
 

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That's a late production board. You really should insulate that exposed fuse. There are no 1w fuse resistors so unless there's something wrong with it, there's no need to replace it. There are also no carbon film fuse resistors. Not sure what that one is. The rest are probably right.

A word of caution about buying these types of resistors from Digikey or Mouser, they are typically modern replacements and can be very very tiny. They are technically correct but will look funny next to the other resistors on the board. So check the size before hitting add to cart.

- Pete
 
Where these all originally ceramic resistors? Is there a place that sells period correct size resistors?
Thanks again for all of your help - Ron
 
R Stumpf said:
Where these all originally ceramic resistors? Is there a place that sells period correct size resistors?
Thanks again for all of your help - Ron
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Ceramic ? Most likely were all carbon film.
 
If you are careful about what you buy/order, the resistors will be almost the same size - just check their dimensions before you add them to your cart - as you have been advised. (Strongly recommend you don't alter the wattage ratings - try to keep them as per the service manual).
 
Placed the order for these 4 items -

R29/R30 (390-1/4W) - Digi key part No. S390CACT-ND (Metal Film) total 3
R43/R44 (22-1/4W) - Digi key part No. S22CACT-ND (Metal Film) total 3
R45/R46 (150-1/4W) - Digi key part No. RNF14FTD150RCT-ND (Metal Film) total 3
R47/R48, R49/R50 (4.7-1/4W) - Digi key part No. S4.7OCT-ND (Carbon Film) total 10

Total of $1.31 plus .08 tax shipping should be $3.60 = $4.99
I order more than I needed
 
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