RC 1090 Output Jack repair

[cfrahme52]

Hello, all.
My 1090 preamp's left output jack is now producing a loud hum (even with no source powered on.) Anyone ever attempt to replace these jacks? I believe they are sealed units in sets of 2/4, but not sure. Two years ago, the one of the CD inputs did the same thing. Repairs, with shipping to B&W Group in MA, it was close to $200. I'm relatively handy with a soldering iron, and thought I could save some money. Thanks.

[Glen B]

Are you sure the hum is not being caused by a bad ground connection at the RCA jack, maybe from a cold-solder joint ? Have you eliminated the possibility of a problem with your interconnect ?

I have done many RCA upgrades and conversions that involved replacing PC-board mounted RCAs and 1/4" pro connectors. You just need to apply a little creativity. Looking at pictures of the insides of the RC1090, it does appear the RCA jacks are mounted to the main PC board, in sets of two and three.

You can replace a defective jack with a chassis mounted jack, and jumper the wires to the PC board. You will also have to replace all the others in the group. The Dayton gold chassis mount RCA jacks from Parts Express, part # 091-1120 are a good, inexpensive choice.

091-1120

[cfrahme52]

Thanks for the information, Glen.
Looking for a DIY solution, as Rotel Support charges a flat $150 service pre-approval fee.
The interconnects are hum-free used in another application, so I've ruled them out.
The problem arose as I was dusting/cleaning around the preamp and bumped into the output cables. Of course, I had music playing and the resulting hum caused both myself and 4 year old grandson to jump out of our skins!
I was able to cause it happen intermittently once or twice, now it's constant.
I have some experience soldering-put together a Hafler DH200 kit when they came out. That was mostly point to point wiring and very little on a PC board. Nothing to lose looking inside the 1090. Maybe I'll do the that tonight.

[Glen B]

It sounds a lot like when you bumped the cable, the force damaged the ground connection. Check the RCA jack assembly and inspect the point where the ground pin is soldered into the PC board. Judging by the position of the output jacks, it appears that you will need to do quite a bit of disassembly to gain access, including pulling the IR trigger and balanced input/output boards

[cfrahme52]

I had a peek inside this morning. Seems the easiest part of the job is removing the 8 screws holding the cover on! This looks to be over my head. Just wish there was unobstructed access to the board. Afraid I'll cause more damage, so guess it'll go to the pros. Of course, the repair wasn't in the budget (son in college) so it looks like it will wait til the first of the year.
Again, thanks, Glen .

[PewterTA]

check out http://vintagehifipgh.com/ and talk to the owner Tom... he'll have it fixed for you in probably about the amount of the service fee Rotel will charge just to evaluate it. Tom's a great guy, he fixed up my RB-1090 when I had an issue with it and I'm going to have them modify my RSP-1098 with new Op-amp sockets so I can start rolling op-amps to get a better sound from it.

Tell him Dan that comes in and brings his Rotel equipment sent you. He'll probably claim he doesn't know me...but if you mention Dan & Bill that stop in... then he should know.

[cfrahme52]

Thanks for the link to Vintage Hi Fi. Always good to find such service...electronics repair seems to be a vanishing art.

[madmac]

In my opinion, Change out your cables first. It would be sad if it was only a bad cable causing this issue.

[wkhanna]

Thanks for the link to Vintage Hi Fi. Always good to find such service...electronics repair seems to be a vanishing art.

Agreed.
Skilled craftsmen are a dying breed. The company I work for makes precision machined products with tolerances in some cases held to to +/ - .001 inches or less. A human hair is typically .003 inches. Our products range from medical implants, US military components, aviation to civil transportation. We have some V modern machining equipment, all computer controlled of course, some of which cost up to nearly $1 million each.

We also have some V skilled operators who set up, program & run these machines. Sadly, V few of them could go to one of our 40 year old manual Bridgeport milling machines or manual Hardinge lathe and be capable of making the most simple of parts.

The lack of backward compatibility means even skilled technicians lack the most basic concepts of the physics behind material removal. It is these very principals that one learns when operating the ‘old fashion’ machines.

Regarding, VHF of Pgh, Tom & Anders posses multiple skill sets. One of which is consummate bench Tech. I have trusted them with my most prized components. They have often worked with Bob Carver , most recently helping to develop a small tube amp kit.

[cfrahme52]

Different cables, same result. Thanks, Dan. I think part of the problem are the TaraLabs cables...very stiff and rather large/heavy connector barrels.

[srb]

That's one of the reasons why I really appreciate seeing RCAs that are threaded with a retaining nut on the back of the panel. It doesn't have to necessarily be a hard wired panel mount RCA, there are also PCB mounted versions that also have a thread for the retaining nut as well.

It makes it near impossible to lever the jack and create a bad connection on the PC board regardless of how large a plug and how stiff a cable, but they don't seem to exist on AVRs, and then it is hit and miss with preamplifiers and amplifiers.

Steve

[cfrahme52]

George Miller at B&W Group Tech Support has been very helpful. They have the replacement jack units at only $2 each, so I have an order in. When the part arrives, I'll have a closer look inside and weigh my skill set with work needed to be done. George M has mentioned that a lot of disassembly will be required to access the pc board connections, as had George B. Thanks all. Will keep you posted on my progress.

[Glen B]

That's one of the reasons why I really appreciate seeing RCAs that are threaded with a retaining nut on the back of the panel.

The name for them is "chassis mount RCAs". 😊

[srb]

The name for them is "chassis mount RCAs".

"Chassis Mount" generally denotes jacks that are wired to the circuit board with hookup wire versus "PCB Mount" that are directly soldered to the circuit board (and the jack assembly secured by a single screw in the plastic housing.

The jacks I am referring to are combination "PCB/Chassis Mount" jacks. Best of both worlds.

Steve

[cfrahme52]

Jack Repair Successful! (Long Post)

Happy Thanksgiving, all!

I had a couple hours down time this afternoon, and thought I might tackle replacing the output jack.
I ordered one directly from B&W Group in No. Reading , MA
According to George Miller at B&W Group Tech Support, some Rotel stereo pre-amps have an access panel (to the pcb) on the bottom; I found the RC 1090 does not. This being the case, he advised to remove all back panel screws, remove the back panel and this will allow access to the board and chassis mount jacks. Disassembling/re-assembling was the most time consuming part of the job. De-soldering/soldering difficult due to limited access to board. (At least, at the angle I approached it.)

Tools
25 watt soldering pencil
Vacuum de-soldering pump (de-soldering bulb)
Solder
Fine flush-cut nippers (Xuron)

Padded work surface for dis-and re-assembling
Solid surface suitable for working on electronics

For those just interested, possibly wanting or needing to do this at home, here's what I did:

1. Remove all back panel jack mount screws (input/output/trigger/power,etc.)
• Keep track of which are used where: there are several different sizes
2. Remove four (4) screws holding back panel on from the side. For the life of me, I could not dis-connect the leads to the IEC power receptacle.. (They were under shrink wrap...perhaps soldered on?) I opted to leave it, along with the back panel, attached. This was awkward, as it dangled throughout the job.
• At this point, I decided to leave all Molex connectors attached to the mini-pcbs and take care not to disturb them during the repair
3. Remove four (4) screws holding down main pcb.
4. Remove screw holding main pcb on the bottom of unit, roughly centered on pcb
• I did the above steps so that I could hinge the main board out from the chassis to allow more room to work at the connections. This gave me about 1.5" clearance
5. Identify preamp output jack. This paired unit is used throughout the 1090. It has seven (7) gold-plated connector pins. These pins are easily located from underside of pcb. Clean new pins.
6. After pre-heating soldering pencil, carefully heat each solder joint, use vacuum. When I could clearly see each pin leg, I clipped it off close to the board. This would allow me to free the unit easier. Continue heating/vacuuming pins, checking the jack assembly and wiggling it to loosen it from the board. There are two (2) clips on the side of the jack to help position it and secure it to the board. I used the point of my side nippers to push these out of the board and the unit came free when completely un-soldered.
7. With the old jack assembly out of the board, I cleaned up the mounting holes on the board by heating/vacuuming.
8. Fit new unit into position, being sure each leg protrudes though the board at the correct location and that the two clips are engaged.
9. Carefully solder each leg onto board. Check that you have good solder joint(s) and that none look cold. Reheat and apply solder if you are not satisfied with work.
10. Assemble pre-amp. I did this in reverse order of dis-assembly. Make rear panel connections, power up and test. Ah, all music, no hum!

This was my first experience working with these types of connectors on a pc board. I'm very happy with the outcome. I would not say that this was a hard repair. However, the tight access to the area of the board where the jacks are soldered did present a challenge, but in the end, do-able. Wish I had taken photos along the way.

[wkhanna]

Well done!
Congratulations!

[cfrahme52]

Bill:
Any idea how Rotel made the connections to the IEC power socket? (Just curious)
Thanks,
Charlie