Rotel RX-1603 -Repaired !!

[Scotteboy]

Hi all in AK land ! It is with great joy and a wonderful sense of accomplishment that I announce the arrival of my friends new best friend in one newly repaired and working Rotel RX-1603 !

It took me about a week to recap and get so it powered up but it would not come out of protection. After much measuring and upgrading of parts I finally was able to pinpoint that the dang protection circuit itself was to blame. ( that only took months) It had some added parts and a NTE thyristor at the center and now with correct parts installed and a new ON semi mcr-100-6 in place it is up and running punching out 200 watts before it even begins to clip.

I had to sub out the main output transistors to MJ15015's (two of the original sc1586's were toast) but it works and sounds great ! I even ran square waves at close to full output from 1000- 20,000 hz and they were almost perfect ! Below that it was not useful waveforms.

Anyone familiar with these knows how rare they are and how little info is available for repair so I didn't know where else to put this announcement. So , here it is and thanks for all the info on related subjects that helped me to get to this point.

Hope everyone is well and enjoys the knowledge that a beast of this magnitude is once again singing its heart out !! I repaired it for my friend and learned a lot more on the way.

 

[sregor]

Nudies (insides) and final product. Good work!

 

[Scotteboy]

 

[Scotteboy]

So sorry for the duplicate, didn't take a bunch but may lift the lid tomorrow and a final, here it's the preamp output, square wave at 1000hz and final before outputs were installed.

 

[OMGCat!]

Congrats on the repair of such a fine amp! The sense of accomplishment when you bring something back from the dead is great and worth sharing for sure

 

[Scotteboy]

 

[Scotteboy]

Ask for anything more you would like to see, I'm not very good at this photo post stuff. Thanks!

 

[arts]

Congratulations,I know exactly how you feel. I have one on my bench right now. The owner originally dropped it off for a minor repair and checkup,but when we realized that it was all original,he decided to go for a re-cap and several other minor upgrades at the same time. I'm awfully glad that this model splits; I really can't imagine having to work on one of these as a ''full lump''.Even so,this machine is a very time-consuming piece of equipment to work on,and is delaying several other projects. Darned thing takes up most of my bench too!

 

[Scotteboy]

Congratulations,I know exactly how you feel. I have one on my bench right now. The owner originally dropped it off for a minor repair and checkup,but when we realized that it was all original,he decided to go for a re-cap and several other minor upgrades at the same time. I'm awfully glad that this model splits; I really can't imagine having to work on one of these as a ''full lump''.Even so,this machine is a very time-consuming piece of equipment to work on,and is delaying several other projects. Darned thing takes up most of my bench too!

 

[Scotteboy]

Yep, also can't believe how hard it is to glean needed info from any version of the SM!! Hope your repairs and upgrades goes fast and well, this one graced my bench 5 months!!

 

[hunter00]

Funny i purchased one yrs ago then eventually put it in storage when we moved only to bring it back about a yr later with the same issue where by it wouldnt come out of protection as well,my tech had it sorted eventually tho...kind of miss that reciever it was my last SS piece to sell before i got hooked on tubes

 

[arts]

Yep, also can't believe how hard it is to glean needed info from any version of the SM!! Hope your repairs and upgrades goes fast and well, this one graced my bench 5 months!!

That service manual (well,the versions that are available on the net at least) is frickin useless. I don't know what information an ''original'' contained or how it was layed out,but if it was anything like what I have been able to find online,it's gotta be one of the worst I have ever seen.

5 Months!?!? Oh,that doesn't bode well..........

 

[arts]

Funny i purchased one yrs ago then eventually put it in storage when we moved only to bring it back about a yr later with the same issue where by it wouldnt come out of protection as well,my tech had it sorted eventually tho...kind of miss that reciever it was my last SS piece to sell before i got hooked on tubes

The protection circuit seems to be a VERY common complaint in this model.

 

[SoCal Sam]

Nice fix! My RX-1603 was one of the first Monster Receivers in my collection and it may very well be the last survivor after many herd culls. My example has the smallest of hair scratches so I can't rightfully call it minty...except when it goes to ebay, hehe. I also have the original box and documentation. I've never had the cover off mine so the look is much appreciated. On a side note, the power switch is weakness. I use a power strip to save the contacts.

 

[Scotteboy]

Thanks for all the replies! I posted this also to offer whatever help I can provide while the info is fresh in my head. I plan to post tranny subs tomorrow and other tips ,notes and best SM I can find. I have fixed about 200 different amps over the last 5 years and this one really stands out. I am totally hooked on tubes overall and miss ss for rattling the walls but SET is hard to beat on some klipsch speakers! I plan to " settle" on a bedini 200 for my ss setup and a sv811-10 for my tube setup. That is a bottle head 2a3 with RCA 1960's tubes in the back on the table. 5 months was mostly due to lack of time and disbelief that it was the protection circuit and not something else. The parts were also soldered in under the pcb and shrink wrapped so I had to cut it open then subtract from the schematic. Good luck all !!

 

[Dlocreeb]

Glad to hear its up and running. I am in the process of recapping and getting mine up and going, also any info you have on which transistors to use and where and what to look for would be greatly appreciated. I have had my unit for years and decided to take the plunge and get it up and running. The only experience I have is some solder replacing of parts but I have confidence in myself to get it done. yes it it hard to read the service manual on HiFi Engine.. Thanks for any help.. Glad to finnaly see an updated post of the Rotel RX1603.

 

[ZORGBLATS]

Nudies (insides) and final product. Good work!

 

[Reliving.]

Great Work and lovely set up ...just going upstairs to power up a ROTEL RA 611 1973 ..I have just recapped ...was hard because PCB is all over the place.....

 

[tater415]

I've had mine 1603 for about a year now I have never even plugged it in I'm waiting for my tech to finish up some of my other receivers before I give him the 1603

 

[sajjad amer]

Thanks for all the replies! I posted this also to offer whatever help I can provide while the info is fresh in my head. I plan to post tranny subs tomorrow and other tips ,notes and best SM I can find. I have fixed about 200 different amps over the last 5 years and this one really stands out. I am totally hooked on tubes overall and miss ss for rattling the walls but SET is hard to beat on some klipsch speakers! I plan to " settle" on a bedini 200 for my ss setup and a sv811-10 for my tube setup. That is a bottle head 2a3 with RCA 1960's tubes in the back on the table. 5 months was mostly due to lack of time and disbelief that it was the protection circuit and not something else. The parts were also soldered in under the pcb and shrink wrapped so I had to cut it open then subtract from the schematic. Good luck all !!

Any chance you could share the information? I am not a tech and have taken on the challenge of repairing dead 1603. I would appreciate your help.