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DEC Rainbow repair thread

I do not know what this is. The writing on mine is:

16-18998-00 Rev B
ARTTED 10265 HIPOTTED
8310

I tried searching for these numbers or text. But did not find anything useful.
 
A small round transformer? Sure, makes sense its epoxy encased and has 8 legs.
 
I have to order the parts for my power supply. But I'll have to pad the order to be worth paying shipping or get to the point of free shipping. As of now I just need that one cap.
 
Still waiting on a few caps for the mainboard. Once I have those in and swap them ill try them out with my known good psu and report back.
 
Got my parts so removed the one cap from the PSU. I can't tell if this orange is from the cap or something else. It doesn't appear to be glue. The cap charges properly to 9v with a 9v battery connected. I don't really have an ESR tester. Here is a picture of said cap. The rubber appears to be a bit buldged but not by much. It's not a great pic from my old phone. Now I am not sure if this is the problem with my PSU or not.
 

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If it was glue I'd expect to see more attached to the board itself. I was hoping to see another part with glue, but don't see any. Why glue this particular cap?
 
If it disolves instantly with isopropyl alcohol its cap juice.. if not its glue.... And i mean that. Instantly.
 
Guess it's glue, as most came off with alcohol, but not all. Some stayed on the board too.
 
So I received the Capacitors I was looking for. Bit of a nightmare with two sellers online. One who shipped them and they were lost and another who shipped them only 2 days after I oped a claim for no product.
s-l1600.jpg


They were the same caps as on my working Dec rainbow.

I received the other parts as well that I needed to try and repair the board. I was going to use my good psu and see whats what.

Well I wont beat around the bush. The system is very much dead. All the main ICs that are socketed are completely fried. Even the rx50 floppy controller and the 8088 daughterboard (tried the 8088 cpu as well as the other main chips, controller, z80, FDC controller, etc in good system all ics dead)

This system saw water damage. Probably for a long while. I have to assume someone tried powering it on without looking inside. Shes toast. Short city. I will keep the cards and put it back together. IF I dont find a board in a years time its going to the dump. I dont like doing it but what can you do. Ill probably keep the boards though. I spent enough time and money on this already.. Maybe ill just toss it. I have enough other things to work on.

What a shame.
 
I have another axial ceramic capacitor I could use some help identifying. IT has both ASC 224 and M85 611 stenciled on it. Is it a type 224 0.22nf?
 
VERAULT said:
I am continuing this from another thread: https://forum.vcfed.org/index.php?threads/rainbow-100-pickup-where-to-start.1242775/#post-1311409

Thanks to some photos from @tradde I was able to replace the disolved ceramic diodes. I replaced all but the two largest 820UF 250V caps and one 330uf 20v cap (I have those 330uf caps on order as I dont have one with a value anywhere near that low).

View attachment 1256076
View attachment 1256077

So I got my working rainbow out of storage so I can do some comparisons etc. Of course its a different model PSU and mainboard.

The PSU on the faulty unit has a model number of 5015186D while the psu on my working Rainbow has a model of 5015186E1-P4 The faulty psu has a connector that breaks off into molex connectors with 8 pins, while the working psu has a molex cable with 10 pins.
View attachment 1256078View attachment 1256079

Going off the PDF @tradde posted in the last thread: https://forum.vcfed.org/index.php?attachments/psu-pdf.1255668/
I took some measurements
View attachment 1256080
The faulty psu measurements are in blue and the working psu in red for reference. We have 12V.. Almost. Thats a start right?
Click to expand...
Did you have any luck? I have a very similar outputs / issue...
 
SamP said:
Did you have any luck? I have a very similar outputs / issue...
Click to expand...
This system was a basketcase. IT was clearly underwater. Every IC I tested was failed. I saved a couple dead boards from it but it was beyond saving otherwise.
 
Cool thread, I am learning a few things. I have a 100A that won't boot and gives a RAM card error. After reading here I now have the courage to open my box and take a look for user serviceable issues.
 
I am in the process of reviving a 100A. When I am done I will post about it on my blog. So far I have had to replace a Screen RAM chip and now I have another video error that I am struggling to understand although I have made a lot of progress in understanding how the firmware's self test works.
 
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