• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Marantz 1150 Help!

Richs_Trains

Richs_Trains

Well-Known Member
Hey all,

Been awhile since I played around, been tough since Kim passed. Found an 1150 that the seller said was packed poorly and dropped in shipping. It had the usual bent faceplate and a busted shaft. The seller had purchase the new board with the "stereo" shaft attached and included it with the unit. I disassembled the unit, pulled the shaft from each pcb and replaced the broken one. Put it back together and tried it on a DBT, all was good. Played about and hour on the DBT, moved it to main power and it blew a fuse, turned out it had a 2 amp and spec is 5 amp. Replaced the fuse and played another hour or so, decided I'd put it in place of the 1060 I have for outside and used it about 1/2 day and boom, static out of both channels. Pulled it from service and hooked it up on a DBT, no shorts, but static from both channels with no input and volume all the way down. I am guessing it is a transistor in the pre amp section, but I am only guessing. If I plug RCA cables into the main in on the back with no source, the static is gone, but you can hear just the faintest static in the way back. I know this is a common problem, but I just need the mentoring of the experts on AK. Thanks in advance! Rich
 
Register to hide this ad
Both channels? I'd check and clean all the grounds, and rebuild the power supply. Could be a transistor or diode in the PS dumping noise into the preamp.

Possibly preamp transistors too, just seems a little strange that one in each channel would go bad at the same time.
 
Both channels, was playing about an hour or so at just under half volume, sounded great (much better than the 1060 on the outside speakers) and boom, heavy, heavy static in both channels, I hooked it to the bench speakers and static was so loud, I feared for the speakers (after all, whatever was coming out of the pre-amp was being dumped into the power amps uncontrolled). I then replaced all the electrolytics on the power supply and set the +44/-44 no problem. Pulled the PE01 board and replaced the 4 electrolytic caps on the board, put it back together and now have nothing from the pre amp. The power amps still work fine using the main-in. I have pulled the PE01 completely and there was one on auction that appeared to be re-capped and listed as fully functional, so I am going to swap out the boards when it arrives. I am guessing that PE01 gets it's power from PH01 through the pin connector, once I get the new board, where can I test to make sure the proper power is getting to PE01? Thanks Rich
 
Probably a dumb question, but it appears the PE01 is pretty much for conditioning the signal and I have the board completely removed (pulled the pins and made a diagram) waiting for a replacement. The PCB has three double shielded lines (Blue/Orange/Green) and then pair of single shielded lines (orange and white) with a shared ground. Is there any way to bypass the board and complete the connection between and output and input without doing damage (I know the power amps are functioning as I can use them on the "main in"), since I don't have the proper test equipment, this would let me know if the PE01 is my problem. Thanks Rich
 
PE01 is the tone amp, it won't work without that board. Does the 1150 have all those modular pin connections? You'll need to check all those to make sure the solder joints aren't cracked.

Did you replace the semiconductors in the power supply? I'd think there's a transistor or diode failed since the problem just showed up out of nowhere. Losing sound completely from the preamp, I'd lean toward those board to board connectors. Got pictures of the boards you're working on?
 
Look at the pre out amp in. Sometimes it is intermittent. Use a set of interconnects to test.
 
Tried modular cables, did not help, it's apart now with PE01 removed. How would I go about checking the power supply and which diodes are the most suspect? Thanks Rich
1150_1.jpg
1150_2.jpg
1150_3.jpg 1150_4.jpg 1150_5.jpg
 
Looking at the SM, I only see 4 diodes on P-800. 2 large black ones listed as DS133B 200V and H811 listed as wz-120 and H812 IS2471. Just be easiest for me and probably better to replace them all. Would anyone know the replacements for these and if Mouser stocks them?? Thanks Rich
 
See all those little blue gobs and red gobs marked CE21, CE22, and such? Those all have to go, unreliable tantalum caps. They're noted as electrolytic caps on the parts list in the service manual.

I'd take a look at H803 and H804 for faults. H803 would take a KSC2073, H804 a KSA940.
 
The new board has been recapped with electrolytics in place of the tantalum, are they OK? I will go ahead and order some ksc2073/ksa940 from Mouser, what should I order to replace H801/802 and H811/812? Thank you Rich
 
H811 is just a 12V, 500mW zener diode, 1N5242 should do. H812 will take a 1N4148. I haven't seen the big DS133B fail, I don't know a sub for those.
 
I don’t know if you saw this thread, but there is a discussion that results in a decision by the OP to use two 1N4007’s in series (anode to cathode) to replace the DS133B. He considered it a success. I read somewhere else that you connect them so as to get a Middle lead for three pins total. The photo of the board looks like there are three leads to the component. Obviously, polarity is important when placing it. Be your own judge whether to use this.
Steve
http://audiokarma.org/forums/index.php?threads/1300dc-blown-fuses.443961/
 
Thanks Steve, I did see that when I search DS133B on the forum, but I didn't really understand how to construct them and there was no picture. I think I am going to replace the other two diodes and the transistors and see where that leaves me. It looks from the previous post a failing DS133b should cause more of a failure than I am experiencing. Thanks again everyone.... Rich
 
I think I would do the same. But if you decide later that you need it, I think it’s as simple as connecting two diodes in series, but leaving a leg in the middle. You can see from the schematic that that middle connection needs a lead into the board. Just have to make sure polarity is correct. Good luck!
 
Jailtime said:
1N5242 should do. H812 will take a 1N4148
Click to expand...
So, parts came today but the 1N4148 seems I ordered wrong, it looks like SMT rather than through hole. The part# did not show a picture on Mouser and I went ahead and ordered it, any better part number or source?? Thanks Rich
 
You must log in or register to reply here.
Back
Top Bottom