Discussion in 'Marantz Audio' started by paultlaw, Jan 9, 2018.
Visual check first, NPN in a PNP 'hole' or vice versa, diodes in backwards, solder bridges.
Back of board, not seeing any solder bridges, did not replace any diodes. All transistors and electrolytic and pots replaced.
H706,H705, H707 H708 - Replaced with KSC945 - Partially right H708 and H707, should be replaced with KSA733
H710, H709, H704, H703 Replaced with 2N3440 -
H711 and H712 replaced with 2N5416 Correct
H701 and H702 replaced with KSC1845 -Wrong Should be KSC945
H707 and H708 should be replaced with KSA733, or another suitable PNP transistor. You have NPN's in there. Most likely your main problem. I also usually see H701 and H702 replaced with KSC945 as well. Not sure if the KSC1845's would pose a problem.
OK thank you so much. Do i need to pull al the transistors and check them?
How deep do I need to go?
Hard to say how many components were damaged. Looks like there are quite a few things in the path of the resistors that blew up though. Checking all transistors and replacing the cheap ones with new would probably be a good start. Where did you get your transistors, btw?
I'm no expert but I also think there's a chance your H715-H718 could have been compromised too. Maybe give those a check and have some BAT41's on hand just in case...
I dont agree with the site :
for drilling out the switches to clean them. Its clever and may work but I say this because of what I found inside my 2285B switches and my 2230 switches. In both cases, the contacts had green corrosion on the small sliders that move on each side. And that was *after* a bath of DeOxit used in the normal way of soaking the switch. I ended up using DeOxit with several Q-Tips ( electronic wooden stick, not ear versions) to scrub the contacts after I removed them. Then I used L206 ( think that is the PN) DeOxit non-conductive grease on them. Between the two, I measured a decrease of .5 ohms across the contacts. I did this because I had issues with the switches after the normal soak. Its alot of work just to clean if they work OK from the start. But if the unit is really dirty or abused, I would assume the worst and take them apart. In 2285B, it was just nasty like it had sat on a porch or patio for years. The 2230 had not been used in years so the switches just corroded as a matter or course. I'm guessing a quick check with an ohm meter would give an indication as to the condition.
Not to mention, there's always a chance some shavings from the drilling could remain in the switch and make your problems even worse.
Thank you for your help - without it i would have a doorstop.
I have edited the post above to ensure people see my mistake and the correction kindly provided by jwjarch.
I am going to try and get to this asap - really busy with work and other life related activities - need to order some parts too, i have very little resistors so i will make up a list from whats on the board.
I will make sure that this thread is seen to completion and i will make sure i include pictures.
Thank you all, especially Jailtime, Restorer John, Cohiba Joe, Steven tate, Quadramatrix82, Mike Sweeney, Richs_trains & JWJARCH
Here is why I dont think soaking the switches with DeOxit really works as well as some think. If the switch is in good shape and not corroded, maybe its fine. But the switch on the inside is pretty fragile and subject corrosion since they are infrequently used. Unless they are used alot, the metal doesnt get "brushed" which cleans off most crap. In the pic you can see why just hoping that wicking DoOxit into the switch is not an effective way to really clean these switches. The brass slides are up and above the bottom of the switch and touch a matching small slide on the center shaft. You would need to FILL the switch with DeOxit for it to really work well.
In this case, I had to un-solder the switch, take it apart on the bench, scrub the connectors ( slides) and then put it all back with some DeOxit non-conductive grease which has DeOxit mixed in. THen solder it all back together and reinstall the board which was wirewrapped and soldered in. Next time I'll take better pictures showing the before and after. This is after with the DeOxit grease applied and ready to reassemble.
A PIA ? oh yeah.. did it work? really well.. is it worth it? depends . Its been a year I have had zero issues with the switches. No crackle, no drop outs.. zippo. And given how much work it is to get to these switches on the 2285B, it is better to do on the bench when the front is taken apart then after the fact when they crap out after 6 months because the soaking just didnt get the job done well enough. The switch maker could have done something like this as OEM but they cut a corner and saved a penny. Then I dont think the lifetime expected was to be 45 plus years for the gear
PS.. I also do the same to the power switches and in 80% of the cases so far, I can salvage the OEM switch with a cleaning, a burnish job and some deoxit grease with a new snubber. I have had a few that were just cooked beyond salvaging.
Pulled both of the sv3a diodes out of circuit to check - both read "OL" in both directions.
Positive and negative then negative and positive - both give same reading on diode check.
Any thoughts on this?
One output transistor is giving funny readings too (out of circuit), so think i think at least one is dead or damaged.
H715 through H718 tested fine -at least that is something
Seems my DMM may not put out enough voltage to check these diodes - (SV3A)
I have read a lot on here about these, is there a confirmed consensus for what will work as a replacement - some say
2 parts - 1N4148 in series. Some say 3 parts 1N4148 in series
Well Paul, I hope you've made some progress with your 1060. After some bonehead moves on my part, I'm in a very similar boat. Last week I had the amp board running great after replacing every component with new parts. Yesterday, I completely toasted R753 in a fiery SNAP, SNAP complete with much magic smoke. You can see the aftermath in the attached photo. I plan to do a little more cleanup of the board and seal it with epoxy before replacing the resistor. The fire also took out R721, R713, C703 and I'm guessing H709 is toast from whatever caused the resistor to burn up. I chalk this blunder up to 1 of, or a combination of 3 things:
1. I over voltaged the amp board when adjusting the pots. My supply voltage at J709 was 71.2 volts, so
as per rule of thumb I adjusted voltage at J713 to half the supply voltage, or 35.6 volts. Maybe this
was too much for the circuit to bear?
2. I depopulated about half of the preamp board in anticipation of my next phase of this build. Probably
a really stupid idea to fire up the amp with the power leads still connected to the preamp board in this
state. Maybe this further unbalanced the supply voltage going to the amp board?
3. I connected a standalone preamp to the amp section to test for any noise in this section after my
rebuild of the amp board. In my hast to hook up the preamp I believe I swapped input for output on the
preamp. Not sure if this would effect anything as far as R753 exploding but nevertheless, after running
for 5-10 seconds it did just that. The preamp I used is a DIY deal I assembled a few months back. It
had preformed well with a class A amp I had built but I'm thinking there may have been a compatibility
issue with the 1060 or it was mainly because I hooked it up wrong.
So after collecting myself I'll be putting a mouser order in for a few new parts plus everything else I still need for the preamp, tone boards, and phono board rebuild. I can say I got a little too confident in my abilities up to this point. From now on I will play it safe, section by section, and not introduce any outside factors like not fully tested DIY components. Hope others can learn from my mistakes as well.
Again, Paul, hope you're having a bit more luck with your 1060. Would like to hear an update on any progress you might have made.
can someone confirm what H705 and H706 are to be replaced with?
Pinout of my KSC945YTA does not match the board is why i ask
You need KSC945CYTA. The C suffix denotes center collector.
Separate names with a comma.