Marantz PM350 Repair / Restoration

[@valentinion7879]

Nice video! Thank you very much for sharing with us!

[@vfdffdd2675]

This is a first video ever in KZbin about repair "how to make"....thanks a lot . I see twice this video. Please upload more same videos with amplifier.

[@antoniosnikolaoy3754]

Thank you very much for your quick answer, my friend I have the Service manual but it is like having a Spaceship that I do not know how to fly. So in order not to tire you I will tell you the history of the amplifier, after I changed the fuses the 3.5 A as soon as I opened it I heard from the front panel something puffy like small explosions, I had the output transistors 29, 30, 31, 32 disconnection from the circuit but again I burn the resistors R745, R733, and one more question the 2 large capacitors 6800/50 the + from one goes to - the other, I have ordered others because at the top they have made a small curve, but it is also an amplifier for 40 years but a good machine, thank you very much and sorry if I tired you.

[@kdas4085]

Woah one of the best videos on restoration

[@walthergarcia243]

Good job Buddy you're a professional bro. I just watched this video in april 2021. I really like it you did a great job. Blessings.

[@antoniosnikolaoy3754]

Good evening from Greece and again, my friend did what you told me, I changed the big capacitors 6800, I also changed the output transistors, I connected the amplifier to the radio, I connected the speakers, and I put it to play, everything was going well, but within 5 minutes of operation the output transistors started to heat up too much, also the R802-2.2k-2watt, R810-82Ω 2watt, R809-39Ω 1watt resistors, the resistors as soon as the amplifier turns on immediately start to heat up, please I know you have a lot of work to do, but If you find some time please help me a little, thank you and be always well. I also changed all the electrolytic capacitors on the power supply side, thank you and sorry if I tired you, but I have not seen another technician do such a good job like you.

[@valentinion7879]

How is your amp now? Did you find the fault?

[@AngelilloSan]

Great work!

[@ЭдуардВасильченко-х9я]

Отличная работа!👍 Люблю я эту марку!)

[@hypergl6974]

Just started mine after a long time, found it in a bin with some transistors missing, changed them long time ago, listended to it, was working. Yesterday i just had some smoke out of it... The drivers of the right channel just blew... So today I am troubleshooting and unsoldering all the broken pieces... Thanks for the video. A question, you didn't check and/or corrected the bias?

[@lbochtler]

I recall having done so, its been a while since i made the video. I do recall that a few things where not shot when i made the video, so its possible the bias was done but not recorded. Another explanation that might explain it, is that bias and offset are among the first things i check when doing a repair and or restoration of amplifiers. Heck, i even do it when testing amplifiers i have designed and built myself. The diagnosing for the pm350 was done long before the video recording was done. If you need help with your amp, i can try to help, though im incredibly busy at the moment so its likely to get drowned out by all the other stuff i have to do.

[@waynegwayneg5159]

Wow..you are amazing at what you do...could you please help me find out what the problem might be with my marantz pm550dc amp..it powers up fine but the sound out of the speakers is very quiet and distorted..

[@lbochtler]

I can try, though without access to the amplifier its self it is a rather difficult task. I am currently downloading the schematics to take a look. First off, some diagnostics questions: - Is there a popping sound heard from the speakers when the amplifier is switched to them? If yes, disconnect speakers IMMEDIATELY else damage to them may a occur! - is there a smell? - is it present on both channels, or just one of them? - is the distorted sound (assuming no pop is heard when engaging the speakers) effected by the built in Equalizers?

[@waynegwayneg5159]

Thank you very much for your reply.have to say tho mate.you put the word pro in professional.such quality in your work.amazing....there is no clicking or strange noise coming from my speakers..have also tested the speakers to illiminate those as the problem..there is a warm burnt electric kind of smell tho....its like i need to turn the volume up full blast to hear anything and it comes over like a radio channel not tuned in correctly..kind of staticy.i know its not the best of situations for me to be asking advice thru messaging but any help is very much apreiciated

[@waynegwayneg5159]

Also.1 set of speaker channels doesnt seem to work.only one side

[@lbochtler]

@@waynegwayneg5159 OK, assuming that the equalizers do not appreciably change the sound, there is a rather good chance that the problem lay within the preamp power supply. Do you have a volt and or multimeter? If so, check the voltage across pins 8 and 4 of opamp QE01 located on the main circuit board around the front left area. (front referring to the control panel). Pin 1 on the opamp is designated by the small circular cutout on the package. The pin to the left of this, is pin 1, the one to the right is pin 8. Assuming you do not have an oscilloscope we will have to resolve this by a process of elimination. The voltage measured across the above mentioned pins 8 and 4 should be around 30V DC, if this is not the case, measure from pin 8 to the chassis as well as pin 4 to the chassis. The voltages should be 15.9 and -14.9 volts respectively. If one of these measured anything deviating more then 1 volt from the above figures the problem lies within the power supply. I would suggest that you check the voltage across Q818, the zener diode located on the top right of the main circuit board. The voltage across this zener diode should be approximately 16V. If this is not the case, replace this diode with a 16V 500mW zener diode. The original part number is HZ16-A2L though any 16V 500mW zener diode will work. For further repair report back the findings from above.

[@waynegwayneg5159]

Hi...me again.....hipe you are well..thankyou again....ive just got back from a local repair shop that i took the amp to. Basically i had to read off the last message that you sent regarding checking across certain positions with the voltage reader..they all came back to be the correct voltage ect...after checking those things he basically told me that he wouldnt be able to fix it for me because i dont have the manual with wiring diagrams for him work from.also i could end up throwing loads of money at it for no reason...me personally want to keep it because of sentimental value and quality.just wondered what you could sujest.sorry for taking valuable time up

[@antoniosnikolaoy3754]

Good evening from Greece, although 5 years have passed since the video you uploaded and it is awesome, I would like to ask you a question, I have the exact same model and it burned my fuses at 3.5 A. as soon as I changed it, it started to my resistors R745 and R733 are burning, can you give me some advice, thank you from the bottom of my heart. R745= 220om 1/2 R733=150om. your work is professional.

[@lbochtler]

I will look into the schematic for you and see if i can find an Exploitation for you. From what you have described thus far its either a short in the output transistors (i don't have the schematic committed to memory anymore, so this is based on my experience in amplifier repair and design), a bad power supply capacitor (the big ones). However it seems likely is a short circuit in the output transistors. Check those with a multimeter on ohms and see if it reads below 1K ohm between any of the transistors terminals. Ill try to get back to you regarding this, if i dont respond in a few days notify me via comment again, since that likely means i forgot about it due to the amount of workload im currently under.

[@Sladovsky1]

What did you replace the two main big capacitors with?

[@lbochtler]

do you want the part number or just the general capacitor type and or series i used?

[@Sladovsky1]

@@lbochtler Anything that will help be buy the right replacement capacitors, really.

[@lbochtler]

@@Sladovsky1 i used the UKW1H682MRD capacitor from nichicon. they are now a retired part but are still available from mouser electronics at least as of writing this comment.

[@Sladovsky1]

@@lbochtler Great, Thanks a lot.

[@pauldl1600]

Great video, very relaxing seeing someone fix an amp. I have the same model and from time to time the bass from the right channel dips. No low frequencies get to the speaker. I have hope that i can repair it. Any leads on where I should start troubleshooting? I have very little experience working on electronics.

[@lbochtler]

elaborate the dip in bass you mentioned. is it like sliding the tone control down, or is it complete lack of bass? Also, have you swapped around the speakers to check if its the amp or the speaker that is causing the problem. Also, are other frequency ranges effected by this effect?

[@pauldl1600]

​@@lbochtler When the bass controller slider is at 0, compared to the left channel it's like there is no bass. When i turned up the bass controller, more bass is present on the right channel, but the difference between the two is still very noticeable. I've switched speaker wires, speakers, and RCA cables.. the problem persists. So i took apart the amp as much as i could. I've noticed that the plastic on the bass controller is much darker than the tremble and mid controller... like it burned or something.

[@lbochtler]

@@pauldl1600 interesting. most likely the problem is a bad capacitor in the tone control board. replacing the signal path capacitors might fix it. ill look into the schematics later

[@ernieschatz3783]

What a round about way to arrive at a bad zener diode. Unregulated good; regulated bad. No need to de-solder so many circuits.

[@HomeroGraco]

Very nice video. I got a faulty Marantz PM 350 and will start the journey of figuring out where exactly the issues are and how to fix them. Mine has a non-working left channel, I already discovered that the left power transistors are dead, and the main caps also look pretty old to me. I don't have the equipment you have, but I hope I can figure it out.

[@lbochtler]

As long as you have a a soldering iron, a desoldering pump, a multimeter and a computer, you should be just fine. My equipment allows me to diagnose more faults, but to fix your problem, that equipment should be fine. Also, do you have an oscilloscope? If not ill see if i can come up with a simple solution using a pc sound card, but i cant guarantee anything. Good luck with trying to repair and restore your amp! If you need some technical help, just post a comment here, and i will do my best to help you.

[@HomeroGraco]

I have a soldering iron, pump, multimeter and computer, but no osciloscope. I guess I can survive without it, but I let you know case I need help. Thanks a lot for your offer!

[@geoepi321975]

You must align the amplifier

[@HomeroGraco]

It's fixed! In the end the crazy tone pots were all damaged... I managed to realign the contacts, clean them and put back together. Can't believe such a simple detail would be the cause. Thanks a lot for helping me!

[@MylarBalloonLover]

I dont get the vol thing on it.... is it loud around 70 and low vol around 8?

[@nasraroshan7875]

Great technical video. But one question; what is the name of the song?

[@lbochtler]

qouted from the description of my video: "Music used: Background: I Don't See the Branches, I See the Leaves by Chris Zabriskie is licensed under a Creative Commons Attribution license (creativecommons.org/licenses/...) Source: chriszabriskie.com/dtv/ Artist: chriszabriskie.com/" Test Music: One Love by TOPAZZIO www.pw-music.com (Licensed by PW-Music Enterprises) since i don't know which of the songs you meant exactly, here are both again. The background track is the first one (I Don't See the Branches, I See the Leaves by Chris Zabriskie), the test track (the one i played threw the amp, is the second one, which is a song called "One Love" Be a bit more clear about your question. if your looking to get either of both songs, the song i used for the background music can be found in the youtube free music library under the creater studio section of your channel, the other song can be found on pw-music.com, as well as itunes, spotify, amazon etc...

[@nasraroshan7875]

lbochtler very nice music and I like it. Also I want to know the name of last song in end of video.

[@lbochtler]

that is one love by Topazzio here is a link to a youtube video of it kzbin.info/www/bejne/Z4malmeEbZWBhLc

[@nasraroshan7875]

lbochtler Thank you so much

[@antoniosnikolaoy3754]

resistances 745 and 733 are no longer shaken now after 4 transistors I changed.

[@ChiyouPWu]

Can you list the component location are and the value of the capacitors n diabe, transistor pls.

[@lbochtler]

all component values, names and locations can be found in the service manual found here: www.hifiengine.com/manual_library/marantz/pm350.shtml

[@레오-v2g]

JBL control 1 pro or extreme?

[@lbochtler]

pro

[@SoddingaboutSi]

EXACTLY the same fault as mine . Blown protection resistors from the regulator and very distorted audio with the amp. Looks like the JRC 4560dd preamps on the tone board.

[@HomeroGraco]

You mean QE02 on PE00? If yes, we might have the exact same issue... I just measured all components, and this one has a weird -13V on pin #1

[@SoddingaboutSi]

I have low high distortion on both channels and one of the 15v rails is being pulled down. Distortion is high out of the tone board but good going in. Looks like one of the two op amps has failed.

[@HomeroGraco]

My left channel is dead and I've been repairing this amp on my free time for the last week or so. I replaced the 2 power amps (2SA1103 and 2SC2578) plus caps and came down (hopefully) to this last issue. My mind is blown by the fact we are doing the exact same troubleshooting at the same time :)

[@SoddingaboutSi]

It is strange. Will upload a video later this week. Try feeding audio into the power amp. That's the ribbon from the tone board. If that works I would look at the tone board.

[@HomeroGraco]

Alright, will try something.

[@Nakamichicarlos]

PLEASE DIAGRAM MARANTZ PM 243 OR PM 143

[@Stereosandotherfun]

Wrong solder technique. Heat the pad and lead then apply solder. Also always check voltage across Zeners against the schematic, if wrong, test Zener in circuit with diode check then out of circuit (I always clip one end of every device I test out of circuit and solder together if they test fine, for speed)

[@arsenelupin2850]

When you put on music during your tutorial, it is super painful, it disturbs listening to your explanation. I know most think it is relaxing, but on the contrary, it is very disturbing. And besides this music sucks. The best is to leave nothing.