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Marantz 1030 P700 Transistor

harlest

harlest

Active Member
I was hoping someone could help with matching the transistors on the 1030 amp board. I really love this little amp and don't want to lose it but she's popping and crackling pretty bad. I've replaced all caps and installed pre out jacks which helped me determine that it's definitely in the amp side (could be out put transistors too) but since I'm in there I would like to replace all transistors. I been searching this site and google and can't seem to find any info on changing the 12 P700 transistors. I've read people are using MJE15032G for the out puts but nothing on the board. Any help would be appreciated. Thanks guys.

P700 Transistor list

H701,702 = C945 Replacement = ?
H703,704 = C1318 Replacement = ?
H705,706 = C371 Replacement = ?
H707,708 = A562 Replacement = ?
H709,710 = C1384 Replacement = ?
H711,712 = A684 Replacement = ?
 
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I know this isn't helpful, but just had to say that the Marantz 1030 was my first "real" piece of audio kit. It was 1976 ('75?) and I washed a lot of dishes at the Village Barn restaurant to make enough to take it home from Two Guys Dept store....
 
I'm not a fan of wholesale transistor replacement. Most of the old ones have to be replaced with a modern sub that is just close in spec. Multiply that by 10 or 15 transistors, and you have a unit that really doesn't resemble the original circuit. I replace known troublesome transistors (like 2SC458) and any that test bad. Otherwise, I leave them alone. That list that Bruno linked to is a pretty good start on which ones are considered troublesome.
 
Thanks SOooo much guys! I don't want to replace anything that's not bad but unfortunately I'm not sure how to test transistors. I do have a cheap tester but I'm not sure what I'm looking at. I did test one of the main outputs (D315E) and it read hFE=148 Ube=562mV IC=6.4mA. Maybe If all the main outputs read close than they might be ok. The popping and crackling was coming from both channels so I'm thinking both sides are having issues. Any thoughts on those readings?
 
I think there are the infamous 2SC458's on the tone board. (P500.) I would look at changing those 1st. That could be where your noise is coming from. Replace with KSC1845 transistors.
 
harlest said:
Thanks SOooo much guys! I don't want to replace anything that's not bad but unfortunately I'm not sure how to test transistors. I do have a cheap tester but I'm not sure what I'm looking at. I did test one of the main outputs (D315E) and it read hFE=148 Ube=562mV IC=6.4mA. Maybe If all the main outputs read close than they might be ok. The popping and crackling was coming from both channels so I'm thinking both sides are having issues. Any thoughts on those readings?
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For transistors that are still working, but noisy, it takes sophisticated equipment to detect the problem. Simple testers won’t show it. When we talk about testing transistors, we are usually looking for a bad, non-working transistor. But when you hear static or crackling sounds intermittently, it may be one of those “troublesome” transistors. Bruno is right. If there are 2SC458’s on your tone board, they are prime suspects. Get them out of there.
 
Bruno Primas said:
I think there are the infamous 2SC458's on the tone board. (P500.) I would look at changing those 1st. That could be where your noise is coming from. Replace with KSC1845 transistors.
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Thanks for the reply. I did a full recap and on the phono and tone board I replaced all 2SC458's. I also added preout jacks so I could separate and Identify if the problem was in the front or the rear of the 1030. Using my Marantz 140 as the amp it sounded great!! No crackling noise. But when I use the 1030 amp I get the noise. The problem should be in the amp board or output transistors.
 
Steven Tate said:
For transistors that are still working, but noisy, it takes sophisticated equipment to detect the problem. Simple testers won’t show it. When we talk about testing transistors, we are usually looking for a bad, non-working transistor. But when you hear static or crackling sounds intermittently, it may be one of those “troublesome” transistors. Bruno is right. If there are 2SC458’s on your tone board, they are prime suspects. Get them out of there.
Click to expand...

Thanks Steven! I figured the transistor problem was going to be hard to trouble shoot. That's why I was thinking of taking the shotgun approach LOL! Change everything. I guess I'm scared of going in between the amp and heat sink to much I don't want to break one of those crazy diod/thermister things that you can't get anymore. Well I guess I'll take it slow and keep changing until I get the bad ones.
 
I'm reporting back to let you guy's know I've found the two noisy transistors :rockon: I'm so happy!! It's H701 and H702 (C945). As soon as I touch and barely move either one the popping and crackling starts. Is it possible that anyone knows what the replacement would be for that transistor (C945)?
 
Hey Guys, I'm back with a positive update. My 1030 is all back together and working great. Those two transistors H701 and H702 (C945) were definitely the problem. I replaced them with the KSC945CYTA which I ordered from Mouser and no more snap,crackle and pop. Thanks so much Steve, Bruno and arcsound. I really appreciate all your help.
 
harlest said:
Hey Guys, I'm back with a positive update. My 1030 is all back together and working great. Those two transistors H701 and H702 (C945) were definitely the problem. I replaced them with the KSC945CYTA which I ordered from Mouser and no more snap,crackle and pop. Thanks so much Steve, Bruno and arcsound. I really appreciate all your help.
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Just a thanks for the debug on h701 and h702. Same thing here (on the right channel). Just watch the pin out to anyone that follows along.
 
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