Marantz model fifteen repair.

tonebells

tonebells

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I picked up a model fifteen that someone has been into. The two amp have different serial numbers and some design differences. One channel is working the other is not. Q113 DTM-13 was replaced previously with a MJ15015G. I don't know if that is a good sub. Q101 DTM-6 is bad and I need to find a sub. If anyone knows any good upgrades or service mods please let me know.

Short cord half.
16501192770_1103734bb8_z.jpg



Thanks

Tony
 
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I have done a few 15s and have one running with a 7c/20 & Walsh 4 speakers. They are sweet....

Looks like that unit is an early one.

New electriclytics are key. Check the heat sinks for a rough finish near the power transistors. Some heat sinks were not machined to a smooth surface and tend to "cut thru" the mica insulators.

Change the overload lamps.

Jk
 
You seem to have an early and a late unit together. From the factory they were matched.

The later ones seemed to sound slightly different. But that could be just me.

Does the later unit have the small to-33 transitors on the heat sink ? Near the power xtors?

If I remember correctly....

Early unit.... No relay.
Middle Rev.... Relay and to-33s
Late Rev.... Relay and no To-33s.


I would say, I always loved monoblock designs and the 15 shows all the positive traits of a monoblock and of being a Marantz!

They all need a electrolytic cap refresh to wake them up.... I use mine with a 7c and like it better than my tube amp. Monoblocks rule...

Jk
 
I have not been into the later one to much yet. I did not see them (to-33s) with the top and bottom off.
(It does have Q109/112 TO-66s)
Tony
 
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I've got a 16 that was fun to rebuild. The 15 looks somewhat simpler in design. Good luck with your 15, these early SS amps sound great.
 
I am in the process of restoring my 15. It's a later model and I only a serial number on one of the two blocks - no. 14791. Being new to restoration, I have been taking it real slow since there's no schematic available for the later variation. No to-33s, has relay, and there is also a current limiting board added causing the resistor values to vary from the schematic and additional components on the board. Working on replacing the electrolytics, film resistors, couple of burned out carbon resistors, and lamps as they have all strayed far from their original value. Trying to stick as close to stock value as possible here but upgrading quality of the parts. Going to check the relay, transistors, and coupling caps as well though hopefully they're good to leave in.

Any thoughts on the best electrolytics for the power supply? These are axial through-hole (10uf, 100v; 50uf, 50v; 100uf, 25v; and 350uf, 50v). Already have computer grade screw terminal Sprague cans for the 5450uf caps.
 
I bought these.

TVA1308-E3 50uF 50volts
TVA1207 100 uF 25V
53D351F200JL6 350uF 200v

TVA1406 10uF 150v

Tony
 
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tonebells said:
I bought these.

TVA1308-E3 50uF 50volts
TVA1207 100 uF 25V
53D351F200JL6 350uF 200v

TVA1406 10uF 150v

Tony
Click to expand...

I ended up buying Sprague Little-Lytics for the smaller values and Powerlytics for the larger cans. The film coupling caps look fine so I will leave them in for now. Did you ever find a sub for Q101 DTM-6?
 
I am looking for a good replacement for Q110 (DTM13) and Q113 (DTM14). I have seen posts of people using either MJ15003/4, MJ15015/16, and MJ15025/26. Anyone know which set is the best replacement?

John
 
For these early SS Marantz amplifiers, it is recommended to avoid using "fast" output transistors. The MJ15025/26 are rated at 4MHz (min) but are typically ~8MHz devices. The MJ15015/16 parameters are not very well matched: the NPN is rated at 0.8-6.0MHz, but the PNP complement is rated at 2.2-18.0MHz. This MJ15003/4 pair is well matched ard are rated at 2.0MHz. I have used the MJ15003/4 pair in a recent Marantz 15 repair to good effect.
 
Leestereo said:
For these early SS Marantz amplifiers, it is recommended to avoid using "fast" output transistors. The MJ15025/26 are rated at 4MHz (min) but are typically ~8MHz devices. The MJ15015/16 parameters are not very well matched: the NPN is rated at 0.8-6.0MHz, but the PNP complement is rated at 2.2-18.0MHz. This MJ15003/4 pair is well matched ard are rated at 2.0MHz. I have used the MJ15003/4 pair in a recent Marantz 15 repair to good effect.
Click to expand...

Thank you Leestereo!
 
Leestereo said:
For these early SS Marantz amplifiers, it is recommended to avoid using "fast" output transistors. The MJ15025/26 are rated at 4MHz (min) but are typically ~8MHz devices. The MJ15015/16 parameters are not very well matched: the NPN is rated at 0.8-6.0MHz, but the PNP complement is rated at 2.2-18.0MHz. This MJ15003/4 pair is well matched ard are rated at 2.0MHz. I have used the MJ15003/4 pair in a recent Marantz 15 repair to good effect.
Click to expand...


Thanks Lee. I too will give this a try. I my be some time before I get back to it though.

Tony
 
I'm also restoring a 3rd-revision Model 15 (with the relay, and with no TO-33s on the heatsinks). I think it's useful to get a list of known transistor substitutes. So far, we have:
Q101, Q102, & Q103; originally DTM6; substitute 2N5401 (closely matched for Q102 and Q103).
Q108 & Q112; originally DTM11; substitute NTE291
Q102 & Q111; originally DTM12; substitute NTE292
Q110; originally DTM14; substitute MJ15004
Q113; originally DTM13; substitute MJ15003
That leaves:
Q104; originally DTM9; substitute ??
Q105 & Q106; originally DTM8; substitute ??
Q107; originally DTM10; substitute ??

If anyone knows any good substitutes for Q104 through Q107, please reply.

I traced the gainstage amp board to ID the components, fixing three errors in the service manual, which had Q102 and Q103 swapped, and misidentified Q105 as Q107. Here's my result:
https://dl.dropboxusercontent.com/u/37073121/Marantz/AmpBoard.pdf

This is the first later-model Model 15 I've worked on. Are the missing Q109 and Q112 TO33's from the heatsinks replaced with something else elsewhere? Are they on the current limiter board?

I'd also welcome sources for replacements for the big 5450uF caps, C15 and C21.
 
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:D I am green with envy :D

It is so cool to:

Have something like that

DIY Repair/restore something like that

Actually use something like that

You get two out of the three, you're so bad, bad, bad, bad, you're nationwide...
 
I traced the gainstage amp board to ID the components, fixing three errors in the service manual, which had Q102 and Q103 swapped, and misidentified Q105 as Q107. Here's my result:
https://dl.dropboxusercontent.com/u/...z/AmpBoard.pdf
Click to expand...

Good info here. I like the way you highlighted the components. I made these to help me out.



I think Q2/Q3 where swapped on the schematic but were correct on the board. Here's hoping others will confirm.
 
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