• 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 2216 amplifier board question

Stereoboy70

Stereoboy70

Active Member
8C9DBBB0-8A36-4FCD-BF77-818B7D53C9F8.jpeg 37D74630-4DE4-409B-B69C-3B828C133241.jpeg E343900A-1861-477A-81C6-06BBAEE41CC7.jpeg Have a quick question for any Marantz gurus. I have a 2216 that had a blown right channel. Since I was replacing the output transistors I went ahead and totally rebuilt the board. New caps, new output transistors, new trim pots, new resistors at R735-R738. The transistors I used were as follows: H711-712 2SD313. H713-714 2SD507 (eBay). H701-701 2SA992 (mouser). H703-704 2Sc1384 (eBay). H705-706 2SC1815 (mouser). H707-708 2SC1384 (eBay) H709-710 2SA 1281 (mouser) Trim pots are Bourns 3296
Caps are direct replacement values. R735-738 are .22 ohm 3watt. C719-720 are .1uf films. Schematic shows ceramic caps. C 701-702 are 1uf EC caps but someone suggested 1uf bipolar wimas. I didn’t use the wimas. I had issues with some of the traces pulling up at the holes but they all make connection across the traces. The issue I’m having is that when I fire it up using a DBT it is super bright indicating a short. When I remove the red power wire going to the amp the bulb is super dim. I pulled the other wires off and it made no difference regarding the short. Something on the board is pulling down the voltage because when I hook the power wire back up and check voltage it’s only about half of what it should be. I have scoured this board looking for bad solder and blobs of flux. Checked a bunch of connections and can’t find a short. Ive checked all the resistors off the board and rechecked the transistors and caps. All seem good. BTY this amp has 4 diodes soldered on the bottom of the board. 2 from pin J706 to R736 and R735. And 2 from pin J707 to R737 and R738. Don’t know if they are really necessary because the 2215B amp is the same but it doesn’t have these. Sorry for the long post. Any thoughts?? I’ll Post some pics. The board looks like crap.
 
Register to hide this ad
First of all, don't use old transistors from eBay! If you need to replace transistors use modern equivalent bought from a reputed seller like Mouser, Digikey, etc.
Finally, first, solve the problem bring the unit in working condition then do the restoration. At this point, I will suggest putting back old original transistors if those are not tested bad and if tested bad use modern equivalents. If you have repaired the trace in the back of the board check those works to find any short. DBT bright when the amp has power connection and DBT dimmed when there is no power to amp means it has short somewhere in the amp board.
 
sanjib said:
First of all, don't use old transistors from eBay! If you need to replace transistors use modern equivalent bought from a reputed seller like Mouser, Digikey, etc.
Finally, first, solve the problem bring the unit in working condition then do the restoration. At this point, I will suggest putting back old original transistors if those are not tested bad and if tested bad use modern equivalents. If you have repaired the trace in the back of the board check those works to find any short. DBT bright when the amp has power connection and DBT dimmed when there is no power to amp means it has short somewhere in the amp board.
Click to expand...
Will do. Thanks Would I set the trim pots to zero ohms to start out ?
 
Rechecked the transistors and they are good. I removed the little 6v red bulbs on the board and they are also ok. When they’re removed the DBT barely glows. When they’re in it gets brighter. I plugged into a regular outlet and the L side outputs got hot fast. This thing is driving me nuts.
 
I’m not sure what the problem is with your amp, but maybe I can nudge you a little further along.

The schematic is available online with voltages so you could confirm which transistors are seeing bad voltage (on DBT of course). You don’t have a pic of the final assembly but make sure you’ve used mica insulators between the heatsink and all those output transistors and that they’re installed straight/correctly. Triple check for any solder bridges. These are sometimes hard to see or missed. Make sure there aren’t any component legs that were left un trimmed and are now touching metal.

Hopefully someone else will be back soon to help further.
 
Thanks.
MBuras said:
I’m not sure what the problem is with your amp, but maybe I can nudge you a little further along.

The schematic is available online with voltages so you could confirm which transistors are seeing bad voltage (on DBT of course). You don’t have a pic of the final assembly but make sure you’ve used mica insulators between the heatsink and all those output transistors and that they’re installed straight/correctly. Triple check for any solder bridges. These are sometimes hard to see or missed. Make sure there aren’t any component legs that were left un trimmed and are now touching metal.

Hopefully someone else will be back soon to help further.
Click to expand...
I have a service manual with all the voltages mentioned. I’m getting ready to check now. Will update. I’ve looked at this board a hundred times with readers AND magnifiers and I can’t see any solder traces touching. Thanks for the input
 
Schematic shows H713 and H714 as PNP but the transistor marked as 2SD507 in the schematic (it is NPN) but I believe it should be 2SB507 (in the parts list it is listed as 2SB507) which is PNP. Check your replacement for H713 and H714 make sure they are PNP. If you have used 2SD507 for H713 and H714 then that's where your problem lies.
 
Last edited:
Stereoboy70 said:
BTY this amp has 4 diodes soldered on the bottom of the board. 2 from pin J706 to R736 and R735. And 2 from pin J707 to R737 and R738. Don’t know if they are really necessary because the 2215B amp is the same but it doesn’t have these.
Click to expand...
they are on the schematic . so long as they aren't shorted and the right way round they are fine to be there .
 
as for powered on testing some valid testing can be done by reading voltages . i tend to check b to e and look for 600mv ish there . i have found transistors that were installed wrongly that way in a unit others had tried fixing after someone tried "fixing" it in the first place .
 
sanjib said:
Schematic shows H713 and H714 as PNP but the transistor marked as 2SD507 in the schematic (it is NPN) but I believe it should be 2SB507 (in the parts list it is listed as 2SB507) which is PNP. Check your replacement for H713 and H714 make sure they are PNP. If you have used 2SD507 for H713 and H714 then that's where your problem lies.
Click to expand...
Thank you. I will check tomorrow.
 
You must log in or register to reply here.
Back
Top Bottom