americannigh
Active Member
* Please read my post #62 which has a summary of how the project ended up and lessons learned since this original post.
Some of you may have seen my earlier thread seeking advice for a good replacement transistor to the original Sansui 210 outputs (TR809/811 and 810/812) which are 2SD315 (no longer in production and are TO-66 which is a form factor no longer in production). This thread is a step by step guide as I have now replaced the outputs successfully. The main challenges encountered in this project were selection of the replacements, dropping in the TO-220 style transistors into the TO-66 heat sink, location and mounting of diodes D801 and D802.
A link to the transistor choice thread is here:
http://audiokarma.org/forums/index....r-replacement-of-2sd315.813283/#post-11399937
I decided to use MJE15032G, Mouser PN# 863-MJE15032G.
This is a TO-220 style transistor so required just a little modification to fit into the TO-66 heat sink mount.
First, a photo of the original transistors as installed by the factory:
Of note here are the diodes D801 and D802 which are held on with clips to the back of the center two originals. As noted by others, these kind of diodes have leads which can break off easily so care is required when encountering them. As seen here, the heat sink comes off by removing two screws. It is easier to replace the transistors with the heat sink unscrewed from the chassis.
Here is a picture from the other side of the heatsink:
Note the collector (case of the transistor) is soldered to the white/red/orange/yellow wires to a washer which goes on the mounting screw threaded through a plastic washer to insulate the collector. It is important to use and retain this mounting hardware in the method I used.
Also note each transistor has a blue and brown wire soldered directly to the Emitter and Base of the transistor (blue to base and brown to emitter). The blue and brown wires run to the amp PC board and are labeled as 8E/F/H/U (for the blue/base wires) and 8D/G/A/C (for the brown/emitter wires). These connections are labeled as such on the schematic for easy reference should one want to double check their connections. I can't say the PC boards are screened this clearly on all 210 models but it was the case with mine.
Next I removed the first transtor (I chose an end one with no diode attached):
In the method I used, I clipped off the middle lead (collector) and bent the base and emitter leads to fit through the original hole. One lesson learned in this first transistor was a need to bend the lead farther down than I anticipated, about 1/8" up from where the lead goes into the transistor. I used needle nose pliers to do this. A mica insulator was used with standard heat sink compound between the transistor and mica and between mica and heat sink. I chose to put some white shrink wrap as insulators on the base and emitter leads to guard against short should someone work on the receiver in the future and accidentally bump a lead. They are easy to bend and cause short against the heat sink. As seen here, a single screw is used for the new transistor along with the plastic washer to insulate the collector from the heat sink.
Next here is an example of all transistors installed so you can see the ones which had accompanying diodes. This was a bit more tricky.
I improvised here. Someone may have a better way to do this. I used the original clip which held the diode to the old transistor case. This was a pressure fit only. The diode was not fixed to the original transistor. I tested the diodes and the case was non-conductive. What I did was bend the clips so they would fit snugly against the diodes placed to the side of the transistors when screwed down. This did take some experimentation bending them with my needle nose pliers. Hopefully what I did is OK here. Everything works but if I made some major misstep here maybe someone can let me know if there's a better way. I thought about desoldering them and finding a sexier place to put them but those leads scare the heck out of me based on what others have said so I tried to keep things as non-intrusive as possible with the diodes.
Here's a picture of the connection side with the new transistors:
Note that I used the bottom hole. This is the way the TO-220 transistors lined up so the bent leads would go through the heat sink. Nicely enough the new transistors also then have the blue wire on left and brown on right just like the originals. You can also see here in this picture the white heat shrink I used as an extra insulator on the leads just to guard against short.
The last step is that I took my meter and did a continuity test between the collector connection (the screw with the ring) and the heat sink. I did this to make sure there was no continuity and thus no shorts anywhere. For example if I had tightened one down too much and cracked the insulator, this could cause a short. So I wanted to check for that. I learned that the heat sink should not be screwed down when doing this check because this connects it to ground and so you will see some continuity. With the heat sink unscrewed, I put a towel under it so it wasn't touching ground, then tested between each collector and the heat sink to make sure there were not shorts. I also used my cell phone camera and flashlight to look at each lead and make sure it was soldered on good and didn't have any shorts.
Once everything looked good, I fired it up.
So far so good. I am a couple hours into listening to it and enjoying the receiver quite a bit. It will take me a few days to really decide how it stacks up against my other receivers but the warm character and similarity to my 330B which attracted me to this receiver are still present even with all the transistor replacements and cap replacements I've done on it. If anyone is wondering why I decided to change the outputs in the first place, I had an issue with intermittent static in the right channel when the receiver got warm (not hot just warmed up). After replacing all preamp and amp transistors (besides the outputs) the problem remained. This left the outputs as suspect in my mind. Again so far so good. No static on right channel after a couple hours listening to it.
Some of you may have seen my earlier thread seeking advice for a good replacement transistor to the original Sansui 210 outputs (TR809/811 and 810/812) which are 2SD315 (no longer in production and are TO-66 which is a form factor no longer in production). This thread is a step by step guide as I have now replaced the outputs successfully. The main challenges encountered in this project were selection of the replacements, dropping in the TO-220 style transistors into the TO-66 heat sink, location and mounting of diodes D801 and D802.
A link to the transistor choice thread is here:
http://audiokarma.org/forums/index....r-replacement-of-2sd315.813283/#post-11399937
I decided to use MJE15032G, Mouser PN# 863-MJE15032G.
This is a TO-220 style transistor so required just a little modification to fit into the TO-66 heat sink mount.
First, a photo of the original transistors as installed by the factory:
Of note here are the diodes D801 and D802 which are held on with clips to the back of the center two originals. As noted by others, these kind of diodes have leads which can break off easily so care is required when encountering them. As seen here, the heat sink comes off by removing two screws. It is easier to replace the transistors with the heat sink unscrewed from the chassis.
Here is a picture from the other side of the heatsink:
Note the collector (case of the transistor) is soldered to the white/red/orange/yellow wires to a washer which goes on the mounting screw threaded through a plastic washer to insulate the collector. It is important to use and retain this mounting hardware in the method I used.
Also note each transistor has a blue and brown wire soldered directly to the Emitter and Base of the transistor (blue to base and brown to emitter). The blue and brown wires run to the amp PC board and are labeled as 8E/F/H/U (for the blue/base wires) and 8D/G/A/C (for the brown/emitter wires). These connections are labeled as such on the schematic for easy reference should one want to double check their connections. I can't say the PC boards are screened this clearly on all 210 models but it was the case with mine.
Next I removed the first transtor (I chose an end one with no diode attached):
In the method I used, I clipped off the middle lead (collector) and bent the base and emitter leads to fit through the original hole. One lesson learned in this first transistor was a need to bend the lead farther down than I anticipated, about 1/8" up from where the lead goes into the transistor. I used needle nose pliers to do this. A mica insulator was used with standard heat sink compound between the transistor and mica and between mica and heat sink. I chose to put some white shrink wrap as insulators on the base and emitter leads to guard against short should someone work on the receiver in the future and accidentally bump a lead. They are easy to bend and cause short against the heat sink. As seen here, a single screw is used for the new transistor along with the plastic washer to insulate the collector from the heat sink.
Next here is an example of all transistors installed so you can see the ones which had accompanying diodes. This was a bit more tricky.
I improvised here. Someone may have a better way to do this. I used the original clip which held the diode to the old transistor case. This was a pressure fit only. The diode was not fixed to the original transistor. I tested the diodes and the case was non-conductive. What I did was bend the clips so they would fit snugly against the diodes placed to the side of the transistors when screwed down. This did take some experimentation bending them with my needle nose pliers. Hopefully what I did is OK here. Everything works but if I made some major misstep here maybe someone can let me know if there's a better way. I thought about desoldering them and finding a sexier place to put them but those leads scare the heck out of me based on what others have said so I tried to keep things as non-intrusive as possible with the diodes.
Here's a picture of the connection side with the new transistors:
Note that I used the bottom hole. This is the way the TO-220 transistors lined up so the bent leads would go through the heat sink. Nicely enough the new transistors also then have the blue wire on left and brown on right just like the originals. You can also see here in this picture the white heat shrink I used as an extra insulator on the leads just to guard against short.
The last step is that I took my meter and did a continuity test between the collector connection (the screw with the ring) and the heat sink. I did this to make sure there was no continuity and thus no shorts anywhere. For example if I had tightened one down too much and cracked the insulator, this could cause a short. So I wanted to check for that. I learned that the heat sink should not be screwed down when doing this check because this connects it to ground and so you will see some continuity. With the heat sink unscrewed, I put a towel under it so it wasn't touching ground, then tested between each collector and the heat sink to make sure there were not shorts. I also used my cell phone camera and flashlight to look at each lead and make sure it was soldered on good and didn't have any shorts.
Once everything looked good, I fired it up.
So far so good. I am a couple hours into listening to it and enjoying the receiver quite a bit. It will take me a few days to really decide how it stacks up against my other receivers but the warm character and similarity to my 330B which attracted me to this receiver are still present even with all the transistor replacements and cap replacements I've done on it. If anyone is wondering why I decided to change the outputs in the first place, I had an issue with intermittent static in the right channel when the receiver got warm (not hot just warmed up). After replacing all preamp and amp transistors (besides the outputs) the problem remained. This left the outputs as suspect in my mind. Again so far so good. No static on right channel after a couple hours listening to it.
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We replied at the same time kevzep, can't oscillation cause overheating and damage?