Fisher RS-2010 Darlington pack STK-0080 or 0105?

[mcnealv]

I have repaired at least 4 or 5 Fisher RS-2010's over the last few years and they all had STK-0080's. I don't know about the STK-0105. Maybe they were in a early production run. Don't know. The STK-0080 is very reliable power pack as long as you dont drive them at near clipping levels into low speaker impedances of 4 ohms or less. If you do they are toast.

Bill from Indy

How would i know if my STK-0080's are blown? I have a Fisher RS-2007. When i turn it on it plays for about 30 seconds then the speakers sound like they clipped out, but I still have power. Do I need to replace them and if so is it something i can do myself?

 

[Watthour]

You may want to investigate a modern replacement in lieu of an imitation module. These can be built with 200W ratings: https://audiokarma.org/forums/index.php?threads/stk-0050-replacement-for-sx-780-and-others.721181/

 

[tarior]

He should probably start his own thread where we might be able to help him narrow down the problem.

 

[Super Noob]

 

[Watthour]

Good man! (Better than a thousand words...)

 

[suzook]

Bringing this thread back from the dead....I think I found out what's going on with the discrepancy of stk 80, and stk 015 in these rs-2010's. The first series, with the A SN seem to have the stk 0105, and round beefy transformer. These I believe were made the 1st year. I'm thinking Fisher designed the unit before Sanyo took over. Once they did, the 2nd, and 3rd gen units came with the square transformer, and stk 80's. Probably done to save money. IMO, the 1st gen is the unit to get. I would bet it puts out more power, with lower distortion. Would be nice if some would chime in with diff serial numbers, to figure this out.

 

[larryderouin]

Seem to remember something about PIONEER raising hell over someone copying parts of the power supply of the SX-1280 or 1080, which ever had the toroidal transformer (NOTE: I looked up both and SX-1080 and SX-1280 and they both had Toroidal transformers) It's pretty fuzzy in my mind. Needless to say it was short lived and the offending units were converted to I-E transformers. As the RS-20xx series came out at the same time as the SX-xx80 series, it's a distinct possibility.

 

[suzook]

Seem to remember something about PIONEER raising hell over someone copying parts of the power supply of the SX-1280 or 1080, which ever had the toroidal transformer (NOTE: I looked up both and SX-1080 and SX-1280 and they both had Toroidal transformers) It's pretty fuzzy in my mind. Needless to say it was short lived and the offending units were converted to I-E transformers. As the RS-20xx series came out at the same time as the SX-xx80 series, it's a distinct possibility.

Yes, they also did the same with the realistic receivers with the transformer. But why downgrade the stk chips from the 015 to the 080. I understand they are similar, but the 0105 is definitely more robust. Very strange, and interesting.

 

[Chilibrother]

Serial number on mine is 10048. Has the toroidal transformer, STK-0105 Darlingtons, and sounds great!

 

[suzook]

Well my theory is failing. LOL. I have a unit with SN 15024 and it has the toroidal trans, but stk-080 packs. So maybe the 1000 sn units have toroidal. But the stk thing is definitely odd. Why am i upset I have the little 080's??? I will say this unit is a beast. Well built, and sounds great!

 

[suzook]

Well, I got some minor distortion in my right channel. Wonder if it could be the relay, like the issues that plague the pioneer units. Anyone know where to begin? Maybe i will post on solid state forum.

 

[Chilibrother]

Well, I got some minor distortion in my right channel. Wonder if it could be the relay, like the issues that plague the pioneer units. Anyone know where to begin? Maybe i will post on solid state forum.

I had the same problem. Distortion but never no sound at all. Went through the controls three times before determining that it was in fact the relay. Replaced it and all is well.

 

[suzook]

I had the same problem. Distortion but never no sound at all. Went through the controls three times before determining that it was in fact the relay. Replaced it and all is well.

Kind of figured it probably is that. I opened it up, cleaned contacts, but still persists. Ill give a new one a try. Although it looks like there are 2 of them?

 

[suzook]

I had the same problem. Distortion but never no sound at all. Went through the controls three times before determining that it was in fact the relay. Replaced it and all is well.

Does your relay kick in as soon as power is pushed? I am getting the relay to instantly switching on, creating a turn on thump. Wondering if I have other issues. I wish there were more fisher gurus here, like the pioneer forum.

 

[Chilibrother]

Does your relay kick in as soon as power is pushed? I am getting the relay to instantly switching on, creating a turn on thump. Wondering if I have other issues. I wish there were more fisher gurus here, like the pioneer forum.

Mine
My relay kicks over in about one second. Only one relay on the PS board, accessed from the bottom of the unit (arrow is a little high on the photo).

Can't answer the thump question but it doesn't sound encouraging. On all my receivers I turn them on with the speaker selector set to off. This receiver isn't hooked up right now to check.

 

[suzook]

Mine
My relay kicks over in about one second. Only one relay on the PS board, accessed from the bottom of the unit (arrow is a little high on the photo).

Can't answer the thump question but it doesn't sound encouraging. On all my receivers I turn them on with the speaker selector set to off. This receiver isn't hooked up right now to check.
View attachment 2633430

Thanks. Unfortunately i have distortion in one of the channels. Not sure where to begin.

 

[ChrisP2]

Another RS-2010 saved from the scrap heap, here are a few notes that should help someone (I hope).

This was a late model RS-2010 w/STK0080's and the extra 2SC1708 Pre-Drivers In Front of Q11 & Q12 as noted elsewhere above.

I used STK0080's from eBay, supposedly "Sanyo" OEM, we will see....so far so good.

This one took some time.....smoky !!

Issues:

• Q12 Shorted, Q16 Smoked, R44 Smoked (See Pic)
• Several Zeners Dead Shorted
• C09 Popped Open
• R35/36 & R59/60 - 2 OK, One Open, One 50% of Value
• R54 (Emitter Resistor) Open

Notes:

• Full Recap of Electrolytics - Most Tested OK, a few out of Tolerance
• Tested All Resistors > 1/4W - Replaced R44, R59/60, R35/36, R51-R54
• Replaced all Small Signal Transistors
• Replaced all Zeners & Small Diodes
• Replaced STKs
• Sub List Below
  
• Watch Pin Outs Q11 & Q12 - OEM is BCE, Replacement ECB (Flip It)
• Watch Pin Out on Predriver Transistors Piggy Backed on Q11 & Q12 - OEM is BCE, Replacement ECB (I had to sketch that one out)
• Dirty Volume POT Caused ~ 5% Signal Differential L/R Channel
• Final Pic Attached

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


Part OEM OEM PIN NEW New PIN
Q01 2SC1571HL ECB KSC1815 ECB
Q02 2SC1571HL ECB KSC1815 ECB
Q03 2SA1016K ECB KSA992 ECB
Q04 2SA1016K ECB KSA992 ECB
Q05 2SA1016K ECB KSA992 ECB
Q06 2SA1016K ECB KSA992 ECB
Q07 2SA1016K ECB KSA992 ECB
Q08 2SA1016K ECB KSA992 ECB
Q09 2SA1047 E ECB KSA1381 ECB
Q10 2SA1047 E ECB KSA1381 ECB
Q11 2SC2441E BCE KSC3503 ECB
Q12 2SC2441E BCE KSC3503 ECB
Q13 2SD438D ECB KSC2383 ECB
Q14 2SD438D ECB KSC2383 ECB
Q15 2SB560D ECB KSA1013 ECB
Q16 2SB560D ECB KSA1013 ECB
Q17 2SC2362K ECB KSA1845 ECB
Q18 2SC2362K ECB KSA1845 ECB
Q19 2SC2362K ECB KSA1845 ECB
Q20 2SC2362K ECB KSA1845 ECB
Q21 2SC1175 ECB KSC1815 ECB
QX, QY 2SCC1708 BCE KSC1815 ECB

D01 DS-442 1N4148
D02 DS-442 1N4148
D03 DS-442 1N4148
D04 DS-442 1N4148
D05 05Z12U Zener 12V - 500mW
D06 05Z12U Zener 12V - 500mW
D07 DS-442 1N4148
D08 DS-442 1N4148
D09 DS-442 1N4148
D10 DS-442 1N4148
D11 DS-442 1N4148
D12 DS-442 1N4148
D13 DS-442 1N4148
D14 DS-442 1N4148
D15 RD3.6E Zener 3.6V - 500mW
D16 RD3.6E Zener 3.6V - 500mW
D17 RD3.6E Zener 3.6V - 500mW
D18 RD3.6E Zener 3.6V - 500mW

 

[Dave07997S]

Bringing this thread back from the dead....I think I found out what's going on with the discrepancy of stk 80, and stk 015 in these rs-2010's. The first series, with the A SN seem to have the stk 0105, and round beefy transformer. These I believe were made the 1st year. I'm thinking Fisher designed the unit before Sanyo took over. Once they did, the 2nd, and 3rd gen units came with the square transformer, and stk 80's. Probably done to save money. IMO, the 1st gen is the unit to get. I would bet it puts out more power, with lower distortion. Would be nice if some would chime in with diff serial numbers, to figure this out.

No Fisher was sold to Sanyo in 1975, the RS-2010 was first sold in 1978.

 

[larryderouin]

The 2010 was built to "compete" with the Pioneer SX-1250 or 1280 (I can't remember which). They basically lifted the toroidal transformer specs and cloned it. Pioneer found out and went to court. Sanyo then swapped a standard transformer in. There is an old thread from about 10-11 years ago either in the PIoneer forum or here. Which is also why the stk015 is in the early version with the toroidal transformer and later versions with the 80 had standard Power transformer. Having said that, there have been some guys who replaced their 08;s with 015's and they hold up just fine. There is also a thread from 2-3 years ago one of the guys did on a 2010 where he integrated RCS16's separate amp board(s) for the 0050 (SX-780) and it handles the increased loads very well.

 

[drjim]

I'm rebuilding an RS-2010 right now. I was amazed at how many electrolytics were running at >90% of their rated voltage. I replaced all the electrolytics with new ones rated at higher voltages and temperature. I checked all the ones I pulled, and about 1/3 of them were leaky, and several were open, something I don't recall seeing before. The SN on this unit is 28389 B 8035, and there are numerous differences between "AS BUILT", and the Service Manual from HiFi Engine. It has the toridial power transformer and STK-0080's.The dial cord is strung very differently, it's missing the extra pulley shown in the manual, there are two inductors on the bottom of the Power Amp Board, and four electrolytics on the top side. Also there's also two 5.6k resistors and a 1000uF cap mounted on a terminal strip and connected to the PA board that looks like they're used to delay the 60 Volt supply from coming up too fast.

This one's been worked on a couple of times before, including a replacement of Q99 and Q11. They were replaced with 2SD758's, rather than the 2SC2441's on the schematic.

And it looks like I'll be in the market for some replacement STK-0080's, or equivalent.