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Yamaha CA-610 (MK1) - Gave it a birthday.

M

MonkeyRelish

Active Member
I had previously replaced the filter caps on this amp with the same size.
Next on the list was to replace the TA7136P op amps (SIL 7 pin) in the phono section, as well as the preamp section.
I replaced these with Burr Brown OPA604 op amps, to see if it would make any difference to the sound.
I used Brown Dog TA7136P adapter boards.
https://www.cimarrontechnology.com/browndog-111002-ta7136ap-upgrade-adapter

TA7136P pins:
1. frequency comp
2. non-inverting input (+ input)
3. inverting input (- input)
4. V-
5. voltage comp
6. outout
7. V+

The OPA604 does not have a frequency comp or voltage comp pin, so pins 1 and 5 are not used.

Phono Circuit 1

Phono Circuit 1

For the phono section,I removed C305, C306, C307 and C308 (Freq Comp), as these are no longer required, and may affect the circuit.
I also removed R319 and R320 (Voltage Comp), though they would not cause any issue if left in. I also replaced C301, C302 electrolytics with WIMA box film capacitors.
Phono With Brown Dog Adapters

Phono With Brown Dog Adapters


Preamp Circuit 1

Preamp Circuit 1

In the preamp section, I removed C411, C412, C419 and C420 (Freq Comp), as these are no longer required, and may affect the circuit.
I also removed R415 and R416 (Voltage Comp), though they would not cause any issue if left in.
Preamp Right With Brown Dog Adapter

Preamp Right With Brown Dog Adapter

Preamp Left With Brown Dog Adapter

Preamp Left With Brown Dog Adapter

Of course, the original preamp op amps are right underneath the selector shafts, so it was a bit tricky to install the adapters. The right fit fine, but the left had to be installed with a lean on it.

Fusible Resisters

Fusible Resisters

While I was in there I replaced the 47 Ohm 100mA Fusisters with Vishay 47 Ohm 1/2W resisters.

1K Bias Trimmer

1K Bias Trimmer

I also replaced the 1K bias trimmers with Bourns 20 turn 1K trimmers. Much nicer to adjust.

Protection Relay

Protection Relay

I also replaced the protection relay with a new Panasonic HC2-HP-DC12V-F, the same as used in the CA-1000.

So, was it worth it ? Oh yes it was.
I back to back tested it with my CA-1000 (Has only had new same size filter caps, Class A/B micro switches, protection relay and disassembled and cleaned the coupling and phono switches at the back).
I played side 1 of Sgt. Peppers (2017 Remaster) on my Technics SL-1400 (MK1) on both, hooked up to a pair of Polk Monitor 5A's. Previously, the CA-1000 was well ahead, with much better bass, more detailed and more dynamic. Now, there's not a whole lot of difference (at moderate listening levels), with the CA-1000 having slightly tighter bass. The CA-610 has livened right up, and I am quite happy for it to be the main amp in my retro system while the CA-1000 is getting worked on.

Happy Days.

Mr Relish
 
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jFF_Bulbo said:
i´ll try to apply it to my marantz 2385 for a full upgrade!!
Click to expand...
I recently serviced a Marantz 2385 that had fallen in the truck during a move, there was a cracked/broken circuit board, open traces, all I can say is it is one BIG PITA to take apart and service. You might want to think twice on that one.
 
Just a follow up.

It is good practice to place a “decoupling capacitor” across the +ve and -ve supply of the op-amp, as close to the op-amp as possible, to reduce the chance of oscillation in high speed op-amps like the OPA604.

A 0.1uF (100nF) 50V X7R Ceramic is most commonly used.

Solder the capacitor on the back of the brown dog board between op-amp pins 4 (- VS) and pin 7 (+ VS).

Thanks to @zebulon1 for his thread showing these on the brown dog adapters here :-
https://audiokarma.org/forums/index...-now-working-and-sounding-great.707379/page-5

While I didn’t use them on my 610, and didn’t notice any oscillation, YMMV, and it’s worth doing while you are at it.

Mr Relish
 
rcs16 said:
I recently serviced a Marantz 2385 that had fallen in the truck during a move, there was a cracked/broken circuit board, open traces, all I can say is it is one BIG PITA to take apart and service. You might want to think twice on that one.
Click to expand...
I am more than aware that it is a huge challenge, in terms of difficulty, technique and very expensive for me (I plan to replace about 200 pieces ...) but it will be a unit for life and a job that I will be proud of every day.
 
:bowdown:
hi Mr. MonkeyRelish.
I bought a Yamaha Ca-601 a few days ago and today I come across this amazing upgrade job :eek2:.
thank you very much for sharing your experience.
unfortunately my 610 needs a pair of power transistors :(
 
Homemade Brown Dog for the OPA604 and "spare parts" (the 2 filter capacitors are still missing).

Q2qK3dl.jpg


KHhsH9y.jpg
 
Today, last day of the year, my Yamaha ca-610 anticipated the fireworks.
After replacing the trimmers to adjust the idling current as specs, I turned on the amp and an immediate "stick" and subsequent smoke of a resistor (R526).
Fortunately, the the relay has not tripped.
I hope the damage is related to the right channel only.

I wish the group a Great and Happy New Year.
 
Hello everybody.
Unfortunately, after the last intervention dedicated to the replacement of electrolytic capacitors not replaced previously, to the replacement of the pot trimmers to regulate the quiescent current and to the replacement of the Phono pre IC my Yamaha Ca-610 is having a tantrum.
The R 526 / 1K resistor, which you see indicated by a red arrow in the diagram, heats up to burn out.
Of course and fortunately the relay does not trip, so the amp remains in protection.
A remote diagnosis is very difficult, I know.
In all of Budapest and the surrounding area I can't find a repairman who wants to spend a little time checking this amp.

Thanks in advance for any suggestions.

TbewTp1.png
 
gretels said:
replacement of the pot trimmers to regulate the quiescent current
Click to expand...
Did you reset the trimmer to minimum resistance before power up?
Try power up with DBT, does bias respond to trimmer adjustment, eg, set bias low to 2-3mV...
 
mbz said:
Did you reset the trimmer to minimum resistance before power up?
Try power up with DBT, does bias respond to trimmer adjustment, eg, set bias low to 2-3mV...
Click to expand...

Hi mbz.
no, unfortunately I have not set the trimmer to the minimum.

what is meant by "Try power up with DBT"?
 
Build a Dim Bulb Tester, it's a current limiting device, it will help prevent further damage, numerous plans on AK, google "Audiokarma Dim Bulb Tester build". It's basically an incandescent (not LED,,,) bulb in series with the mains active line.

gretels said:
no, unfortunately I have not set the trimmer to the minimum.
Click to expand...
So, possibly the bias is set too high?
 
Reviving an old thread here,

I know the CA-610 has a small following by vintage Yamaha owners on AK so I'm hoping some will chime in on my question. This thread shows a number of upgrades and work that has been done to the CA-610. I recently obtained one as part of a vintage system purchase. When I got it, it was not working very well. I went through all the switches and pots with deoxit and got it fully functioning.

Now my question is would you recommend going farther with a full recap and rebuild? It's pretty dusty and dirty inside as it appears to have never been opened previously. The local vintage technician wants about $450 USD to fully rebuild and recap it. Not sure if putting that kind of money into this amp makes sense. I'm thinking I might sell it as is and hunt for a fully rebuilt/recapped Sansui for less than $1000. What would you do?
 
How does it sound to you? I did a full recap myself on a CR820 and whilst it gives me peace of mind I don’t believe it made a significant impact on the way it sounded. Unless you are able to do the work yourself I don’t believe spending that much on a CA-610 makes sense. A nice Sansui will sound quite different and likely more engaging though less neutral.
 
Derek Roo said:
How does it sound to you? I did a full recap myself on a CR820 and whilst it gives me peace of mind I don’t believe it made a significant impact on the way it sounded. Unless you are able to do the work yourself I don’t believe spending that much on a CA-610 makes sense. A nice Sansui will sound quite different and likely more engaging though less neutral.
Click to expand...
Hi Derek, thanks for your feedback.

I was thinking along the same lines. I believe if I put the $450 USD towards a purchase of a higher end Sansui or Marantz then it maybe a wiser choice. Somehow I don't think a $450 investment into the CA-610 would prove to be worthwhile. It might be a different situation if I had a CA-810 or CA-1010, but the CA-610 doesn't seem to equate to that level of dollar investment. I might be compelled to pursue a recap/rebuild for $300 but it doesn't seem like that price is acceptable to the local techs around here.
 
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