And I removed TR511 and it's heat sink. It tests good.
,
James
,James
Denon POA 6600 Thread
- Thread starter Bratwurst7s
- Start date
analogwisdom
When in doubt, stuff in a WIMA
Maybe a few months on the shelf will be a good thing!I just took a detour and looked over the 3rd, damaged amp. I'm thinking that it looks repairable. There are a couple of damaged traces to fix but they don't look terrible.
Someone has done lots of things in there. It has been at least partly re-capped, mostly with Roederstein, which are actually not bad. Whoever it was put a 22µF63v cap in place of C524, one of those 1µF things that we were talking about.
The drivers have been replaced with ISC 2SA1006 and 2SC2236, which are not a completely bad choice I think, 25w, but only 80mhz.
They unwrapped the wire wrap posts, so that sux.
2 of the outputs have been replaced with ISC parts, one in each bank, and both are shorted.
I'm thinking that after I get some other projects out of the way I will revisit this thing, late summer or Fall, and get it working.
Cheers,
James
For that one perhaps, there is no rush with that one, it will just be my backup. But I would really like to get 2 of these working soon.
Finding that bad 2SA968B really sucks. Almost any other part than the drivers would be better. I can replace pretty much anything else. I am really unsure about the viability of using the KTA/KTC parts with only 20 watts compared to the original 25w. I have no idea if they will hold up.
But I checked that driver with 2 different testers and both the UK and China agree, "It's dead James".
I may need more than 2 beers tonight.
,James
It's an elegant design. I'm more repairman minded then design & analysis. It's been 30 years since I went to op amp school. But I do remember their feedback loops are crucial for gain & stability.
Fellow mechanic point of view...Don't connect your battery backwards, lol. Bad things happen. Polarized caps are like batteries.Those 3 polarized caps we're talking about are designed to be a one way street for DC. They block DC and pass AC. Notice the anodes of those 3 are tied to the positive source, +15v & +1.8. The cathodes are tied to the negative source. -15v & -1.8. I think the NP Wima's are cancelling the feedback loops to the op amp.
Cool....typical of the burn outs I've seen before. I'd focus on the PNP side if ya suspect further issues.
Is R565 or 566 open?
Wtf is up with that? Looks like a dude stuffing his pants. I'd put that diode on the boards bottom. Weird
OK, thanks for the info. I'm still a bit confused because I thought that a cap would block DC regardless of direction and regardless of it being NP or not.
Nonetheless I will take the advice to heart.
,James
I have lots of these pairs and using them is up for consideration. I know that I used them to replace a 2AS1306B in that Yamaha A-1020, and they worked.
There is just a reluctance to replace this 100mhz part with a 30mhz one, but there is a lot more reluctance replacing a 25w part with a 20w one.
I could buy some ISC 2SA1006/2SC2336 locally, on paper they look like a pretty good sub, but there is a major reluctance to buy ISC parts.
,James
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Too late, that part is installed and now forever destined to be a snake in the , ah, er, grass.
Soo, I'm thinking that now is a good time to listen to all 3 of you.
Today/tomorrow I will go through the rest of the board and look for any more bad parts and take things as far as I can go at this time.
Then the amp will go to the side for a month until I get back from our little trip and can make a Mouser order and get some 1µF elcos.
In the mean time I will decide about using the ON Semi drivers. I am interested in hearing you guys' extended thoughts on them. I have over 25 pairs of MJE15033G/32G so that is not an issue. I may still buy some of those ISC parts just to have the option. I'm posting a datasheet for the 2SA1006, haven't found the other one yet.
There is one long shot. My brother in law has a Pal that used to run a small electronics supply shop and has retired and closed up the shop. He apparently still has a very large stock of transistors and is willing to share. I'll be taking a shopping list with me, you never know, I might get lucky and find some rare treasures over there.
,James
Found it.
I thought the polarized caps charge up at one half cycle and discharge on the other half cycle for regulation and stability.OK, thanks for the info. I'm still a bit confused because I thought that a cap would block DC regardless of direction and regardless of it being NP or not.
Nonetheless I will take the advice to heart.
James
That sounds right. I am not as good at this stuff as you may think. In any case, I am heeding your advice and will not go forward with the film caps in those positions. Better a delay than a disaster.I thought the polarized caps charge up at one half cycle and discharge on the other half cycle for regulation and stability.
There were a couple of resistors around the drivers that I hadn't checked yet, R580, 589 and 560, 4.7, 4.7 and 100 ohms respectively, all checked good. Replaced with RN60 1/4w.
The 8 10K resistors in parallel with the output emitters, R581~588 all checked good. Replaced with SFR25 types.
The 0.18 ohm emitter resistors R584~587 all checked good. Re-installed.
After lunch I'll check the 4.7ohm fusibles on the output base(s) and then the outputs.
,James
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R6ß1~608 4.7ohm fusible all checked good, replaced with RN60 1/4w.
R593, 180ohm and R573, 3.8kohm both checked good, replaced and re-installed respectively.
TR518 and TR515 outputs are shorted. The rest of the outputs checked good.
The only thing left on the board to inspect/test is the protection section. That will get done tomorrow.
,
James
R593, 180ohm and R573, 3.8kohm both checked good, replaced and re-installed respectively.
TR518 and TR515 outputs are shorted. The rest of the outputs checked good.
The only thing left on the board to inspect/test is the protection section. That will get done tomorrow.
,James
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I don't feel like doing any more soldering today so I took a small detour and started getting the new outputs ready for installing.
As I said earlier, I ordered 30 sets of these 2SA1962/2SC5242 parts and tested/sorted them all for hFE. Again, yeah, I realize that everyone says that outputs don't have to be matched. But when the batch is so close and it takes so little time I can't see any reason not to.
For this I'm just using some cheap 0.2mm TO-2220 sized silpads to keep the spacing right.
,
James
As I said earlier, I ordered 30 sets of these 2SA1962/2SC5242 parts and tested/sorted them all for hFE. Again, yeah, I realize that everyone says that outputs don't have to be matched. But when the batch is so close and it takes so little time I can't see any reason not to.
For this I'm just using some cheap 0.2mm TO-2220 sized silpads to keep the spacing right.
,James
Karl vd Berg
Super Member
Hi James,
I now saw your POA-6600 thread.
I'm curious to know how the OPA1642 performed in your monoblock amp. I have a Denon PMA-737 integrated which uses the M5218 as DC Servo, too. After putting in an IC socket and trying a bunch of different opamps, I found that the "old" FET input TL072 vastly outperforms the stock one and is even better than the 5532. But this was in the PMA-737.
An opamp acting as DC Servo is almost always in the audio path, so I wanted to try a few ones, including newer ultra-low noise ones.
I just wanted to share this here: a while ago, last year, I was advised to increase the supply capacitance from 47uF to 100uF for the opamps to guarantee that their Icc (supply current) wouldn't drop with the voltages too much using another opamps with a higher Icc like the 5532 (8mA to 16mA!!!), but that did not happen. I left the 100uF caps in any way because they are new caps. Supply voltage dropped from 14.9V to 3V using OPA2134 and the L1113 and DC offset raised to over 250mV with them. OPA2107 was okay with current and voltage but the sound was pretty much the same as the M5218P.
The 5532 (BJT) sounded dull and lifeless, worse than the stock M5218. But the TL072 surprisingly sounded much more vivid with no voltage/current drop. The other good thing about the TL072 was that the DC offset dropped from ~5mV (stock M5218) to around 1.4mV.
Below is a quick list of the opamps used in place of the Mitsubishi M5218P, which is not (nowadays) considered a good opamp for audio.
A quick reference of parameters:
Opamp - noise in μV or nV - bandwidth in MHz - slew rate in V/μs - Supply current (Icc) in mA - topology BTJ or Fet (or CMOS)
M5218P - 2μV - 7MHz - 3V/μs - Icc 3mA ~ 6mA (p/ch) / BJT
TL072 - 15nV / 4MHz / 16V/μs / Icc 1.5 ~ 2.5mA (p/ch) / Fet
OPA2107 - 8nV / 4.5MHz / 18V/µs / Icc 4.5 ~ 5mA (p/ch) / Fet
LT1113 - 4.5nV / 5.6MHz / 3.9V/μs / Icc 5.3 ~ 6.5mA (p/ch) / Fet
JRC4558 - 8nV / 3MHz / 1.7 V/μs / Icc 3.5 ~ 5.7mA (p/ch) / BJT - 178mV
OPA2134 - 8nV / 8MHz / 20V/μs / Icc 4mA ~ 5mA (p/ch) / Fet
NJM2068 - 0.56µV / 27MHz / 6 V/μs / Icc 5mA ~ 8mA (p/ch) / BJT
NE5532 - 5nV / 10 MHz / 9V/μs / Icc 8mA ~ 16mA (p/ch) / BJT
* Still to try out (sometime in the future) ==================
* OPA1678 - 4.5nV / 16MHz / 9V/μs / Icc 2mA ~ 2.5mA (p/ch) / CMOS
* OPA1642 - 5.1nV / 11MHz / 20V/μs / Icc 1.8 ~ 2.3mA (p/ch) / Fet
* OPA2189 - 5.2nV / 14MHz / 20V/μs / Icc 1.3 ~ 1.7mA (p/ch) / CMOS
* OPA2210 - 2.2nV / 18MHz / 6.4V/μs / Icc 2.2 ~ 2.5mA (p/ch) / BJT
* OPA1662 - 3.3nV / 22MHz / 17V/μs / Icc 1.5 ~ 1.8mA (p/ch) / BJT
* OPA1602 - 2.5nV / 35MHz / 20V/μs / Icc 2.6 ~ 3.2mA (p/ch) / BJT
* OPA1688 - 8nV / 10MHz / 8V/μs / Icc 1.6 ~ 1.8mA (p/ch) / CMOS
I now saw your POA-6600 thread.
I'm curious to know how the OPA1642 performed in your monoblock amp. I have a Denon PMA-737 integrated which uses the M5218 as DC Servo, too. After putting in an IC socket and trying a bunch of different opamps, I found that the "old" FET input TL072 vastly outperforms the stock one and is even better than the 5532. But this was in the PMA-737.
An opamp acting as DC Servo is almost always in the audio path, so I wanted to try a few ones, including newer ultra-low noise ones.
I just wanted to share this here: a while ago, last year, I was advised to increase the supply capacitance from 47uF to 100uF for the opamps to guarantee that their Icc (supply current) wouldn't drop with the voltages too much using another opamps with a higher Icc like the 5532 (8mA to 16mA!!!), but that did not happen. I left the 100uF caps in any way because they are new caps. Supply voltage dropped from 14.9V to 3V using OPA2134 and the L1113 and DC offset raised to over 250mV with them. OPA2107 was okay with current and voltage but the sound was pretty much the same as the M5218P.
The 5532 (BJT) sounded dull and lifeless, worse than the stock M5218. But the TL072 surprisingly sounded much more vivid with no voltage/current drop. The other good thing about the TL072 was that the DC offset dropped from ~5mV (stock M5218) to around 1.4mV.
Below is a quick list of the opamps used in place of the Mitsubishi M5218P, which is not (nowadays) considered a good opamp for audio.
A quick reference of parameters:
Opamp - noise in μV or nV - bandwidth in MHz - slew rate in V/μs - Supply current (Icc) in mA - topology BTJ or Fet (or CMOS)
M5218P - 2μV - 7MHz - 3V/μs - Icc 3mA ~ 6mA (p/ch) / BJT
TL072 - 15nV / 4MHz / 16V/μs / Icc 1.5 ~ 2.5mA (p/ch) / Fet
OPA2107 - 8nV / 4.5MHz / 18V/µs / Icc 4.5 ~ 5mA (p/ch) / Fet
LT1113 - 4.5nV / 5.6MHz / 3.9V/μs / Icc 5.3 ~ 6.5mA (p/ch) / Fet
JRC4558 - 8nV / 3MHz / 1.7 V/μs / Icc 3.5 ~ 5.7mA (p/ch) / BJT - 178mV
OPA2134 - 8nV / 8MHz / 20V/μs / Icc 4mA ~ 5mA (p/ch) / Fet
NJM2068 - 0.56µV / 27MHz / 6 V/μs / Icc 5mA ~ 8mA (p/ch) / BJT
NE5532 - 5nV / 10 MHz / 9V/μs / Icc 8mA ~ 16mA (p/ch) / BJT
* Still to try out (sometime in the future) ==================
* OPA1678 - 4.5nV / 16MHz / 9V/μs / Icc 2mA ~ 2.5mA (p/ch) / CMOS
* OPA1642 - 5.1nV / 11MHz / 20V/μs / Icc 1.8 ~ 2.3mA (p/ch) / Fet
* OPA2189 - 5.2nV / 14MHz / 20V/μs / Icc 1.3 ~ 1.7mA (p/ch) / CMOS
* OPA2210 - 2.2nV / 18MHz / 6.4V/μs / Icc 2.2 ~ 2.5mA (p/ch) / BJT
* OPA1662 - 3.3nV / 22MHz / 17V/μs / Icc 1.5 ~ 1.8mA (p/ch) / BJT
* OPA1602 - 2.5nV / 35MHz / 20V/μs / Icc 2.6 ~ 3.2mA (p/ch) / BJT
* OPA1688 - 8nV / 10MHz / 8V/μs / Icc 1.6 ~ 1.8mA (p/ch) / CMOS
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I like to use Noctua brand PC CPU coolers and they come with these long L-shaped screwdrivers for mounting them to a mainboard. Since I have 2 of them I cut one short and it is the perfect little helper for doing this.
First, it make a nice alignment tool to get all of the transistors lined up like good little soldiers before snugging them down in position.
,
James
First, it make a nice alignment tool to get all of the transistors lined up like good little soldiers before snugging them down in position.
,James
Hi Karl!!!
I was thinking about you and Bubo and wondering how you are doing. I hope that life is treating you well.
Give me a few minutes to finish up what I was doing and I will be right back to answer.
,James