A couple resistor and transistor questions

[abuttino]

Bought a Denon on eBay, looks brand new, major issues on the 5ch amp board.

With the help of the service manual, I've nailed it down to some 22ohm/1W, .47ohm/2W and 3 channels of 2SD2560P/2SB1647P

First, I would like to ask, how important the "P" is on those transistors. The DC current gain is the difference. Encompass seems to be the only way to guarantee the 'P' rank transistors.. Unless that number doesn't mean much.

Also, Encompass seems to be the only company I can find those white/green shielded resistors, I was hoping for ideas that can benefit in a couple ways.. Maybe a different brand would help the wallet AND sound better? $7 per resistor seems a little steep.

I would like to get these parts soon, most of them are on backorder at Encompass... So, any suggestion you have is greatly appreciated

 

[Tony Stewart]

P defines hFE bin
no letter means unsorted

hFE Classifications
O P Y
5000-12000 O
6500-20000 P
15000-30000 Y

Datasheet Pinagem - Transistor Darlington PNP 2SB1647-P - Características e Substituição

Datasheet Transistor Darlington PNP 2SB1647P: Vce = -150V, Vcb = -150V, Vbe = -5V, Ic = -15A, Pt = 130W, substituição, pinagem, características…

www.fvml.com.br

Look for an equivalent

 

[Tony Stewart]

There are good reasons to have shielded inductors and high voltage shielded resistors but low value higher power low voltage resistors have no reason to be shielded.

https://www.digikey.ca/en/products/filter/through-hole-resistors/53?s=N4IgjCBcoExaBjKAzAhgGwM4FMA0IB7KAbXADYBOMAFggF18AHAFyhAGVmAnASwDsA5iAC%2B%2BAMzwQSSGix5CJcgA5qIfGDBj6TVpA7d%2BQ0eDAwA7JOmyc%2BIpFJwGIFmwCSfZtgHYuI9RSUKSxQMGwV7EAAGEDpjAFo4aCkobgBXeTtSAFYY4TygA

 

[abuttino]

I meant that the leads were shielded.

 

[Nigel Goodwin]

I meant that the leads were shielded.

I've no idea what you're on about

Resistors don't have shielded leads, or shielded resistors at all - do you perhaps mean insulated leads?, which would be rare, and doesn't really matter. Regardless, they will have no effect whatsoever on sound quality.

The gain rating of the transistors will make sod all difference, the gain of the amplifier regardless is massively higher than required, and is brought down to the required level by feedback. There will be no audible difference, any most probably no measurable difference.

But as for repairing amplifiers, it's rare that just replacing the output transistors (and odd burnt up resistor) cures the issue, very often they all blow again, as it's essential you cure the reason for the fault - and DC coupled amplifiers are like a chain on dominoes, one falls they all fall.

 

[abuttino]

I've no idea what you're on about

Resistors don't have shielded leads, or shielded resistors at all - do you perhaps mean insulated leads?, which would be rare, and doesn't really matter. Regardless, they will have no effect whatsoever on sound quality.

The gain rating of the transistors will make sod all difference, the gain of the amplifier regardless is massively higher than required, and is brought down to the required level by feedback. There will be no audible difference, any most probably no measurable difference.

But as for repairing amplifiers, it's rare that just replacing the output transistors (and odd burnt up resistor) cures the issue, very often they all blow again, as it's essential you cure the reason for the fault - and DC coupled amplifiers are like a chain on dominoes, one falls they all fall.

Yes, I meant insulated leads.

Where would you suggest I start looking? Because, if I am going to rebuild this board, I certainly don't want it to just blow again

 

[Nigel Goodwin]

Yes, I meant insulated leads.

Where would you suggest I start looking? Because, if I am going to rebuild this board, I certainly don't want it to just blow again

It's difficult, a common solution is to change all semiconductors in the DC path, as any one of them failing could be catastrophic - and one could even be intermittent. Dry joints is another possibility, check visually for any which look dodgy.

I'm a bit concerned three channels are blown - channels are usually entirely separate, so one blowing shouldn't affect the others - so has someone done something stupid like connecting loads of extra speakers and blowing the amps?.

What model number is it?, we can try and find a service manual for it.

I presume it's a surround sound amp?, as it got at least three channels - these are usually notoriously difficult to work on, as there's so much stuff crammed in a small space, and you usually require special extension leads to make it possible to work on them.

 

[abuttino]

It's difficult, a common solution is to change all semiconductors in the DC path, as any one of them failing could be catastrophic - and one could even be intermittent. Dry joints is another possibility, check visually for any which look dodgy.

I'm a bit concerned three channels are blown - channels are usually entirely separate, so one blowing shouldn't affect the others - so has someone done something stupid like connecting loads of extra speakers and blowing the amps?.

What model number is it?, we can try and find a service manual for it.

I presume it's a surround sound amp?, as it got at least three channels - these are usually notoriously difficult to work on, as there's so much stuff crammed in a small space, and you usually require special extension leads to make it possible to work on them.

The service manual is very easy to find.

Denon AVR-X4500H.

Thanks for helping me look into this.

If it's of any difference, that is my only problematic board. Disconnect just that and it functions just fine.

 

[Nigel Goodwin]

I'd certainly replace the Vbe multiplier Q7125 (references from FL amp), and drivers Q7121 and Q7118.

 

[AnalogKid]

The service manual is very easy to find.

Since you are the one asking for free help, why don't you post a link to it so we are sure we are looking at the same schematic / version / rev / etc.

ak

 

[abuttino]

Absolutely.

https://data2.manualslib.com/pdf7/280/27983/2798277-denon/avrx4500h.pdf?982ec44c8a1dcd951a709987691a731e&take=binary

The US version slightly changes with serial number, I don't think you'll need that info, it's just the 5 channel board.

Didn't know the forum would allow me to post links with just joining and all.

Just in case, it's also attached.

I just tested every 2SD2560 and 2SB1647 (out of circuit). The hFE numbers were staggeringly low 50-500; spec is 5000 minimum, this also caused resistors to spark and they got destroyed as well, reading way of their spec. The KTC3964 transistors in 2 channels didn't read and the other 3 channels read 1.8k; spec is 500 minimum.

The house is 69°F, if that matters.

In the original post, I was asking if I can get 'better more AND more affordable resistors'. Better is basically meant to be anything that can add to sound for warmth. The attached picture is the one that they sell on the Denon site.

Thanks for the help! Any other questions, answer.

 

[Nigel Goodwin]

In the original post, I was asking if I can get 'better more AND more affordable resistors'. Better is basically meant to be anything that can add to sound for warmth. The attached picture is the one that they sell on the Denon site.

'Warmth' isn't a specification for quality, it's just a scam term used to try and convince people something sounds 'better'. If anything 'warmth' would be lower quality, poorer frequency response, higher distortion etc. as you get from valve amplifiers.

But basically resistors will have zero effect on any definition of 'quality', and won't alter imaginary 'warmth'.

 

[abuttino]

'Warmth' isn't a specification for quality, it's just a scam term used to try and convince people something sounds 'better'. If anything 'warmth' would be lower quality, poorer frequency response, higher distortion etc. as you get from valve amplifiers.

But basically resistors will have zero effect on any definition of 'quality', and won't alter imaginary 'warmth'.

Sounds good to me, never heard of a resistor but have come acrossed it a couple times when talking about Tantalum Resistors.

The price also grinds my gears, $7/per resistor and the 3964 is $17/per.

Biting the bullet and ordering from Denon isn't the problem. It's the fact that I know they are using parts I can find much cheaper elsewhere, still real.

 

[Nigel Goodwin]

Sounds good to me, never heard of a resistor but have come acrossed it a couple times when talking about Tantalum Resistors.

The price also grinds my gears, $7/per resistor and the 3964 is $17/per.

Biting the bullet and ordering from Denon isn't the problem. It's the fact that I know they are using parts I can find much cheaper elsewhere, still real.

Never get a laser/optical assembly from Denon to repair a Denon CD Player - it's just a standard Sony part (most CD Players use Sony laser/optical assemblies), but Denon charge five times as much for the same part

On a similar theme, at one time years ago Sony used to buy their VHS VCR's from Hitachi - now we were both a Sony Dealer, and an Hitachi Dealer - and we noticed that if you ordered any part from Sony it was exactly 50% more expensive than ordering from Hitachi. Obviously Sony simply ordered from Hitachi Spares, and bunged 50% profit on the price

Needless to say, we ordered any out of warranty spares from Hitachi, but any warranty parts had to be ordered from Sony, and you (eventually) got the cost refunded, along with a paltry warranty payment 'towards' your costs.

 

[Tony Stewart]

Carbon resistors will give a warm and fuzzy noise, but who wants noise

 

[ZipZapOuch]

Carbon resistors will give a warm and fuzzy noise, but who wants noise

Noise can be good sometimes. Kind of like the "soft focus" Sophia Loren mandated for her photo shoots as she aged. I think Eva Longoria is asking for the same soft focus treatment in her ads for facial cream. Noise and slow response can soften the harshness of some instruments and auto-tuned "vocals".

 

[abuttino]

Tantalum seems overkill then.. Besides, it's $8 per resistor, I was trying to save money and help sound at the same time

 

[ZipZapOuch]

Tantalum seems overkill then.. Besides, it's $8 per resistor, I was trying to save money and help sound at the same time

If "saving money AND sounding better" were that easy, don't you think Denon would have picked the better and cheaper option from the beginning? I mean, a staff of audio experts with access to all of the transistor producers saying, "no thanks, I'll pick this inferior and more expensive transistor instead". Really?

 

[abuttino]

I understand, this isn't the average amp. Upscale.

 

[ZipZapOuch]

Carbon resistors will give a warm and fuzzy noise

Especially as they get hot.