• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Accuphase help needed

R

reddish75

Well-Known Member
Ok while the accuphase e202 is back on the bench having some brittle/cut short wires replaced and its apart I really would like to replace the relay, preferably with something like an omron ly2 but is this possible and how would I go about it with respect to the wiring?

Also the power switch is something I'd like to replace, does anyone have. Replacement part number fo this?

Thanks
 
Register to hide this ad
Already have the manual and already have restored 99% of the amp, just these last two things, and I thought as I have to remove the power switch to get to the underside of the relay, I might as well replace both as the switch pops slightly.
 
In know of no replacement for the relay. There is an online seller that had used ones, but the ones I ordered from them looked worse than the one in the unit.
 
Coil voltage? Contact/pin arrangement? Space?

There might be a solder-down retrofit with a little manipulating. FWIW, I've rewound my own brushless positioning and slow-syn speed resolvers, so there ARE ways to solve these kinds of problems.
 
EchoWars said:
In know of no replacement for the relay. There is an online seller that had used ones, but the ones I ordered from them looked worse than the one in the unit.
Click to expand...

Thanks for the replys, i know there's no replacement for the relay, thats why i wanted to rewire/rework the unit to just take a normal dpdt relay, but definetly need more than a few pointers on this.

On a side note i did give some thought to a replacing the relay with an ly4, socketed with the mounting plate (ptp-1) fastened to a bracket in the space the original relay was, however the mounting plate i'snt in stock anywhere and being in the UK its almost impossible to source parts like this.

Chris
 
I got your PM, but will answer here. I can help steer you in the proper direction, but I've got a barrelful of my own fish to fry here and most of my projects are many months behind. Hopefully I can supply some basics, and you can take it from there.

First, you said in your PM that you were looking to eliminate the power-on impedance test. One, I don't think it's a good idea, and Two, it's unnecessary to do so.

Let's take a look at a simplified block diagram of how this circuit works. The speakers are connected to the 'common' terminals of the relay, the AC test signal to the NC (normally closed) terminals (labeled 'B' in the drawing), and the power amplifier channels connected to the NO (normally open) terminals (labeled 'M' in the drawing). Here we have a standard DPDT arrangement, but the actual relay is a 4PDT. Missing from the drawing are the other two terminals of the relay, which Accuphase uses to short the preamp output to ground when the relay is not energized. We'll come back to that later.

When the relay is 'off' and power is first applied, the AC from the transformer secondary is fed to the NC relay terminals through resistor R1. Now the speakers and resistor R2 are in parallel, and along with resistor R1 form a voltage divider. If the speaker impedance is below a specified point (usually about 1.7Ω or so), the voltage at point 'A', which is sampled by the relay control circuitry, will be too low and the relay will refuse to close. Under normal conditions, this voltage is sufficient to allow the relay to close, and this then connects the speakers to the amplifier output.
 

Attachments

  • E202_Simplified_Prot.jpg
    E202_Simplified_Prot.jpg
    60 KB · Views: 74
Last edited:
With the full relay schematic below, you can see the relay wiring all labeled for you. The AC test signal line is marked in yellow, and the ground line on the right is marked in whatever that weird color is. ;)

There's no reason you can't use a regular DPDT relay to replace the stock relay (such as an Omron LY2-style job, which is probably the best choice here). The only issue is that you'd lose the ability for the preamp grounding. I'm not sure how important this is, but the fact that Accuphase thought that they needed to include the circuitry to do so steers me towards believing that it's a good idea to continue this practice. Thing is, using two high-current contacts of a power relay seems to be wasteful. What I'd consider doing is to wire up your new LY2 relay in a proper fashion, and add a second small reed-relay to handle the shorting of the preamp signal. This means mounting a second small PC board hidden somewhere near the power relay location, but I'd simply want the whole deal to work as Accuphase intended.

I looked and I could not find a DPDT DIP relay that might work (there was one for $50+, but that's insane). Digikey has a TE Connectivity 24V DPDT box relay (#PB1126-ND) that is contact rated for 2A and has a very low coil current (6mA). It also measures only about 20mm x 10mm x 11mm, so it should be easy to find a place to mount it. The tricky part is to find a proper voltage source. Since the speaker relay runs from +55V and the current is dropped via R001 (470Ω 3W), I'd use a 24V relay for the speakers, and since the small box relay only draws 6mA, the current limiting resistor won't have to be a huge power job.

So...an LY2-DC24 relay, wired as the stock one is minus the preamp grounding deal. This means disconnecting all the wires from the stock relay and labeling them. Honestly, that's probably the hardest part. If we figure the voltage at the 10,000µf caps as +55V, then R001 gets changed to 750 ohm 3W and R25 on the regulator/protection board gets changed to 91 ohms 1/4W. The small box relay to short the preamp will get it's power from the +55V side of the new 750 ohm 3W resistor, and that will go to a 4.3K 1/2W resistor to limit the current to the reed relay coil. The other side of the relay coil will go to the collector of Q8, but easier to connect at the power relay where Q8 attaches at that point. The new little box relay will have to go on a small prototype board, but it should be doable. And yeah, you'll need to replace the protection diode D5 with a new 1N4004 (label is erased in my posted pic to make room for my wiring label).

I'd mention that Q8 (the driver transistor for the relays) has to have a very low saturation voltage. Something like the Fairchild KSC2690AY (Mouser) will do.
 

Attachments

  • E202_Relay_Wiring_Scat.jpg
    E202_Relay_Wiring_Scat.jpg
    137.8 KB · Views: 85
Last edited:
Great thread.

I just have ordered 2 of the original relays EchoWar mentioned above. These are really not NOS but I have time to clean them carefully.

Philipp
 
Well,

I have done the new relay(s), it wasn't as difficult as I imagined see pic's below,

This is how I mounted the LY2-DC24, I utilised the original relay mount, squaring it off with an 'L' piece of aluminium I cut out then using a PT08-0relay socket to mount the relay to the bracket, things have been tidyed up since but this gives the general idea.





The second relay for grounding the pre-amp is shown here, very simple to build using EchoWars instructions.



 
I have however ran into another problem with this amp, maybe someone could help with, but first a little story.

This amp came to me completely hacked, it had the original bridge rectifier missing, which has been replaced, numerous transistors and diodes changed to what it looked like whatever the local shop had in stock, the original heat sinks (how important are these considering it should carry the collector voltage?)on the psu card replaced with bolt ons and the collector pcb tracks jumpered with wires to get the voltage where it needs to be, capacitors changed to very poor replacements, speaker selector switch broken, etc. etc.

Ok so story over, the amp has been apart for a while now and I have finally got it to a point where I've tested the voltages, which seem ok......but for a few problems,

I will say at this point both meters are disconnected as they seem to have been wired wrong, also I have the wires disconnected from the output of both power amps so offset is being measured directly from the output pins, also the speaker switch has been disabled, any problems with this?

1, The main reservoir caps are bolt mount which are obviously clamped and used as conventional caps would be, problem with this is the positive cans have +55 on the can where the 'bolt' is, negative reads 0v.

2, The offset is all over the place when I try to adjust, it does settle eventually to~200mv each side.

I'm sure there's going to be more questions but does anyone have any ideas on these things for now?
 
RE: Relays. Looks like nice work. A lot of trouble to go through, I'm sure, but worth it.

FYI, any socket mounted relay needs a hold-down clip. http://www.digikey.com/product-detail/en/PYC-P/Z796-ND/105885

As far as the speaker switch, would be nice to have it working as Accuphase intended, but if you're only going to connect one set of speakers then it's not anything that will keep you from running the amp. Maybe a project for sometime in the future...

Main caps. You are describing 'screw-terminal' capacitors. The originals are solder tab. But the amp cannot function without split supplies (+/-55V). The configuration is two caps in parallel for the +55V, and two in parallel for the -55V. Scroll through the pics here and you can see how they are wired (mostly). I suspect a broken wire somewhere.
 
Thanks for be reply EchoWars, I don't think I was clear enough about the caps,

Here are the ones that are now installed, I have not used this style of can before (with the mounting bolt) but I cannot think why there would be any difference I'd mounting conventionally.

http://m.rapidonline.com/ProductSearch/ProductDetails?ProductCode=50-4014&ModuleCode=519694

Problem as before, measuring from ground to the 'mounting bolt' i.e the metal top of the capacitor, on the capacitors on the positive supply measures +55v
 
100Kµf? Tenth of a bloody farad each? You can't use those...

And you don't use the bolt, so why do we care what the voltage is there?

Maybe I'm not understanding the problem here.
 
Oops, wrong link same style capacitor but 10000uf each, so I take it that rail voltage on the mounting bolt is nothing to be worried about?
 
I took a look at the spec sheet for those capacitors - there is no mention that the cans +bolt are connected to either of the terminals.

BTW: I would say the bolt fixing is on the BOTTOM of the can.
 
EchoWars said:
I got your PM, but will answer here. I can help steer you in the proper direction, but I've got a barrelful of my own fish to fry here and most of my projects are many months behind. Hopefully I can supply some basics, and you can take it from there.

First, you said in your PM that you were looking to eliminate the power-on impedance test. One, I don't think it's a good idea, and Two, it's unnecessary to do so.

Let's take a look at a simplified block diagram of how this circuit works. The speakers are connected to the 'common' terminals of the relay, the AC test signal to the NC (normally closed) terminals (labeled 'B' in the drawing), and the power amplifier channels connected to the NO (normally open) terminals (labeled 'M' in the drawing). Here we have a standard DPDT arrangement, but the actual relay is a 4PDT. Missing from the drawing are the other two terminals of the relay, which Accuphase uses to short the preamp output to ground when the relay is not energized. We'll come back to that later.

When the relay is 'off' and power is first applied, the AC from the transformer secondary is fed to the NC relay terminals through resistor R1. Now the speakers and resistor R2 are in parallel, and along with resistor R1 form a voltage divider. If the speaker impedance is below a specified point (usually about 1.7Ω or so), the voltage at point 'A', which is sampled by the relay control circuitry, will be too low and the relay will refuse to close. Under normal conditions, this voltage is sufficient to allow the relay to close, and this then connects the speakers to the amplifier output.
Click to expand...

Echowars,

I take it that I can do the same thing with the relay on the updated e202 schematic shown on the pdf below,
 

Attachments

I know this an old thread, but wanted to add that I have the e202 version matching the schematic reddish75 posted above. In this case, the large relay is purely for speaker protection with the 4 poles split into 2 in parallel for left and 2 in parallel for right. A 2nd relay is added for the preamp termination (matching what Echowars proposed above). I don't know which version is newer, but use of a LY2 relay is perhaps not best if 2 sets of contacts in parallel was the later improvement.

Based on this, I decided to swap in a LY4F-02-DC24 to give me the same 2 sets of large contacts per channel and a coil impedance of ~360 ohms which is very close to the original (so no resistor change needed in the coil activation path). I reused the metal bracket by installing it upside-down and having the relay hang by one of the plastic top flanges "F" in the relay part number. Other trimming here/there to get this to fit, but not too bad.
1748109394686.png
 
You must log in or register to reply here.
Back
Top Bottom