Amp 5 FAQ's
I sent Jan an email about the questions I have seen on this forum regarding Amp 5, and here's his response. I told him I would publish it here to assist other Amp 5 builders who have similar questions. Hope this is helpful:
Hi, and thanks for your questions. They should all be in
an updated manual.
> 1) The instructions are unclear about how to attach the power transformer to
> the board. Do the two hot wires go to AC1 and AC2 with the two neutrals
> going to PGND?
On a transformer secondary there are no hot / neutrals, just two ends
of a coil (or two colis). The center leads (two ends of the coil where the
windings end towards each other) go to the PGND. The other ends
to AC1 and AC2. Lock in the documentation for your transformer which
leads are the center leads.
PGND on the board goes to the ground / chassis and then to
the ground / earth connection of your mains plug, if you have one.
It works also without eart connection. Please consult a qualified
electrician, if you are not sure what to do. Mains power IS lethal.
> 2) The instructions state that C60 & C61 are included in the standard BOM,
> while C62 & C63 are included with the high power option. Should C60 and C61
> be installed in those positions on the board, or should they be installed in
> the C61 and C62 positions instead?
You can use either position. It might be slightly better to use C61 and C62
as these are closest to the chip. The differens should be marginal however.
> 3) The purpose of all the pins on J2 is unclear and it's hard to read the
> printing on the board. Please provide clear instructions about how to wire
> J2 if the volume control chip isn't used, especially the last four pins
> beginning with Hmute.
The pins of J2 are:
1. In1
2. Analogue ground (In1 Ground)
3. Analogue ground (In2 Ground)
4. In2
5. Volume chip Up
6. Volume chip Down
7. Volume chip Balance L
8. Volume chip Balance R
9. HMUTE output (indicates amp is muted or not, also drives the LED)
10. Analogue ground
11. Mute (connect 11 to 10 for AWAKE, 11 to 12 for MUTE)
12. +5V
> 4) No information is provided about which pins on J8 should be jumpered if
> the volume chip isn't used. The instructions should include a clear
> statement about which pins on the board go unpopulated when a volume control
> isn't used.
Without volume chip, jumper 1to 2 and 4 to 5
> 5) It isn't clear that R100 and R101 should be jumpered.
Yes, R100 and R101 should be jumperd. They are in series
with R51 and R32, the input resistors.
> 6) The position marked C452 on the board is incorrectly labeled. Should the
> 12th 0.1uF, RM2.5 cap populate that position?
The C452 should be a 0.1 uF RM2.5
> 7) My kit did not include the 22K input and feedback caps. Several other
> builders have said the same thing, and most do not have access to an
> electronic parts store that stocks this part.
Hmm, I made the shipping list from the BOM and of course
there is only one feedback value there and it seems I have not
changed this. Drop me a line if you need these.
I will put them in a letter and send them. There should
have been four 22K and two 47 K in the kit.
> 8) The instructions give no information about where to test the 5V.
You can test the 5V by removing J10 and measuring on the pin
closest to "J" in "J10". Supply power on J99 or a test voltage
of abround 12V to the positive main rail, and ground.
You should then see 5V on J10.
> 9) Several builders have found the input surge to the power transformer
> blows a 200-300ma fuse installed on the primary side. I found the same
> thing. What should one do if that happens?
This depends on the transformer / capacitor combination. You can use
a slow-blow type fuse, and increase the value to 500 mA if required.
> 10) The instructions read "connect the mut switch to J2 pin 10-11-12. How
> does one connect the switch to three pins? (Again, better guidance on how to
> connect the mute switch is needed. For example, what's the function of
> HMute?)
Please see question 3 above. If you have a two way switch,
connect the center to pin J2 11, one side to pin 12 and the other side
to pin 10. In this way, the MUTE (pin 11) wil lbe connected to either
ground (AWAKE) or +5V (MUTED)
> 11) One addition to the instructions that would be very helpful would be a
> drawing of the board indicating the functions of pins on all the headers
> (J1, J2, etc) like you included with the Amp6 instructions.
Yes there should definitly be one. I will add it.
The AMP5 manual is still not in a final state. I will
have to make an effort here and finish it. I will then
include the information given above.
Regards
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