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Need a copy of an Akai AM-A1 Amp service manual

Need this service manual to to replace transformer . This unit is about 20+ years old.

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SOURCE: transformer is blown


Have you checked to see if the thermal fuse has failed on the transoformer. This can be repaired. Get back to me here if you want to know more about it.


Posted on Nov 17, 2008

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I have SONY TA-V715 amplifier with out transformer, please give me transformer details

If the unit is more than a couple of years old, that part is probably no longer available. As to the specs, you have have to obtain a service manual.

Dec 10, 2014 | Sony Amplifiers & Preamps

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Burnt out cap by relay on mains input PCB at front of unit by mains transformers on DAB1 Sonance. Need value. Price of cap plus relay

main filter cap? if so replace them both as well as the rectifier/ diodes. there is probably an overload/short circut issue somewhere else in the amp so I would extensively test the amp before repowering it. I recommend using 20 000 mfd 100 v caps for main filter, they're about $20 each and the relay is under 10, 30 amp rectifier is about 7 bucks. do not use loads of less than 4 ohms with this amp

Mar 21, 2014 | Amplifiers & Preamps

1 Answer

I have a Yamaha preamplifier CX-800/U where the Powertransformer is defect which let the primary 220V transform into secondary voltages.I know the transformer is no longer available but i would like to...

I asked for more info, but I have replaced many hundreds of unobtainable transformers. All the voltages can be found by a bit of logic thinking & observation. If I have the item in front of me I will have the solution in minutes.
Double red with black, expecially together is normally a X-0-X winding, identified by the rectifier & smoothing caps. The voltages on them will give some indication, but tracing the voltage to an regulator is an accurate solution.
What are the voltages used for?
Normally the one winding will be a low voltage like 12-18 volt for the pre-amps mixers etc. This very often will go through oner or more voltage regulators. Their voltage is written on them,and they will have have small heatsink on them & live near the rectifiers & caps. Look for three legged items marked something like 7812. This is a 12 volt reghulater while a 7809 is a 9 volt regulater. The split voltage say from 20-0-20 to 80-0-80 max will drive the power amp. A 20 watt stereo amp will most likely use two integrated circuits. Luckily you can find their operating voltages very easily by typing in their number like TDS2005 into google. As for an output stage like a 60 to 100 Watt amplifier, a voltage like 60 0 60 and 80 0 80 is used. If in doubt, go a bit lower & play safe. All you will loose is a few watts. If logic (computer circuitry) is used, all computers use basic only 12 volt and 5 volt. Very easy.
Before you give up or look for a new transformeer, just check!!!!!
Most *** xformers have a secret fuse inside them which is easily replaced if you know how!
Send photos! (under 60Kb)

Sep 04, 2011 | NAD C352 2-Channel Amplifier

1 Answer

Low volume through amplifier

Turntables generate a very low signal. Phono inputs on receivers containa pre-amp section to boost the signal to "line level" or the same level as other audio devices. I would suspect that you need to add that pre-amp section. Phono preamps are available for around $20 or so and are inserted between the turntable and the standard audio input on the receiver or amp.

Hope this helps,

Apr 15, 2010 | Cambridge Audio Azur 540A Amplifier

1 Answer

Internal fuse on cambridge a1 mk3 has blown and when replaced,blew instantly??

When the fuse blows suspect an overload in either the power supply or Main Amp section.
Check for burnt/damage parts first!
Power Supply faults that will blow the fuse are: Transformer, Rectifier, Voltage Regulator, Large Electrolytic Capictors, Diodes & any other semiconductor connected with it.
Main Power Amp faults are: any semiconductor device on the heatsink.

Jan 04, 2010 | Amplifiers & Preamps

1 Answer

Transformer is blown


Have you checked to see if the thermal fuse has failed on the transoformer. This can be repaired. Get back to me here if you want to know more about it.


Nov 17, 2008 | Amplifiers & Preamps

2 Answers

Technics SUV4X new class A Amp - 20 odd years old but lovely sound !!

Hi guys

Quick check... If the amp still stays in safety mode with the vol turned down and the speakers disconnected, it will have failed in some way. Since you have the safety operation light ON, you can expect that the power transformer is OK. I would expect that you have a DC offset condition on one channel. The most common problems you may have are
  1. dry solder joints about the power stages such as regulators, and output/driver transistors/IC's.
  2. blown output transistors/output IC with possible fusible resistor failures, and or sometimes burnt up printed circuit tracks.
  3. a voltage rail failure from a burnt fusible or power supply component.
If you are up with electronic fault finding, soldering and have the tools, have a go yourself, I could talk you through it. If not, I would suggest you contact you local HiFi specialist and find who can repair it or at least check to see what has failed for you. Good Luck. If you cannot find someone, hit me back and I will try to find someone for you. Cheers


Aug 16, 2008 | Amplifiers & Preamps

3 Answers

Yamaha P4500 service manual

one thing for sure Yamaha will not turn their back on their customers for support. What they normally say is that you contact your nearest service center for assistance. But you know you have a very good chance of getting a copy of the service manual since this is a very old model. i have the same amp being used in our church and yamaha service Japan has sent me by postal mail. technology nowadays is much different so maybe they can even send you in pdf format.

Write them by postal mail :
Yamaha Corporation
A/V PA Service Department
10-1, Nakazawa-cho, Hamamatsu, 430-8650 Japan.

simply tell them you need the manual and you are doing the servicing on your own. No one in your area can help you with it.

anyway, what is wrong with your P4500, it's a good amp but sensitive. very good design, hard to troubleshoot if you're not familiar with Yamaha amps. The main parts you can not replace buying from a local store though you may get the same part numbers specially power/driver transistors. it always comes in complementary pair critically matched by tthe factory. i tell you don't get the replacement anywere but Yamaha only. Yamaha have made to order power transistors tailor made for this Amp. you'll find the same transistor number outside but when you plug the unit, it wont last and worst it bursts !!! be carefull. Very hard to scan a copy of manual for you, but if you dont get a reply from Japan you can email me and we'll try to find a way to send you a soft copy.

Reden (
Yamaha service from Saudi Arabia 1996-2001

Jan 28, 2008 | Yamaha P4500 Power Amplifier 2-Channel

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