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Denon PMA-1500R

I am at last making good progress repairing a blown output channel thanks to the manual from this site. I have replaced about half of the transistors/FETs and some resistors in this stage/channel. The channel is now producing output but one transistors TR513 is getting hot. I found a fusible resistor R525 is open circuit. I would like to replace it with the correct type of 330 ohm fusible resistor if possible but can't find a supplier. The manual states "Part No. 241 2315 983 Part Name Fusible resistor 330 ohm 1/4W Remark RD14B2E331GFRST ". Where or from who can I get these resistors?

StevenG 42

Re: Denon PMA-1500R

Just fixed a PMA-1500R where the right channel had gone out.
It turns out that 3 transistors on each side (TR509 to 514) were not soldered properly.

I saw a guy on a Dutch forum ( http://marantzforum.nl/forum/index.php/topic,11718.0.html ) where a guy had EXACTLY the same problem so I suspect Denon had the wrong soldering procedure on these semiconductors.

Great amp.

Re: Denon PMA-1500R

Just replace it with a 330Ω 1/4W metal film.

Re: Denon PMA-1500R

Hi, The Zener fixed it quiescent (Idling) current now under control with the trim pot as per the manual. Note there is an error in the manual. The polarity of the quiescent current, Test point voltage is the wrong way round. If you connect you meter as shown you will get minus 10+/-1mV. The manual page 12 shows positive 0.008V (8mV). This voltage from across a 0.1 ohm resistor in series with the two output FETs, via two 10K Ohm resistors. It can't be the polarity as shown in the manual. Again thanks to this site and the member who made this manual available. I must also give thanks to another site that suggested using a (60W 230V) bulb in the mains supply for testing and then as it became more stable moved to a (100W 230V) bulb. I had access to a variac, but the repair could have been done without it. But the lamps are necessary when progressing beyond replacing visually damaged resistors and semiconductors that do not show the expected diode junctions. By the way mine was a PMA-1500R2, the difference was available for that as well, thanks all. I must look into what manuals I can scan and upload.

Re: Denon PMA-1500R

my dad had that same reel to reel conected to a keenie iii back when i was just a kid sound is awesome,very warm and clear hard to find systems of good quality today.