A collection of a few hardware PDF's.

Most of them are components used in the  JRC NRD-515  NRD-xxx series or in my own designs
Some easy found, some very hard to find, now all together over here!

Component code Information where used in the circuit

NEC version
Very old, very low power cmos-RAM, used in the NDH-518
Has only 256 - 4 bit locations!
Very hard to get for repair because due to it's 256 locations it has become rather useless.

2101   National


HM-6551   Harris
HM-6551   Intersil
HM-6561   Harris
NMC6551   National


MWS5101   Intersil
CDP1822   Intersil
NTE65101   NTE
TC5501   Toshiba
Functional look alikes of the CMOS RAM above

2101 is only suitable to test the circuit, it is NOT suitable for battery backup, it is NMOS and consumes so much energy your backup is empty within the hour.

The MCM5101, HM435101, S5101 (AMI), MWS5101, TC5501 and NTE65101 are identical. CMOS 4721B, MM74C920 and CDP1822 will probably work also. The HM-6501, HM-6551, HM-6561, NMC6551 although, are a fully equivalent low power RAM for battery backup

Save and keep them if you find them in scrap

PDF link

Diagram sketch of a replacement module for in an uPD5101 socket

Click on the small pictures to see a larger version how I made those modules.

Also take a look at the special
web-page about this module

In Dutch and English available!!
Memory upgrade MCM5101  uPD5101 Memory upgrade MCM5101  uPD5101
HB1 relay
NR-HD relay
HB1E-DC12V used all through the NRD-515
Not only used in the attenuator circuit, also in VFO-control (INT - EXT)

NR-HD-5V used in the NDH-518 memory unit.
MB3712  in Japanese

Very hard to find audio output amp in NRD-515
This is the pdf in Japanese scanned from a service booklet

I found an equivalent circuit ECG1423 and cleaned the PDF
TA7140P  in Japanese

Audio buffer and pre-amp in NRD-515
Scanned from the same Japanese booklet

And finaly I found the Toshiba datasheet, crippled, so I also cleaned it.

Old 256 step R-array D/A converter.
Used in my auto BC-tune circuit for the NRD-515
Unfortunately no longer available........, see next item
Analog Devices
Also an old 256 step R-array D/A converter.
Used in my second version auto BC-tune circuit for the NRD-515
This D/A converter is still available, both can be used!

Programmable bitmap array ( Bipolar TTL Prom ). Used to decode the input filter bank out of the display information.
If this device is blown you have "shot yourself in the foot"! You cannot buy it programmed, nor who will program it for you??
Solution, see next item.

Lattice datasheet

first set of files
to make the 22V10

second set of files
to make the 22V10

Manual sheet in PDF with information how to build the re-wire socket

A self-made solution for the uPB426 above
With a double pin re-wire socket in between a GAL 22V10 will work if the uPB426 gets blown.
Smaller GAL's like the 16V8 and 20V8 have not enough product terms per macrocel.
Keep in mind: This GAL device has to be programmed too!
Put the *.JED file in your GAL-programmer. Tested and works great!

The first (early) version had a lot of don't cares, so I tried to make a better version. It was not easy possible to fit it in a smaller GAL ( 20V8 ), so the result is a different approach with a second version for a 22V10
It still could be possible with a 20V8 with fixed wiring for D3 and using its macrocel as a node. And a different re-wire socket. But the repair is already finished. It worked OK with a 22V10.

Click on the small pictures to see a larger version how I made those re-wire sockets.
Pictures are made by NL10194
Cor van Soelen - now PG9HF
uPB426 JRC NRD-515 uPB426 JRC NRD-515
uA723  Philips
LM723  National
LM723  SGS-Thomson
MC1723C  Motorola
Some variations of the well known 723
Old, but very universal voltage regulator
Used as an extra regulator for each VFO.

NEW !! version

Original Motorola !!
This is NOT a standard CMOS circuit!
Very special phase frequency detector ( PLL ) originally made by Motorola
Used in the synth circuit of the NRD-515
Very hard to get for repair from the original manufacturer. That's why it is new on the market by a second source: Agere Systems!.
U310 FET
Siliconix - Calogic
Well known VHF FET used in the NRD-515 in balanced mixer configuration

U310 is the metal version, in plastic known as J310.

Well known IF chip used in the NRD-515 in the synth part



Some diodes used in the NRD-515 or their equivalents

1SS315 as a replacement for 1S2187
1SV149 as a replacement for 1SV100
at last the real 1SV100 PDF
BB212 is a duo-version used in some BC-TUNE upgrade's

Recently sent to me:
MI301, the input protection PIN diode (bad scan)
MI303, a version that is compatible.
I personally also used standard BC-band/SW switch (PIN) diodes like BA243. Use more of them (double in number) in series.
They are much less rugged, but will work as protection if you have nothing else.!

Some special circuits used in the NRD-525 and NRD-535 in the power supply


Some special OpAmps used in the NRD-525 and NRD-535

However...: M5218AL is compatibel with 4558 and M5237ML is compatibel with 358


Texas Instruments

Two mixer circuits used not only in the NRD-525 and NRD-535, the SN76514 is even used in the Yeasu FRG7!! Found at last!
A pdf under a new component name ( TL442C ) - but exactly the same circuit

Also a simple self made PDF for the SN16913P

A special prescaler used in many synth circuits

"Not found yet"

LR3671D - magnetic encoder interface chip NRD-535 and NRD-525
CX7925B - PLL chip NRD-535
SN16913P - Another mixer circuit
old FC-xx varicap datasheets
Old Toshiba databook to scan the old TA- and TC-xxxx stuff
The same could be said for old ROHM, SHARP LA-xxxx, FUJITSU MB-xxx stuff

Back to the NRD515 page

by Walter - PE1ABR - 2013-04-04