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Frequently Asked Questions - Pace PRD800/900 receivers

PRD800 clones:
Maspro SRE250S/1 (later)
Philips STU802/05M (later)
Ferguson SRD5 (no channel display)
Goodmans ST700 (no channel display) Granada M/N92MR1/A
Mitsubishi ST-PB10
Hitachi SR1050D (two card readers)
Thorn SAT99
Thorn Sat120

Pace PRD800 satellite receiver board assembly

Pace PRD900 satellite receiver

PRD900 clones:
Nokia SAT1600
Grundig STR1 IRD
Maspro 350S/1 (later)
Panasonic TU-SD200
Philips STU824
Finlandia Granada M/N 92LR 1/A

PSR receivers are similar but use a different printed circuit board and have no decoder parts.

Contents
1. Why did my power supply go bang?
2. How do I repair the power supply?
3. Why is the audio distorted on foreign stations?
4. Can I get extra channels?
5. Can I use an "Enhanced" LNB?
6. Can I upgrade to "Enhanced" menu software?
7. Can I upgrade my PRD800 to a twin input PRD900?
8. Are there any "secret" handset codes?
9. I get only a blue screen. What has happened?
10. Can I use a "Universal" LNB?
11. How can I tell how old my receiver is?
12. How can I download the memory?
13. Why do I get no decoder messages on screen?
14. Why do I get intermittent "Card Invalid" message?
15. Where do I get more information/get my PRD repaired?
16. Why doesn't my receiver work with pirate card/PC software?
17. Why won't my receiver go to a single-digit channel?
18. Why does the display show an upside-down "F"?
19. Can I control an external 22kHz tone inserter, ADX, LNB switch?
20. Can I fit a dual bandwidth tuner?
21. How do I repair the broken tags on my front panel moulding?
22. How do I turn the LNB voltage OFF in standby?
23. How can I disable the internal decoder to watch MTV2 and VH1 ?
24. Why do I get a good picture from TV Scart but not from RF ?
25. Tell me more about upgrade/repair kits prdkits.htm
26. How do I get the receiver to select channel X after power failure?

1. Why did my power supply go BANG?
In very early versions R8 was 0.75 Ohm and sometimes caused failure at plug-in. It was upgraded to 1 Ohm fusible.
In some early versions, the mains input socket was often under stress and would pull its pins out of the solder pads, causing arcing.
In later versions, the 105 degree capacitors C5, C7 and C8 were prone to failure when the receiver became too hot. C2 can also fail and cause damage.

2. How do I repair the power supply?
DO NOT REPLACE THE FUSE! It is there to protect YOU and the receiver. If you replace it you can make the damage worse and put yourself at risk!
If the fuse has NOT melted, try replacing C5 (22uF), C7, C8 (10uF) with 105 degree C rated electrolytics. Observe polarity and be extremely careful when soldering/desoldering. The copper tracks and pads are very fragile. Use fine "Multicore desolder wick®" - DO NOT use a pump-action desolder tool! Ensure normal safety precautions. These capacitors are included in "RELKIT 1" which can cure: "whistling noise", "hissing noise", "streaky pictures", "power supply goes tick, tick, tick but won't work", "humming or whining noise on audio", "TV screen goes blank intermittently", "Channel number display changes by itself", "channel number display flashes on and off"...

If the fuse HAS melted, you will need the complete kit of parts SATKIT 1 and probably RELKIT 1 also. I'm not going to list the parts here because some of them are very special and you CAN'T buy them - especially R1 which must be a non-spiral type 10 Ohm 2 Watt (ordinary ones just go "pop").
Remember, these are classed as "Safety Critical" components. You MUST use the Pace-approved parts. If you don't then you risk damage and fire hazard.

3. Why is the audio distorted on foreign stations?
The PRD receivers have narrow audio bandwidth for Astra channels. Only the later PRD-plus versions have wideband and J17 audio choices. The early one CAN be upgraded but it's a workshop job since over a dozen surface mount components must be added, as well as conventional components. A kit with instructions IS available, however, if you really want to do it yourself.

4. Can I get extra channels?
The PRD800 has 120 channels and can easily be upgraded to 199.
Just one I.C. and one resistor are needed.
The following functions are also activated:
1. Favourite channels
2. Colour choice selection
3. Radio blanking option

Low-cost kit with instructions is available.
Note: Does NOT work with 809-8661004 or earlier microcontroller!
Both PRD800 and PRD900 can be upgraded to 250 channels but this is a workshop job.

5. Can I use an "Enhanced" LNB?
Yes, usually. The early PRD receivers had a "75G" tuner but most of these will work up to 2GHz. If not, remove the "224" surface mount resistor next to the tuner solder lugs and replace it with a "684" (680k) resistor. The later receivers were fitted with a "77G" tuner which is designed to work up to 2GHz. These receivers have "2GHz" printed on the serial number label, underneath. Some receivers do not have this 2GHz label but they DO have a "77G" tuner. Make sure that the "684" resistor is fitted if it won't tune up.
You will need to tune EVERY channel frequency higher by 250 in order to receive the signals from an "Enhanced" LNB unless you have Enhanced software.

6. Can I upgrade to "Enhanced" menu software?
Yes. A kit is available and includes a new microcontroller with instructions. However, if you have a very early receiver with an Eprom board fitted upside down on plastic pillars, the Eprom can be changed for one with the "Enhanced" software. The "Enhanced" menu gives you a choice of LNB frequencies so you can choose "Standard", "Enhanced" or "Telecom". There are also other features such as different colour backgrounds. Enhanced Eprom is available.

7. Can I upgrade my PRD800 to a twin input PRD900?
Yes, it's possible, but most PRD800 receivers will need to have at least 30 surface mount components fitted, as well as conventional components (Q60, Q61 etc.) and an expensive two-input tuner. A few PRD800 receivers already had all the surface mount components fitted but the only way to find out is to look under the board; and you still need an expensive tuner.
Unless you have a dead PRD900 to rob parts from, it's not feasible.

8. Are there any "secret" handset codes?
Yes. The "factory reset" will set the first 32 channels to Astra 1A and 1B channels. Early micros will then repeat these channels up to the limit of 120 or 199. If you are happy to lose your customised settings, press:
Menu, P, Store, Right arrow, Left arrow.
You will see "-E2" in the display for a few seconds.
If the reset does not work, you probably have a faulty EEprom.
On the later PRD-Plus versions the "P" key has no function so press:
Menu, 0, Store, Right arrow, Left arrow.
BEWARE! on "PLUS" receivers with a microcontroller number ending with "027" this will reset your receiver to just 99 channels! You will then have to order a new, preprogrammed EEprom or a later microcontroller in order to correct it.

See also 26.

9. I get only a blue screen. What has happened?
The blue screen appears if there is no signal. Press "F" then "store" to turn the blue screen off. Now you can see if there is a weak picture.
The most obvious cause is that your LNB is not connected or, on a twin-input receiver, is connected to the wrong input.
Sometimes R543 near the tuner (1 Ohm) has burned out because you short-circuited the input. There are many more faults which will cause this symptom. Make sure LNB power is ON in the installation menu.
If you get power when input 2 is selected but not input 1 then Q61 (FXT749) may be o/c.
PLEASE use a meter to measure the voltages coming out of the power supply. Make sure that there is 12 volts out of "REG1" and 5.3 volts on pin 1 of "U2" microcontroller. Make sure that there is 13 volts (V) or 17 volts (H) reaching R543 next to the tuner module. No point in asking me for my opinion if you have not made these measurements. (Keep away from the high-voltage power supply!)

10. Can I use a "Universal" LNB?
A "Universal" LNB will work exactly the same as an "Enhanced" LNB unless your receiver incorporates 22kHz tone switching to access "High Band" frequencies. The 22kHz tone switches the LNB internal oscillator from 9.75 GHz to 10.6 GHz. PRD receivers do not incorporate this feature but it CAN be added. An internal tone board kit is available. But first consider why you want to use a Universal LNB. What do you expect to receive on High Band? Or do you want the tone switch in order to utilise an external switcher box?

11. How can I tell how old my receiver is?
The date of manufacture is incorporated in the serial number.
For example: RAAYAH3245xxxxx
The "3" indicates 1993
The "24" indicates week 24 counting from first week in January.
The "5" indicates Friday.

12. How can I download the memory?
You connect a fully wired Scart to Scart cable between the Decoder sockets of identical PRD receivers then follow the on-screen instructions from the Installation menu. You can not download successfully from dissimilar receivers and, to be certain, you should use this transfer facility only between receivers which have identical microcontroller I.C.s (U2).
If you are going to program a large number of receivers, try Kesh Electrics in County Fermanagh (013656 31449). They have designed a PC Windows program and interface to do this. It costs about 200 pounds. Unfortunately they have not designed a Macintosh version.

13. Why do I get no decoder messages on screen?
Try setting the contrast higher in the Installation menu.
If this doesn't work, and you have checked the tuning, you probably have a fault in the decoder section.

14. Why do I get intermittent "Card Invalid" message?
Make sure that the card contacts are clean and the card slot spring contacts are clean and not bent or twisted.
If the fault remains then you may have a faulty diode near the card slot but only if the fault persists with *every* SKY card you try.
If it's only with your card, get a new card.

15. Where do I get more information/get my PRD repaired?
Read the technical HELP FAQ.

16. Why doesn't my receiver work with pirate card/PC software?
I don't know. I don't get involved with cards or software so don't ask.

17. Why won't my receiver go to a single digit channel?
The incorrect "P" mode has been stored. If you want the receiver to require a double-digit channel number ("01", "02", "46" etc.) then press the "P" key until you see two dashes in the display and press [store]. If you want it to respond to single digits press "P" until you see just one dash in the display and press [store].
Note: "Plus" versions do not use the "P" button but rely on a delay instead.

18. Why does the display show an upside-down "F"?
Your receiver is set for a timed event. To cancel the event press [F] then [standby].

19. Can I control an external 22kHz tone inserter, ADX, LNB switch?

If you need to control, for example, an external 22kHz tone inserter box on a "per-channel" basis, this simple modification should do the trick.

Hidden in the PRD microcontroller chip, U2, is an option to control a dual-bandwidth tuner. The PRD receiver does not have a dual-bandwidth tuner so we can use this feature for our own purpose.

The modification is simple; you don't even need to remove the printed circuit board!

You will need:

A 1k 0.25W resistor
A 4k7 0.25W reesistor
A 100R 0.25W resistor
150mm length of insulated wire
Thin solder
Fine tip soldering iron

Refer to the sketch:

schematic

Tin the relevant legs of the ICs with solder.
Tin the wires of the resistors with solder.
Solder the 4k7 resistor from pin (1) of U2 to pin (2) of U4.
Solder the 1k resistor from pin (14) of U3 to pin (5) of U18.
Solder the 100R resistor to the 1k resistor which goes to U3.
Solder the wire to the free end of the 100R resistor.
Solder the other end to pin 14 of the Decoder Scart socket.
(On the top row, count four from the top sharpest corner of the socket).
Pin 14 has NO connection to the circuits underneath the board.
It is free to use. BUT make sure that you cut the wire to pin 14 if you use a decoder.

Now you will see a new feature in the tuning menu.
I.F. BANDWIDTH: NORMAL

If you change this to

I.F. BANDWIDTH: NARROW

the modification will put 12 volts on pin 14 of the Decoder socket.

You can use this to control an external box, such as:

ADX
22kHz tone inserter
LNB switching box

20. Can I fit a dual bandwidth tuner?
Yes you can. Carry out the modification in (19) but do not fit the 100R resistor.
Fit a dual bandwidth tuner. Simple!

PRD900-plus Modification to control external box

Here is an additional way to control an external box on a "per-channel" basis. It works ONLY with microcontrollers type 809-8661027 and type 809-8661029 in the 250 channel receiver.

Hidden in the PRD+ microcontroller chip, U2, is an option to control two card readers. Only the Hitachi receiver uses this option so we can use it for our own purpose.

The modification is simple; you don't even need to remove the printed circuit board!

List of Components.

A 1k 0.25W resistor
A 4k7 0.25W resistor
A 100R 0.25W resistor
150mm length of insulated wire
Thin solder
Fine tip soldering iron

Refer to the sketch:

schematic

Tin the relevant legs of the ICs with solder.
Tin the wires of the resistors with solder.
Solder the 4k7 resistor from pin (1) of U2 to pin (6) of U4.
Solder the 1k resistor from pin (10) of U3 to pin (5) of U18 or to link L57 (12v supply).
Solder the 100R resistor to the 1k resistor which goes to U3.
Solder the wire to the free end of the 100R resistor.
Solder the other end to pin 10 of the Decoder Scart socket.
(On the top row, count six from the top sharpest corner of the socket).
Pin 10 has NO connection to the circuits underneath the board.
It is free to use. BUT make sure that you cut the wire to pin 10 if you use a decoder.

Now you will see a new feature in the channel menu for each individual channel.
CARD READER: 2

If you change this to

CARD READER: 1

the modification will put 12 volts on pin 10 of the Decoder socket.

You can use this to control an external box, such as:

ADX
22kHz tone inserter
LNB switching box

21. How do I repair the broken tags on my front panel moulding?

Use a soldering iron to melt a paperclip into the remaining part of the tag, as shown in this picture. Simple!

Paperclip repair forfront panel lug

22. How do I turn the LNB voltage OFF in standby?

Most satellite receivers run too warm for their own good and my PRD900 was no exception. I had already fitted the reliability upgrade, RELKIT 1, which included a resistor to lower the supply voltages slightly, and mounted the receiver on an open shelf, but still it felt very hot to the touch.

Pace receivers continue to supply current to the LNB, even in standby. The original reason was to protect the LNB from sudden temperature changes. Amstrad receivers and a few other makes turn the LNB supply off in standby so I could see no reason why my PRD shouldn't. Since most modern LNBs require 200 - 250mA at 13 volts, the power saving would be significant. In addition, nobody would be able to send a signal to my smart card while the receiver was "off".

A simple modification to the PRD will cause the LNB voltage to be switched to zero in standby. The sketch shows the position of the components. All you need is a 1ká resistor, 1N4148 diode (or similar) and an FXT749 transistor. This PNP transistor is critical because its rating is 1 Amp with a very low voltage drop in a tiny "e-line" package.

Fitting is simple. You don't even need to remove the board from the chassis. Solder the transistor across existing diode, D17, with its collector (centre leg) to D17 cathode (indicated by the cross on the PCB and emitter to D17 anode ). Now cut out D17 and discard it. Solder the 1N4148 anode to the FXT749 base and solder the 1ká resistor to the 1N4148 cathode (bar end). Finally, solder a wire from the 1ká resistor to pin 15 of U3. This pin goes high in standby, turning off the FXT749.

LNB voltage turn off in standby

Secure the resistor, diode and wire with glue to ensure that they can't touch anything and cause a short circuit. Note that this modification works ONLY if a vertical channel is selected before pressing Standby.

With my receiver there was a significant reduction in heat from the power supply but, if you insist on keeping yours in a nice warm cabinet on top of a video recorder or, if - as with most modern houses - your room temperature is quite high, then you might also consider fitting the miniature cooling fan kit.

Components (Available as a kit for just £0.50p)
FXT749 transistor
1ká resistor
1N4148 diode
Insulated wire

23. How can I disable the internal decoder to watch MTV2 and VH1 ?

Connect one side of a switch to the central test pin labelled "TST2".
Connect the other side of the switch to a 1k resistor.
Connect the free end of the resistor to Pin 1 of U2 microcontroller (5 volt supply).

Thanks to David david29@ndirect.co.uk for helping me with this.

Note: For models that use the PTV111 chip you can use a switch to disconnect one wire of the 1uF capacitor next to the PTV111. This should work OK in Pace MSS, later Nokia models etc.

24. Why do I get a good picture from TV Scart but not from RF ?

Later models with board revision number ending in "4" have an extra surface mount resistor which makes a transistor fail. Remove the PCB and look at its underside. Each component is labelled. Look at the exact centre of the underside. You see a little oval hole? Near to this is resistor R559 marked "331". Remove R559 and throw it away. Remove transistor Q105 and fit a new one. BC846B or BC847C is OK. (NPN type SOT23).

25. Tell me more about upgrade/repair kits prdkits.htm

26. How do I get the receiver to select channel X after power failure?

Press F then Recall then P then the channel number then Store.
Repeat this sequence to turn the feature OFF.

 

A complete fault-finding guide called "The Satellite Repair Manual IV" is available, price £16.95.


DISCLAIMER
This information is given in good faith, based on several years of workshop experience involving thousands of repairs. No responsibility will be accepted for any death, damage or injury caused either directly or indirectly by the use of this information. The reader should check the facts himself. It is assumed and stressed that the reader will be familiar with good, safe, electronic workshop practice and will be familiar with all tools, components and terms used. If there is any doubt about the reader's ability to carry out such work competently and safely, the work should be referred to a specialist engineer.

THIS FAQ IS NOT APPROVED BY SKY OR BY PACE
End of FAQ



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Version 2.1 updated on February 11, 2000
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