Hi there,
I am not sure if I am at the right place as the radiogram I am trying to repair may not be considered vintage!

I am trying to find the schematics for a Pye Radiogram with the model number TS7.

By way of description, it is an early transistor based radiogram with a record player on the left and an AM radio on the right in a floor standing cabinet about 5 feet long. I am guessing it was built on the 60's or 70's, but to be honest I have idea when.

There are a number of faults at this stage with the main one been a dead left channel as well as a blown tweeter (Manganvox 3TC MKII). Conmetically some of the veneer is chipped and missing.

Any advice in where to find technical information and/or parts for the unit would be much appreciated.

Reagrds,
Mike G

Sydney, NSW

In a lot of the early transistor stuff interstage coupling was by electrolytic caps, that "dried out" that will cause a severe or total loss of volume. PNP transistors failed short, NPN Open. Some had axial caps about 3/8" by 1/2" which cracked their jacket often shorted.

In a stereo never tamper with the working amp, if one is dead. That working one, even if its badly, is the reference for fixing the other. Making sure first, that its getting voltage & any switching is not corroded up.

My usual, after rudimentary checks is to feed signal into the dead amp and use an Oscilloscope (signal tracer) to see where it is getting lost.

You really need to do an assessment of it, as the components on the boards are likely an off the shelf item, from most purveyors of parts.

Hi Marcc,
Thanks for the reply!

At this stage all I have done is used some contact cleaner on the pots to reduce some of the crackle when turning the balance and volume knobs.

The push button power switch had also failed in terms of latching on and off and now performs as momentary switch. In the short term I have wired in a temporary switch as I cant find any sort of replacement at the major suppliers (Mouser, Element 14, etc). I'm thinking unless I can find a repacement, I'll keep the original 'momentary' switch in place and use a latching circuit to switch a relay to keep it as original as I can on the outside. I have made up a PCB using a 555 and relay to solve that...

Next I need to do a block/wiring diagram of what connects to what and take a lot of photos for reference.

Re the amplifier, thank you for your advice re the caps, I do have an ESR meter here so will need to go through them. The PCBs are very crowded with through hole components, so access is a challenge as is identifying the transistors given the older styles...

A work in progress...

Thanks again,
Mike

Most of them are not testable in circuit and PC board, especially the older stuff does not like excessive heat. Solder wick is often the best method of freeing them. I would not touch anything in either amp until you have established what, or where the fault is. The risk is of adding another.

Have a look here, you might see a resemblance to your model in the TS23, 24 or 25.

https://www.kevinchant.com/pye3.html

Pye tended to use the same design with minor changes in many models, so yours may be near enough.

The blob-top Fairchild transistors were fairly reliable, but if necessary most of them can be replaced with a BC547 for NPN or a BC557 for PNP.

For higher current parts in output stages the TO-92 BC639 for NPN and BC640 for PNP are good replacements. Note that on these 2 parts the middle pin is collector.

Common faults?
Noisy resistors - crackles and hiss.
Open circuit lime green Shizuki caps
An O/C output transistor. To determine which one, measure the voltage on the two emitters to ground with no signal. Apply signal and the voltage will move up if the bottom transistor is bad and vice versa.

It's pretty easy to fix the mechanical latch on those MSP switches. Generally all they need is removal of the grease-turned-to-glue around the mech.